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Mammals are among the animals in the world
Morphological structure
The highest, physiological
function
The most perfect animal. The most striking feature of mammals compared to other animals is that
viviparism
And their young are fed by the mother's milk. Mammals have more developed brains, so they can produce more complex behavior than other animals, and can constantly change their behavior to adapt to changes in the external environment.
There are more than 4,000 living mammals in the world, and although they are highly evolved, they still have a lot in common: almost all mammals are
Warm-blooded animal
The body temperature is basically constant, and the body is covered with hair to protect the body, isolate hot and cold, and so on.
- Chinese name
- mammal
- alias
- mammalia , beasts , theria
- Foreign name
- Mammal
- world
- animalia Animalia
- The door
- Phyla Chordata
- The outline
- mammalia
- subphyla
- Vertebrata
- subclass
- Protheria, Metatheria, Eutheria
- Lower door
- Gnathostomata gnathostomata
- superclass
- Tetrapoda
The nests of mammals are inferior
Birds
Exquisite, but varied in variety and location.
Mole
The underground caves are often up to 1 meter deep and more than 100 meters long; Most squirrels build their nests in tree holes, but
Grey squirrel
They build their nests on top of trees
twig
A surname; female
Polar bear
To dig holes for nests in the snow; some
Marine animal
Such as
seal
,
seal
They generally do not inhabit the water, but nest on the shore.
Prey on
Many mammals go out to hunt each morning at dusk. As temperatures rise during the day,
reptilia
,
insect
Other cold-blooded animals are mobile and difficult to catch, and mammals have different methods of hunting. Cheetahs often strike at high speeds to catch prey;
Giraffe
Roll it up with a clever tongue
leaf
, twigs, and then pull off the leaves with their canine teeth;
chipmunk
Use your claws to swirl the food around in order to scrape off loose parts of the food and find the parts that are easy to bite.
propagate
viviparism
In mammals, fertilization takes place inside the mother.
zygote
After many divisions, it eventually becomes a fetus. In placental mammals, the fertilized egg passes through the uterus
Umbilical cord
And the placenta, which is attached to the uterine wall. By supplying blood to the placenta, the mother provides the fertilized egg with food and oxygen, and carries the waste away. The baby grows in the womb until it is born.
lactation
For a period of time after the young are born, the female mammal will use
autosecretion
The milk is fed to the young, and the milk is produced by
Mammary gland
Secrete. When the young suckle, milk flows out of the mammary gland. For young, nursing is important because milk is not only rich
glucose
And fat, can accelerate the growth of the young, and contain antibiotics, can help the young fight disease.
The growth of the young
Compared with other animals, mammals spend much more time and energy on their young. Normally, mammals give birth in small quantities at a time, and the young need a lot of care to grow smoothly. Most female mammals not only feed and keep their young clean during breastfeeding, but also guard them and teach them how to survive until they can live on their own.
Macrocephalus wui
A direct ancestor of mammals
paleontologist
It is believed that the cynodonts living in the Triassic period are the direct ancestors of mammals.
Cynodonts
They are small to medium sized
carnivory
Monotreme animals, few of which can exceed 90 cm in length. They have a lot in common with mammals, such as they have several different types
tooth
The limbs are under the body, can run fast and so on.
Mammals come from therodonts
reptile
But we're not sure which one
Theriodonts
. Because in therodonts, the progressive nature and the primitive nature intersect and are very complicated. As in earlier days
therocephalians
Many of its features are primitive, but
Temporal foramen
But increased, and has appeared 2-3-3-3-3-3 mammalian toe. Tristiodon had so many advanced properties that it would almost rank it among mammals, yet it remained
reptile
above
Lower jaw
Connection mode, that is
Articular bone
The connection of one bone. As a result, various hypotheses have been made about the ancestors of mammals, such as canine teeth
beasts
, Baueria,
ictidosauria
Tristidonts. The more consistent view is that mammals are polygenic, that is, that the vast majority of mammals (among them
placentata
Predominately) originated from canines, but in a wide variety of species
Mesozoic mammals
There are also some originating from other therodonts.
Since the
Late Jurassic
From then on, mammals began to mount nature
Historical stage
. The earliest mammal fossils were found in China
Macrocephalus wui
(
Hadrocodium wui
It lived 200 million years ago
Jurassic Period
.
Conghua
One of the most important differences between mammals (especially early mammals) and reptiles is their teeth. Every single one of the reptiles
tooth
They're all the same, they're indistinguishable from each other, and the teeth of mammals are divided into different forms according to where they are on the jaw,
zoologist
Different species of animals can be identified by the arrangement of various tooth types (dentition). Also reptilian
tooth
The teeth of mammals are not renewed except for baby teeth. in
animalia
Only mammals have three bones in their ears. They are made of reptile pieces
jawbone
Evolved. Up to the Third Age all mammals were small. in
Extinction of dinosaurs
After mammals occupy many
Ecological niche
. By the Quaternary mammals had become dominant on land
Dominant position
Of the animals.
[1]
Mammals have many unique characteristics that greatly improve the performance of their offspring
Survival rate
And enhanced the right
Natural environment
the
adaptability
,
The most important features are:
Further development of intellectual and sensory abilities;
Keep a constant temperature
; The increase of reproductive efficiency;
Get food
And enhanced ability to process food; The body surface has hair, viviparous, generally divided into head, neck, trunk, limbs and tail five parts; To breathe with the lungs;
homeostasis
, yes
endothermy
; The brain is large and developed. Nursing and nursing
viviparism
It's the most distinctive feature of mammals. The embryo develops in the mother, and the mother directly produces the fetus. maternal
Mammary gland
Can secrete milk to feed the fetus. It all involves structural changes in various parts of the body, including
Brain volume
Increment sum of
neocerebrum
The appearance of sight and smell is highly developed, hearing more than others
vertebrate
Have greater specialization;
tooth
and
digestive system
The specialization is conducive to the effective utilization of food; The specialization of the limbs enhances mobility. To help obtain food and escape from enemies; Breath,
Circulatory system
The perfect and unique hair covering of the body surface helps to maintain its constant body temperature, thus ensuring that they are in broad
Environmental condition
To survive.
viviparism
Its unique characteristics, such as lactation, ensure that its offspring have a higher survival rate and some kinds of complexity
Social behavior
The development of...
Another characteristic of mammals is that they have
Mammary gland
(both male and female), of which the mammary glands are highly developed. In distinguishing between male and female mammals, we can rely on
Sweat gland
, hair,
tympanum
Auditory ossicle
And the brain
neocortex
On the difference to distinguish. difiver
Monotremata
With the exception of all mammals, all mammals produce their offspring directly. Most mammals have specialized adaptations for it
Living condition
Made of teeth. Mammals use the brain to regulate internal temperature and temperature
Circulatory system
(Including the heart).
Skin and hair are mammalian
Protective layer
They can keep out wind and rain and keep out heat and cold. Therefore, no matter how cold the weather, mammals can rely on them to maintain a constant body temperature to adapt to a variety of complex
Climatic environment
.
Mammals have larger brains than other vertebrates and are better able to control their thoughts
primate
E.g.
monkey
, orangutans) is more obvious. Because of their large brains, mammals have more complex behaviors than other animals. They learn and can constantly change their behavior to adapt to changes in their environment.
Mammals tend to harbor dirt in their hair, and it's easy to become
parasite
the
hotbed
. So mammals developed the habit of keeping clean to prevent the spread of disease. They keep clean in a variety of ways, such as licking, scratching, shaking, rolling, bathing, rubbing, nibbling, etc.
Bone structure
Every mammal has a pair
Condylus occipitalis
The skull and the first cervical vertebra form joints that allow for more freedom of movement. The secondary oral bone hard jaw, so that the nasal cavity and the mouth isolation, breathing air, gas will not enter the mouth, so that mammals can chew food at the same time to breathe air. In addition, the ribs of the neck of mammals heal on the cervical spine and become an integral part of the cervical spine.
Ear
Most mammals have external ears that allow sound to flow directly into the brain, such as a cat's funnel
auricula
It can direct sound waves into the inner ear, so that the cat can quickly pick up the sound and judge
Sound source
The direction of... consequently
canidae
Many mammals, represented by animals, are able to turn their ears back to the direction of the sound in order to better capture the sound.
nose
The mucous membrane at the back of the nose of many mammals
Much larger than
human
Nasal mucosa
Therefore, the sense of smell is more developed than humans. Sometimes a mouse caught by a man will spill out
urinate
Use smell to warn companions to escape quickly;
African lion
Can be used
Olfactory trace
Marking the territory of its population; Pigs are trained to sniff out those that grow underground
truffle
.
tongue
The tongue of mammals is well developed and can move flexibly in the mouth. For example, deer, cattle and so on
herbivore
The tongue can easily pull grass into the mouth; Tiger,
Lion
Etc.
carnivore
You can lick water into your mouth with your tongue; Dogs in the hot summer or after strenuous running, often stretch out a long tongue, using the tongue to dissipate the heat in the body.
The teeth of mammals are incisors, canines,
Premolar teeth
Different from the molars, the morphology and function are different. In addition, mammalian tooth morphology is further specialized due to differences in feeding habits, for example
carnivore
The canine teeth are well developed, and the premolar and molar teeth are sharp, which are good for tearing and cutting food; Herbivores have developed incisors and molars to tear and grind thinner, softer plants.
tail
The tail of a mammal is an extension of its spine. The size, shape, and function of the tail of different species of mammals vary. Horsetail is thick and long, can drive mosquitoes and insects; The tail of the fox is covered with thick hair, which has a good thermal insulation effect;
beaver
Their tails are from when they swim
rudder
. Sometimes, some mammals use their tails for defense.
Mammals belong to
animalia
,
Chordate phylum
,
Vertebrate subphyla
,
mammalia
. The industry estimates that there are 5,400 species of mammals, divided into about 1,200 genera, 153 families, and 29 orders. Mammals are divided into two groups
subclass
: Promammalian class (contains
ovipary
the
Monotremata
Animals),
theria
(Contains placental mammals and
ovoviviparity
the
marsupial
Animals). Most mammals (including the 6 largest orders) belong to the group of placental mammals. Three of the biggest items are
rodentia
,
Chiroptera
and
Soriciformes
. Rodents include rats, chiroptera include bats, and Shreiculata include
shrew
,
Mole
and
Solenodon
. The other three biggest items are
Carnivora
(Dog, cat, weasel, bear,
seal
Etc.), artiodactylus (
ungulate
,
Whale
),
primates
(Including humans). Mammals are divided into three main groups according to the way they reproduce
subclass
: Monotremes, marsupials, placental mammals.
Mammals are diverse and widely distributed, mainly according to their appearance, skull, teeth,
appendage
And reproductive methods, etc., traditionally divided into three
subclass
:
Prototheria
(including 1~3 below),
Metatheria
(including 4~9 below),
Eutheria
(including the following 10-28), there are about 4,000 species of 28 orders in existence.
mammal
Refer to
Vertebrate subphyla
Under the
mammalia
(
Latin
:
Mammalia
) in the same category
Pulmonary respiration
Warm blood of the air
vertebrate
Because it can pass
Mammary gland
It gets its name from producing milk to feed the young.
According to the book Mammal Species of the World in 2005,
mammalia
There are about 5,676 (2008 edition of IUCN
Red book
There are 5488) distinct species, distributed in 1229 genera, 153 families, and 29 orders, accounting for approximately
Chordate phylum
10% of all species on Earth. 0.4%.
rodentia
(Rat,
porcupine
,
beaver
,
capybara
Etc.),
Chiroptera
(bats, etc.) and
Soriciformes
(
shrew
It is the most diverse order of mammals.
The body structure of mammals is complex, which is different from other groups
brain
Structure, constant temperature system and
Circulatory system
Have breastfed for offspring, most belong to
viviparism
, has hair follicles and
Sweat gland
And other common external characteristics. They are diverse in appearance, ranging in size from 30 mm long to winged
Hollow-faced bat
It is as large as 33 meters long
fish
the
Blue whale
. They have a good environment
adaptability
It is found in a wide range of regions, from oceans to mountains, from the tropics to the poles. Man is also a member of mammals.
Summary of mammal taxa:
1.
Monotremata
4.
dasyurida
5.
phalangeria
Seven.
marsupiata
9.
kangaroo
10.
edentata
11.
Insectivora
12.
Tree shreicida
13.
Dermatoptera
14.
Chiroptera
Fifteen.
primates
16.
Carnivora
17.
cetacea
18.
Sirenia
19.
Proboscidea
20.
Perissodactyla
Twenty-one.
hyracoida
Twenty-two.
Tubulodonta
Twenty-three.
artiodactyla
24.
Squamopsida
Twenty-five.
rodentia
Twenty-six.
lagomorpha
28.
Pinnipedia
Humans (
Highest grade
Mammals), lion, tiger, gray Wolf, red fox, white rhinoceros, hippopotamus, giraffe, common zebra, fine striped zebra, Mountain zebra, Muntjac, donkey mule, horse mule, Liger, Tigerlion, Pygmy hippo, okapi, mouse, small Sorex, Moose, 鼷 deer, Elk, Sika deer, sable, monkey, camel, Malayan Tapir, Central American Tapir, Lowland Tapir, Mountain Tapir,
sloth
, Greyhound, English Bulldog, Border Collie, French Bulldog, Pekin, Pomeranian, Shih Tzu, Teddy, Irish Wolfhound, Samoyed, Alaskan Malamuge, Chihuahua, Husky, Schnauzer, Shiba Inu, Corgi, Bichon Frise, Doberman, Yorkshire Terrier, Bullterrier, Maltese, Pug, Papillon, Beagle, West Highland White Terrier, Chinese Crested, Habanese, Jack Russell Terrier, Scottish Terrier, Afghan Hound, Bristle Fox Terrier, Great Dane, Pit Bull, Cormondor, Bloodhound, Basset, Boxer, Rottweiler, German Shepherd, Akita, Dachshund, Dalmhound, Coccapo, Labrador, Shetland Shepherd, Belgian Shepherd, Scotch Shepherd, Golden Retriever Dogs, Labradors, horse dogs, Tibetan Mastiff, Persian cat, Burmese cat, Siamese cat, Singapore cat, Somali cat, British shorthair Cat, Ragdoll cat, Kingilla cat, Isle of Man cat, Maine Cat, Coyote, Wolverine, pig badger, dog badger, honey badger, American badger, Beluga whale, Yangtze River finless porpoise, white flag dolphin, Porpoise, Tiger weasel, Sichuan Golden Monkey, Yunnan Golden Monkey, Guizhou Golden Monkey, Asian wild dog, deer dolphin, argali, sheep, goat, iguana Dogs, cheetahs, black-backed jackals, brown bears, Sun bears, Sloth bears, spectacled bears, Asian Black Bears, American black bears, Porcupine, Dingoes, Asian elephants, African elephants, Mammoths, American Mastodons, Stegodon, Bulltooth, Dinodon, Dipterodon, Protozoa, Eintatheria, Bucky whales, Mesopotamia Andrei, Diprotodon, Giant short-faced Kangaroo, Glyptodon, Startail, Leopard, Musk ox, small
panda
, Warthogs, meerkats, Impala, Thomson's gazelle, Springbok, Longhorn, Longnecked, pronghorn, Great Tetra, Great Horned, Spinhorned, Tibetan antelope, Purple antelope, Horned Oryx, Sable antelope, Dog antelope, Donkey antelope, civet, Red and White flying Squirrel, Ferret Badger, hooded deer, African Wild dog,
Reindeer
, koala,
lynx
,
pangolin
Giant panda, big
anteater
Small anteater, red hair
orangutan
Gorillas, chimpanzees, gibbons,
manatee
, dugong,
otter
, sea otter, small
Civet cat
, Civet cat, tree bearmonkey, tarsier, Primorda, Golden jackal, Oryx, Wombat, tree kangaroo, Plateau Pika, Atlantic Black and white Dolphin, woolly mouse, Dormouse, Jerboa, hopping rabbit, Bowhead whale, Gray whale, Indian rhinoceros, Sumatran rhinoceros, Javan rhinoceros, black rhinoceros, fenna fox, prairie fox, big eared fox, Gray fox, Elephant Seal, fur dog, Sea lion, bee monkey, broad-nosed
Dolphin
,
walrus
,
platypus
, Echidna, Star nosed Mole, Ring-tailed lemur, collared lemur, white-headed lemur, White collar lemur, grey-headed lemur, red-collared lemur, crested lemur, blue-eyed Black lemur, Brown Lemur, black lemur, Mongoose lemur, red-bellied lemur, red-fronted lemur, Sang's Lemur, Golden Bamboo Lemur, Gray Lemur, Sang River Lemur, Platynosed lemur, Great Bamboo Lemur, Red collar lemur, Blue horse antelope, running rhinoceros, canine bear, ancient giant pig, fear jaw pig, fear Wolf, cave lion, horse island mongoose,
Hedgehog
,
Arctic fox
, polar bears,
kangaroo
, Poserk, bandiculby, Quoll, Thylacine, Thylacion, Primitive Horse, Horned Gophers, ground sloth, Bladedon, Sacrodonta, Arrowdon, Rathratherium, Egyptian heavy foot, Platydon, Woolly rhinoceros, Primatorhynchus, Sarcophagus, Caribbean leopard Seal, giant rhinoceros, Thai pig-nosed bat, marmosets, horse deer, grassland peccaries, white-lipped peccaries, ringnecked peccaries,
armadillo
, Greenland Seal, tip whale, Humpback whale, Blue Whale, Sperm whale, killer whale, pseudo-killer whale, fin whale, Bryde's Whale, Rorqual, Minke whale, Weasel, yellow throated marten, stone marten, horse, cow, donkey, pig, sand fox, giant squirrel, ground squirrel, rabbit, squirrel, guinea pig, hamster, Rock sheep, alpaca, vicuna, wildebeest, Takin, beaver, Tasmanian devil, raccoon, Mandrill, baboon, The roe deer, deer deer, Lemmings, gerbils, marmots, clouded leopard, black-footed cat, ocelot, African buffalo, Red River Pig, yellow mouse, Mongolian wild donkey, African wild donkey, Tibetan wild donkey, wild boar, Indian bison, American bison, Przewalski's Mustang, European wild horse, mountain lion, jaguar, yak, coatis, skunk, Binturong, red deer, Caracal cat, Serval, Snow leopard, maned Wolf, rabbit, black-footed weasel, striped Civet cat, fox weasel, Capybara, aardvark, flying fox, vampire bat.
Among them the platypus,
echidna
(also known as
Echidna brevirostris
), proto-mole (or
Echidna longirostris
) are special mammals, they are not viviparous, but
ovipary
However, it is still classified as a mammal, belonging to the egg-laying mammals. They all live in
Australia
.
July 2022, United States
University of Illinois
Urbana
- Kevin Johnson, a biologist at the University of Champaign
coauthor
"For mammalian"
louse
Tree "carried on
genome
The study found that lice that colonize today's mammals can be traced back to the same ancestor that colonized mammals before the extinction of non-avian dinosaurs. The findings were published July 4 in Nature Ecology and Evolution.
[2]
December 2022, Japan
Nagoya University
The team's study points out that the brain
Preoptic area
EP3
neuron
It plays a key role in regulating the body temperature of mammals.
[3]
In April 2024, the research team of Peking University found through research that the neuron cluster called "suprachiasmatic nucleus" (SCN) in the deep brain region of the mammalian brain can calculate time through the "collective decision" of many neurons, and the time decoding accuracy can reach 99%. This result is published online in the international authoritative journal Cell Research.
[4]
The skin of mammals is dense, has a perfect structure, has an important protective effect, and has good resistance
Water permeability
, control body temperature and sensitivity
Sensory function
. In order to adapt to changing external conditions, its skin texture, color, smell, temperature and so on can change
Environmental condition
Be in harmony.
The main features of mammalian skin are:
Perfect structure
mammal
Derivative diversity
1.
Glandulae cutanea
: Very developed, from the epidermal germinal layer, according to the structure and function of the different, can be divided into
Mammary gland
,
Sweat gland
,
Glandulae cutanea
,
Scent gland
(
Musk gland
), etc.
Mammary gland
for
mammalia
It is characteristic of a gland that can secrete it in abundance
nutrient
The milk to feed the young. The mammary gland is a complex gland consisting of tubular and vesicular glands, usually opening with a protrusion
nipple
Up. Nipples are divided into real nipples and
False nipple
In both types, the true nipple has one or more ducts opening directly outwards; pseudopapillary
Mammary duct
It opens in the base cavity of the nipple, and then opens outwardly through the nipple by the general duct. The number of nipples varies with species, from 2 to 19, and is often related to litter size. Lower mammal
monotreme
Without a nipple, the milk secreted by the mammary gland flows out along the hair, and the young directly lick it. Mammals without lips, such as whales, have muscles in the mammary glands that automatically press milk into the mouth of the young whale.
The other skin gland is
Sweat gland
Is a tubular gland, its main function is to steam heat and eliminate part of the metabolic waste. Water on the surface of the body
Evaporative heat dissipation
That is, sweating is an important way for mammals to regulate body temperature, and some species with underdeveloped sweat glands mainly rely on evaporation from the surface of the mouth, tongue and nose to dissipate heat.
Sebaceous gland
It is a vesicular gland that opens at the base of the hair follicle and is
Whole plasma secretory gland
Its secretions contain oil, have the role of lubricating hair and skin, and are also an important source of pheromones. Odor glands are derivatives of sweat glands or sebaceous glands, the main function is to mark the field, transmit information, and some also have the role of self-defense protection. There are dozens of odor glands, such as musk glands,
Anal gland
,
Ventral gland
, lateral glands,
Dorsal gland
,
Preputial gland
Let's wait. The appearance and degree of development of odor glands are usually related to the fact that the main hunting mode of mammals is smell, and the main hunting mode is vision
localizer
The olfactory and odor glands were significantly degraded.
2. Hair: a structure unique to mammals, for
Epidermal keratosis
The product of... Mayu
Hair shaft
and
Hair root
Make up. The hair shaft is composed of a cortical part and
Medullary substance
Part composition; Hair is rooted inside and outside the follicle
Coat hair
Sheath, bulbous at the end
hairball
Its base is composed of dermis
Hair papilla
There are rich blood vessels, which can transport nutrients necessary for hair growth. There are sebaceous gland openings in the hair follicle, which can secrete oil and lubricate hair and skin; And the base of the follicle
Arrector pili muscle
Attached, retracted to make the hair stand upright, helps
thermoregulation
. setal
Morphological structure
The wool can be divided into long and tough and has a certain hair direction
acicle
(
seta
), soft, hairless hairs, and specialized from acicular hairs
cirrus
. The coat in vitro of mammals often forms a coat, and its main function is heat insulation and heat preservation. Largely hairless species of aquatic mammals such as whales have developed
Subcutaneous fat
To keep your body temperature constant. The hair is often worn and faded, usually one or two times a year, the general summer hair is short and thin, the absolute heat is poor, the winter hair is long and dense, and the thermal insulation performance is good. The fur color of land mammals is different from that of
Living environment
The fur of mammals is usually dark in forests or dense understory vegetation, gray in open areas, and sandy yellow in desert areas.
3. Horn: It is the product of the specialization of the epidermis and dermis of the head of mammals. The epidermis produces horny horns, such as the horny sheathes of cattle and sheep and the epidermal horns of rhinoceros, and the dermis forms bony horns, such as deer antlers. Mammalian horns can be divided into
Cavity Angle
,
Solid Angle
,
Forked horn antelope horn
There are five types, such as giraffe horn and epidermal horn.
Cavity Angle
It is composed of a bone core and a horn sheath, which is commonly called a horn, and is born in pairs
Frontal bone
On, life is not replaced, there is a growing trend. Cavity Angle is
bovid
Unique.
platypus
4. Claws, nails and hooves: all are derivatives of the skin, which refers to the deformation of the cuticle of the (toe) end, but the shape and function are different. Claws are possessed by most mammals, and those engaged in digging activities are particularly well developed.
carnivore
The claws are perfectly sharp, such as
feline
The claws are sharp and retractable, making them effective prey weapons. Nail, essentially a flat claw, yes
primate
Unique. Hooves, for thickened claws,
ungulata
Especially developed, and can continue to grow to compensate for wear parts.
Giraffe
Axial skeleton
1. Skull: Due to the development of mammalian brain, senses and oral chewing, it is cranial
Phase of bone
Let's be big.
Cranial cavity
by
Frontal bone
,
Parietal bone
, occipital bone,
Sphenoid bone
,
Ethmoid bone
,
squamosal
,
Tympanic bone
Among them, occipital bone, sphenoid bone, ethmoid bone, etc. are all healed by most of the bone fragments. The reduction and healing of bone fragments make the skull hard and light, which is an obvious feature of mammals. The brain is located inside the cranial cavity behind the skull
Foramen magnum
It's connected to the spinal cord. There are one occipital malleolus on each side of the foramen magnum and related segments of the first cervical vertebra. The orbital, nasal and oral cavities of mammals are mainly composed of
Lacrimal bone
, visual bone, nasal bone,
Turbinate bone
,
Upper jaw bone
,
premaxilla
, palate bone,
Pterygoid bone
,
vomerine
,
mandible
,
Hyoid bone
Equal composition. The lower jaw consists of a pair of mandibles (teeth), a characteristic feature of the mammalian skull. The posterior end of the mandible is jointed with the squamosal bone.
2. Spine: consists of a series
vertebra
Composed of cervical vertebrae (
cervical
),
Thoracic vertebra
(thercic), lumbar spine (THERCIC)
lumbar
), sacrum and Sacrum
Coccygeal vertebra
(
caudal
Five parts. Cervical vertebrae usually have 7, with only a few species having 6 (e.g
manatee
) or 8 to 10 pieces (e.g
Three-toed sloth
Most mammals, regardless of the length of the neck (such as giraffes and
Hedgehog
All seven cervical vertebrae. The first cervical vertebra
atlas
, the second cervical vertebra
axis
The atlas is annular and forms a pair at the front
Facies articularis
Associated with the occipital malleolar segment, the anterior end of the axial vertebra is formed
Odontoid process
Radiate into the atlas
Vertebral foramen
To give the head the flexibility to turn. The thoracic vertebrae are usually about 13, each thoracic vertebrae is connected with the ribs, and with
Ribs and sternum
co-constitute
thorax
; Divided sternum, flying bats and camp-burrowing creatures
Mole
Such mammals, have with
Birds
similar
keel
A protrusion. The lumbar vertebrae were 4 to 7.
sacrum
3 ~ 5 pieces, and fused into one, and related to the belt segment; Without hind limbs
cetacea
Sacral bone is not obvious. The number of coccygeal vertebrae varies greatly with the length of the tail, ranging from 3 to 150.
Appendicular skeleton
1. Shoulder strap: By
scapula
,
coracoid
,
clavicle
Constitute. In land mammals, the scapula of the shoulder strap is well developed, and the pecker bone is reduced to a protrusion on the scapula. The clavicle tends to degenerate, and some have no clavicle, such as
perissodactyla
and
artiodactyla
. The clavicle is developed in the species suitable for climbing, digging and flying. It can be seen that the degree of clavicle development is closely related to the mode of forelimb movement. The clavicle of the species with forelimb movement is degraded, while the species with forelimb movement is developed.
2. Belt: composed of skeleton,
ischium
and
Ossa pubis
Constitute. Iliac bone and sacral bone related segment, left and right ischium and pubic bone
Ventral median line
Coalesce into a medullary bone, forming a closed pelvis. The mammalian girdle heals, strengthening the support of the hind limb
fastness
.
3. Anterior limb bones and posterior limb bones: their structure is general
Terrestrial vertebrates
The pattern is similar, but the front and back feet (metatarsal), finger (toe) bones, with different lifestyles have large changes, such as bats specialized in winglimbs, whales are
flipper
Odd ungulates and even-toed ungulates are agile limbs. In addition to
cetacea
,
Sirenia
,
Chiroptera
Sum part
marsupiata
In addition, most species of mammals have the anterior inferior femur
Knee cap
,
Knee joint
Turning forward improves the ability to support and move, which distinguishes mammals from others
Mainland Chinese students
Characteristics of vertebrates. Foot types can be divided into different ways of walking on all fours in land mammals
plantigrade
,
Digital row
And hoof-walking. Among them, hoof walking and ground contact is the least, is adapted to fast running foot type.
mammal
Musculi cutaneus
Very well developed. Mammalian cutaneous muscles can be divided into two groups: one group is
Pannicularis muscle
It can make the whole body or local skin vibrate to expel mosquitoes and flies and shake off attached foreign bodies. The membranous muscles also curl the body
balling
Or erect a thorn to defend against an enemy, as
pangolin
,
porcupine
Hedgehog. In the higher species of mammals, the lipidomuscular degeneration occurs only in the chest, shoulders, and shoulders
groin
There are occasional reservations. The other group of skin muscles is the neck
sphincter
, its surface
platysma
Extending along the ventral side of the neck to the chin and face, forming facifacial muscles
Expressive muscle
. The lower species of mammals have no expressive muscles,
carnivore
There are expression muscles, the expression muscles of primates are well developed, and the expression muscles of humans are the most developed, with about 30 pieces. There are complex lip muscles around the mouth that play an important role in sucking. In addition, distribution in
cranial
and
Zygomatic arch
Terminating in the mandible (tooth bone)
temporalis
And strong chewing muscles, which are closely related to predation, defense, and chewing of the mouth.
Septal muscle
It is a muscle unique to mammals
Transverse position
the
Voluntary muscle
It divides the internal cavity into the chest and abdominal cavity, and the activity of the septum muscles helps with breathing.
mammalian
digestive system
include
Digestive duct
and
Digestive gland
. The main features of the structure and function are that the digestive tube is highly differentiated, oral digestion occurs, and the digestive capacity is significantly improved. Associated with this is a well-developed digestive gland.
Digestive duct
Including oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, anus and so on.
1. Oral cavity: the way mammals chew and digest in the oral cavity causes great changes in the oral structure. Fleshy lips appear, which are important organs for sucking milk, feeding, and assisting chewing, and are part of the articulation and articulation organs.
herbivorous
The lips of mammals are particularly developed, and some have upper lips
harelip
Like a rabbit. Adapted for oral chewing, mammals
stomatoschisis
The cheeks shrink and appear on the lateral sides of the teeth on both sides, and in some species the cheeks develop a bag-like structure
Cheek pouch
Used to store food, as in monkeys. The parietal wall of the mouth is bony
Palatum durum
and
Soft palate
Is formed to open the nasal cavity (
Nares internus
Separated from the mouth, the nasal passage is along the hard palate. The soft palate moves backward until it's right up against the throat,
choana
Open with
Cavum pharyngeum
. There are often horny epithelial ridges in the palate to prevent food slippage. Herbivorous and carnivorous species have developed horny edges. The mouth has a very developed muscle tongue, which helps to ingestion, stirring and swallowing, and is an auxiliary organ for human pronunciation. There are taste buds distributed on the surface of the tongue
Gustatory organ
. There are births on the upper and lower jaws
heterodont
, tooth U
alveoli
Grow out, there is
Medullary cavity
Filled with connective tissue, blood vessels and nerves. Due to the different shape and function of the teeth, it can be divided into incisors to cut food, canine teeth to tear food, molar teeth to bite, cut, press, grind food and other functions. Mammals have subear glands in their mouths,
Submaxillary gland
and
Sublingual gland
Equal three pairs
Salivary gland
Has a catheter opening in the mouth, can secrete
Salivary amylase
Oral digestion of food. In addition, some mammals have oral salivary glands
Evaporative water loss
As a form of thermoregulation. Rabbits and deer have four pairs of salivary glands.
2. Pharynx: The pharynx of mammals has a perfect structure, which is connected to the mouth before and passes through the throat and esophagus after. On account of
Secondary palate
The formation of the inner nostril also opens up to the pharynx, so the pharynx is the digestive tube with
respiratory tract
The intersection of... On both sides of the pharynx
Eustachian tube
(
Eustachian tube
The opening of the middle ear cavity can be adjusted to protect the air pressure
eardrum
. Lymph glands (tonsils) are located around the pharynx. There's a momma outside the larynx
gristle
It opens and closes to solve the contradiction between breathing and swallowing in the cross parts of pharynx and larynx.
3. Esophagus: Immediately after the pharynx, there is a slender tube with the lower end connected to the stomach. The esophagus is the passage through which food passes and has no digestive function.
4. Stomach: It is an important part of the digestive tract of mammals, and its shape often changes due to different feeding habits, most mammals are
Simple stomach
;
herbivory
Mammals for the compound stomach, also known as
Ruminant stomach
It is generally composed of 4 chambers, that is
rumen
, honeycomb (
reticulum
),
omasum
and
Glandular stomach
(
abomasum
). Only the glandular stomach is the stomach body, having
Glandular epithelium
It can secrete gastric juice, and the other 3 gastric chambers are all deformation of the esophagus. Herbivorous animals with a compound stomach have to digest food several times during the process
regurgitation
Until the food is fully broken down.
5. Small intestine: The mammalian small intestine is the longest part of the digestive tract, including
duodenum
,
jejunum
and
ileum
. The small intestine is highly differentiated, and its mucous membrane is rich in villi, blood vessels, lymph and lymph
Chyle ducts
, enhanced on nutrients
absorption
.
6. Large intestine: shorter than the small intestine, no villi on the mucosa, its
Mucous gland
It can secrete alkaline mucus to protect and lubricate the intestinal wall and facilitate stool discharge. A blind branch at the beginning of the large intestine
caecum
It has a vermicular process at the end. The cecum is unilocular in the stomach
herbivore
Especially developed, except
walrus
,
armadillo
,
The giant anteater
,
hyracodes
Except for one pair of cecum, all other mammals have only one cecum. The large intestine of mammals can be divided into the colon and the rectum, which opens directly through the anus.
cloaca
Disappeared), is a mammal with
amphibians
The remarkable difference between reptiles and birds.
Digestive gland
In addition to the three pairs of salivary glands, the digestive glands of mammals also have liver and liver behind the transverse septum near the small intestine
pancreas
, secreted separately
bile
and
Pancreatic juice
And inject into the duodenum. In addition to producing bile, the liver also stores it
glycogen
Regulate blood sugar to make excess
Amino acid
Deoxygenation forms urine and other compounds that will certain
Toxic substance
Conversion to non-toxic substances, synthesis
Plasma protein
And other functions.
mammalian
Respiratory system
Very developed, especially in
Respiratory efficiency
There has been a marked improvement. Air passes through the outer nostrils, nasal cavity, throat,
trachea
And into the lungs.
Nasal cavity
The nasal cavity of mammals can be divided into an olfactory part at the upper end and a respiratory part at the lower end. The upper part of the nasal cavity is well developed
turbinate
, its mucous membrane inside
Olfactory cells
. In addition, there are also protruding into the cavity of the skull
Paranasal sinus
It enhances the warm, moist and filtering effect of the nasal cavity on the air. At the same time, it's vocal
resonator
. Generally one outer nostril, but cetaceans specialize in
blowhole
, for
Single nostril
.
throat
The larynx of mammals is well constructed. The larynx is the enlarged part at the front of the trachea, which is both a passage for breathing and
Articulatory organ
. Reason of larynx
gristle
The composition of ligament, muscle and mucous membrane. The entrance of the larynx
Aditus laryngis
The operculum cartilage of the anterior abdominal edge of the laryngeal wall can cover the laryngeal opening when swallowing, and food and water enter the esophagus through the operculum, which can prevent food and water from strayed into the trachea. Usually, the throat is open, which is the portal for air to enter and exit the trachea. by
thyreoid
Made of cartilage and cricoid cartilage
Cavum laryngis
In the middle of the lateral wall there is a mucosal fold formed by the vocal cord
Vocal organ
It first appears in anuran amphibians, but is most developed in mammals (only monotremes and
marsupial
Missing).
trachea
It is located in the abdomen of the esophagus and splits into a pair after entering the chest cavity
bronchus
Into the lungs. The main structural features of the trachea and bronchus are that the tube wall is supported by many cartilage rings that do not connect with each other on the back side, thus ensuring the smooth flow of air.
Tracheal mucosa
With ciliated epithelium and mucous glands, the air can be filtered. The mucus secreted by the mucous glands can stick to the dust particles in the inhaled air. The dust particles are moved to the throat under the push of the cilium and discharged through the nose or mouth.
Lungs and thorax
The structure of mammalian lungs is the most complex and is made up of complex"
Bronchial tree
"Is composed of bronchial branches
caecum
That is
Alveolus pulmonalis
. The number of alveoli is very large, which greatly increases breathing
Surface area
For example, the total area of the alveoli of the sheep can reach 50 ~ 90m2, the alveoli of the horse can reach 500m2, and the alveoli of the human is 70m2, which is equivalent to
Body surface area
40 times, a significant increase
Gas exchange
The effect of... There are elastic fibers distributed between the alveoli, which can passively retract the lungs with the coordination of breathing.
The chest holds the lungs
coelom
Unique to mammals, when breathing activities are carried out, the elastic position of the lungs makes the chest cavity a state of negative pressure, thus making the pleura
Parietal layer
And stick to the visceral layer. In addition, unique to mammals, it separates the thorax from the abdominal cavity
diaphragm
The volume of the chest can be changed during movement, coupled with the rise and fall of the ribs to expand or shrink the volume of the chest, so that the mammalian lungs passively expand and retract to complete the exhalation and inhalation.
mammalian
Circulatory system
Including blood, heart, blood vessels and
Lymphatic system
. Its distinguishing feature is that it is very prominent in maintaining rapid circulation to ensure that there is enough oxygen and nutrients to maintain a constant body temperature. Ju Zuo
Somatic arterial arch
.
erythrocyte
There is no nucleus.
blood
Mammalian blood and other
vertebrate
The difference is that the red blood cells have no nuclei and are in the shape of two concave oblate disks, only
camelidae
and
giraffidae
The red blood cells are oval in shape; The erythrocyte volume was smaller than that of other vertebrates. For example, the erythrocyte length and diameter were 22.8μmX15.8μm in frog, 14.7μmX6.5μm in pigeon, 5.1μmX5.1μm in cow, and 2.5μmX2.5μm in musk deer. Mammals also have a higher number of red blood cells than other vertebrates, such as
beasts
6 to 13 million. These features greatly increase its surface area and improve its ability to bind to oxygen.
heart
The mammalian heart is located in the middle left of the thoracic cavity
pericardium
Inside the cavity, there is a small amount of liquid in the cavity, which can reduce the friction when the heart beats. The internal structure of the heart is basically the same as that of birds, also four chambers, complete
bicirculating
(First, mammals came before birds.
Venous blood
It's not mixed in the heart.
Atrium dextrum
,
Ventriculus dexter
It is formed with pulmonary arteries and veins
Pulmonary circulation
. The walls of the right atrium and ventricle are thin, and venous blood is stored in the right atrium and ventricle
Tricuspid valve
.
Atrium sinistrum
,
Ventricle sinistrum
It is composed of arteriovenous body
Systemic circulation
. Left atrium and ventricle wall thicker, internal storage
Arterial blood
, atrioventricular
Mitral valve
. The function of all these valves is to keep the blood flowing in one direction and prevent the blood from going backwards. The blood supply to the heart muscle is made by
Coronary circulation
Finished.
Blood vessel
Including arteries, veins and
capillary
. The prominent feature of the mammalian arterial system is that it has only the left arterial arch. The left arterial arch is curved back to back
aorta
All the way to the tail, branching out all the way to the body. mammalian
Venous system
Tends to simplify to a single
Anterior great vein
(
Superior vena cava
) and after
Vena cava
(
Vena cava inferior
) Instead of lower
tetrapod
paired
Anterior major vein
and
Posterior major vein
.
Renal portal vein
Disappeared. Blood from the tail and hind limbs was injected directly into the large vein. This reduces the number of steps through the tiny blood vessels once and helps speed things up
Blood flow velocity
And raise blood pressure. Also, mammalian
Vena abdominalis
Disappear in the adult body.
Azygos vein
(right) and
Hemiazygos vein
The posterior main vein is replaced (left).
lymph
The lymphatic system of mammals is very developed, which may be due to the high pressure of blood vessels in the arteries and veins,
Interstitial fluid
It is difficult to direct transvenous return to the heart.
Lymphatic vessel
It originates from the interstitial tissue, and the apex is blind
Capillary lymphatic vessels
Part of the tissue fluid enters the lymphatic capillary through osmosis. Interstitial fluid entering the lymphatic capillary, similar in composition to plasma, but
protein
Low content, no erythrocyte and
platelet
. The capillary lymphatic vessels converge into larger lymphatic vessels, which mainly pass through
Ductus pectoralis
Large vein return before injection. Therefore,
lymph
Only one-way flow from tissue to vein to heart. There are valves in the lymphatic vessels that prevent lymphatic fluid from reversing. Lymphatic vessels assist the return of tissue fluid and play an important role in maintaining blood volume. In addition, lymphatic vessels are also the main route of fat transport, and the lymphatic vessels of the small intestine (chylous canals) carry fat back to the heart through the anterior great vein through the thoracic duct.
Lymph node
Section is generated
lymphocyte
The main organ, and has the function of blocking foreign bodies and protecting the body. Mammalian lymphatic segments are highly developed and spread throughout the whole body lymphatic system, especially in the neck, armpit, rat stream,
mesentery
The other parts are more concentrated. In addition, the tonsils, spleen and thymus are also a type
Lymphatic organ
.
mammalian
Excretory system
Well constructed, including kidneys,
ureter
Bladder and urethra. In addition, skin is also unique to mammals
Excretory organ
. The main function of the excretory system is to
Cell metabolism
The excretion of waste products from the body, as well as the maintenance of cell survival depends on
Internal environment
It's relatively stable. The kidneys are the main excretory organs, and the mammalian kidneys usually consist of a pair located on the back of the abdominal cavity, on either side of the spine. The kidney is piniform and its inner margin is concave
Hilus renalis
Is the artery, vein, nerve buckle ureter and other access. The kidney is composed of two parts: the cortex and the medulla. At the hilum, the ureter expands into
pyelon
. The cortex in the outer layer of the kidney is made up of countless
Renal corpuscle
,
Renal tubules
And vascular composition. Each renal corpuscle and renal tubule form one
nephrone
Each kidney has hundreds of thousands or even millions of nephron, and the kidney body is formed by the convoluted capillaries
glomerulus
Having a double wall enclosing it
Renal capsule
Make up. The small tubules of the kidney extending from the cortex to the medulla are slender and convoluted. The renal tubules converge into the medulla
Collecting tube
Many collection tubes are formed
Renal papillae
The opening is in the renal pelvis, through which urine flows into the bladder through the ureter, and then out through the urethra.
The formation of urine includes the glomeruli
filtration
, renal tubule to collecting duct
reabsorption
and
Secretory action
. Blood flows through the glomeruli as the ball exits
arteriole
The diameter of the pipe is relatively
Entering glomus arteriole
Small, so the capillary blood pressure increases, so the plasma water and removal
protein
Most other substances can pass through
Capillary wall
And the wall of the renal capsule and enter the renal capsule. Therefore, the production of urine is caused by the filtration of high and low blood pressure. Mammal urine is made of
urea
Composition, and other
Amniotic animal
Is made of uric acid. Urea is produced by the secretion of renal tubules and can thicken urine.
mammalian
nervous system
Highly developed, mainly in
brain
and
cerebellum
It grew in size, developed
neocerebrum
Complex folds (sulci and gyri) are formed on the surface of the brain, greatly increasing the surface area of the new cerebral cortex.
neocerebrum
Be due to
paracele
Nerve material from the outer wall grows and surrounds the primary cortex (
archicerebrum
The remnant of the protocerebral cortex, called the hippocampus, remains the olfactory center in the lateral ventricle.
Cerebral cortex
Composed of a well-developed neocortex, it receives a variety of substances from all over the body
sensillum
Incoming impulses are analyzed and synthesized, and corresponding responses are generated according to established neural connections. around
Cerebral hemisphere
Through many
Nerve fiber
Connect with each other. The pathway of nerve fibers
Corpus callosum
Is a mammal (
placentata
) Unique structure.
Covered by the hemispheres of the brain, which have
Pineal body
It is an endocrine body, and the mammalian pineal gland tends to shrink. From the ventral part of the diencephalon
Optic nerve
To form a cross weight
Chiasma optic nerve
, followed by a handle and under the head
hypophysis
Association.
Diencephalic cavity
Also known as...
Third ventricle
It is very developed. The neural structure in the diencephalon wall is mainly dorsolateral
thalamus
Also called colliculus and ventral
hypothalamus
. The thalamus is the lower center of the cerebral cortex
analyzer
between
Intermediate station
The sensory impulses from the whole body are concentrated here, between the channels
cinerea
A new neuron reenters the cerebral cortex. The ventral hypothalamus is
Autonomic nerve
The activity center is closely related to the coordination of visceral activities, and is
Thermoregulatory center
.
The midbrain of mammals is underdeveloped, very small in size, and the midbrain cavity is narrow in a tube, said
The midbrain aqueduct
, and third,
Fourth ventricle
Traffic. Mesencephalon dorsalis
Quadrigeminal bodies
The first pair is visual
Reflex center
The rear pair is the auditory reflex center. Descending from the base of the midbrain
Motor nerve
Fiber bundle
Form a more prominent cerebral foot.
cerebellum
mammal
tritencephalon
The back of the body is a highly developed cerebellum, whose main function is to coordinate the body
Muscle movement
And the balance center that maintains the body's normal posture. The structural characteristic of the mammalian cerebellum is that it has
Cerebellar cortex
The gray matter covers the surface and forms
Cerebellar cortex
,
alba
Branching into the gray matter. Also, in two
Cerebellar hemisphere
Between to run amok
Nerve fiber bundle
Constituting mammalian endemic
pons
The pons are an intermediate station in the communication pathway between the cerebellum and the brain.
Connected to the spinal cord, both
Structural similarity
. In addition to the pathway that connects the spinal cord with the higher center, there are ascending and descending conduction pathways in the white matter. The gray matter is dispersed into some
Neural nucleus
The nerve fibers of the nerve nucleus are associated with the corresponding sensations and
Motor organ
Get in touch. It is also an important visceral activity center that regulates respiration, digestion, circulation, sweat gland secretion, and various other functions
Defensive reflex
. There is a fourth ventricle on the dorsal side of the medulla.
All parts of the mammalian brain produce 12 pairs
Cranial nerve
, respectively the division of sensory and motor functions or both. The names, locations, distribution and main functions of these 12 pairs of cranial nerves will be discussed later. mammalian
Autonomic nervous system
It is very developed, and its main function is to regulate internal activities and metabolic processes and maintain the body
Internal environment
The balance of... The autonomic nervous system can be divided into
The sympathetic nervous system
and
The parasympathetic nervous system
.
Sympathetic nerve
The system consists of nerve fibers originating in the thoracolumbar segment of the spinal cord and distributed through sympathetic nerve chains to the internal organs.
The parasympathetic nerve
The system consists of parts of the cranial nerves
Oculomotor nerve
,
Facial nerve
,
Glossopharyngeal nerve
,
Vagus nerve
It is composed of nerves originating in the sacral part of the spinal cord. The role of sympathetic and parasympathetic nerves on internal organs is antagonistic, that is to say, the vast majority of internal organs are subject to the dual innervation of sympathetic and parasympathetic nerves, such as stimulation
The cardiac sympathetic nerve
To speed up the heart beat, stimulate the vagus nerve (parasympathetic) to slow the heart beat.
intelligence
The nervous system of mammals is highly developed, especially the brain becomes more complex, and the new brain skin that appears in reptiles is highly developed and formed by mammals
Higher neural activity
The hub.
neuron
The number increased, and transverse nerve fibers, called the corpus callosum, formed between the two hemispheres. And the cerebellum developed, the first appearance of the cerebellum hemisphere. The mammalian cerebral cortex is unprecedenently developed, which provides the necessary basis for calculation and logic. This is not true of any animal before mammals. Therefore, the intelligence of mammals is higher than that of other non-mammals.
Sense organ
Mammals rely on highly developed senses to detect food, avoid enemies, and find suitable habitats, as well as to communicate between species and a range of behavioral responses
indivisible
The organs of... Of course, not all taxa senses have reached a highly developed level, and some species are in a state of degradation in many respects, while in one respect they are highly specialized. For example, some species of vision degradation in mammals, when moving rapidly, have also developed special high and low frequency acoustic pulse systems, through hearing and sound waves
echo
To locate, bats use high-frequency sound waves
echolocation
,
Dolphin
Echo-location by high-frequency and low-frequency acoustic waves in water. This is...
bionics
The study has important significance.
Mammals have highly developed senses, mainly reflected in their
Visual, auditory and olfactory structures are perfected.
smell
Most mammals have enlarged nasal passages and developed turbinate bones, and have a sensitive sense of smell. Such as carnivores, cloven-hoofed and
rodent
The sense of smell is well developed. But whales, primates, the olfactory part of the brain is not developed, so its sense of smell is not sensitive, dolphins and
porpoise
Be short of
Olfactory organ
.
vision
mammalian
Visual organ
Similar to most amniotic animals. The eyeballs of most mammals are well developed. But some live under the camp
insectivora
The eyes of rodents and whales are extremely degraded, and some species only retain the ability to distinguish between light and dark. In general, mammals are sensitive to light waves, but for
Colour vision
The sensitivity is poor, which is different from most
beasts
All related to nighttime activities. Primates have the ability to distinguish colors and judge the size and distance of objects more accurately.
mammalian
Endocrine system
Extremely developed. It's made up of endocrine glands scattered throughout the body, including the brain
hypophysis
, thyroid gland,
parathyroid
,
Adrenal gland
Islet glands, thymus and gonads, etc. They secrete different hormones, have different roles, there is a certain correlation between each other, together to form an endocrine system.
mammal
Reproductive system
The main feature of the female animal is that both ovaries are organic, and the eggs are in
oviduct
Internal fertilization, in which the embryo fills with fluid in the uterus
Amniotic membrane
Sac development,
Embryonic development
Required nutrients from
Maternal placenta
Blood.
male
gonad
The male gonads of mammals are a pair of testicles, the location of which often varies from species to species. Most types of testicles are in
Breeding season
There is displacement or descent. In addition to
Monotremata
Animal elephant,
rhinoceros
The testicles of the majority of mammals descend from the abdominal cavity through the groin to the scrotum outside the abdominal cavity as embryos. The displacement of testis can be summarized into three types: ① abdominal testis. Testis do not change position, located behind the kidneys, such as monotrema,
Proboscidea
,
hyracoida
Manateales and
Insectivora
Part of a family of animals. ② inguinal testis. The testicles move into the groin, as in
Erinaceidae
,
Squamopsida
,
Tubulodonta
,
seal
,
tapiridae
and
Microbats
. ③ Scrotal testis. The testicles move into an overhanging or non-overhanging scrotum, as in
ruminant
,
primates
And most marsupials are suspensory scrotum;
rodentia
, apomorpha,
Carnivora
,
equidae
,
suidae
,
seal
Branch,
Megalopterinae
The scrotum is not overhanging.
Testicles are made up of numerous
Curved seminiferous tubules
Composition is the organ that produces sperm. Interspermatic flexure with
Mesenchymal cell
Can secrete
androgen
. With curved fine seminiferous ducts
Efferent tubule
jointed
epididymis
, its tube wall
Cell secretion
Weakly acidic mucus to ensure suitable conditions for sperm survival. Lower end of epididymis vs
Deferent duct
The lower end of the vas deferens reaches the urethra. Semen transurethra,
penis
Outside the body. In addition,
Seminal vesicle
,
prostate
,
Glandulae bulbi urethralis
They are important accessory glands whose secretions form the bulk of semen and promote sperm activity. The prostate gland secretes it
prostaglandin
Can promote
Uterine contraction
It is helpful for fertilization. The penis is a mating organ, mainly composed of
Cavernous bodies
The urethra runs through it.
Female gonad
Is a pair of ovaries, whose surface layer is
Germ epithelium
There are produced by the reproductive epithelium at different stages of development
follicle
Each follicle contains one
oocyte
, which has follicular fluid outside, containing
estrogen
Egg maturation follicle rupture, egg and
Follicle (pl. folliculi)
The liquid is discharged immediately. The remaining follicles are atrophied and filled with a kind of yellow cell that becomes
Corpus luteum
Can secrete hormones that promote the uterus and
Mammary gland
Develop and prepare for pregnancy. The mature egg is discharged into the opening at the front of the fallopian tube, and after fertilization is completed in the upper fallopian tube, it travels down the fallopian tube to the uterus, where the fertilized egg is planted on the uterine wall for development. The uterus opens outside the body through the vagina. There are many types of mammalian uterus, some of which are primitive
Uterus duplex
For example
lagomorpha
Rodentia and Ungularis; Some are bimolecular, such as cetacea; Some are...
Uterus bicornis
Such as Insectivore, Squamata, Carnivore, Manatee, Proboscida,
Perissodactyla
,
artiodactyla
Some species of chiroptera and primates; There is also a form in which the two wombs completely heal into one
Uterus simplex
Such as chiroptera and some species of primates. The development of these different types of uterus is from the original double uterus to a single uterus. The number of babies born in a single uterus is usually lower than in a twin uterus.
Largest mammal: Blue whale
The largest land mammal:
African elephant
Tallest land mammal: giraffe
The fastest mammals:
cheetah
Smelliest mammal: America
skunk
The lowest mammal: the platypus
