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Animal Bio - Mammals
last one motha f-ers
52
Biology
Undergraduate 2
04/07/2012

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Term
General features of mammals! (5)
Definition
1. All have hair even if extremely reduced
2. most have a specialized placenta and mammary glands to feed the embryo and newborn
3. They are endotherms so they can live in many areas
4. Most have specialized teeth and jaws
5. Their nervous system is more advanced than in other groups (except for birds)

- also they interact with humans more than any other group
Term
Synapsids
Definition
a reptile with a single lateral opening behind the orbit, the only surviving ones are mammals
Term
Therapsids
Definition
the only synapsids that survived, appeared 280-240 million years ago…. They required upright limbs under their body, they need to get advanced muscular coordination for their upright limbs (have to acquire better coordination and balance)
Term
Cynodonts
Definition
– they had high metabolic rates (know this from the fossil record), better jaw musculature, differentiated teeth (heterodont teeth), a secondary bony palate… helpful when you’re a baby and want to breathe and suck at the same time, they have ribs, a diaphragm etc.
Term
Early mammals were probably ectotherms or endotherms?
Definition
endotherms! They know this from the fossil record by evidence of the growth rate of bones
Term
What happens to skin that is subject to abrasion?
Definition
the outer layers become thicker and keratinized (example our heels)
Term
What are the functions of hair?
Definition
1. Thermal insulation
2. Protection
3. Concealment
4. Waterproofing and buoyancy
5. Signaling
6. Sensory
Term
What are the two main kinds of hair?
Definition
underhair - insulates --> warm, soft and traps layers of air

guard hairs --> protect against wear and provide coloration
Term
Eccrine sweat glands
Definition
secrete a watery fluid found in hairless regions

- it is thermoregulatory in function --> drws heat away from the skin surface
Term
Apocrine sweat glands
Definition
develop at puberty and open into hair follicles
- they secrete a mix of salt, urea and water

- may correlate with reproductive cycles ex: gland under your arms
- convoluted and large
- stinky
Term
Scent glands
Definition
mostly found around the face, feet and anus
- involved in communication with conspecifics
- marking territory
warning and defense
attraction of mates
Term
Sebaceous glands
Definition
produce and oily sebum that keeps skin and hair pliable and glossy - usually found all over the body
Term
Mammary glands are most likely related to what type of skin glands?
Definition
apocrine skin glands... they have similar developmental patterns
Term
Why do males have nipples?
Definition
Because the nipples are present/in place in both males and females before development starts
Term
Though mammary glands may look different in all mammals, what is their function for all?
Definition
they secrete milk via nipples or teats to feed the babies!
Term
What is characteristic about mating of rabbits, ferrets and mink?
Definition
they are induced ovulators... which means copulation causes ovultation so the odds of success are very high
Term
Describe reproduction in Monotremes (ex: duck-billed platypus)
Definition
They are the only egg laying mammals
They only have on breeding season per year
They build a nest or abdominal pouch where the egg is incubated then they hatch into helpless/hopeless babies
- they nurse from their mothers at an opening in their fur
Term
Choriovitelline placenta
Definition
the primitive yolk sac in marsupials
Term
Describe reproduction in marsupials
Definition
they are pouched, viviparous mammals that give birth to very underdeveloped young
- after fertilization the embryo is encapsulated by shell membranes and floats free for several days
- after they hatch, instead of "implanting" the embryo erodes a shallow depression in the uterine wall where they lie and absorb nutrient secretions from the mucus from their vascularized yolk sac
Term
Eutherians
Definition
placental animals
Term
lazyyyyy see slide 11 of mammals
Definition
Term
how many cervical vertebrae to mammals have?
Definition
7
Term
What is the function of the 1st two cervical vertebrae?
Definition
they are modified to support the skull and permit pivoting
Term
As animals become larger what happens to their bones?
Definition
they become more upright and they eventually thicken
Term
What occurs as a result of changes in jaw articulatoin?
Definition
the quadrate and articular bones migrate to the middle ear (incus and the malleus)
Term
Heterodont dentition
Definition
differentiation of teeth
Term
Types of heterodont dentition: Incisors
Definition
sharp edges for snipping or biting
Term
Types of heterodont dentition: Canines
Definition
specialized for piercing
Term
Types of heterodont dentition: Premolars
Definition
for shearing and slicing
Term
Types of heterodont dentition: Molars
Definition
for crushing and grinding
Term
Some animals have one deciduous set and a permanent set... which types fall under each respective category?
Definition
deciduous --> incisors, canines and premolars
permanent --> molars
Term
Insectivores (give an example and define)
Definition
shrews, moles, anteaters and most bats

they eat little fibre and have a short digestive tract
Term
Herbivores (ex and define)
Definition
grazer examples: horses, deer, antelope
gnawer examples: rodents, rabbit and hares

- have a high fiber diet and a long digestive tract
Term
How do herbivores handle their high fibre diet
Definition
anaerobic fermentation of cellulose, ceca and by eating fecal pellets
Term
Carnivores
Definition
feed on herbivores
they are specialized to kill prey which requires intelligence and organized behaviour
short digestive tract
Term
Omnivores (ex and define)
Definition
pigs, racoons, rats, bears, most primates
- primarily carnivores but will switch to plants when normal food is scarce
Term
Do small or large animals eat more per unit size?
Definition
SMALL
Term
In hot climates how do small animals thermoregulate?
Definition
they live underground or are nocturnal
Term
How do large animals thermoregulate in hot climates?
Definition
pale fur
concentrate fat in humps
allow body temperature to drop at night and rise during the day

ps... some mammals have large extremities to get rid of heat
Term
In cold climates, how to mammals thermoregulate?
Definition
increase insultation and/or heat production --> shivering
their fur becomes thicker in winter
Limbs cool near freezing
Small mammals store food and live under snow
Term
depending on size animals in cold climates may enter daily torpor, hibernation or go into a prolonged deep sleep
Definition
Term
where is the heart in mammals?
Definition
in the thorax and it is covered by pericardium
Term
When blood is returning from the lungs what is its pathway?
Definition
it flows from pulmonary veins-->left atrium--> left ventricle--> body via the aorta
Term
When blood is returning from the body what is its pathway?
Definition
vena cavas-->right atrium --> right ventricle --> back to lungs
Term
Why do birds have a better respiratory system than mammals?
Definition
mammals don't have a flow through system, and always retain 20-35% of air
Term
what is the pattern of air flow?
Definition
trachea --> two bronchi --> bronchioles --> alveoli where gas exchange occurs
Term
How does inhalation occur in mammals?
Definition
when the ribs are pulled upward and the diaphragm flattens, the volume of the chest cavity is increased
Term
how does exhalation occur in mammals?
Definition
muscles relax, ribs and diaphragm return to their regulation position = chest volume declines
Term
in mammals what controls most integrative functions?
Definition
the cerebral cortex
Term
where are touch receptors located?
Definition
the base of hair follicles
Term
mammals have poorer _____ than reptiles or birds.
Definition
color
Term
Why do scientists believe that early mammals were nocturnal?
Definition
because rods are more abundant than cones in most species
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