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BIOL2204
Mammals
57
Zoology
Undergraduate 2
10/29/2016

Additional Zoology Flashcards

 


 

Cards

Term
What were the first synapsids?  What were some of their characteristics?
Definition
Pelycosaurs: Unmodified synapsid skull, articular - quadrate jaw articulation, body shape of a large lizard - limbs sprayed out to side, early to late Permian
Term
What evolved from an early carnivorous pelycosaur lineage?  How was it successful?
Definition
Therapsids: limbs elongated and shifted under body (more active, could run faster), regionally differentiated teeth (heterodonts), expanding of fenestra to accommodate larger jaw muscles and increasing brain size.
Term
What are the two main groups of therapsids, and which gave rise to the early mammals?  What are the characteristics of that lineage?
Definition

Gorgonopsids and cynodonts.

 

Cynodonts gave rise to the mammals.  They had a great enlargement of the lower margin of the temporal fenestra, appearance of the masseter muscle (associated with chewing by cheek teeth), presence of cusps on cheek - well developed heterodonty, loss of ribs from lumbar region - diaphragm, well developed bony secondary palate, two occipital condyles, probably endothermic

Term
Give a pocket summary of evolution of mammalian line
Definition
Pelycosaurs>Therapsids>Cynodonts>first mammals
Term
Describe the first mammals
Definition
Small shrew like animals, diphyodont teeth (replaced once), hair, only had dentary in lower jaw, 3 middle ear bones, turbinate bones, diaphragm, mammary glands, endothermic
Term
What evidence suggests that the first mammals were probably nocturnal?
Definition

Fur (insulation), monochromatic vision (seeing at night, only see grey)

 

From fossils: large olfactory bulbs (smell), large somatosensory region of cerebral cortex (touch), middle ear bones (keen hearing)

Term
What is the dentary?
Definition
Bone in the lower jaw (articulates with upper jaw)
Term
What are occipital condyles?  Do mammals have the same amount as other amniotes?
Definition
bones that articulate with the cervical vertebrae, mammals have 2 whereas other amniotes only have 1
Term
Give some of the distinguishing characteristics of the mammalian skull
Definition

Modified synapsid

Bony secondary palate

Turbinate bones

Zygomatic arch

Auditory bulla

Two occipital condyles

Single bone in lower jaw - dentary

Regionally differentiated teeth

Term
What are turbinate bones and why are they neccesary in mamamls?
Definition
Complex scrolls of bone in nasal cavity that reduce respiratory water loss.  Neccessary because of mammalian high metabolic rate - lungs continuousy ventilated (with a high body temperature) therefore a large potential for high rate of respiratory water loss with every breath.  Turbinate bones reduce this by heating and humidifying air as mammals breathe, warm water saturated air from lasses causes water to condense on bones during exhalation.
Term
What are the advantages and disadvantages of panting in dogs?
Definition
Exhalation bypasses turbinate bones, maximises heat loss but also evaporative water loss, need to replace water
Term
Name the biological order of sound transmission in mammals
Definition
Eardrum>malleus>incus>stapes>oval window
Term
What are the 3 bones in the middle ear?
Definition
Incus, malleus, stapes
Term
Which middle ear bone transmits vibrations from jaw to middle ear?
Definition
Stapes
Term
How many cervical vertebrae are found in most mammals, including giraffes?
Definition
7
Term
Name the 5 regions of the post cranial mammalian axial skeleton
Definition
Cervical>Thoracic> Lumbar>Sacral>Caudal
Term
What are the main characteristics of a single vertebrae?
Definition
Centrum, neural spine, neural arch, neural canal, transverse process, zygopophyses
Term
What are the names of the two vertebrae that articulate with the occipital condyle?
Definition
Atlas, then the axis
Term
Why do most mammals have higher neural spines on thoracic vertebrae?
Definition
More muscle attachment to hold head up off ground
Term
What is the diaphragm?
Definition
A membranous muscle that separates the thoracic cavity from the abdominal cavity - used to ventilate the lungs through negative pressure breathing
Term
Give an example of a mammal with prehensile caudal vertebrae
Definition
A monkey
Term
What are the characteristics of mammalian lumbar vertebrae?
Definition
Variable number, no ribs but have very large blade-like transverse processes
Term
What are the characteristics of mammalian sacral vertebrae?
Definition
Always fused together, typically 3 or 4, articulates with pelvic girdle
Term
Explain high gear and low gear ratios
Definition

High gear ratios:  Fulcrum closer to in lever length that out lever length.  For very powerful forces, strong muscles

 

Low gear ratios: Fulcrum at equal distance, small muscle contraction/force, large arc of movement. (output force relatively large)

Term
A horse has a high gear ratio (Lo/Li) designed for speed, whereas an armadillo has a low gear ratio designed for power.  True or false?
Definition
True
Term
How do mammals compensate for increasing inertia (mass times velocity)?
Definition
Minimize the mass of distal parts of the limbs, minimize force needed to swing limb back and forth.  Faster animals also have distal skeletal bones reduced in size and muscles associated with limb movement close to the body (proximal)
Term
What influences running speed and what do these factors depend on?
Definition

Stride length x Stride rate

 

Rate depends on: Speed of muscle contraction gait

 

Length depends on: limb/bone length, limb posture, spinal flexing, time off ground

Term
Describe the three types of foot posture seen in mammals
Definition

Plantigrade:  entire foot on ground, humans

 

Digitigrade:  Only digits on ground, dogs and cats

 

Unguligrade: Nail on ground, ungulates

Term
Inserting muscles closer to a joint will shorten stride length but result in greater speed of movement of distal elements if muscle contraction speed is the same, true or false
Definition
False, it results in greater stride length
Term
What faciitates spinal flexing?
Definition
Articulating instead of interlocking zygopophyses
Term

Do herbivores exhibit much spinal flexing?  Why?

Definition
No, they have to carry around heavy stomachs, need more support therefore rigid spines
Term
What stores elastic energy from body motion?  What's the trade off?
Definition
Tendons.  Trade of with loss of dexterity
Term
Describe changes in the pectoral girdle associated with running
Definition
Deer: loss of clavicles, narrow ribcage
Term
Why is bipedal locomotion in macropods an efficient adaptation?  Is there a trade-off?
Definition
More efficient than quadrapedal locomotion due to large elastic tendons (no extra energy cost with faster speed (plateaus)), but very slow speed locomotion very inneficient
Term
When is expiration not passive?
Definition
During excercise or disease internal intercostal and abdominal muscles contract as well
Term
What gives rise to "dead space"
Definition
Bi-directional ventilation
Term
What are surfactants and what secretes them?
Definition
Phosphocholines, act as a detergent.  Secreted by type II epithelial cells that line the alveoli and decrease surface tension, without them we wouldn't be able to inhale
Term
What constitutes pulmonary ventilation, alveoli ventilation and residual volume?
Definition

Tidal volume (ml) X breathing rate per minute = pulmonary

 

(Tidal volume - anatomical dead space) X breathing rate = alveoli

 

Residual volume = Pulmonary ventilation - alveoli ventilation

Term
A higher percentage of PO2 means more efficiency at getting O2, true or false?
Definition
True
Term
Why are avian lungs better than fish, amphibian and reptile lungs for different reasons than mammalian lungs?
Definition
Better than fish, amphibian and reptile lungs because of greater surface area, better than mammalian lungs because of the unidirectional flow of gas decreases dead space gas mixing and thus increases the effective PO2 at the gas exchanging surfaces.
Term
Why do mammals seek shade/cooler environments and/or increase their thermal conductance?
Definition
Because the temperature of the air approaches the temperature of their body.
Term
How do some animals such as rabbits increase their thermal conductance?
Definition
Have 'thermal windows', vasodilate areas of skin that are poorly insulated, heat lost through capillaries down thermal gradient
Term

How do antelope ground squirrels and camels cope with heat stress?

 

 

Definition
Squirrels go and lie on cold surfaces, camels fluctuate their body temperature much more rapidly when they are dehydrated daily
Term
What is the biggest danger of heat stress in endotherms and how can it be prevented?
Definition
Brain overheating, vascular heat exchanges cool blood before it enters the brain
Term
Blood cools from bones in a countercurent heat exchange, true or false?
Definition
True
Term
How do kangaroos manage heat stress as opposed to humans?
Definition
Don't have sweat glands, lick exposed skin
Term
What reflects different types of diets in mammals?
Definition
jaw articulation and teeth arrangement, length and complexity of gut
Term
Contrast the mammalian gut of carnivores and herbivores
Definition

Carnivore: Easily digested food - short and simple digestive tract, rapid transit time

 

Herbivore: hard to digest food - use symbiotic microorganisms to break down cellulose, long and complex digestive tract, slow transit time, have specialised "fermentation vats" in digestive systems

Term
Compare mammalian herbivore and carnivore skulls and teeth
Definition

Carnivore: Large sagittal crest for origin of large temporalis muscle, prominent coronoid process of mandible, very small pterygoid muscle (not much sideways movement) and relatively small masseter muscle.  Large canines, no diastema

 

Herbivores: Diastema separates molars and incisors, incisors used for clipping motion/molars for grinding, large pterygoid muscle for sideways movement, upper/lower jaw come together synchronously across molar surface, large masseter muscle, small temporalis muscle (less powered bite)

Term
Describe hindgut fermentation
Definition

Hindgut: less efficient at extracting nutrients, occurs after "true" stomach and smal intestine, faster gut passage time, allows smaller sized animals and to feed on poorer quality food, some have very large caecum where most fermentation occurs

 

Term

Describe the different foregut fermentations in ruminants and non-ruminants

Definition

Ruminants: Grass chewed in mouth, watter added via saliva, passed into large reticulorumen, regurgitated and chewed again then move back into reticulorumen, pass into omasum once small enough where water is absorbed, passes into abomasum where regular digestion occurs

 

Non-ruminants: Not regurgitated and rechewed, no restrition of food particle size before passing into true stomach, less efficient extraction of nutrients because of larger particle size and faster gut passage times, can survive on poorer quality pasture because of faster gut passage time (don't starve to death)

Term
Name the two subclasses of mammals
Definition
Prototheria (monotremes) and Theria (metatheria and eutheria)
Term
What are the two infraclasses of the subclass Theria?
Definition
Eutheria and metatheria
Term
What are the main characteristics of the subclass prototheria?
Definition
Have cloaca, lay and incubate eggs but suckle hatchlings
Term
What is the difference between female marsupial and female placental reproductive tracts?
Definition
Marsupials have a lateral vagina and a pseudovaginal canal
Term
Describe the reproductive pattern of a red kangaroo
Definition
Controlled embryonic development - embryonic pause.  Females may have young at 3 different stages at one time - an embryo in uterus, small joey attached to tit, a joey at foot.  Allows greater survival rates in deteriorating conditions
Term
Marsupials can have inflected dentaries (bent 90 degrees, so perpendicular to axis of dentary)
Definition
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