1
Q
explain/describe gills in amphibians
A
- external gills in amphibian larvae and some salamanders (paedomorphosis)
- frog gills are internalized as part of buccal pump system after larvae stage
- external gills are reliant on flowing water or being waved in stagnant water
2
Q
describe cutaneous respiration in amphibians
A
- low keratinization of skin to allow efficient gas exchange (causes water loss in air)
- requires blood capillaries near surface of exchange
- requires increased surface area
3
Q
describe tetrapod lungs
A
- paired
- high surface area to volume ratio
- joined to larynx + buccal cavity by trachea
- compartmentalization increases from amphibian to reptile to mammal
4
Q
how does amphibian buccal pump work?
A
positive pressure forces air into lungs
components - nostrils, buccal cavity, glottis + lungs
5
Q
how do reptiles aspirate?
A
- with bidirectional air flow
- ribs + intercostal muscles power pump to create negative pressure to suck air into lungs
6
Q
how does aspiration work in mammals?
A
- bidirectional air flow
- diaphragm muscle + rib cage produce lung ventilation
- negative pressure sucks air into lungs
7
Q
describe respiration in birds
A
- unidirectional air flow, two cycle breathing
- aspiration pump, lungs also have air sacs
- air in lungs flows from dorsobronchus to parabronchi to ventrobronchus
- gas exchange occurs in capillaries in the walls of parabronchi
8
Q
how does gas transfer at respiratory surfaces change between mammals, birds and fish?
A
Mammals - blood encounters relatively constant gas concentrations (uniform pool)
Birds - blood encounters increasing gas concentrations
- allows for progressive loading of oxygen in a cross-current exchange system
Fish - blood encounters increasing gas concentrations
- equilibrated with oxygenated water in counter current system
9
Q
what are the general trends of the evolution of circulation?
A
- double circuit systems
- increase in divisions in the atrium + ventricle
- increase in blood pressure on land
- increase in one-way valves on land
10
Q
describe tetrapod circulation
A
- double circuit (blood passes thru heart 2x in each circuit)
11
Q
describe the amphibian circulatory pump pattern
A
- double circuit
- 3 chambered heart (2 atria, 1 ventricle)
- de-oxygenated blood from body enters thru right atrium
- oxygenated blood enters thru left atrium
12
Q
describe squamate + turtle circulatory pump pattern
A
- double circuit
- 3 chambered heart (2 atria, 1 partially divided ventricle)
- ventricle partially divided into 3 cava
- de-oxygenated blood from body enters thru right atrium
- oxygenated blood from lungs enters thru left atrium
13
Q
what function does squamate + turtle ventricular cava offer?
A
-allows for transfer of de-oxygenated blood to lungs when breathing air + a lung bypass while diving
- saves energy
14
Q
describe the crocodilian circulatory pump pattern
A
- double circuit
- 4 chambered heart (2 atria, 2 ventricles)
- de-oxygenated blood from body enters thru right atrium
- oxygenated blood from lungs enters thru left atrium
- when underwater no blood flows to lungs (due to increased pulmonary resistance), causes drastic drop in heart rate
15
Q
describe the circulatory pump pattern in birds
A
- double circuit
- 4 chambers (2 atria, 2 ventricles)
- complete separation of pulmonary + systemic circulation (no mixing)
- de-oxygenated blood from body enters thru right atrium
- oxygenated blood from lungs enters thru left atrium
- absence of cardiac shunt
16
Q
how does circulation change for fetal placental mammals?
A
- uptake of oxygen + nutrients occurs at placenta
- blood must be shunted away from developing lungs and into systemic circulation
17
Q
how do the 2 circulatory bypasses in placental mammals change blood flow?
A
bypass 1 - blood enters right atrium -> exits thru foramen ovale to left atrium + ventricle -> flows to head + upper body
bypass 2 - remaining blood enters right ventricle -> exits pulmonary artery -> travels thru ductus arteriosus -> to lower body + placenta to be oxygenated
18
Q
name the main components of the digestive tract
A
- mouth
- pharynx
- tubular parts (esophagus, stomach, intestines
19
Q
name the accessory organs + glands of the digestive tract
A
- tongue
- teeth
- salivary glands
- pancreas
- liver
20
Q
how does the mouth differ between vertebrates?
A
ancestral - filter feeders w/ small mouths
agnathans - jawless, no true teeth, small buccal cavity
fishes - specialized mouths, firm tongues
tetrapods - increase in physical + chemical digestion
21
Q
explain salivary glands and their primary function
A
- multicellular glands w/ ducts
- only in tetrapods (not fish)
primary function - to moisten food for lubrication
22
Q
what are the specialized functions of the salivary glands
A
frogs + anteaters - makes tongue sticky to assist in prey capture
mammals - start of starch digestion
snakes/lizards - mod’d into venom glands
marine reptiles - salt secretion near orbits
birds - start of starch digestion
- salt secretion near orbits
23
Q
describe tooth structure/composition
A
- derived from bony dermal armor of placoderms (similar to placoid scales)
- composed of dentin
- covered by enamel crown
24
Q
what are the 3 types of attachment for teeth?
A
- acrodont dentition
- pleurodont dentition
- thecodont dentition
25
what is acrodont dentition?
- teeth attached to the outer surface/summit of the jawbone
- in many teleosts
26
what is pleurodont dentition?
- attachment to the inner side of the jaw bone
- in anurans, salamanders, and many lizards
27
what is thecodont dentition?
- teeth are embedded within bone sockets or alveoli
- in some fishes, crocodilians, fossil birds and mammals
28
describe the 2 types of tooth variation
homodont - teeth all the same size + shape
- fish, amphibians + reptiles
heterodont - teeth vary morphologically
- species-specific number of teeth
- evolved ability to chew
- mammals
29
what is the esophagus and how does it vary between groups?
- the muscular tube between pharynx + stomach
- folded w/ distensible lining, many mucous glands
- mod'd into crop in some birds
- short in fish (hard to distinguish from stomach)
- aids fish in closing the pathway to stomach during respiration
30
describe the stomach in general terms
- muscular chamber, starts after the esophagus and ends at the pylorus
- contains gastric glands which produce hydrochloric acid
- chemically breaks down food (very little absorption)
31
how is the stomach specialized for birds + crocodiles?
modified into 2 parts:
- glandular proventriculus (secretes digestive enzymes + hydrochloric acid)
- muscular gizzard (thick walled layer for grinding + mixing food w/ gastric secretions)
32
how is the stomach specialized in ruminant mammals?
modified into 4 parts:
**rumen** - stores + churns, holds bacteria that produce cellulase (which breaks down cellulose)
**reticulum** - receives food from rumen + forms cud, regurgitates for further chewing
**omasum** - temporary holding site
**abomasum** - lined w/ gastric glands, enzymatic digestion
33
what are the intestines + their main function?
- long + tubular, highly folded, moved by peristalsis
- secretes **mucous + digestive enzymes**
- **selective absorption** of nutrients + water
- other enzymes are secreted into intestine from pancreas + bile from liver
34
explain the differences between the small + large intestine
differentiation common within tetrapods
**small** - chief site of digestion + absorption of nutrients
- pancreas + liver empty their products into the duodenum
**large** - mostly recovers water
- can be used for fermentation
35
how does diet shape the digestive tract?
**carnivores** - shorter, relatively unspecialized guts
**herbivores** - long guts w/ intestinal specializations to promote fermentation
36
describe the structure of the gut wall + its 4 layers
**serosa** - connective tissue + mesentery
**muscularis externa** - 2 layers of smooth muscle
**submucosa** - connective tissue
- autonomic nerves
**mucosa** - smooth muscle fibres
- connective tissue
- epithelial lining
37
how does caeca increase digestive surface area?
- blind ended extensions of the gut
- function: digestion/absorption in fishes, fermentation in mammals
ex. pyloric caeca, colic caeca
37
what are the 3 strategies for increased surface area within the digestive system?
1 - caeca
2 - spiral valve
3 - foldings
38
how does the spiral valve increase digestive surface area?
- corkscrew shaped structure of the intestinal tract
- forces food along a spiral path, increases path length
- in chondrichthyans, ancestral fishes + lungfishes
39
how do foldings increase digestive surface area?
- coils of the canal, folds, villi + microvilli on the internal surface
40
What does the urogenital system consist of?
Excretory system
- removes nitrogenous waste and other harmful substances
- controls osmosis to achieve water and salt balance
- involves; kidneys, gills, skin, part of digestive system, salt glands
Reproductive system
- produce and release gametes, bring them together, provide nourishment to young
- involves; gonads, ducts, cloaca, copulatory organs
41
What is the developmental origin of kidneys?
- in sequence from anterior to posterior in three broken sections
- anterior regions degenerate as posterior regions become functional
- posterior break may not form so only two instead of three pairs of kidneys are formed
42
What are pronephros?
- early part of kidney development
- segmented, usually first 4 segments
- drained by pronephric duct
- appears in all vertebrates but degenerates quickly
- functional in fish larvae, adult hagfish and some teleosts
- in most teleosts, pronephros degenerates into 'head kidney'
43
What are mesonephros/opisthonephros?
- early part of kidney development
- reduced segmentation
- drained by mesonephric or opisthonephric duct
- late larval and adult anamniotes, all or most of the mesomere posteriorto pronephros forms one kidney
- among amniotes the middle part of the nephrogenic cord, the mesopros, develops right after the pronepros, is present in fetuses and then degenerates
44
What are metanephros?
- early part of kidney development
- never segmented
- kidney of adult amniotes
- most posterior part of nephrogenic cord that replaces mesonepros in development
- old mesonephric duct degenerates in females but persistes in males to carry sperm
- metanephric kidney is drained by a new duct, the ureter
45
What are the variations in kidney structure based on different environmental challenges?
Terrestrial Environment
- water loss through skin and lungs
- dehydrating environment
- produce urea or uric acid
Freshwater Environment
- water uptake, salt loss through skin and gills
- produce ammonia
Saltwater Environment
- water loss, salt uptake through skin and gills
- produce ammonia
46
What 2 sources do the gonads develop from in the embryo?
- mesomere genital ridges that develop into supportive/connective tissues of gonads (ovaries or testies)
- primordial germ cells that become gametes (sperm or eggs), they arise from the endoderm and migrate to genital ridge early in development
47
What are the principal urogenital ducts in embryos?
- mesonephric ducts
- mullerian ducts
- ureter ducts
- accessory ducts
48
What are the urogenital ducts in male species?
Sharks and amphibians
- mesonephric duct to carry sperm, accessory urinary duct to carry waste
Amniotes
- mesonephric duct to carry sperm, ureter to carry waste
Teleosts
- testicular duct to carry sperm, opisthonephric duct to carry waste
49
What are the urogenital ducts in female species?
Sharks and amphibians
- mullerian duct to carry ova, opisthonephric duct to carry waste
Amniotes
- mullerian duct to carry ova, ureter duct to carry waste
Teleosts
- ovarian duct to carry ova, opisthonephric duct to carry waste
50
What are shark/chondrichthyan reproductive strategies?
- generally internal fertilization
- males have claspers
- females have nidamental (shell) gland for sperm storage
- some are oviparous (lay egg capsule called 'mermaid's purse')
51
What are teleost reproductive strategies?
- generally external fertilization
- when fertilization is internal males have a specialized anal fin called a gonopodium
- in females ovaries are often fused together or only have one functioning one
52
What are amphibian reproductive strategies?
- generally external fertilization in frogs and internal in some salamanders
- male frogs are modified for grasping during copulation, tailed male frogs that use internal fertilization have a tail-like extension of the cloaca
- some female salamanders have a spermatheca to store sperm
53
What are reptile reproductive strategies?
- internal fertilization, eggs typically laid on land
- male turtles and crocodiles have a penis, lizards and snakes have hemipenes
- some female species use asexual reproduction
54
What are avian reproductive strategies?
- internal fertilization
- reproductive organs decrease in size outside of breeding season
- males can display cloacal swelling, others have a spiralled penis
- some females have sperm storage tubules, they typically have a single ovary shell gland for eggshell formation
55
What are placental mammal reproductive strategies?
- internal fertilization
- males generally have a baculum (penis bone)
- females lack epipubic bone for expansion of abdomen during pregnancy
56
What composes the nervous system by location?
- central nervous system, brain and spinal cord
- peripheral nervous system, nerves and ganglia outside of CNS
57
What composes the nervous system by function?
- somatic nervous system, sensory or motor fibres to voluntary skeletal muscles
- visceral (autonomic) nervous system, sensory or motor fibres to viscera, glands and involuntary muscle
58
What are the two divisions of the autonomic nervous system?
- sympathetic division, prepares body for stressful situations (fight or flight response)
- parasympathetic division, slows body down (rest and digest response)
59
What is the function of the spinal cord and nerves?
- receives incoming impulses and sends responses to the PNS
60
What are the spinal nerve distributions?
- cervical; neck flexors/extensors, diaphragm, shoulders/arms
- thoracic; intercostals and trunk muscles, abdominal muscles
- lumbar; hip, thigh/legs
- sacral; hip, foot/toes
61
What are the functions of the different brain regions?
- forebrain; telencephalon controls voluntary actions, diencephalon maintains homeostasis
- midbrain; tectum receives sensory information, cerebral peduncles refine motor movement and maintain balance/posture
- hindbrain; pons conveys information to cerebellum, medulla oblongata regulates autonomic function, cerebellum maintains equilibrium and refines motor actions
62
How does chemoreception differ between species?
- fishes; variable sense of smell, nasal pits with olfactory epithelium
- air-breathing vertebrates; add mucous cells to dissolve odorants
- tetrapods; size and complexity of nasal chamber increased
- mammals; complex nasal turbinates to increase surface area of olfactory epithelium
63
why is photoreception better in birds vs mammals?
- larger eyes
- higher density of photoreceptor cells
- tetrachromates, so have superior colour vision, they see four primary colours; UV, blue, green, red
64
What is mechanoreception?
- the lateral line system in aquatic animals (present in all fishes and larval amphibians)
- thousands of neuromasts on body surface or inside lateral line canal
- neuromasts contain hair cell mechanoreceptors that detect water movement
65
What are the modifications of the ear in different species?
- fishes; only inner ear, no cochlea
- amphibians; middle and inner ear, no cochlea
- reptiles; crocodilians and lizards hear sound waves via tympanic ears, stapes, and simple cochlea, snakes and turtles are limited to ground-borne vibrations felt via jaw and quadrate bones
- birds; funnel-shaped outer ear, single bone middle ear and simple cochlea
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