Anatomy & Physiology of Reptiles, Amphibia, Fish Flashcards
What is an ectotherm
reliant on external sources of heat
limited production from metabolism
what is ectothermic regulation controlled by
hypothalamus
stimulation of appropriate behaviour depending on temp of blood
pineal gland detects light levels
what are the advantages of ectotherms
less energy waste in maintaining body temp
~10% of equivalently sized mammal
what are the disadvantages of ectothermic regulation
activity depends on ambient temp
poor aerobic capacity may limit endurance
what are the thermoregulation mechanisms in reptiles (4)
1. heart rate and blood shunting: HR increases with increasing temp, 3-chambered reptilian heart allows lungs to be bypassed, peripheral vasodilation and vasoconstriction
2. body mass and shape: body position can affect heat transfer (contact with ground)
3. behaviour: burrow, alter pigmentation of skin, shade skeeing
4. UV light important for normal behaviour
identify the general anatomy of the lizzard
identify the general anatomy of the snake
what are the 3 layers in the reptile integument
- stratum germinatum
- intermediate lipid-rich
- stratum corneum - keratinized scales
where are the colour generating cells in reptiles
between dermis and epidermis
what is ecdysis
shedding of skin
whole skin in snakes and patches in lizzards
new skin develops from intermediate layer of epidermis
what is ecdysis controlled by
thyroid gland
what is failure to shed the integument called
dysecdysis
where is most of the calcium stored in reptiles
in the bone
what is the optimal Ca:P ratio for reptiles
2:1
how many chambers does the reptile heart have
3
2 atria
single ventricle supplying lungs and body
are the reptile erythrocytes nucleanted or enucleated and what blood tube should be used
nucleated
may be lysed by EDTA
better taken into lithium heparin
how does lymph travel in the reptile
large lymphatic networks have smooth muscle
what is the blood flow through the reptile heart
where is the glottis
fairly rostral
closed at rest
what are the functions of the lungs in the reptile
- gas exchange
- vocalization
- buoyancy
- display
do reptiles have mucociliary lining
primitive
poor at cleaning debris
does the respiratory system contain a diaphragm
no
negative pressure breathing
inspiration, expiration and relaxation/breath-holding phases
relaxation 30-33h
what controls respiration
temperature
increased temp increases oxygen demand
what is the chelonian respiratory system
easily swithced to anaeobic metabolism –> difficult to anaesthesize
nose breathers
short trachea
lungs occupy dorsal half of body cavity
trunk muscles used to drive resp
no diaphragm = no effective cough = prone to pneumonia
what is the differences in digestive system of reptiles vs. mammals
shorter
what is the rate of digestion related to in reptiles
stops at <7 degrees
diet dependent –> longer in herbivores
drops when ill –> oral medication may have delayed action
what is the cloaca
common exit for digestive and genitourinary systems
what are the 3 chambers of the cloaca
- copradeum: anterior, collects feces
- urodeum: middle, drains urteres and reproductive tract
- proctodeum: caudal, common path for excrertion
how do reptiles osmoregulate
water in: environment, diet, drinking
water lost through: evaporation, respiration, urine and feces
how do reptiles retain water (5)
- uric acid: pasty white excretion (can build up and cause gout when dehydrated –> urate cyrstal deposition in joints and viscera)
- cloacal resorption
- reduced GFR
- salt glands: active excretion of Na/K
- renal portal system: renal portal vein (from system venous sytem) passes blood directly to kidney tubule (bypassing glomerulus)
where are the kidneys in reptiles
caudal to coelom
no loop of henle, pyramids or pelvis
what reptiles have bladders
chelonians and some lizards
where do ureters open into in reptiles with no bladders
into cloaca directly with reflux into colon for water absorption
when do small lizards reach sexual maturity
1-2 years
when do snakes reach sexual maturity
2-3 years
when do chelonia reach sexual maturity
3-8 years
how is sex determined chromosomally
female heterozygous ZW
male homozygous ZZ
what is temperature dependent sexual determination (TSD)
incubation temp determines sex (sex hormones involveD)
range varies between species (high temp for male lizzards and female chelonia)
when does testicular size vary
with season
where are the testes located
close to vena cava (R) and left adrenal (L)
what type of testes do lizards/snakes have
paired extracloacal hemipenes
what type of testes do chelonia/crocodiles have
single intracloacal phallus
how long can sperm be stored in the female repro tract
>6m to 7 y
what do oviducts secrete which help form the eggshell
albumin, calcium
open direct into urodeum
what is the female repro cycle
- quiescent
- vitalligenic: hypertrophy of ovaries/oviduct, yolk moved to ovarian follicles, increased circulating Ca
- gravidity/pregnancy: fertilized eggs/embryos in oviducts
what is oviparity
eggs laid early
what is the source of nutrients in the eggs
yolk
what is viviparity
some placental exchange
better for cooler climates
how many clutches during breeding season for oviparity species
2-3
how many clutches per season for viviparity
1 per season
what species are viviparity species
boas, vipers, chameleons
what is the structure of the reptilian egg
3 membranes and shell
what are the structures inside the reptilian egg
- embryo
- amniotic membrane
- allantois (storage of urea/uric acid)
- chorionic membrane
- shell (calcium for embryo)
what species show maternal care
indian python
crocodiles
but most do not
what species have an external ear
only crocodiles
where is the tympanic membrane in some species
outer margin in others (not in snakes, chameleon, tuatara)
what is the single middle ear bone and its funciton
columella
transmits vibration from air and from ground (via quadrate bone)
what is the function of accessory (jacobsen’s) organ
pheromones
how do reptiles see
eyes + pineal gland
what type of muscle is the iris
skeletal
doesn’t respond to atropine
do reptiles have a consenual light reflex
no
how do adult amphibians gas exchange
simple paired lungs
buccopharyngeal
external cutaneous
how do amphibian larvae gas exchange
gills
how does air reach the lungs in amphibians
cannot create negative pressure
force air in by contractions of throat muscles
what are the functions of amphibian integument
- protective
- osmotic
- respiratory functions
what are some practical considerations when dealing with amphibians
- handling: wear gloves (skin toxins, skin easily damaged, susceptible to toxin absorption through skin)
- anaesthesia: immersion, gaseous induction can be slow
- euthanasia: pithing, intra-cardiac/venous or intra-peritoneal injection
what are elasmobranchii or chondrichthyes
cartilagenous fish
what are osteichthyes
bony fish or teleosts
what is poikilothermic
temp depends on environment
optimum temperature range
what is the outer surface of the integument in fish
cuticle
slimy layer –> mucopolysaccharides, skin cells, mucus
what is the epidermis layer called in fish
stratified squamous epithelium
what is the dermis layer in fish
collagen, pigment fibres
what are the scales in fish
flexible calcified plates originating in dermis
what is the lateral line system and their functions
canal along flank lying dermis
seen as series of pores
mechanoreceptors –> changes in water pressure, nerve supply derived from vagus, some adaptation to detect electrical pulses
what are the shape of vertebrae in fish
cylindrical bodies
dorsal and ventral elastic ligaments
dorsal neural arch and spine
what are fins
pectoral girdle attaches to skull
series of bony rays support fin structure
where are the majority of muslces in fish
along trunk
what are the shape of muscles in fish
segmental
folded, interlocking blocks (myotomes)
quartered by dorsal, ventral and horizontal septa
what type of muscles do fish have
mix of red (aerobic “slow”) and white (anaerobic “fast”) fibres
what is the shape of the fish heart
4 chambered linear heart
blood through gills and then to body
where does respiratory exchange mainly occur
at gills
what are gills also important for in fish
in salt and nitrogenous regulation and excretion
how does gas exchange occur in the heart in fish
through countercurrent mechanism
water in through mouth, out through opercula
where are fish kidneys
retroperitoneal
extends length of body cavity
what are the divided functions of the kidney
cranial (head) hematopoiesis
caudal (trunk) excretory
what is the swim bladder in fish and its function
gas filled
swallowing air at surface
movement of gas from arterial blood
maintains neutral buoyancy
what are practical considerations when dealing with fish
- initial visual exam in environment
- anaesthesia: place agent in tank water
- venepuncture: caudal vein
- injections: intramuscular, intraperitoneal
- euthanasia: anathesize then sever spinal cord caudal to braincase
