Reptiles Flashcards
What is the cause of most reptile diseases in the UK?
Poor nutrition and husbandry e.g. Think lizard with calcium problems in bones
What does stress do?
Reduces immune response and predisposes to infection
Describe the taxonomy of reptiles.
Kingdom? Phylum? Class? And various orders?
Animalia
Chordata
Reptilia
Chelonia, Squamata, crocodilia, rhynocephalia
What do you need to keep crocodilia spp as pets
A dangerous/wild animal licence
What is the only reptile belonging to the group rhynocephalia
Tuatara
These are endemic of nz. They have a pronounced third eye involved in circadian and seasonal cycles
Which is the largest order?
What animals are in this order?
Squamata
Snakes. Lizards and worm lizards
Reptiles are ectothermic (rely on external sources of heat). They have a slower metabolism. They utilise mainly aerobic respiration but can switch to anaerobic if extra energy is needed. What’s the consequence of this?
Build up of lactate. Little ok as dealt with by buffering system but too much leads to lactic acidosis
What 4 things does metabolism depend on?
Diet and feeding behaviour
Size
Body temperature
Species
Describe thermoregulation in reptiles
Thermoregulation is controlled by the hypothalamus, specifically the pre optic nucleus.
Blood passes from the heart to the hypothalamus via the internal carotids.
Appropriate behavioural mechanisms can then be undertaken.
Heliothermy= direct solar radiation
Thigmothermy= contact with warm object
What other things are altered for thermoregulation?
Heart rate
Vasodilation/constriction
Lungs bypassed by shunt to reduce heat loss by evaporation
Behavioural means- position, shape, burrowing, pigmentation
What are UVA and UVB important for?
A- stimulates reproductive behaviour in lizards
B- important for calcium metabolism
What factors triggers hibernation?
Temp Size/weight Photoperiod Reproductive cycle Food availability
Why is hibernation important?
Triggering reproduction activity
Maintaining normal thyroid activity
Describe the process of hibernation?
Withhold food for 2 weeks before to ensure nothing in gut that will ferment, reduce temperature, check and weigh regularly. Hibernate from November through to march. When waking up, bathe in water water to encourage drinking and expulsion of faeces.
Give some facts about the skeletal system of reptiles
Not Haversian canal system
Bone healing slow
When dealing with fractures must correct nutritional deficiencies
Chelonions and snakes have modifications to their axial and appendicular skeletons
Chelonions, snakes and crocodiles never stop growing- growth plates never shut
Lizards growth plates do shut, but later on
What happens when plasma ca levels are unsufficient to support neuromuscular activity?
PTH mobilises calcium from the bones
This is why you see lizards with metabolic bone disease
On X-rays bones appear clear rather than white
Name the three skull types, how do they differ? What species have each?
Anapsid = no temporal fenestrate = Chelonia
Synapsid = 1 subtemporal fenestrae
Diapsid= supra and subtemporal fenestrae= snakes, lizards, crocs, tuatara
How would you describe a snakes skull?
Kinetic
Has moveable joints between upper and lower jaw
What does ecdysis mean?
Skin shedding
Name the layers of the skin compared to normal
3 layers opposed to 5: stratum corneum, intermediate layer, stratum germinativum, stratum basale
5: cats love gravy so bad= corneum, lucidium, granulosum, spinosum, stratum basale
What controls ecdysis?
The thyroid
What does dysecdysis mean?
What is the usual cause?
Name 2 things ecdysis requires
Failure to shed
Husbandry
Humidity and shedding surface
What tube would you use to take reptiles blood?
When doing a smear, you’d use edta- why would you not use this with reptikes?
Lithium heparin
EDTA can lyse RBCs
How many chambers are there in the reptile heart?
Except which? Which is this similar to?
3
Crocodiles have 4= same as mammals and birds
There are 2 Atria and 1 ventricle, but the ventricle is split into 3 by muscular ridges, name the parts
Cavae arteriosum, pulmonae and venosum
Think veins, arteries and lungs
What two things keep mixing of oxygenated and deoxygenated blood in this ventricle to a minimum?
Timing of contractions
Division of chambers
What happens when reptiles breath hold?
Pressure in lungs increases
Therefore blood bypasses the lungs and passes into aortic arch
This has implications during anaesthetics
Which veins drain the hindlimbs?
External Iliac veins
The external iliac veins drain into the _________, this goes directly into the ________.
What 2 things need to be considered because of this?
Renal portal vein
Kidney
Drugs injected can’t be nephrotoxic and may be flushed out before they have even had a chance to take effect
Most reptiles have an easy to visualise larynx and paired lungs- except which? Which lung is Vestigal?
Snakes
Left is Vestigal!
The functional unit in mammals is called the alveoli- what’s the functional unit in reptiles called?
Describe the lung itself
Faveoli
Lung is a simple sac structure with a reticular pattern of ridges which increases surface area for gas exchange
(Ridges to inc SA cf to alveoli)
Name 3 other things that the respiration system aids with except respiration
Vocalisation
Display (think jurassaic park)
Buoyancy
Name the 3 phases of respiration
Expiration, inhalation and rest phase (can last long periods)
What is the controlling factor for respiration?
Temperature
With increased temperature, oxygen demand increases and pulmonary resistance reduces
What things help with prehension?
What glands are found in the oral cavity?
Which species have no teeth?
Tongue, jaw etc.
Mucus secreting to help snakes swallow whole, some glands are modified into venom glands
Chelonions
The structure of the reptile tooth is the same as mammals e.g. Cementum/enamel etc. How is it different thought?
No periodontal ligament
Name and explain the three tooth types
Acrodont= water dragon/chameleons= attached to surface, easily damaged
Pleurodont= attached to medial aspect of bone,lateral eroded away= snakes etc.
Thecodont= crocodiles only. Like mammal tooth but no periodontal ligament
What’s the process called by which teeth are replaced throughout life
Polyphydonty
The egg tooth is used for rupturing the leathery egg and rupturing membranes, what’s it called in chelonions and crocodiles compared to snakes and lizards?
Egg caruncle
Modified Maxillary tooth
Chelonions don’t have teeth, how do they eat?
Hard keratinous beak
Name 3 things that effects rate of digestion
Temp (stops if drops below 7degrees)
Diet (herbivore diet takes longer to digest)
Health status (decreased rate if poorly)
Do reptiles have a gall bladder?
Yes
What does the reptiles GI tract end in?
Name the parts
Cloaca
Copradeum, urodeum, proctodeum (remember cup, faeces, urine/repro, common)
What’s the end product of protein catabolism?
Uric acid
Where do you find the kidneys?
Caudal coelomic cavity
Name 3 things reptile kidneys don’t have that mammals do
Renal pelvis
Renal pyramids
Loop of Henle
(They have the tubules- nothing else!!!)
Do reptiles have a bladder?
No!!!
Except chelonions!!!! They do!
Name some ways reptiles conserve water
Not much by kidneys but instead use:
Cloaca reflux
Reduced GFR
Renal portal system
Eggs are water proof but what do they allow?
Some gas exchange
Females can have babies ages later when kept alone. This is because sperm can be stored for long periods of time. Is fertilisation external or internal?
Internal
In oviparous species, what’s the benefit of the yolk?
Nutrient for neonates
What does viviparous mean?
Eggs hatch internally
During development, which 2 things determine the sex of the reptile?
Sex chromosomes and temperature
Deprive where you would find the testes?
Internally
The right one is near the vena cava
The left one is near the adrenal gland
These increase in size during the breeding season
How do penis’ differ in reptiles?
Lizards and snakes have paired extracloacal hemipenes which are everted during mating
Chelonia have a single phallus, this develops from the proctodeum (last part) and everts during mating
(Remember double: snakes & lizards)
What’s a common problem with reptile penises?
Prolapse
Like birds, reptiles have many follicles on their ovaries. Name the parts of the oviduct
Infundibulum Uterine tube Isthmus Uterus Vagina
Name the three phases of the repro cycles
Quiescent
Vitelline
Gravid
It’s important to realise that sperm is _________
Stored for years
Describe the snakes eye
Fused transparent eyelids called spectacle.
Light is detected through the eye and the pineal gland is involved
How the the eye of a snake differ to a mammal?
The iris is skeletal muscle rather than smooth muscle
How do snakes detect pheromones?
What other species has this?
Vomeronasal organ
Horses
How do snakes feel?
They have receptors on their tongue and oral epithelium
Which reptile has external eyes?
What do the others have?
Crocodiles
The others have a short eustatian tube and an outer margin tympanic membrane
Describe travel of vibrations in the ear
Down short Eustachian tube to tympanic membrane
Vibrates the membrane
Which vibrates the 1 Middle ear bone called the collumella
To the quadrate bone of the skull
What does the third eye look like?
Not an eye, it’s a modified scale, located on the top of the head between the two lateral eyes
Chelonia have 2 neck shapes, name them, and how do they differs?
Pleurodira= side neck= 3 bends= can’t draw head into shell
Cryptodira= 2 bends= head can go into shell
Are Chelonia heliothermic or thigmothermic
Heliothermic
They bask in the sun
Name the three muscles which give lizards a very strong jaw
Depressor mandible
Pterygoideus
External adductor muscle
