Reptiles Flashcards
What term is used to describe species that rely on external sources of heat to regulate their body temperature?
Ectothermic
What is thermoregulation controlled by?
Hypothalamus
What are the advantages of being ectothermic?
- Less energy expendure for maintaining body temperature
- Less food requirements
- Ability to better survive hibernation and cool temperature at night
What are the disadvantages of being ectothermic?
- Activity is dependant on the ambient temperature
- Poor aerobic capacity
What is the preferred optimum temperature zone (PTOZ)?
20-38oC
Where would the kidneys be positioned in a reptile and how does this differ from mammals?
Sit more caudal in the pelvic canal region rather than the mid abdomen
True/False
Reptiles and fish have no diaphragm.
True
Therefore they have no clear abdominal and thoracic cavities
What is the name for the body cavity present in all reptiles and fish?
Coelomic cavity
What sits immediately behind the heart in lizards?
Liver
What shape is the stomach of a lizard?
J-shaped
What is autonomy?
The casting off of a body part
(e.g- the tail in lizards)
How many rows of teeth do snakes have?
6
(one on each lower jaw and two on each upper jaw)
What luck is either rudimentary or missing in snakes?
Left
What is the function of the cranial portion of the right lung in snakes?
- Vascularised function
- Gas exchange
What is the function of the caudal part of a snakes lung?
Has non-respiratory functions and functions mainly as an air sack
What organs may be fused in some species of snake?
Gall bladder, spleen and pancreas (splenopancreas)
Is the gall bladder attached to the liver in snakes?
No
Splenopancreas forms a little triad that is seperate from the liver
True/False?
The kidneys are lobulated in the snake.
True
Since snakes have no urinary bladder what do the ureters empty into?
Urodeum of the cloaca
How many hemipenes do snakes have?
2
Why are reptiles more prone to respiratory infections?
The primitive mucociliary lining is poor at cleaning debris
True/False
Snakes have a small lung size but have a larger surface area and more subdivision.
False
snakes have a large lung size but have a limited surface area and less subdivision
What effect does an increase in temp have on O2 demand?
Increases O2 demand
What is the name of the top of a chelonians shell?
Carpace
What is the name of the bottom of a chelonians shell called?
Plaston
What are scutes?
A thickened horny or bony plate on a turtles shell.
Is mouth breathing in chelonians normal?
NO!
Mouth breathing is completely abnormal
Where are the lungs located in chelonians?
Expand over most of the dorsal half of the coelomic cavity
What divides multichambered lung fields in chelonians?
Trabeculae
What are ediculi?
Wider and flatter alveoli
What % of a tortoises body weight is taken up by its bladder?
25%
How do the lungs expand and contract in chelonians?
Movement of the legs (mostly front limbs)
(thats why their cranial end should be elevated under GA if possible)
Why is it difficult to gaeously anaesthetise chelonians ?
They can easily switch over to anaerobic respiration
How many chambers does a reptiles heart have?
3
(2 atria, 1 ventricle)
What are 3 cavities within the ventricle of a reptile heart?
Cavum Arteriosum
Cavum Venosum
Cavum pulmonale
What part of the ventricle recieves oxygenated blood from the left atrium?
Cavum arteriosum
What part of the ventricle recieves deoxygenated blood from the right atria?
Cavum venosum
What veins pump is deoxgenated blood into the sinus venosus?
Left and right precaval veins
Left hepatic vein
Post caval vein
What is the function of the sinus venosus?
Contains pacemaker cells and aids with filling of the right atrium
What vein delivers oxygenated blood from the pulmonary circulation into the left atrium?
Pulmonary veins
Describe the flow of deoxygenated blood during respiration in the reptile.
Deoxygenated blood from general circulation is pumped via the left and right precaval veins, left hepatic vein and post caval vein into the sinus venosus.
It moves from the right atrium into the cavum venosum then the cavum pulmonale
Ventricular systole initiates contraction of the cavum venosum pushing blood from the venosum and pulmonale into the pulmonary circulation (via the pulmonary artery)
Describe the flow of oxygenated blood during respiration in the reptile
Oxygenated blood is delivered from the pulmonary circulation via the pulmonary veins into the left atrium.
From the left atrium it moves into the cavum arteriosum.
The AV valve then closes over and blood is directed into the cavum venosum and out via the left aorta (straight into the general circulation) and the right aorta (CNS first then into the general circulation).
During periods of apnoea what artery is constricted?
Pulmonary artery
What does constriction of the pulmonary artery result in?
Raises pressure in the pulmonary circuit which causes a R to L shift.
Increased pressure in the cavum pulmonale which then pushes blood into the cavum venosum. The blood then leaves mainly via the left aorta into systemic circulation.
Why is IM or IV induction of anaesthesia preferred over gaseous induction?
To prevent the ‘dive response’ being initiated
In reptiles where is blood from the tail and hindlimbs passed to before systemic circulation?
Kidneys
Why should drugs be injected into the cranial half of reptiles and not the caudal half?
Reduces the risk of nephrotoxicity and RPS
Why might the RPS be activated?
If the patient is ill or dehydrated
True/False?
Reptiles have nucleated red blood cells.
True
How long can red blood cells last for in reptiles?
800 days
(very slow turnover)
What blood tubes can cause haemolysis in some species so should be avoided?
EDTA tubes
What blood tubes should be used in reptiles for haematology and biochemistry?
Heparin tubes
Where are the preferred venepuncture sites for Chelonians?
Jugular and Subcarapacial sinus
Where are the preferred venepuncture sites for lizards?
Jugular and ventral tail vein
What is the preferred venepuncture site?
Ventral tail vein
What % of body weight does blood volume make up in reptiles?
5-8%
What % blood volume can be sampled safely in reptiles?
10%
What type of glands are the venom glands that are present in snakes?
Modified labial glands
How many times does a snakes metabolism increase by when it ingests a prey item?
40 times
How long does a snake take to fully ingest a meal?
4-5 days
What 3 chambers make up the cloaca in reptiles?
- Urodeum
- Coprodeum
- Proctodeum
What is the function of the coprodeum?
Collects faeces
What is the function of urodeum?
Drains ureters and reproductive tract
What is the function of the proctodeum?
Common for excretion
What is the cloaca in reptiles?
Common exit for the digestive, repro and urinary systems
Why do reptiles not produce hypertonic urine when they are dehydrated?
Lack of loop of henle, pyramids and cortex
Where do the ureters enter into in reptiles?
Urodeum
What is the name for the paired penises in the snake?
Extracloacal hemipenes
What is the name of the chelonian penis?
Intracloacal phallus
What is the function of the oviduct in reptiles?
Transports egg and secretes albumin, protein and calcium for the formation of egg shells
Where do reptiles vaginas open into?
urodeum of cloaca
What are the 3 ovarain cycles of reptiles?
- Quiescent
- Vitelligenic
- gravidity/ pregnancy
What happens during the vitelligenic cycle?
- Hypertrophy of ovaries/ oviduct
- Yolk is transported from liver through the blood stream to the ovarian follicles
- Increased circulating calcium levels
What is oviparity?
Eggs are laid quite early after fertilisation
What species is oviparity seen in?
Chelonians, pythons, colubrids, iguanas, monitors and geckos
How many clutches of eggs are laid during the breeding season by species which show oviparity?
2-3 clutches
What is viviparity?
Development of embryo inside the body of the mother
What are the advantages of vivparity?
- Some nutritional exchange through the placenta.
- Proper development so better chance of survical especially in colder climates
What are the disadvantages of viviparity?
- Reproductive rate is reduced (1 clutch per season)
- Gestation can last 6 weeks - 6 months
- Developing young compress the maternal gastrointestinal system which leads to decreased capacity for food and a reduction in body weight.
Give examples of species that show vivparity.
Boas, vipers and some chameleons and skinks
Why is there a high bicarbonate level in chelonians?
Allows them to buffer high lactic acid accumulation when they are in an anaerobic state
What does the amniotic membrane cover?
Embryo
What is the function of the allantois membrane?
Storage of urea/uric acid
What does the chorionic membrane cover?
Inside of the egg
What provides a source of calcium for the embryo?
shell
What reptiles have no tympanic membrane?
Snakes and chameleons
What is the name of the paired accessory organ present in all reptiles that detects odour particles and pheromones?
Jacobsons organ
What is the Jacobsons organ innervated by?
vomeronasal nerve
What are the 4 living orders of reptile?
Crocodilia
Sphenodontia
Squamata (snakes and lizards)
Testudines (terrapins and tortoises)
What reptile is an exception to being an ectotherm?
Female python when brooding eggs
What are problems that reptiles might face due to being exposed to suboptimal temperatures?
- Immunosuppression leading to infection
- Change in behaviour
- Lethargy
- Increase in basking time
- stress
- reduced appetite/ reduced drinking
- Reduced metabolism leading to poor growth and poor wound healing/ drug absorption
What is a preferred heat source for diurnal reptiles?
Basking light
What is a preferred heat source for nocturnal reptiles?
Heat pad
What should the hot end of the temperature zone be for reptiles?
32-35oc
(up to 40oC in bearded dragons)
What should the cold end of the temperature zone be for reptiles?
25oC
During the night the difference in temp should be no more then what for reptiles?
5 oC
What light should be provided in a reptiles indoor enclosure?
- White light
- UV light
Why is UVb light exposure important in reptiles?
It is important for calcium absorption
Where should a UV light be placed in order for it to actually benefit a reptile?
- Should be placed 20-30cm away from the animal
- Should be inside he enclosure itself
- Should be placed near a heating source because warm skin activates the entire processs of vit D3 production
What type of supplementation is required for reptiles that are herbivores or insectivores?
Calcium supplementation
What supplements are neccessary for absorbing calcium from the gut?
Vit D3 supplements
What leads to metabolic bone disease?
Calcium deficiency
What might an animal with metabolic bone disease have?
- Flat carapace
- deformed soft shell in tortoise
- beak deformity
- poor bone density
What reptiles can only drink from running water?
Chameleons
What type of tortoise has no spurs and has a pointy tail?
Hermann’s tortoise
(testudo hermanni)
What type of tortoise has spurs and a rounded tail?
Spur-thighed tortoise
(testudo graeca)
What type of tortoise has a pointy tail, spurs and a lighter shell colour?
Horsfield tortoise
(testudo horsfieldii)
What is the 3rd largest tortoise in the world?
African spurred tortoise
(geochelone sulcata)
What are differences that can be seen between male and female and tortoises?
Males have a longer tail and their cloaca is positioned distally near the tip of the tail whereas females have a shorter tail and their cloaca is positioned close to the body.
There is plastron concavity in males.
Males have a penis situated in the ventral midline of cloaca.
What reptile is a vivarium not appropriate for?
Tortoise
(they should have an open top enclosure)
True/ False?
Tortoises are herbivores.
True
Why should iceberg lettuce be avoided?
Inverses the Ca:P ratio
What age or size should hibernating mediterranean tortoises be?
Older than 2-3 years or longer than 10cm
What temperature should hibernating tortoises should be kept at?
4 oC
