ANATOMY - Reptiles Flashcards
Which central structure regulates temperature in ectotherms?
Hypothalamus
What is the preferred optimal temperature zone (POTZ) for most reptiles?
20 - 38°C
What is the main advantage of being ectothermic?
Lower energy requirements
What is the main disadvantage of being ectothermic?
Activity dependent on ambient temperature
Which species’ does chelonian refer to?
Tortoises
Turtles
What is the chelonian shell made up of?
The chelonian shell is made up of dermal bone
Which four anatomical features is the dermal bone of the chelonian shell fused to?
Spine
Ribcage
Pelvic girdle
Pectoral girdle
What is the name for the top of the chelonian shell?
Carapace
What is the name for the bottom of the chelonian shell?
Plastron
What is the name of the external plates on the chelonian shell?
Scutes
Name the carapace scutes
Name the plastron scutes
What is autotomy?
Autotomy is the self-amputation of the tail of a lizard when they feel as if they are under threat
Which breed of lizard doesn’t grow their tail back following autotomy?
Crested gecko
Which breed of lizard does grow their tail back following autotomy?
Leopard gecko
Why can undergoing autotomy cause further health issues in leopard geckos that are already ill?
Leopard geckos use their tails as a fat store
Why do reptiles only have a single body cavity?
Reptiles only have a single body cavity as they do not have a diaphragm
What is the name of the single body cavity present in reptiles?
Coelomic cavity
What are the three chambers of the reptilian heart?
Left atrium
Right atrium
Ventricle
What are the three functional divisions of the reptilian ventricle?
Cavum arteriosum
Cavum venosum
Cavum pulmonale
What is the function of the cavum arteriosum?
Cavum arteriosum receives oxygenated blood from the left atrium
What is the function of the cavum venosum?
Cavum venosum receives deoxygenated blood from the right atrium
What is the function of the cavum pulmonale?
Cavum pulmonale receives deoxygenated blood from the right atrium via the cavum venosum and directs the flow into the pulmonary circulation
Describe the flow of deoxygenated blood during normal reptilian respiration
Deoxygenated blood flows from the systemic circulation via the hepatic vein, left and right precaval veins and post caval vein into the sinus venosus. Blood flows from the sinus venosus into the right atrium, to the cavum venosum, to the cavum pulmonale, to the pulmonary trunk and into the lungs
Describe the flow of oxygenated blood during normal reptilian respiration
Oxygenated blood flows from the pulmonary veins to the left atrium, to the cavum arteriosum, to the cavum venosum and to the left and right aorta. The blood that flows into the left aorta flows directly into the systemic circulation and the blood that flows into the right aorta is transported to the central nervous system followed by the systemic circulation
What is reptile apnoea?
Reptile apnoea is the suspension of breathing through removing their pulmonary circulation from general circulation
How do reptiles cut off their pulmonary circulation from general circulation during apnoea?
When reptiles enter apnoea, their parasympathetic tone increases causing vasoconstriction of the pulmonary trunk. This leads to increased blood pressure within the cavum pulmonale causing the blood to be pushed back into the cavum venosum and shunted into the left aorta and the systemic circulation - essentially cutting off their pulmonary circulation
How should reptiles be anaesthetised?
Reptiles cannot undergo gaseous induction as they will enter apnoea so intravascular or intramuscular induction should be carried out instead. Once the animal is under general anaesthesia, they can be maintained using gaseous anaesthetic as their parasympathetic tone will be lost and they can no longer enter apnoea
How does the renal portal system maintain renal tubular function in reptiles?
The renal portal system transports blood from the hindlimbs and the tail directly to the kidneys before the systemic circulation
Why should you only inject the cranial half of the body in reptiles?
Injecting drugs at the caudal end of the body can cause drugs with renal excretion or nephrotoxic drugs to have a direct effect on the kidneys due to the renal portal system and thus only cranial injections should be carried out in reptiles
What is the structure of reptile erythrocytes?
Reptiles have large, nucleated erythrocytes
What are the two reasons for using heparin tubes for blood sampling reptiles?
- EDTA tubes cause haemolysis in some species
- Heparin can be used for haematology and biochemistry, reducing the volume of blood required for a full profile
What are the two preferred venepuncture sites for chelonians?
Jugular vein
Subcarapacial sinus
What are the two preferred venepuncture sites for lizards?
Jugular vein
Ventral tail vein
What is the preferred venepuncture site for snakes?
Ventral tail vein
What are the two anatomical features that make reptiles so prone to respiratory infections?
Lack of diaphragm and thus no coughing reflex
Primitive mucociliary lining of the respiratory tract
Which structure separates the lungs from the rest of the coelomic cavity in chelonians (tortoises)?
Horizontal septum
How is respiration achieved in chelonians (tortoises)?
Tortoises cannot expand their body wall when breathing due to the rigidity of their shell so respiration is achieved through muscular movement of the limbs