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