Avian and Reptilian GI and Urogenital tracts Flashcards
What are the components of the avian GI tract?
- mouth
- oesophagus
- crop
- proventriculus
- ventriculus (gizzard)
- intestine
- caeca
- rectum
- cloaca
What is the difference between avian organs and mammalian?
- large number of organs with greater number of interorgan cooperation than mammalian counterparts
Describe the mouth of an avian - in terms of digestion:
- rapid transit of food through the mouth
- lack of mastication and relatively low addition of saliva
- low number of taste receptors results in poor taste acuity
Describe the oesophagus in avian’s:
- oesophagus extends down the neck into the thoracic cavity and is expandible due to series of longitudinal folds
What do the longitudinal fold in the oesophagus allow for?
- can stretch lengthways to accommodate prey (owl)
The oesophagus widens into the crop just before entering the thoracic cavity - what does the crop allow for?
- bird can constantly have a supply of food in some species (seed eating)
- owls have no crop
What issues can occur in the crop?
- crop impaction
- sour crop when food isn’t passing usually due to a GI issues further down the tract
What is present in the proventriculus - glandular stomach?
- tubular glands = secrete mucous
- gastric glands = secrete HCL and pepsinogen
What is the structure and what happens in the ventriculus - muscular stomach?
- 2 pairs of smooth muscles arranged in distinct bands that both originate and terminate on a circular tendon
- can have grit here to aid in mechanical digestion
Describe the duodenal loop of the intestines in birds:
- encircles the pancreas and receives the pancreatic and hepatic ducts (empty here)
Describe the jejunum and ileum in birds:
- they are not clearly demarcated
Where does the short colon in birds empty?
- into a pair of caeca
What can food do in birds?
- move between both ventriculus and proventriculus
Raptors can regurgitate food - where does the regurge come from?
- from the proventriculus
What are the caeca like in psittacine and passerines and then in domestic birds?
- 2 distinct caeca
- psittacine and passerines = vestigial
- domestic birds - very well developed
What does the rectum extend between in birds?
- extends between the ileocecal junction and the cloaca
What is the cloaca?
- the terminal junction into which digestive tract and urogenital ducts empty
What are the accessory organs to the GIT in some species of birds?
- liver
- gall bladder (not all species)
- pancreas
What type of teeth do snakes and lizards have?
- acrodont - on summit of piece of bone and are an extension of this bone
What are the teeth like in non-venomous snakes?
- have teeth on 4 sets if bones
- maxilla, dentary, palatine and pterygoid bones
How do the palatine and pterygoid allow for larger prey to be taken in?
- separate bones moving independently if each other allowing prey to be ratcheted into mouth
- there is no dislocation of the jaw
- bones are joined by ligaments
What limits the size of prey snakes can take in?
- the size of the skull
In a normal resting state what is the glottis like in snakes ?
- always closed
What can the snake di with its glottis while feeding?
- snakes can extend glottis out the side of their mouth while eating to allow for respiration
