Rat dissection 1: external features, alimentary canal and associated vasculature Flashcards
Laboratory rat
Rattus norvegicus
Aboral
The end opposite the mouth
Oral
The end containing the mouth
Anterior
The head end:
Usually the end of a thinner animal that meets the environment
Posterior
The tail end
Caudal
Toward the tail
Cephalic
Toward the head
Distal
Away from the point of attachment of a structure on the body
(E.g the toes are distal to the knee)
Dorsal
The back of an animal, usually the upper surface, synonymous with posterior for animals that walk upright
Ventral
The belly of an animal, usually the lower surface, synonymous with anterior for animals that walk upright
Inferior
Below a point of reference
E.g. the mouth is inferior to the nose in humans
Superior
Above a point of reference
E.g. the head is superior to the neck
Lateral
Away from the plane that divides a bilateral animal into mirror images
Medial (median)
On or near to the plane that divides a bilateral animal into mirror images
What is the buccal cavity
The area inside the mouth bound
- anteriorly & laterally by the lips and cheeks
- posteriorly and medially by the teeth and/or gums
- also know. As the oral vestibule
Which two cavities are separated by the roof of the mouth?
Oral cavity separated from nasal cavity
Dental formula of rat
1 0 0 3
Dental formula for human
2 1 2 3
Deductions from dental formula of rat
- large incisors made from hard enamel = teeth are for biting hard substances such as vegetables and seeds
- molars at back of mouth = chewing
- no canines or premolars, thus not designed to tear or chew meat
- designed for herbivorous environment
Deductions from dental formula of human
- Humans have incisors and molars = nite and chew harder foods - vegetables
- humans adapted for omnivorous diet
Which system do the lymph nodes belong to
The lymphatic system
Function of lymph nodes
- Form part of the immune response
- filter blood and create lymphocytes which attack pathogens in our blood
What is the function of the Harderian gland?
- photo protective organ
- locomotion of immune response
- source of thermoregulatory lipids
- source of pheromones
- site of osmoregulation
- lubricant of eye and nictitating membrane (third eyelid)
Function of the pectoralis membrane
Enables the movement of the arms towards the body
Do rats have a gall bladder?
Explain.
No
Rats do not have a gall bladder as they do not need to store bile
- bile is secreted directly from the liver into the small intestine via the hepatic bile duct
Function of cardiac region of stomach
Prevents reflux back up to the oesophagus
Function of pyloric region of the stomach
(Specifically pyloric sphincter)
Prevents food from exiting stomach until lit has been sufficiently digested and broken down
Function of the caecum
- absorbs water & salts from undigested foods after intestinal digestion
- mixes it with mucus for lubrication
Why don’t humans have a caecum?
- in herbivores: caecum stores food material where bacteria are able to break down the cellulose
- function no longer occurs in human caecum
- (in humans) deadened pouch forming part of the large intestine
What is the function of the spleen and to which organ system does it belong?
- filters bloods
- aids in homeostasis of bodily fluids
- aids in immune system
- forms part of lymphatic system in the body
What does it mean if a vessel is unpaired?
The vessel does not have a matching branch
What is the function of the hepatic portal vein
- carries deoxygenated blood from digestive organs and spleen to liver
Function of mouth
- site of ingestion
- where saliva and teeth break down food
Oesophagus
- pathway of boils between mouth and stomach
- movement through peristalsis
Liver
- Provides bile
- used to emulsify fats
Stomach
- chemically and mechanically breaks down the bolus further
Gallbladder
Bile storage
Pancreas
Secretes pancreatic juices
Large intestine
Pathway for chyme to allow for absorption of water from chyme
Small intestine
Absorption of nutrients
Appendix
Storage of good/ ‘helpful’ bacteria
Rectum
Intermediate storage of feces
Anus
Region through which feces exit the body
