Flashcards in Lab 1: Rat Dissection Deck (69)
List the main internal differences between rats and humans.
How are the teeth of rats different to those of humans?
Adapted for gnawing. The paired incisors grow throughout life and lack enamel on their posterior surfaces, so that rapid wear of the posterior surface produces a characteristic chisel shape. Rats do not have canines because they are herbivores.
How do the jaws of rats differ from humans?
The lower jaw (mandible) is in two pieces, hinged in the middle. The spacing between incisors can be varied at will.
At what age are rats full grown? What is their life span?
How do the fore and hind limbs of rats compare to humans?
Both have pentadactyle fore and hind limbs.
Compare the tails of rats and humans.
Rats use their tails for balance. Human embryos possess a distinct tail but do not retain it through fetal life.
What is special about rat nostrils?
The nares can be closed under water.
How are the long hairs on the faces of rats useful?
The vibrissae are tactile organs which allow the rat to navigate confined spaces in the dark.
Describe the genitalia of male rats
The scrotum, which contains the testes is seen near the anus. Anterior to this is the prepuce, a skin fold concealing the glans of the penis.
How are male rat genitalia different to that of other primates?
In primates the penis is external tot he body wall for most of its length but in rats, the flaccid penis is contained within the abdominal wall.
Describe the genitalia of female rats.
Vaginal opening is in front of anus. Urethral opening is on the tip of a papilla anterior to the vagina.
What is meant by a papilla?
A small, rounded protuberance in a part or organ of the body.
Which membrane is bonded to the abdominal wall? What does it surround?
Peritoneum surrounds the peritoneal cavity.
What is the name of the peritoneum covering the abdominal wall?
What is the parietal peritoneum continuous with? What does it do?
A double layer of peritoneum called a mesentry. It suspends the intestines.
What is the name of the peritoneum covering the intestine?
What are the four ventral body cavities?
Two pleural cavities
What type of organ is the thymus gland? What is its function?
Lymphoid organ which has a role in the formation of T-lymphocytes. Also secretes hormones important in the development of other lymphoid tissues.
Why is the gut tube long?
In order to increase surface area for absorption and secretion.
What are the three tubular portions of the gut?
Oesophagus, small intestine, large intestine
What are the two sacs of the gut?
Stomach and caecum
What happens to the contents of the gut in the sacs?
It temporarily comes to rest.
Where does absorption and secretion occur in the gut tube?
Everywhere downstream of the oesophagus.
What other structures secrete into the gut?
Two large glands (liver and pancreas)
Which side does the stomach mostly lie on?
The left side
What are the two types of curvature?
Greater and lesser
Where does the oesophagus enter the stomach?
Part-way along the lesser curvature.
What are the dimensions of the small intestine?
Four body lengths from inlet to outlet.
What are the three regions of the small intestine?
Duodenum, jejunum and ileum entering the caecum