LAB 1: Digestive system and Body Cavities

Question 1

What are the organs in the digestive system from the beginning to the end

Answer 1

Food enters through the oesophagus which connects to the stomach, then goes through the small intestine - duodenum, jejunum and ileum - then to the large intestine - caecum, colon, rectum and anus

Question 2

What are the main differences between rats and humans

Answer 2

Rats lack enamel on posterior dental surface, giving chiselled incisors. They don’t have canines. They don’t have a gall bladder for storing bile and have a y shaped uterus to increase surface area for implantation. Penis is in the abdominal wall. They have 2 parts of the stomach

Question 3

What separates the thoracic and abdominal pelvic cavity

Answer 3

the diaphragm

Question 4

How many ventral body cavities are there in total, which one is in the abdominal pelvic cavity and what are the names

Answer 4

4, 2 pleural cavities for lungs + 1 pericardial cavity for heart + 1 peritoneal cavity for gut which is in the abdominal pelvic cavity.

Question 5

What cells are serous membranes made of and what do serous membranes cavities have inside

Answer 5

Mesothelial cells that secrete serous fluid, serous fluid only

Question 6

What is the difference between the parietal and visceral sides of a serous membrane cavities

Answer 6

The membrane is like a balloon, the side of the membrane that is touching the body wall is called the parietal …eum membrane and the side that is touching the organ is called the visceral …eum membrane.

Question 7

What is the mesentery

Answer 7

A double layer of peritoneum suspending the small intestine, which is continuous with the parietal and visceral peritoneum membrane.

Question 8

How do you tell if a cavity is left or right

Answer 8

You take the orientation from the POV of the patient

Question 9

How is the anterior lateral portion of the stomach different from the medial posterior portion (pyloric) in a RAT stomach

Answer 9

A.L portion is has thin and translucent wall for food storage, first part where the oesophagus comes and then the M.P portion is glandular and opaque, and release acid and digestive enzymes

Question 10

What is the pyloric sphincter

Answer 10

A collar of smooth muscle that controls the flow of chyme into the duodenum

Question 11

Where do the blood vessels supplying the small intestine go and what are they carrying to and from where

Answer 11

Blood vessels in the mesentery, arteries carry high pressure oxygenated blood through 2 dorsal aorta. The veins draining the nutrient laden blood are tributaries of the hepatic portal vein that goes to the liver.

Question 12

What are the two dual purpose glands involved in the digestive system

Answer 12

pancreas and liver

Question 13

What are the two purposes of the pancreas and what it looks like

Answer 13

releases alkaline digestive juice with enzymes into the duodenum as well as secrete hormones for endocrine function. It looks like a piece of fat around lower curvature of the stomach

Question 14

What are the purposes of the liver and what it looks like

Answer 14

Liver produces bile as a byproduct and this aids in the digestion and absorption of fats and vitamins. It also detoxifies blood and has endocrine functions. It is highly vascular, 4 lobes, 2nd largest organ, largest gland.

Question 15

What are the differences between where bile goes in humans vs rats

Answer 15

in humans its stored in gall bladder which has a cystic duct that joins the bile duct to the duodenum but in rats, the hepatic duct joins a common duct with the pancreatic duct to go straight to duodenum

Question 16

What does the spleen look like and what system is it part of

Answer 16

dark red, leaf shaped in rats, behind the stomach

Question 17

What is the purpose of the caecum and what is the difference between rat and human

Answer 17

Caecum is large brown bag where bacteria act on food to break down cellulose. Human caecum terminates into the veriform appendix which has lymphoid tissue but rats lack a true veriform appendix

Question 18

What is the main purpose of the colon

Answer 18

to reabsorb water, with contents becoming firmer at the end. It is has 3 parts in rats

Question 19

Why is the anus said to be under partial voluntary control

Answer 19

It has two layers of muscle in the sphincter- one skeletal and one smooth

Question 20

Where are the kidneys found and what is the special term for this location

Answer 20

Found behind the parietal peritoneum with dorsal surface attached to body wall and ventral surface covered with parietal peritoneum.So it is retroperitoneal.

Question 21

When you cut open the rat which membrane are you cutting through

Answer 21

the parietal membrane

Question 22

In what way are the passageways for air and food orientated in the rat from the anterior

Answer 22

From the anterior : the nasal passages are dorsal to the mouth, and then cross over at the epiglottis where the oesophagus (for food) is dorsal to the trachea

Question 23

What is the epiglottis and its purpose

Answer 23

triangular flap covering the trachea at the glottis (trachea opening). It closes during swallowing to prevent food and water entering the air way

Question 24

Where is the hard palate in relation to the soft palate and what are their functions

Answer 24

hard palate is anterior roof of mouth that bony partition separating the nasal cavity and mouth. Helps the food to be sorted by size. Soft palate is posterior to this and lacks bone.