Lecture 8 Gi Tract

Question 1

Intraperitoneal organs

Answer 1

Stomach
Transverse colon
Small intestine

Question 2

How many layers of smooth muscle does the muscularis externa of the stomach have?

Answer 2

Three

(From inner (mucosa) to the outer layer)

1. Oblique muscle layer
2. Circular muscle layer
3. Longitudinal muscle layer

Question 3

What is the small intestine responsible for?
How long is the small intestine ?

What is the small intestine comprised of and how long are these bits?

Answer 3

Absorbing most nutrients over at least a 12 hour period.

6m long thin-walled tube from pylorus of the stomach to the cecum of the large intestine.

1. Duodenum (25cm)
2. Jejunum (2.5m)
3. Ileum (3.6m)
   Distal end terminated at the ileocecal valve, a sphincter that controls the entry of materials into the large intestine.

Question 4

Large intestine (colon) 
How long is it?
Name a characteristic and what does it do.

Answer 4

Large intestine 1.5m long
- absorbs most of the water, electrolytes, some nutrients from the remaining digested material to solidify the feces.

• stores fecal material until ready to shit out (defecate)
• has haustra. Collapses and expands
• Tenia colia (3 longitudinal bands of smooth muscle on outersurface of colon)

Question 5

Large intestine

Rectum

Answer 5

Large intestine. Opening of rectum. Anus.

Internal anal sphincter - rings of smooth muscle.

External anal sphincter - rings of skeletal muscle.

Question 6

Acessory digestive organs: the liver

Answer 6

Located inferior to the diaphragm
Causing doming on right side

receives arterial blood via hepatic artery and portal blood via hepatic portal vein which mix in the hepatic sinusoids

Question 7

What the hell is hepatic sinusoids?

Answer 7

Mixes oxygen rich and nutrient blood together.

From hepatic artery and hepatic portal vein respectively.

Question 8

What role does a liver have.

4 roles

Answer 8

1. Haematopoiesis
2. Detoxification
3. Vitamin storage
4. Metabolism

Question 9

Accessory digestive organs: gallbladder

Answer 9

• located inferior and posterior to the right lobe of the liver.
• concentrates bile produced by the liver and stores 40-60ml of this concentrate until it is needed for digestion
• participates in the bilinary system. Transports bile to duodenum

Question 10

Of small intestines which part has the widest lumen?

Answer 10

Duodenum