Major Organs

Question 1

Stomach

Answer 1

Sphincters: The sphincters are a muscular valve that prevents the acid-soaked food from going back up the esophagus.
Stomach is the main area for protein absorption beacuse of the fact that it contains pepsin - which breaks down protein.
- The stomach also performs peristalsis - the churning and mixing of the food (mechanical digestion)
- At the end of the stomach the food is a semi-liquid material (chyme)
- Food spends about 2-6 hrs in the stomach

Question 2

2 types of sphincters

Answer 2

• Lower esophageal sphincter
  Prevents the acid-soaked food from going back up the esophagus
• Pyloric sphincter
  Helps push the food into the small intestine from the stomach when the food is ready

Question 3

Chemical digestion in the stomach

Answer 3

Nerve cells detect the food - nerve cells withdraw a hormone called gastrin into the bloodstream - release gastric juices (2L per day) in the stomach

The acid in the gastric juices kills harmful microorganisms - which stop the amylase from working and actives pepsinogen (the active form of pepsinogen is pepsin)

• the HCL in gastric juices converts pepsinogen into pepsin -which breaks down protein into amino acids
• Only happens when protein is made

Question 4

What do gastric juices contain

Answer 4

HCL, mucus, and digestive enzymes

Question 5

Small intestine

Answer 5

• Spiral organ about 6-7m long
• Peristalsis mixes the food that remains in the small intestine - for about 2-6 hours

Question 6

Duodenum

Answer 6

• The first part of the small intestine
• Receives secretions from the pancreas, liver, and gallbladder

Question 7

Absorption in the small intestine

Answer 7

occurs in the small intestine (jejunum and ileum)
The small intestine is lined with villi
- Each villus contains microvilli and this increases the surface for absorption (by a factor of 500)
- Once absorbed, nutrients enter the bloodstream via the capillary networks in the villi.

Question 8

Lacteal

Answer 8

Fats enter the lymphatic system via lacteals (eventually into the blood stream)

Question 9

Large intestine

Answer 9

• Cecum - pouch at the beginning of the intestine
  Colons - Ascending, transverse, descending.
  Rectum
  Anus

No absorption happens in the large intestine only some absorption of water and nutrients

• All the waste that is not for energy production gets moved into the large intestine - which consists of dead cells, mucus, digestive secretions, bacteria, and yeast.

Question 10

Bacteria in the large intestine

Answer 10

Makes compounds such as vitamin K and B
by-product of bacteria is gas
Most of the gas in absorbed but some of it can in escape (farting)
The amount of gas is based on the food eaten.
_ Aids in compacting undigested materials into feces.

Question 11

Rectum

Answer 11

• Final segment of the large intestine
• Solid feces pass through the rectum by peristalsis