Body Systems: Digestion (Digestion)

Question 1

The small intestine is composed of 3 sections:

Answer 1

Duodenum, Jejunum, Ileum.

Question 2

In what part of the small intestine does most digestion occur?

Answer 2

In the Duodenum.

Question 3

Chyme (from stomach) moves through the small intestine by:

Answer 3

Peristalsis.

Question 4

Small intestine (Physical digestion)=

Answer 4

Segmentation= chyme sloshing back and forth.

Question 5

Ridged inner lining of the small intestine are covered in tiny projections called:

Answer 5

Villi, which are covered in micro villi.

Question 6

What do villi and micro villi do?

Answer 6

Increase the surface area of the small intestine.

Question 7

Each villus is supplied with:

Answer 7

Capillary networks and lymph vessels called lacteals.

Question 8

What do capillary networks do?

Answer 8

Allow fluid and gas exchange to occur with blood stream.

Question 9

What do lacteals do?

Answer 9

Transport products of fat digestion.

Question 10

The pancreas:

Answer 10

Releases enzymes to the small intestine.

Question 11

Enzymes chemically digest:

Answer 11

Proteins (trypsin), carbs (amylase), lipids (lipase).

Question 12

Protein digestion in the small intestine (1):

Answer 12

Chyme enters the small intestine soaked in HCl and pepsin (from gastric secretions). The HCl triggers the conversion of the hormone prosecretin into secretin.

Question 13

What is secretin?

Answer 13

Secretin: tells pancreas to release bicarbonate ions (HCO3-).

Question 14

Protein digestion in the small intestine continued (2):

Answer 14

Bicarbonate ions (HCO3-) —> to increase the pH from 2.0 to 9.0 (becomes more basic).
-Secreted from pancreas.
-Basic pH inactivates (released in stomach).

Question 15

Protein digestion in the small intestine continued (3):

Answer 15

Trypsinogen —> gets converted into trypsin by the enzyme enterokinase. (Secreted from small intestine).
-Secreted from pancreas.
-Chemical digestion of long chain proteins.

Question 16

What’s the full process of protein digestion in the small intestine:

Answer 16

1.Chyme enters the small intestine soaked in HCl and pepsin (from gastric secretions). The HCl triggers the conversion of the hormone prosecretin into secretin. Secretin: tells pancreas to release bicarbonate ions (HCO3-). 2.Bicarbonate ions (HCO3-) —> to increase the pH from 2.0 to 9.0 (becomes more basic).
-Secreted from pancreas.
-Basic pH inactivates (released in stomach).
3.Trypsinogen —> gets converted into trypsin by the enzyme enterokinase. (Secreted from small intestine).
-Secreted from pancreas.
-Chemical digestion of long chain proteins. 4.Erepsin —> completes the protein digestion by breaking down shorter chain peptides and converting them into amino acids.
-Secreted by both the pancreas and the small intestine.

Question 17

Protein digestion in the small intestine continued (4):

Answer 17

Erepsin —> completes the protein digestion by breaking down shorter chain peptides and converting them into amino acids.
-Secreted by both the pancreas and the small intestine.

Question 18

Carbohydrate digestion in the small intestine:

Answer 18

The pancreas also releases amylase enzyme. Continues chemical digestion of complex carbs in the small intestine into disaccharides. Small intestine releases disaccharidase enzyme (lactase, maltase, sucrase) to break them down into monosaccharides. Completes the chemical digestion of carbs.

Question 19

What converts pepsinogen into its active form pepsin?

Answer 19

HCl.

Question 20

What converts the hormone prosecretin into its active form secretin?

Answer 20

HCl.

Question 21

What converts trypsinogen into its active form trypsin?

Answer 21

The enzyme enterokinase. (Secreted from the small intestine).

Question 22

Lipid digestion in the small intestine:

Answer 22

Pancreas releases lipases which break down lipids (fats). Two types: 1.Pancreatic lipases- breaks down fats into fatty acids and glycerol. 2.Phospholipases- break down phospholipids.

Question 23

The liver:

Answer 23

Breaks down components of hemoglobin from blood. Converts glycogen to glucose and glucose to glycogen depending on the bodies blood sugar needs. Stores vitamins A, B12, and D. Detoxifies harmful substances in the body by making them soluble and therefore will dissolve in blood and eliminates in urine. (Ex. Alcohol). Secretes bile, which is made up of bile pigments (waste products) and bile salts.

Question 24

Gallbladder:

Answer 24

The liver produces bile salts, which are stored in the gallbladder when not needed. When fats are present in the small intestine, hormone cholecystokinin (CCK) is released by the small intestine triggering the release of bile salts from the gallbladder.
-Emulsify large fat globules into smaller droplets = greater surface area for lipases to digest.

Question 25

Liver and gallbladder problems (Gallstones):

Answer 25

Hard masses in the gallbladder. Cholesterol in bile can precipitate out and form crystals. Block bile duct. Impairs fat digestion.

Question 26

Liver and gallbladder problems (Jaundice):

Answer 26

Build up of bile pigments in the blood.

Question 27

Liver and gallbladder problems (Cirrhosis):

Answer 27

Alcohol and hepatitis C can destroy liver tissue. Cirrhosis of the liver: chronic inflammation of liver (due to major damage).

Question 28

Large intestine (1):

Answer 28

Digestion does not occur in the large intestine. Concentrates and eliminates wastes. Undigested chyme passes down to the colon. Water and salt are absorbed, bacteria tries to digest remaining waste.

Question 29

Large intestine continued (2):

Answer 29

Remaining undigested waste and bacteria passes to the rectum. Cellulose cannot be broken down by humans but provides “roughage”. As waste builds up in the large intestine, receptors provide information to central nervous system to prompt bowel movement. Feces moves out anus via peristalsis.

Question 30

Full function of large intestine:

Answer 30

Digestion does not occur in the large intestine. Concentrates and eliminates wastes. Undigested chyme passes down to the colon. Water and salt are absorbed, bacteria tries to digest remaining waste. Remaining undigested waste and bacteria passes to the rectum. Cellulose cannot be broken down by humans but provides “roughage”. As waste builds up in the large intestine, receptors provide information to central nervous system to prompt bowel movement. Feces moves out anus via peristalsis.

Question 31

Full Lipid digestion in the small intestine:

Answer 31

The liver produces bile salts which are stored in the gallbladder when not needed. When fats are present in the small intestine, hormone cholecystokinin (CCK) is released by the small intestine triggering the release of bile salts from the gallbladder. Bile salts emulsify large fat globules into smaller droplets = greater surface area for lipases to digest. Pancreas releases lipases which break down lipids: 1.pancreatic lipases- breaks down fats into fatty acids and glycerol. 2. Phospholipases- break down phospholipids.

Question 32

Hormones-control of digestion (Gastrin):

Answer 32

Produced as the walls of the stomach are distended by presence of food. -Signals the parietal cells of the stomach to release HCl (aq).

Question 33

Hormones-control of digestion (Secretin):

Answer 33

Released from the duodenum when stomach acid and chyme move from the stomach to the small intestine. -Initiates the release of bicarbonate ions from the pancreas that raise the pH of the small intestine. -Inhibits contraction of the stomach to prevent additional chyme from entering the duodenum.

Question 34

Hormones-control of digestion (CCK):

Answer 34

Released from the duodenum after consumption of a fatty meal. -Stimulates gallbladder to contract and release bile into the duodenum to digest fats. -Slows digestion and allows more time for fat to be digested and absorbed.