Physiology Block 3 Week 14 06 Absorption

Question 1

How much water is ingested and leaves the body?

Answer 1

Oral intake of 2000 mL

7000mL secreted:

• saliva
• gastric juice
• pancreatic juice
• bile
• intestinal secretion

Absorption:

• small intestine 78%
• colonic 21%

=100 mL (1%) excreted in stool

Question 2

Small Intestine Surface

Answer 2

Submucosal plexus responsible for the folds in inner lining of intestinal tract–valvulae conniventes

Valvulae conniventes covered by villi

Question 3

Brush Border

Answer 3

Brush border are microvilli on each villi for absorption in small intestine

Not static–are moving and absorbing things

Villi/microvilli damaged when have Celiac Sprue–Gluten intolerance

Question 4

Small Intestine Water Absorption

Answer 4

Hypoosmotic chyme–water diffuses into cells by osmosis

Hyperosmotic chyme–water moves from plasma into chyme

Question 5

Sodium Absorption

Answer 5

**Na+/K+ ATPase pumps Na into interstitial fluid (plasma)

Gradient formed to drive Na from intestine lumen to inside the cell

Na+/AA cotransport
Na+/Glucose cotransport

**Na+/H+ EXCHANGE

Question 6

Small Intestine Chloride Absorption

Answer 6

Chloride follows the movement of Na+ into the interstitial fluid

Question 7

Small Intestine Bicarbonate Absorption

Answer 7

Large amounts of bicarb are secreted from pancreatic and hepatic solutions

Bicarb/Chloride EXCHANGER

Bicarb combines with H+ from Na+/H+ EXCHANGER

Carbonic acid catalyzes formation of H2O and CO2

H2O stays in Intesine Lumen
CO2 expired through lungs

Question 8

Aldosterone Function

Answer 8

Functions in colon to prevent sodium chloride and water loss

Question 9

Calcium and Iron Absorption

Answer 9

Duodenum

Question 10

Potassium, Magnesium, Phosphate Absorption

Answer 10

Throughout GI tract

Question 11

Bile Salts and Vitamin B12 Absorption

Answer 11

Ileum

Not on test
When patient has low Hb, look at MCV to determine
Vit B12 deficiency causes MACROcytic anemia

Question 12

Small Intestine Carbohydrate Absorption

Answer 12

80% absorbed as glucose
20% absorbed as galactose and fructose

Glucose and Galactose absorbed in combination with sodium by active transport

Fructose does not utilize sodium active transport

Question 13

Small Intestine Protein Absorption

Answer 13

Majority absorbed by co-transport with sodium

Several AA have own transport proteins on cell membrane

Question 14

Fat Absorption

Answer 14

Micelles move to cell surface and the monglycerides and the fatty acids diffuse out of the micelle and into the interior of the cell

Upon absorption into cell, are reconverted into TG and absorbed into lymphatic duct and ultimately circulate blood as chylomicrons

Small amounts of Short and Medium chain fatty acids are directly absorbed without conversion to triglycerides

Question 15

Large Intestine Absorption

Answer 15

1500 mL enters colon, but 100-200 mL excreted as stool

Proximal Colon = absorption of water
–teniae coli shorten = mixing movements

Distal Colon = storage

Question 16

Large Intestine Sodium Absorption

Answer 16

Actively absorbed

-enhanced by aldosterone

Question 17

Large Intestine Chloride Absorption

Answer 17

Follows sodium absorption

-enhanced by aldosterone

Question 18

Large Intestine Bicarbonate Secretion

Answer 18

Exchanged for chloride into cell (follows sodium)

Bicarb neutralizes bacterial acidic waste products

Question 19

Large Intestine Water Absorption

Answer 19

Sodium and Chloride absorption cause gradient that results in absorption of water into interstitial fluid

Question 20

Regarding the colon, true statements are all of the following except?

A. It is involved in sodium absorption
B. It is involved in water absorption
C. It is involved in Amino acid absorption
D. It is involved in bicarbonate secretion

Answer 20

C. It is involved in Amino Acid Absorption

There is no absorption of AA, FA, or carbs in colon

Question 21

Which of the following conditions is most likely to result in Vitamin B12 deficiency?

A. Diabetic Gastroparesis
B. Ulcerative Colitis
C. Crohn’s Disease
D. Achalasia

Answer 21

C. Crohn’s Disease

Affects from mouth to anus all GI layers
Ulcerative Colitis affects colon only

Vitamin B12 absorbed on brush border of in small intestine. Damage to the villi will result in Vitamin B12 deficiency