Physiology Block 3 Week 14 06 Absorption Flashcards Preview

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Flashcards in Physiology Block 3 Week 14 06 Absorption Deck (21)

How much water is ingested and leaves the body?

Oral intake of 2000 mL

7000mL secreted:
-gastric juice
-pancreatic juice
-intestinal secretion

-small intestine 78%
-colonic 21%

=100 mL (1%) excreted in stool


Small Intestine Surface

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

Valvulae conniventes covered by villi


Brush Border

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


Small Intestine Water Absorption

Hypoosmotic chyme--water diffuses into cells by osmosis

Hyperosmotic chyme--water moves from plasma into chyme


Sodium Absorption

**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



Small Intestine Chloride Absorption

Chloride follows the movement of Na+ into the interstitial fluid


Small Intestine Bicarbonate Absorption

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


Aldosterone Function

Functions in colon to prevent sodium chloride and water loss


Calcium and Iron Absorption



Potassium, Magnesium, Phosphate Absorption

Throughout GI tract


Bile Salts and Vitamin B12 Absorption


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


Small Intestine Carbohydrate Absorption

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


Small Intestine Protein Absorption

Majority absorbed by co-transport with sodium

Several AA have own transport proteins on cell membrane


Fat Absorption

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


Large Intestine Absorption

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

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

Distal Colon = storage


Large Intestine Sodium Absorption

Actively absorbed
-enhanced by aldosterone


Large Intestine Chloride Absorption

Follows sodium absorption
-enhanced by aldosterone


Large Intestine Bicarbonate Secretion

Exchanged for chloride into cell (follows sodium)

Bicarb neutralizes bacterial acidic waste products


Large Intestine Water Absorption

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


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

C. It is involved in Amino Acid Absorption

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


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

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