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Tomorrow’s quiz on NEJM paper

Bring two questions about NEJM

Exam I provided today

Which of the following enzymes work most effectively at a very low pH?

A. Salivary amylase

B. Trypsin

C. Pepsin

D. Pancreatic amylase

E. Pancreatic lipase

In zero gravity environment of space, how does food swallowed by an astronaut reach her stomach?

A. Swallowing hard

B. Running around wheel creates -> artificial gravity

C. Involuntary muscle contractions

D. IV administration of nutrients

Which of the following organs is incorrectly paired with its function?

A. Stomach –protein digestion

B. Oral cavity -starch digestion

C. Large intestine –bile production

D. Small intestine –nutrient absorption

E. Pancreas –enzyme production

Salivary glands Secretes enzymes that digest carbohydrates

Liver Secretes molecules required for digestion of fats

Gall bladder Stores secretions from liver; empties into small intestine

Pancreas Secretes enzymes and other materials into small intestine

1. Mouth Mechanical and chemical processing (chewing reduces size of food; saliva digests carbohydrates)

2. Esophagus Transports food

3. Stomach Mechanical and chemical processing (digestion of proteins)

4. Small intestine Chemical processing and absorption (digestion of proteins, fats, carbohydrates; absorption of nutrients and water)

5. Large intestine Water absorption and feces formation

End of esophagus

Sphincter seals offstomach from esophagus

Sphincter seals offstomach from smallintestine

Lumen(interior)

Beginning ofsmall intestine

Layersof muscle

Stomach

Canal empties to lumen

Parietal cells(secrete HCl)

Chief cells(secrete pepsinogen)

Stomach lining

HCO3– HCO3

–

Cl– Cl–

To blood

From blood

CO2 + H2O H2CO3

H+

Cl–

H+/K+ pump

Chloride channel

Cl–

H+

HClto lumen

Canal emptiesto lumenParietal cell

Secretion of HCI by parietal cells

K+

Enzymes, Hormones, other?

•Enzymes: pepsinogen (inactive)-> pepsin (protease) from chief cells

•Other: HCl -> denature ECM bacteria, from parietal cells, activator of pepsin•Other: Mucins/mucus protective from goblet or mucus cells•Other: mechanical churning -> acid chyme

•Hormones: Gastrin (+), CCK/secretin (-), enterogastrone (-- pyloric sphinct)

Enzymes, Hormones, other?

•Your turn

4. Lipase digests the small fat droplets into glycerol and free fatty acids.

DIGESTION OF LIPIDS IN SMALL INTESTINE

1. Large fat globules are not digested efficiently by lipase.

2. Bile salts (produced in liver) act as emulsifying agents.

3. Small fat droplets result from emulsification.

Lipase

Glycerol

Fatty acids

115 µm

Cross-section of small intestine

Villi

Fold

Lumen of small intestine

Na+

Glucose

Na+/glucose cotransporter

GLUT-2 transport protein

Na+/K+-ATPaseK+

K+

Blood

Osmosis

H2OOsmosis

ATP

ADP

Glucose

Basolateral side

Apical side

H2O

Na+

Capillaries are small and extremely thin walled.

GlucoseGlycogen

Insulin causes cells in the liver and skeletalmuscle to synthesize glycogen; fat storage

cells synthesize triglycerides.

HOMEOTASIS(normal glucoselevels in blood)

Glucoselevels fall

Glucoselevels rise

GlucoseGlycogen

If glucoselevels too high

If glucoselevels too low

Glucagon causes cells in liver and skeletalmuscle to catabolize glycogen; fat storage

cells catabolize fatty acids.

Pancreas secretesGLUCAGON

Pancreas secretesINSULIN