Peter Mitchell: Diffusion is the answer!

Paul Boyer: I think it actually twists!

Masasuke Yoshida “check this out.”

Masasuke Yoshida “check this out.”

Masasuke Yoshida “check this out.”

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

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

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

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

CO2 + H2O H2CO3

Canal emptiesto lumenParietal cell

Secretion of HCI by parietal cells

CA

HCO3–

H2CO3

H+ H+

Canal emptiesto lumenParietal cell

Secretion of HCI by parietal cells

CO2 + H2O

ATP

HCO3– HCO3

–

Cl– Cl–

To blood

From blood

H2CO3

H+

Cl–

Chloride channel

Cl–

H+

HClto lumen

Canal emptiesto lumenParietal cell

Secretion of HCI by parietal cells

CO2 + H2O

ATP

Stomach -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

enzymes? -> Protocol Expert (PE)hormones? -> Data Recorder (DR)other -> Laboratory Technician (LT)poem -> (if have one) Primary Investigator (PI)

Absorption