Mouth, Esophagus, & Stomach

Question 1

What is the general purpose of the mouth?

Answer 1

To create a bolus (glob of food) using a combination of the teeth and tongue

Question 2

What are the two types of muscles in the tongue, and what are their functions?

Answer 2

1) Extrinsic muscles: raise, depress, extend, protrude, and retract tongue
2) Intrinsic muscles: shorten/widen and lengthen/narrow

Question 3

What are the four salivary glands, and what kind of saliva do they excrete?

Answer 3

1. Parotid Gland (serous): alpha amylase
2. Submandibular Gland (serous): alpha amylase
3. Sublingual Gland (mucinous): alpha amylase
4. Von Ebner’s Gland (serous): lingual lipase

Question 4

What is the function of alpha-amylase?

Answer 4

To break down starches into smaller carbohydrates

Question 5

What purpose does lingual lipase serve?

Answer 5

To break down triglycerides into free fatty acids, diglycerides, and monoglycerides

Question 6

What is the purpose of salivary enzymes?

Answer 6

To enhance taste, as their function contributes little to overall digestion

Question 7

What are at the top and bottom of the esophagus?

Answer 7

Sphincters, including the upper esophageal sphincter (composed of skeletal muscle) and the lower esophageal sphincter, which is actually comprised of the diaphragm

Question 8

What is the purpose of the esophagus? Does it aid in digestion?

Answer 8

No, the esophagus is merely a way to transport food from the mouth to the stomach via peristalsis, the wave-like propulsion of food.

The top 1/3 is skeletal muscle, the middle 1/3 a mix of both, and the lower 1/3 is smooth muscle.

Question 9

What three steps is the stomach responsible for?

Answer 9

1) Receiving the bolus of food from the esophagus.
2) Churning food (mechanical extracellular digestion)
3) Hydrolysis (only of protein)

Question 10

What are the three types of cells located in the stomach lining?

Answer 10

Parietal cells, chief cells, and mucus cells

Question 11

What do parietal cells do?

Answer 11

Parietal cells release HCL

Question 12

What is the function of chief cells?

Answer 12

To release pepsinogen, which is activated into pepsin by HCL. Pepsin hydrolizes peptide bonds, and in doing so breaks down proteins. Proteins are the only macromolecule broken down in the stomach.

Question 13

What is the role of mucus cells?

Answer 13

Mucus cells are responsible for secreting mucus to line the stomach, preventing its degredation by HCL and pepsin (known as ulcers).

They also release gastrin, histomine (acid production), and serotonin (smooth muscle contraction)