Essay Questions

Question 1

Defecation Reflex

Answer 1

1.mass movements bring feces to rectum
2.Feces stretches rectum wall activating the PSNS Defecation reflex
3.rectum contracts as the internal sphincter relaxes
4.Message is sent to brain “to poo or not to poo”
5.voluntary external sphincter relaxes to poo now or waits for next mass movement

Question 2

Describe haustal contraction and mass movement. What is the purpose of each?

Answer 2

1. Haustal Contractions
   a. slow segmenting movements that last about 1 minute and happen every 30 min.
   b.contractions in the descending and sigmoid colon colon promote the final drying out of feces. Stores the feces until mass movement propels feces into rectum
   2.Mass Movement
   a.long, slow moving, and powerful
   b.contractile waves that move over large areas of the colon 3-4 times daily and forces contents toward rectum

Question 3

Lipids

Answer 3

1.Sources:
-saturated=animal products
-unsaturated=plant products
2.uses
- cushion
- Insulation
- Calorie storage
- Absorbs fat soluable vitamins
- Plasma Membrane Stabilizer
3.Requirements
-65g/day
-30% of calories
-excess–> fat

Question 4

What digestive processes occur in the mouth?

Answer 4

1. Ingestion= eating food
2. Mechanical breakdown=mastication/ tongue making bolus
   3.Chemical Digestion
   -release saliva
   -amylase break down carbs
   -lipase breaks down lipids

Question 5

List the cell types found in the stomach and their functions?

Answer 5

1. Parietal Cells
   -pump H+ ions into lumen and join w/ cl+
   -creates HCL(pH1.5-3.5) denatures proteins
2. Chief Cells
   -lipase=15% of lipolysis
   -pepsinogen to activate pepsin by HCL
   -Protease cleave proteins into polypeptides
   3.Enterendocrine Cells
   -G cells make gastrin increasing stomach activity (motility)

Question 6

What are the main functions of Liver?

Answer 6

-stores glucose as glycogen
-converts glucose to fat for storage
-synthesizes cholesterol from acetyl-coa and catabolizes cholesterol to the bile salts
-stores vitamins A, D, B12, and Iron
-metabolizes alcohol, drugs, and toxins

Question 7

Water Soluble vs Fat Soluble Vitamins

Answer 7

Water Soluble:
- absorbed by GI Tract
-B’s, C’s
-excess secreted in urine
Fat soluble:
-absorbed w/ lipids
-D’s, K’s
-excess stored in liver

Question 8

What is the importance of bacteria in the large intestine?

Answer 8

1. bacteria= 1/3 of stool and there are 1000+ types
2. Metabolic Role
   -fermentation= breakdown undigested food and mucus
   -makes vitamin Bs and Ks
   -keeps bad bacteria in check
   -maintains overall health