Lecture 21 Flashcards
How are virtually all monosaccharides absorbed by?
Secondary active transport processes
What are the two final monosaccharide products of digestion?
Glucose (80%) and galactose (20%)
What are the steps in the sodium co-transport mechanism?
- Active transport of Na through basolateral membrane into interstitial fluid this depletes Na inside the epithelial cell
- Na from the intestinal lumen enters the cell by combined with a transport protein. This protein will not move the Na in unless some other substance combines with it. Na and other substances both transported into the cell
- Once inside the epithelial cell, other transport proteins and enzymes facilitate diffusion of substance through basolateral membrane, into paracellular space and into the blood.
How are fats first emulsified by the liver secretion?
Bile into 3-6nm bile micelles
Why is bile soluble in chyme?
Highly charged exterior
Where does the monoglycerides and free fatty acids diffuse into after leaving the micelle?
Interior of the epithelial cell (cell membrane is a phospholipid bilayer)
What are triglycerides released to form?
Chylomicrons
How do chylomicrons move into the blood?
Through the basolateral membrane, up through the thoracic lymph duct
What is the function of the large intestine?
Removes water, salts, sugar and vitamins
- can absorb 5-8L of fluid and electrolyte per day
What are the five regions of the large intestine?
- Caecum (compresses material into fecal matter)
- Ascending colon
- Transverse colon
- Descending colon
- Signoid colon
What are areas of lymphoid tissue for local immune protection?
peyers patches
What does bacteria serve as in the large intestine?
Immune protection against potentially harmful substances that were ingested
What is the Tenia coli?
3 bands longitudinal muscle
What is the Haustra?
pockets which give a segmented appearance
slow movement of contents
no villi
What do the goblet cells provide?
Mucus secretion
How does aldosterone enhance Na absorption?
When dehydrated, large amounts of aldosterone are secreted by the cortices of the adrenal glands. Within 1-3 hours, increased activation of enzyme and transport mechanisms for Na absorption by intestinal epithelium which leads to increased Cl and water absorption
What is the function of the proximal colon?
Water reabsorption and fermentation
What does fermentation allow?
Allows some of the vitamins to be relieved
What does general shunting allow?
Push feces down towards colon
What is the acid produced by bacterial fermentation buffered by?
HCO3
What is steatorrhea?
More fat in faeces
Gelatinous
Smell is unique
Reddy-black color
What are needed to maintain gut health?
fibers
What is the normal brown color caused by?
stercobilin and urobilin
- derivatives of bilirubin
- bilins are salts secreted from liver
What is the odor of faeces caused by?
Bacterial action and vary from one person to another depending upon colonic flora and types of food eaten
odouriferous compounds
- indole, skatole, mercaptans, and hydrogen sulphide
