Part 4.8: Digestion Flashcards
____ contractions give the colon its segmented appearance
haustral contractions give the colon its segmented appearance. Tehse contractions are generally slow and non-propulsive
how do contractions fill the cecum in herbicores?
anti-peristaltic contractions
the slow movement of the large intestine purpose
1) allows for the packaging and storage of feces
2) more time for water and salt absoprtion
3) enhances hindgut fermentation
typically, the large intestine moves fairly slow. when do mass movements occur?
after a meal, especially the first meal of the day. Large segments of colon contract at once and quickly moves material to the distal portion of the intestine until defectation.
gastrocolic refelx in humans
the reflex where food in the stomach triggers gastrina and extrinsic autonomic nerves for gut motility
the defection reflex triggered by ____ receptors on the colon
stretch
what are the two anal sphincters? which ones are voluntarily controlled?
1) internal anal sphincter and rectum: smooth muscle
2) external anal sphincter: made of skeletal muscle and is voluntary
t/F hindgut fermentation occurs in all animals but is not necessarily important for igestion
true
T/F: Hcl is presnt in the small intestine
false. allows bacteria to proliferate
describe coprophagy in rabbits. what allows this to occur?
rabbits produce two kinds of pellets:
1) day time pellets: nasty hard pellest
2) nighttime pellest; nutrient rich pellets.
the production of nutrient rich food is due to hind gut fermentaiton
what is rumination
cud chewing. voluntary regurgitation for mechanical breakdown of structual plant materal.
where does fermenation occur in rumunants
in the foregut. usually its in the hind gut, but in ruminants, the foregut is enormous and allows for the bacterila digestion of cellulose
4 chambers of a ruminant stomach
1) rumen
2) reticulum
3) omsaum : camels and llamas do not have an omasum
4) abomasum: acid-secreting region
Purpose of the rumen and reticulum
where most of the foregut fermentation occurs. there is some digestion and absoprtion
what occurs in the abomasum of the ruminent stomach
digests microbes and some nutrients absorbed. Most absorption still is still in the small intestine
largest portion of hte ruminant stomach
the rumen.
difference between ruminant stomachs
- rumen are dependent on diets
NON SELECTIVE FEEDERS have larger forestomach have a greater digestive capacity in which to ferment lower-quality plant material.
- increase in total intestinal length and a reduction in transit time through the intestine.
- rumen is LARGER to accomodate large loads of lower-quality material and to ruminate and ferment large amounts of food.
- SELECTIVE FEEDERS consume only the most nutritious parts of the herbage.
- Associated with the high-quality diet is an increased rate of VFA production
- Their rumens are more highly folded, which increases the available surface area for absorption of amino acids and VFAs
- smaller rumens relative to body size as well as shorter total intestinal lengths. The pillars and ruminal structure have evolved to increase the passage rate of di-gesta. Antelopes are examples of ruminants that require frequent meals and whose forestomachs are comparatively less developed.
contents of the rumen must be stabilized pillars of muscular tissue, which divide them into ___ and ____ sacs
dorsal and ventral sacs
the reticulum is continuous with the rumen and helps ____ the digesta back to the ____ for rumination. this is called:
the reticulum is continuous with the rumen, and helps propel the digesta back to the esophagus for rumination. This is known as REVERSE PERISTALSIS
The manufacturing of structural proteins and secertory products, and the manufacturing of fuel stores(glycogen etc) is known as ____, where as the hydrolysis of macomolecules and oxidation of monomers for ATP production is known as _____.
The manufacturing of structural proteins and secertory products, and the manufacturing of fuel stores(glycogen etc) is known as ANABOLISM, where as the hydrolysis of macomolecules and oxidation of monomers for ATP production is known as CATABOLISM.
If the glycogen stores are maximized, then excess glucose becomes:
converted to fatty acids and glycerol for triglyceride synthesis
Amino acids are first stored as proteins via protein synthesis, but excess AAs becoem:
converted to glucose and fatty acids which eventually end up stored as triglycerides
compare the absorptive and postabsorptive states of carbs, fats and proteins
why is fat stored at a higher rate than glycogen?
glycogen stores water with it and is heavy because it’s hydrophillic. Lipids have much more higher energy C-H bonds for oxidation than glucose too. Glycogen is dominated by C-O bonds, which are already oxidized and can’t really be used.
glucose is tightly regulated between 70 and 110mg/100ml using balancing effects of ___ and ___ hormones from the pancreas
insulin and glucagon
What happens when an animal fasts for a longer period of time?
after liver glycogen is depleted, other tissues shift to fatty acids from glucose to spare it. There is also a catabolism of proteins to allow gluconeogenesis from amino acids.
Osmotic effects of hyperglycemia
chronically high blood sugar results in increased osmotic pressure, causing cell dehydration.
Hyperglycemia results in glycation. What is this?
glucose can react with proteins such as Hb and gollagen, affecting function
how does hyperglycemia cause cataracts
glucose gets converted to sorbital in the eye, resulting in accumulation of cloudy substances in the lens, resulting in cataracts
____ cells secrete insulin and _____ cells secrete glucagon
BETA cells secrete insulin
ALPHA cells secrete glucagon
3 things induced by insulin
1) STIMULATES glycogenesis: creation or glycogen in the muscle and liver
2) INHIBITION of glycogenolysis: reduces glycogen breakdown in the liver
3) INHIBITION of gluconeogenesis: prevents synthesis of glucose from amino acids in liver.
How does insulin interact with fat?
1) glucose is tranported into adipose tissue, where glucose is converted to triglycerides
2) facilitates fatty acid transport into adipocytes
3) activates enzymes for fatty acid production from glucose
4) inhibiton of lypolysis. (fat breakdown)
How does insulin interact with protein?
1) promotes active transport of amino acids into muscles and other tissues
2) stimulates rate of amino acid incorporation
3) inhibition of protein degradation
