Part 4.8: Digestion

Question 1

____ contractions give the colon its segmented appearance

Answer 1

haustral contractions give the colon its segmented appearance. Tehse contractions are generally slow and non-propulsive

Question 2

how do contractions fill the cecum in herbicores?

Answer 2

anti-peristaltic contractions

Question 3

the slow movement of the large intestine purpose

Answer 3

1) allows for the packaging and storage of feces
2) more time for water and salt absoprtion
3) enhances hindgut fermentation

Question 4

typically, the large intestine moves fairly slow. when do mass movements occur?

Answer 4

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.

Question 5

gastrocolic refelx in humans

Answer 5

the reflex where food in the stomach triggers gastrina and extrinsic autonomic nerves for gut motility

Question 6

the defection reflex triggered by ____ receptors on the colon

Answer 6

stretch

Question 7

what are the two anal sphincters? which ones are voluntarily controlled?

Answer 7

1) internal anal sphincter and rectum: smooth muscle
2) external anal sphincter: made of skeletal muscle and is voluntary

Question 8

t/F hindgut fermentation occurs in all animals but is not necessarily important for igestion

Answer 8

true

Question 9

T/F: Hcl is presnt in the small intestine

Answer 9

false. allows bacteria to proliferate

Question 10

describe coprophagy in rabbits. what allows this to occur?

Answer 10

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

Question 11

what is rumination

Answer 11

cud chewing. voluntary regurgitation for mechanical breakdown of structual plant materal.

Question 12

where does fermenation occur in rumunants

Answer 12

in the foregut. usually its in the hind gut, but in ruminants, the foregut is enormous and allows for the bacterila digestion of cellulose

Question 13

4 chambers of a ruminant stomach

Answer 13

1) rumen
2) reticulum
3) omsaum : camels and llamas do not have an omasum
4) abomasum: acid-secreting region

Question 14

Purpose of the rumen and reticulum

Answer 14

where most of the foregut fermentation occurs. there is some digestion and absoprtion

Question 15

what occurs in the abomasum of the ruminent stomach

Answer 15

digests microbes and some nutrients absorbed. Most absorption still is still in the small intestine

Question 16

largest portion of hte ruminant stomach

Answer 16

the rumen.

Question 17

difference between ruminant stomachs

Answer 17

• 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.

Question 18

contents of the rumen must be stabilized pillars of muscular tissue, which divide them into ___ and ____ sacs

Answer 18

dorsal and ventral sacs

Question 19

the reticulum is continuous with the rumen and helps ____ the digesta back to the ____ for rumination. this is called:

Answer 19

the reticulum is continuous with the rumen, and helps propel the digesta back to the esophagus for rumination. This is known as REVERSE PERISTALSIS

Question 20

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 _____.

Answer 20

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.

Question 21

If the glycogen stores are maximized, then excess glucose becomes:

Answer 21

converted to fatty acids and glycerol for triglyceride synthesis

Question 22

Amino acids are first stored as proteins via protein synthesis, but excess AAs becoem:

Answer 22

converted to glucose and fatty acids which eventually end up stored as triglycerides

Question 23

compare the absorptive and postabsorptive states of carbs, fats and proteins

Answer 23

Question 24

why is fat stored at a higher rate than glycogen?

Answer 24

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.

Question 25

glucose is tightly regulated between 70 and 110mg/100ml using balancing effects of ___ and ___ hormones from the pancreas

Answer 25

insulin and glucagon

Question 26

What happens when an animal fasts for a longer period of time?

Answer 26

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.

Question 27

Osmotic effects of hyperglycemia

Answer 27

chronically high blood sugar results in increased osmotic pressure, causing cell dehydration.

Question 28

Hyperglycemia results in glycation. What is this?

Answer 28

glucose can react with proteins such as Hb and gollagen, affecting function

Question 29

how does hyperglycemia cause cataracts

Answer 29

glucose gets converted to sorbital in the eye, resulting in accumulation of cloudy substances in the lens, resulting in cataracts

Question 30

____ cells secrete insulin and _____ cells secrete glucagon

Answer 30

BETA cells secrete insulin

ALPHA cells secrete glucagon

Question 31

3 things induced by insulin

Answer 31

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.

Question 32

How does insulin interact with fat?

Answer 32

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)

Question 33

How does insulin interact with protein?

Answer 33

1) promotes active transport of amino acids into muscles and other tissues
2) stimulates rate of amino acid incorporation
3) inhibition of protein degradation