ch 23 digestive system p3

Question 1

small intestine

Answer 1

extends from pyloric sphincter to ileocecal valve

Question 2

3 subdivisions of small intestine

Answer 2

duodenum, jejunum, ileum

Question 3

duodenum

Answer 3

1st portion of small intestine, digestive juices of liver and pancreas empty into duodenum via major duodenal papilla (shortest)

Question 4

jejunum

Answer 4

connects duodenum to ilium, middle portion, slower rate of digestion and absorption

Question 5

ileum

Answer 5

last portion of the small intestine, joins small to large intestine at ileocecal valve.

Question 6

circular folds of small intestine

Answer 6

permanent folding of submucosa and mucosa, ribbed to move chyme slowly and increase absorptive capacity. very efficient

Question 7

villi

Answer 7

projections of mucosa, increase SA of small intestine so absorption can go faster. each villi center has blood supply n lacteal.

Question 8

villi are largest where

Answer 8

duodenum. becomes smaller in jejunum and ileum. duodenum does the most nutrient absorption, leaflike in small intestine

Question 9

microvilli

Answer 9

villi on villi, creates brush border. many enzymes on surface completes digest process. these enzymes found here complete digestion of carbs n proteins

Question 10

intestinal crypts

Answer 10

tubular glands in small intestine wall, contain different cells that secrete products. similar to gastric glands in stomach. different cells in there secrete dif products

Question 11

cells of villi and crypts

Answer 11

enterocyte, goblet cells, enteroendocrine cells, paneth cells, stem cells

Question 12

enterocytes of small intestine

Answer 12

simple columnar cells with microvilli, mostly made of these, absorbs nutrient in villi and secretes intestinal juice in crypts

Question 13

does intestinal juice have a function

Answer 13

no just a carrier fluid

Question 14

goblet cells of small intestine

Answer 14

mucus secreting cells, must protect membrane

Question 15

enteroendocrine cells of small intestine

Answer 15

release many hormones to control bile pancreatic and intestinal juice secretions

Question 16

paneth cells of small intestine

Answer 16

release defenses and lysozyme, immune defense there

Question 17

stem cells of small intestine

Answer 17

continuously dividing cells that replenish mucosa, can replace any other cells when cells get damaged

Question 18

digestive roles of small intestine

Answer 18

has enzymes for digestion, the digestive enzymes are mostly imported from accessory organs liver and pancreas. the brush border enzymes produced by small intestine breakdown macro to monomers.

regulates chyme, too much acidic chyme is hypertonic to blood plasma

Question 19

solute concentration in chyme vs blood

Answer 19

chyme has higher solute concentration than blood, small intestine and chyme and blood interact, chyme in small intestine may cause water to leave circulation and enter small intestine

Question 20

what effect would a large amount of acidic chyme entering small intestine have on Blood volume

Answer 20

damage walls of small intestine, blood volume would decrease and could lead to hypovolemic shock.

Question 21

segmentation in small intestine

Answer 21

contractions in small intestine slows movement of chyme, contractions push chyme back ad forth into next pocket.

Question 22

what cells initiate contractions and how in small intestine

Answer 22

pacemaker cells, cells in duodenum depolarizes faster than ileum and allows for forward movement. back and forth motion mixes chyme with bile and pancreatic juices to increase absortopton

Question 23

duodenum and pacemaker cells

Answer 23

pacemakers depolarize faster in duodenum, contracts more and more with each segmentation. a unidirectional movement

Question 24

small intestine after a meal

Answer 24

parasympathetic enhances segmentation, chyme is slowly moved to increase digestion and absorption.

Question 25

small intestine between a meal

Answer 25

motion released when absorption has already occurred. long peristaltic waves begun in small intestine, waste and shit is moved to large intestine.

Question 26

what happens as soon as new meal incomes

Answer 26

motion decreases, segmentation starts again

Question 27

ileocecal valve control

Answer 27

ileum has unusable stuff, so it'll go to large intestine for excretion. the valve controls the passage of materials from small to large intestine.

Question 28

ileocecal relaxes due to

Answer 28

gastroileal reflex- increases segmentation by making segment increase waste away gastrin- hormone increases small intestine motility and relaxes ileocecal valve so undigested material passes

Question 29

large intestine

Answer 29

has 3 structures seen no where else in alimentary canal, teniae coli- bands of smooth muscle tissue from longitudinal layers pulls on wall of colon making small pockets haustra- the pockets formed from teniae coli, gives colon segmented appearance. epiploic appendages- idk what they do maybe immune defense bc they have immune cells

Question 30

haustra functions

Answer 30

contractions of individual haustra aid motility in colon, independent of its neighbors and has circular and longitudinal layer

Question 31

6 subdivisions of large intestine

Answer 31

cecum, appendix, colon, sigmoid colon, rectum, anus

Question 32

cecum

Answer 32

sac like structure on bottom making up first part of large intestine. water and salt not absorbed is there a bit.

Question 33

appendix

Answer 33

not true part of alimentary canal, prevents bacteria from large to small, bacteria dies but we keep good bacteria as a reserve there. its a lymphoid organ, so immune system a bit. appendix is tiny so stuff can get stuck there, bacteria can't leave and reproduce and may get stuck then we remove it

Question 34

colon parts

Answer 34

ascending - up R side of abdominal cavity transverse - crosses R to L abdomen descending- travels down L side of abdominal cavity

Question 35

sigmoid colon

Answer 35

point where colon enters pelvis

Question 36

rectum

Answer 36

temporary feces holding site, has rectal valves which prevent feces from being passed with gas

Question 37

anus and its sphincters

Answer 37

opens to exterior of body, end of alimentary canal. has 2 sphincters internal- smooth muslce, not voluntary a reflex external- skeletal muscle, voluntary and tells us when to poop

Question 38

microaantomy of large intestine

Answer 38

simple columnar epithelia, but anal canal is stratified squamous epithelia. abundant crypts are packed with the goblet cells, which secrets mucous which helps poop friction

Question 39

does digestion occur in large intestine

Answer 39

NO, all digestion occurs before it meets large intestine. there's no villi, brush border, or circular folds which is needed for digestion

Question 40

bacterial flora of large intestine

Answer 40

1000 plus types of symbiotic bacteria that comes into body through anus, or survives harsh stomach conditions

Question 41

importance of bacterial flora

Answer 41

vitamin synthesis- B complex which have coenzymes to speed up process, vitamin K synthesized by gut bacteria (blood clots) fermentation- bacteria can ferment indigestible carbs and mucin, produces short chain fatty acids to fuel the body cells. 500 mL gas per day, more carbs more gas.

Question 42

digestive processes in large intestine

Answer 42

slow, sluggish contraction in haustra. not much goes on just moves stuff. allow mixing of residue to increase water absorption.

Question 43

mass movements in large intestine

Answer 43

forces residue towards rectum, promotes drying out of feces and last of water is removed, fiber strengthens movement and softens feces. new food in old out

Question 44

defecation

Answer 44

pooping, initiated by stretching of rectal walls. sigmoid colon and rectum contract o internal sphincter relaxes. allows opening of external anal sphincter (voluntary), if not allowed reflex ends and begins again in a few minutes. more intense each time