Phys 63

Front 1

type of food person seeks is determined by

Back 1

appetite

Front 2

amount of food person eats determined by

Back 2

hunger

Front 3

anterior teeth (incisors)

Back 3

strong cutting action

Front 4

posterior teeth (molars)

Back 4

grinding action

Front 5

closing force of jaw muscles

Back 5

55 pounds on incisors and 200 pounds on molars

Front 6

innervation of chewing muscles

Back 6

motor branch of fifth cranial nerve, controlled by nuclei in brainstem

Front 7

chewing reflex

Back 7

presence of bolus of food in mouth first initiates reflex inhibition of mastication (lower jaw drop), drop initiates stretch reflex of jaw muscles-rebound contraction; repeat

Front 8

what is chewing most important for and why

Back 8

fruits and veggies-indigestible cellulose membranes around nutrient portions that must be broken

Front 9

deglutition

Back 9

swallowing

Front 10

swallowing stages

Back 10

voluntary stage-initiates; pharyngeal stage-involuntary-food through pharynx into esophagus; esophageal stage transports food to stomach

Front 11

where is food in voluntary swallowing stage

Back 11

posteriorly into pharynx by P of tongue upward and backward against palate

Front 12

automatic pharyngeal muscle contractions step 1

Back 12

soft palate pulled upward to close off posterior nares-prevent food reflux

Front 13

automatic pharyngeal muscle contractions step 2

Back 13

palatopharyngeal folds pulled medially-form sagital slit through which food must pass into posterior pharynx; lasts <1 sec

Front 14

automatic pharyngeal muscle contractions step 3

Back 14

vocal cords strongly approximated-larynx pulled up and anterior by neck muscles; cause epiglottis to swing backward over larynx opening

Front 15

automatic pharyngeal muscle contractions step 4

Back 15

pulls up and enlarges opening to esophagus-upper 3-4 cm esophageal muscular wall relaxes (upper esophageal sphincter)

Front 16

automatic pharyngeal muscle contractions step 5

Back 16

entire muscular wall of pharynx contracts beginning in superior part and spreading downward propeling food by peristalsis into esophagus

Front 17

what can destruction of vocal cords or muscles around cause

Back 17

strangulation

Front 18

fxn of upper esophageal spincter during respiration

Back 18

prevents air from entering GI tract

Front 19

most sensitive area for initiating pharyngeal stage of swallowing

Back 19

ring around pharyngeal opening, tonsillar pillars

Front 20

sensory signals from tonsillar pillars

Back 20

sensory trigeminal and glossopharyngeal nerves into medulla then into/close to tractus solitarius

Front 21

motor impulses from swallowing center to pharynx and upper esophagus transmitted by

Back 21

5, 9, 10, and 12 CNs and a few of upper cervical nerves

Front 22

esophagus primary peristalsis

Back 22

simple continuation of peristaltic wave that begins in the pharynx

Front 23

how long does the peristaltic contraction beginning in pharynx take to reach stomch

Back 23

8-10 secs

Front 24

food transmision to stomach time

Back 24

5-8 secs if upright due to gravity

Front 25

secondary peristaltic waves of esophagus

Back 25

result from distention of esophagus-continue until all food emptied into stomach

Front 26

what neurons initiate secondary waves

Back 26

intrinsic circuits in myenteric plexus

Front 27

stomach and somewhat duodenum state when food is coming

Back 27

wave of relaxation via myenteric inhibitory neurons (also allows relaxation of lower esophageal sphincter)

Front 28

achalasia

Back 28

lower esophageal sphincter doesn't relax satisfactorily

Front 29

orad portion of stomach

Back 29

first 2/3 of body

Front 30

caudad potion of stomach

Back 30

remainder of body plus antrum

Front 31

limit of food in completely relaxed stomach

Back 31

0.8-1.5 L

Front 32

what secretes digestive juices in stomach

Back 32

gastric glands-in entire wall of body except narrow strip on lesser curvature

Front 33

constrictor waves

Back 33

weak peristaltic mixing waves in mid to upper portions moving toward antrum; about once every 15-20 seconds when food present

Front 34

hunger contractions

Back 34

occur when stomach has been empty for several hours or more; rhythmical peristalic contractions in body of stomach

Front 35

what occurs when hunger contractions fuse

Back 35

cause continuing tetanic contraction that sometimes lasts 2-3 minutes; usually do not begin until 12-24 hours after last ingestion of food

Front 36

contraction of pyloric sphincter

Back 36

open enough for water and other fluids to empty from stomach to duodenum with ease; prevents food passage until almost fluid consistency

Front 37

gastrin and stomach emptying

Back 37

promotes-enhances pyloric pump

Front 38

inhibitory reflexes from duodenum to stomach

Back 38

1) directly through enteric nervous system 2)through extrinsic nerves that go to prevertebral sympathetic ganglia and back through inhibitory sympathetic nerve fibers 3) slighltly via vagi to brain stem; all inhibit pyloric pump and increase pyloric sphincter tone

Front 39

what can initiate enterogastric inhibitory reflexes

Back 39

1) distention 2) irritation 3) acidity 4) osmolality of chyme 5) breakdown products of chyme (proteins, somewhat fats)

Front 40

stimulus for hormone release that cause stomach inhibition

Back 40

fats in duodenum

Front 41

most potent hormonal inhibitor of stomach from upper small intestine

Back 41

cholecystokinin (CCK)-released by jejunum mucosa in response to fat in chyme; blocks gastrin

Front 42

main effect of gastric-inhibitory peptide (GIP) at physiologic concentrations

Back 42

stimulate secretion of insulin from pancreas

Front 43

mixing contractions of small intestine (segmentation contractions)

Back 43

chop chyme 2-3 times per minute; localized concentric contractions lasting a fraction of a minute; resemble chain of sausage

Front 44

what are contractions not effective without

Back 44

background excitation from myenteric nerve plexus-as indicated when atropine blocks

Front 45

peristaltic waves

Back 45

toward anus at 0.5-2 cm/s; very weak-die out after 3-5 cm; net movement ~1cm for chyme

Front 46

time for chyme to travel from pylorus to ileocecal valve

Back 46

3-5 hours

Front 47

gastroenteric reflex

Back 47

initiated by distension of stomach and conducted through myenteric plexus from stomach down along wall of small intestine

Front 48

hormonal factors that enhance peristalsis

Back 48

gastrin, CCK, insulin, motilin, and serotonin

Front 49

secretin and glucagon on small intestinal motility

Back 49

inhibit

Front 50

gastroileal reflex

Back 50

chyme blocked until another meal eaten-this intensifies peristalsis and moves chyme into large intestine

Front 51

peristaltic rush

Back 51

initiated partly by nerous reflexes (autonomic NS and brain stem) and partly by intrinsic enhancement of myenteric plexus; powerful peristaltic contractions traveling long distances within minutes

Front 52

what causes peristaltic rush

Back 52

intense irritation (infectious diarrhea)

Front 53

chyme V that enters cecum each day

Back 53

1500-2000 ml

Front 54

reflexes from cecum to iliocecal sphincter and ileum are mediated by

Back 54

myenteric plexus and extrinsic autonomic nerves (espeically prevertebral sympathetic ganglia)

Front 55

Haustrations (aka mixing movements) in colon

Back 55

large circular constrictions; ~2.5 cm of circular muscle contracting

Front 56

3 longitudinal muscle strips in colon

Back 56

teniae coli

Front 57

feces expelled each day

Back 57

80-200 ml

Front 58

time to move chyme through colon

Back 58

8-15 hours

Front 59

mass movement sequence in large intestine

Back 59

constrictive ring in response to distended/irritated colon; 20 or move cm colon distal to this ring lose haustrations and contract as a unit, propelling fecal material; a series persist 10-30 minutes

Front 60

what facilitates mass movements in colon

Back 60

gastrocolic and duodenocolic reflexes-transmitted via autonomic nervous system

Front 61

what prevents continual dribble of fecal matter through anus

Back 61

1) internal sphincter immediately inside anus 2) external anal sphincter (striated voluntary muscle)

Front 62

what nerve sends fibers to external anal sphincter

Back 62

pudendal nerve

Front 63

intrinsic reflex of defecation mediated by

Back 63

local enteric nervous system in rectal wall; normally weak by itself

Front 64

parasympathetic defectaion reflex

Back 64

sacral segments of spinal cord via pelvic nerves; greatly intensify peristaltic waves

Front 65

peritoneointestinal reflex

Back 65

results from irritation of peritoneum-strongly inhibits excitatory enteric nerves and an cause intestinal paralysis

Front 66

renointestinal and vesicointestinal reflexes

Back 66

inhibit intestinal activity as result of kidney or bladder irritation