Movements of the small intestine. Movements of the colon. Defecation

Question 1

Movements of the small intestine - 1

Answer 1

PERISTALSIS

rhythmic contraction + relaxation of smooth muscles
functions to push chyme from stomach -> small intestine
- involuntary
- controlled by ENS
- wave-like propulsion

Question 2

Movements of the small intestine - 2

Answer 2

SEGMENTATION

localised contractions that targets specific regions of SI

• absorption of nutrients into walls
• digesting contents
• mixing food with gastric enzymes

Question 3

Movements of the small intestine - 3

Answer 3

MOTOR MIGRATING COMPLEX

= combination of electrical + muscular movements between meals
- clearance of undigested food to prevent bacteria from growing
-regulated by motilin which is released when stomach is empty

Question 4

Movements of the small intestine - 4

Answer 4

PENDULAR MOVEMENTS

slow backward-forward movement of lower-mid part of small intestine

function to spread food around to help make contact with whole small intestine

happens 15 mins

Question 5

Movements of the small intestine - 5

Answer 5

TONIC CONTRACTIONS

prolonged/ sustained contractions of circular muscle

generate enough pressure to push chyme along

Question 6

Movements of the large intestine - 1

Answer 6

HAUSTRAL CONTRACTIONS

colon is divided into small pouches called haustra

haustra contract to keep food moving

local/ slow/ 25-30 minutes

Question 7

Movements of the large intestine - 2

Answer 7

MASS MOVEMENTS

powerful contractions that happen many times a day

generate enough force to push fecal content to rectum (long distances)

= gastrocolic reflex

Question 8

Movements of the large intestine - 3

Answer 8

wave like contractions
pushing food along colon

Question 9

defecation - definition

Answer 9

final phase of digestion
removal of fecal matter

Question 10

defecation - component group 1

Answer 10

colon - absorbs water/ electrolytes from chyme to convert into feces

rectum - stores feces

anus - removes feces

Question 11

defecation - mechanism 1

Answer 11

colon -> rectum
- stretch receptors activated
- receptors send signals to spinal cord in brain to activate defecation reflex

Question 12

defecation - mechanism 2

Answer 12

more abdominal pressure
- diaphragm contracts
- abdominal muscle contracts
- internal anal sphincter relax

Question 13

defecation - mechanism 3

Answer 13

ANS sends signals to rectum to contract

rectum pressure increases

Question 14

defecation - mechanism 4

Answer 14

external anal sphincter contracts + relaxes
= poo out