GIT tract 1

Question 1

GI tract includes

Answer 1

mouth 
oesophagus
stomach 
intestines
anus

Question 2

structural organisisation throughout GI tracts

Answer 2

mucosa
submucosa
sub plexus
connective tissue

Question 3

purpose of the accessory organs and name them

Answer 3

• organs which contribute to the breakdown of food
• control secretions for breakdown of food
• liver, pancreas, gull bladder, and parotid, salivary glands

Question 4

function of GI tract

Answer 4

Breaks down ingested food into small molecules which can be taken into body tissue

Question 5

how does the GI tract perform its fuction

Answer 5

digestion
- chemical and mechanica
Absorption (movement across gut mucosa into circulation)

Question 6

food and water once ingestied

Answer 6

Food and water forms a bolus

• broken down into stomach,
• smaller particles broken down further via enzymes in small intestine
• then absorbed
• smaller particles put together to then be excreted from the body

Question 7

swallowing

Answer 7

process in which food passes from mouth to stomach

Question 8

phases of swallowing

Answer 8

oral phase
pharyngeal phase
oesophageal phase

Question 9

oral phase

Answer 9

• voluntary phase
• tongue compresses bolus by moving upwards against hard palate
• respiration inhibited
• retraction of tongue forces bolus into pharynx

Question 10

pharyngeal phase

Answer 10

• involuntary
• pushes bolus from pharynx into oesophagus
• soft palate reflected backward closing nasal pharynx
• epiglottis closes to stop food going into respiratory system

Question 11

oesophageal phase

Answer 11

• upper oesophageal sphincter relaxes an bolus moves into oesophagus
• start primary peristaltic wave (vagal nerve)
• secondary peristaltic wave (enteric, intrinsic nerve wave)
• lower oesophageal sphincter relaxes

Question 12

oesophagus

Answer 12

muscular tube
2cm diabeter
from pharynx to stomcah
contract/relax moves stomach down

Question 13

lower oesophageal spincter

Answer 13

prevents reflux of material back into oesphagus

acts as barrier from stomach

Question 14

regions of the stomach

Answer 14

1) fundus
2) cardia
3) body
4) pylorus

Question 15

openings of the stomach

Answer 15

oesphagus

duodenum

Question 16

roles of stomach

Answer 16

motility
digestion
protection
absroption

Question 17

motility of stomach

Answer 17

• Gastric accommodation (temporary storage reservoir)
• trituration (dissolve, mix and grind food particles)
• gastric emptying (control delivery to small intestine)

Question 18

digestion of stomach

Answer 18

• initiate digestive process (proteins) via gastric juice

Question 19

protection of stomach

Answer 19

• foreign invasion (Acid/proteases)
• mechanical abrasion (mucus)
• prevents autodigestion (mucus)

Question 20

what does the stoomahc have

Answer 20

rugae

gastric pits

Question 21

HCL in stomach purpose

Answer 21

• provides low pH
• prevents bacterial growth
• catalyses cleavage of pepsinogens to pepsin

Question 22

pepsinogens

Answer 22

• proenzyme of pepsin

- pepsin breaks down proteins into peptides

Question 23

glycoproteins purpose in stomach

Answer 23

• binds to vitamin B12, allowing digestion in the ilium

Question 24

what does mucus do

Answer 24

protects gastric mucorsa

Question 25

gastrin

Answer 25

from G cells | regulated acids secretion

Question 26

gastric glands and secretions

Answer 26

``` Cardiac glands - mucus - HCl Oxyntic glands (acid secreting) - mucous - HCl - pepsinogen - intrinsic factor Pyloric glands - mucous - pepsinogen ```

Question 27

gastric secretly response to a meal

Answer 27

1) Cephalic phase - site - smell - thoughts of food triggers gastric secretion - instigated by vagal fibres (central NS) - i.e. prepares the stomach for food 2) Gastric phase - food entering stomach stretching it - triggers secretion via long (vagal) and short (myenteric) reflexes 3) Intestinal phase - intestinal gastrin release in response to distension of duodenum and/or products of protein digestion

Question 28

regions of small intestine

Answer 28

duodenum jejunum ilium

Question 29

what are the 3 orders of folding creating the area for absorption

Answer 29

1) plicae - naked eye 2) villi - light microscope 3) microvilli - Electron microscope

Question 30

function of large intestine

Answer 30

remove water salt sugar vitamins

Question 31

regions of large intestine

Answer 31

1) cecum 2) acending colon 3) transverse colon 4) decending colon 5) sigmoid colon

Question 32

what is found in the intestine

Answer 32

``` Tightly packed mucosa - goblet cells for mucosa secretion - help with movement of reforming material through intestine Areas of lymphoid tissue - Peyers patches for local immune protection Lots of bacteria - for fermentation of fibre - helps us make short chain fatty acids ```

Question 33

control mechanisms and what do they regulate

Answer 33

Control mechaisms 1) Autonomic NS 2) enteric NS - local NS 3) gut peptides - paracrine - endocrine Regulate: - Reflexes - long and short - peristalsis and motility - secretion and absorption

Question 34

autonomic nervous system

Answer 34

extrinsic nerves i.e. outside the gut | speed up or slow down the sysem

Question 35

enteric NS

Answer 35

``` guts own NS 2 nerve plexi in the gut wall - sense luminal contents controls muscles and glamds can respond to signals from central NS ```

Question 36

what does the ENS contain

Answer 36

``` ENS contains all elements of an independent nervous system - sensory - motor - interneuron - muscle - glands Complex system of motility and secretion controlled by reflexes - autonomic reflexes ```

Question 37

ENS vs CNS reflexes

Answer 37

Long reflexes - external stimuli i.e. sight and smell of food - involves CNS - alters activity of ENS - causes changes in motility and secretion Short reflexes - internal stimuli i.e. when molecules in lumen - ENS - local neural circuits - causes changes in motility and secretion

Question 38

Hirschprungs disease

Answer 38

Innervation of large intensive either non existent or reduced - surgical removal of the colon - congenital disorder - all or part of colon has no innervation

Question 39

what are the hormones secrete by

Answer 39

enteroendocrine cells in mucosa

Question 40

hormonal control

Answer 40

stimulis chemcial osmotic and pH | - negative feedback mechanisms to bring back luminal contacts back to normal

Question 41

enteroendocrine cells and fucntion

Answer 41

present throughout gut between epithelial cells single cells throughout GI tracts - link between luminal contents and capillaries - intestinal ‘ taste cells’ - densely packed with vesicles - sense luminal contents and respond via release of hormones