upper GI physiology

Question 1

nerve supply

Answer 1

parasympathetic and sympathetic

Question 2

parasympathetic nervous system

Answer 2

• 1 pair of cranial nerves (vagus- 10th cranial nerve)
• supplies GI tract
• increases muscle activity (peristalsis) via myenteric plexus and increases glandular secretions

Question 3

sympathetic nervous system

Answer 3

arise from thoracic and lumbar regions

- decreases muscle activity and glandular secretion

Question 4

5 functions of GI tract

Answer 4

ingestion, propulsion, digestion, absorption, elimination

Question 5

ingestion

Answer 5

intake of food into the gi tract

Question 6

propulsion

Answer 6

contents are mixed and moved along the gi tract

Question 7

digestion

Answer 7

a process which breaks down food into simpler constituents

can be mechanical or chemical

Question 8

absorption

Answer 8

products of digestion pass through the walls of the GI tract, into the blood and lymph to be used by body cells
- via active transport or passive diffusion

Question 9

elimination

Answer 9

food which cannot be digested is removed from the body via faeces

Question 10

mechanical digestion

Answer 10

• mastication - chewing
• physically breaking down food
• increases surface area, allowing more exposure to enzymes

Question 11

chemical digesetion

Answer 11

food is broken down into small molecules by chemical enzymes excreted in the different parts of the GI tract
- enzymes are specific to the type of food molecule they are digesting

Question 12

oral cavity physiological processes

Answer 12

• ingestion

- mechanical and chemical digestion

Question 13

oral cavity teeth

Answer 13

• different shapes according to function

- cutting and chewing/ grinding

Question 14

oral cavity tongue

Answer 14

• chewing - mixing food with saliva

- swallowing (deglutition)

Question 15

salivary glands

Answer 15

parotid
submandibular
sublingual

Question 16

parotid glands

Answer 16

• located on either side of the face just below the EAM

- ducts open into the mouth at the level of the second upper molar

Question 17

submandibular glands

Answer 17

• located on either side of face under the angle of the mandible
• duct opens into mouth either side of the frenulum

Question 18

sublingual glands

Answer 18

• lie under the mucus membrane of the floor of the mouth
• located In front of the submandibular glands
• numerous small duct open into the floor of the mouth

Question 19

saliva

Answer 19

released via the parasympathetic nervous system

- reflex secretion - sight or smell or food

Question 20

saliva consists of

Answer 20

water, mineral salts, antimicrobial substances, mucus

Question 21

functions of saliva chemical digestion

Answer 21

• amylase will start to break down complex sugars
• this continues during swallowing
• action of amylase is degraded b strong acidic acid in stomach

Question 22

functions of saliva - lubrication of food

Answer 22

• dry food can be moistened to be formed into a bolus for swallowing

Question 23

function of saliva- cleaning and lubrication

Answer 23

• keeps mouth supple, prevents damage from abrasive food

Question 24

function is saliva - non-specific defence

Answer 24

• antibodies and lysozymes deal with invading microbes

Question 25

function of saliva

Answer 25

moistens dry food, to stimulate taste buds- chemical reaction

Question 26

Deglutition- oral phase

Answer 26

- voluntary muscles of the tongue and cheeks push bolus backwards into pharynx

Question 27

deglutition-pharyngeal phase

Answer 27

- reflex action - propels food bolus into the oesophagus - soft palate rises up closes nasopharynx - tongue and pharyngeal fold block mouth - larynx lifts up and forward, so opening is occluded by epiglottis - protecting the trachea

Question 28

deglutition - oesophageal phase

Answer 28

- presence of bolus stimulates perstalsis - bolus moves from oesophagus towards stomach - lower oesophageal sphincter relaxes to allow bolus into stomach

Question 29

peristalsis

Answer 29

- controlled via parasympathetic and sympathetic nervous systems - occurs from oesophagus onwards - contraction of smooth muscle behind bolus pushes it forward - lubricated by mucus - reduces damage to mucosa by food

Question 30

stomach 3 layers of muscle fibres function

Answer 30

- assist with churning/mixing/peristalsis | - propulsion and mechanical digestion

Question 31

stomach mucosal layer function

Answer 31

- allow stomach to expand/contract - consists of rugae - increase surface area - for secretion of gastric juice and enteroendocrine products - lubricated by mucus

Question 32

the stomach

Answer 32

food is liquified into chyme | - chyme passes through the pyloric sphincter into the duodenum in short bursts

Question 33

functions of the stomach

Answer 33

- chemical and mechanical digestion - limited absorption - preparation of iron absorption - production and secretion of intrinsic factor needed to absorb B12

Question 34

gastric juice 3 phases of secretion

Answer 34

- cephalic - gastric - intestinal

Question 35

cephalic phase

Answer 35

- flow starts before food reaches stomach | - stimulated by reflex stimulation of parasympathetic nerves - sight / smell of food

Question 36

gastric phase

Answer 36

stimulated by presence of food | enteroendocrine and duodenal secrete gastrin into the bloodn- stimulates gastric glands to produce more juice

Question 37

intestinal phase

Answer 37

chyme reaches duodenum and triggers production of secretin and cholecystokinin - these reduce secretion of gastric juice and reduce gastric motility, slowing stomach emptying

Question 38

gastric juice consists of

Answer 38

- water - mineral salts - mucus - hydrochloric acid - inactive enzyme precursors

Question 39

gastric juice functions

Answer 39

- liquifies food - acidifies process/ stops action of amylase - kills digested microbes - digestion to proteins

Question 40

the pancreas

Answer 40

- the exocrine pancreas produces pancreatic juice | - stimulated by presence of chyme in the duodenum

Question 41

the pancreas consists of

Answer 41

water mineral salts specific enzymes inactive enzyme precursors

Question 42

pancreatic juice function

Answer 42

- digestion of proteins - digestion of carbohydrates - digestion of fats

Question 43

bile consists of

Answer 43

- water - mineral salts - mucus - bile salts - bile pigments - cholesterol

Question 44

bile function

Answer 44

- emulsification of fats - making cholesterol and fatty acids soluble - excretion of bilirubin

Question 45

secretion of bile and pancreatic juice

Answer 45

- duodenum secretes secretin and cholecystokinin - which stimulates the contraction of the gall bladder and relaxation of the hepatopancreatic sphincter

Question 46

bile and pancreatic juice are expelled via...

Answer 46

hepatopancreatic ampulla