GIT,Physiology Flashcards by M K

Food ingestion depends on

Hunger and appetite

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Difference between hunger and appetite

Hunger:No specific food desire,can eat anything
Appetite:Desire to eat specific food e.g chicken,omelette

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Layers of GIT and name them

4:in to out
1)mucosa(epithelium +CT+some muscles)
2)submucosa(CT)
3)Muscularis Externa(inner circular smooth muscle,outer longitudinal smooth muscle)————>motor control
4)serosa/Serosa adventitia (CT)

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Syncytium caused by

Gap junctions in muscle bundle

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Smooth muscle bundle
A) dia of Fiber and length?
B)number of fiver in bundle

Dia:2 -10 micrometer
Length:200 to 5 micrometer
No:1000

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Types of waves in git and caused by

A)Slow waves——>Na channels in Interstitial cells of cajal
B)Spike potential——->Na Ca Channels

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Frequency of slow waves

3 [stomach)
12(duodenum)
9 (terminal ileum)

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Threshold of spike potential

-40

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Stimulus of depolarisation

Muscle stretch,Ach released by parasympathetic endings,hormones

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Hyperpolarisation (no git motility,cells less excited) caused by

Epinephrine,norepinephrine released in stress condition,Sypatethic stimulation

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Tone

Partial state of contraction

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Tonic contraction caused by

Excessive spike potential due to stimulus or hormones

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Nervous system of GIT

Enteric Nervous System

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Inhibitory neurotransmitter of myenteric plexus

VIP(vasoactive intestinal peptide)

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Components and functions of enteric nervous system

2:
Meißners:bwMuscles Control git movement and motility
Meisters:in submucosa control local hormone secretion,blood flow,absorption

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Sensory ending of git stimulated by

Mucosa irritation,excessive distension,chemicals

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Sympathetic parasympathetic function

S;release norepinephrine ,inhibit smooth muscle/neuron,motility decrease passage of food difficult and give versa

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Gastro intestinal reflexes types

1)within gut wall——>peristalsis,secretion,mixing contents
2)between git and prevertebral sypatethic ganglia——->gastrocolic
>enterogastric
>colonoileal
3)between git and spinal cord/brain stem
>vagovagal
>pain
>defecation

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Hormones of GIT

*Gastrin,Cholecystokinin,Secretin,GIP,Motilin

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Hormones of GIT

*Gastrin,Cholecystokinin,Secretin,GIP,Motilin

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Peristalsis

Involuntary rhythmic muscle contraction that pushes food forward in git

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Peristalsis occurs when

Distension of wall,physical/chemical irritant,parasympathetic stimuli

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My enteric plexus inhibited by

Atropine which inhibit cholinerguc endings thus no peristalsis

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Movement of git types

Peristalsis and mixing

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Chewing reflex another name

Mastication

Rebound contraction

Reflex inhibition +stretch reflex

Mastication controlled by

Motor branches of 5th CN

Chewing necessary why

Break cellulose covering,increase surface area,easy swallowing

Swallowing stages

Oral,Pharyngeal,esophageal

Pharynx 2 functions

Respiration and swallowing making process of swallowing complicated and does one thing at a time

Peristaltic waves originate at

Esophageal stage of swallowing

Difference between primary and secondary peristaltic movements

1)P originate in pharynx,S anywhere food left behind 2)P intrinsic,S esophagus stretched 3)P-enteric nervous system,S-extrinsic vagus supply

If brainstem damaged in accident secondary work

Yes after some time enteric takes over

Swallowing center

Medulla (tracts solitarius)

Wave of relaxation works on and caused by(receptive relaxation)

Lower esopahgeal sphincter,myenteric inhibitory neurons

How lower esopagus prevent ulcers

1)constricted usually 2)Slit mechanism

Achlasia

Constricted lower oesophagus sphincter causing food blockage

Gerd

Relaxed lower esopahgeal sphincter causing gastric reflux and mucosa damage

Rugae appear when

Stomach empty,not stretched

Stomach reflexes

Vagovagal

Stomach can accommodate how much food

0.8 to 1.5 l

Motor function of stomach

Storage,mixing,chyme inputting

Retropulsion

Digging up of bonus and going back up for mixing in stomach forming chyme

Chyme

Chopped bolus +gastric acid

Chyme fluidity depend on

Food amount,water,stomach secretion

Difference between hunger contraction and pangs

Contraction +pain=pangs

Hunger pangs peak in

3 to 4 days

Peristalsis in stomach function

20% -peristaltic pump 80%- mixing

Stomach emptying promoted by

Pyloric pump and gastric factors(food volume more,gastrin)

Stomach emptying inhibited by

Duodenal factors(enterogastric reflex + hormones)

Effects of inhibition

Pyloric sphincter tone increase,pyloric pump decrease

Small and large intestine movements

Artificial classification of mixing and peristaltic movement (as both occur mixed so no true classification here)

Factors causing emptying inhibitions reflex to take place

Irritant,ph,osmolarkty,increase distension,fats more

Inhibitory hormones

Cc’d,secretin,GIP

Segmentation contraction

Mixing movements in small intestine

Total small intestine time

3 to 5 hrs

Peristaltic movements in small intestine controlled by

Nervous:gastroentric reflex, Hormones:+ CCK,insulin,motilitin,serotonin,gastrin - secretin,glucagon

Peristaltic rush

More propulsive movement due to irritant,ulcers

Haus trative movements,Mass movement

Colon mixing,peristaltic colon movements

Defecation reflex

Intrinsic+Parasympathetic defecatiin reflex

Paralysis of swallowing

Nerve damage,infection,muscle damage

Anaesthesia

Swallowing center inhibit