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GIT (Organisation of the GI Wall (Mucosa (Secretion of gastric juices and…
GIT
Organisation of the GI Wall
Mucosa
Secretion of gastric juices and hormones
Absorption of nutrients from GI lumen
Small blood vessels
Submucosa
Dense connective tissues
Large blood vessels and lymphatic network
Submucous/Meissner's plexus
Muscularis
Double layered muscular wall
Outer longitudinal wall
Inner circular wall
Myenteric/Auerbach
Serosa
Outer fibrous connective tissue layer
Movement in Large Intestime
Segmentation
For mixing food
Propulsive
Moves food forward along the alimentary canal
Divided into two segmants
Proximal
Absorption
Distal
Storage
Ileal spchinter
Prevents backflow of colon material into the ileum
Neural and Hormonal Regulation
Intrinsic regulation
Neural regulation
Myenteric plexus
Motor function
Increase tonic contraction in gut up to hours
Controls the rate and intensity of rhythmic contractions
Meissner's plexus
Sensory function
Regulates neurogenic reflexes
Increase secretion
Increase muscular activity
Extrinsic regulation
Parasympathetic and sympathetic NS
Factors affecting PP activity
Stimulating
Types of food
Protein>Carbo>fats
Protein stimulate gastrin release
Increase activity
Liquid clears faster than solid food
Large amount of food
Anthral distention
Vasovagal excitatory reflexes triggered (parasympathetic)
PP activity increases
Neural
Parasympathetic
Myenteric plexus
Drugs
Metoclopramide, erythromycin
Inhibiting
duodenal content
Strong neural reflex triggered from duodenum to stomach
Irritation of duodenal mucosa
Acidity of chyme (normal pH 3-5.4)
Hyper/hypo-osmotic food clears slower than iso-osmotic content
Presence of breakdown products of protein and fats
Triggers release of cholecystokinin
Block action of gastrin to trigger PP
Drugs
Opioids
Others
Pregnancy
Elderly
DM
Post-operative bowel activity
Neural
Sympathetic
Irritation of duodenal mucosa
Acidity of chyme pH 3.5 -5.4
Hyper/hypo- osmolarity
Mastication
The first step of digestion
Food is crushed and ground by teeth
Net result: increased surface area available for enzymatic action
Reason
Cellulose layer in fruits and plants needs to be broken down for enzymes to act
Teeth provide mechanical breakdown of food into smaller pieces to facilitate swallowing
Salivary amylase enzyme
Breakdown of starch