Disegtion Flashcards
Digestive organs
Mouth, Pharynx, Oesophagus, Stomach, Small Intestine, Large Intestine
Digestive Accessory organs
Teeth, Tongue, Salivary Glands, Liver, Gallbladder, Pancreas
4 layers of digestive tract
Mucousa, submucousa, muscularis externa, serosa
Mucousa made of
mucous membrane: epithelium, lamina propria, muscularis mucousae
Mucousa function
secretion, absorption, folding
Submucousa contains
blood vessels and nerve network
Submucousa function
binds mucousa to musclaris externa
Muscularis externa made of
smooth muscle
Muscularis externa 2 functions
contraction and relaxation
peristalsis and segmentation
Serosa
membrane allowing attachment to abdominal walls
Primary function of GIT
supply body with nutrients, water and electrolytes
GI tract optimises
conditions for digestion/absorption
Food is … by GIT
broken down into small enough substances to be available for cells
6 stages of digestion
-ingestion
-propulsion (peristalsis)
-mechanical breakdown (segmentation)
-chemical digestion
-absorption
-defecation
Ingestion
material enters GIT via mouth
Propulsion
movement of food along GIT
Peristalsis
movement of food along GIT
Mechanical Breakdown
breaks down food into smaller pieces, increasing surface area
Segmentation
breaks down food into smaller pieces, increasing surface area
Chemical digestion
enzymes break down bigger molecules into smaller molecules for efficient absorption
Absorption
movement of substrates (electrolytes, water & vitamins) across epithelium into interstitial fluid
Defecation
removal of indigestible waste from body
Ingestion organs
Mouth
Mechanical breakdown organs
teeth, stomach, small intestine
Propulsion definition
movement down GIT, swallowing, peristalsis
Propulsion organs
oesophagus, stomach, large intestine, small intestine, small intestine,
Absorption organs
primarily small intestine, some water absorbed in large intestine
Peristalsis definition
waves of muscular contraction in a single direction (mouth>anus)
Circular Muscles function
push forward
Longditudinal muscles function
shortens and propels bolus forward
Segmentation
cycles of contraction, churn and fragment bolus, mixing with intestinal secretions. ensures content comes in contact with absorptive layer
Segmentation direction
forward and backward
ANS stands for
Autonomic Nervous System
Parasympathetic nervous system
Rest and Digest
Sympathetic nervous system is
Fight or Flight
Tongue
Sensory analysis of material before swallowing
Teeth, tongue and palatal surfaces
mechanical processing via mastication
Lubrication
mixing food with mucous and saliva
Chemical processing oral cavity
carbs and lipids by salivary amylase and lingual lipase
Daily saliva
1-1.5L
Saliva composition
99.4% water, lgA, lysozyme, enzymes, buggers, mucous, enzymes and waste products
Saliva functions
lubrication
cleanse mouth and teeth
moisten food
dissolve food
begin chemical digestion
Oesophagus is
hollow muscular tube
Oesophagus length
25cm
Oesophagus movement
peristalsis
Deglutition Buccal phase
swallowing bolus
Deglutition Pharyngeal/Oesophageal phase
involuntary peristalsis carrying bolus pharynx > oesophagus > stomach
Stomach sphincters
top and bottom: pyloric sphincter
Rugae
folds
Mucousa rugae function
mucous production
stomach avid pH
2
Stomach muscle layers
out>in: longditudinal, circualr, oblique
Stomach muscle type
smooth muscle
Stomach mechanical digestion
mixing waves every 15-25 seconds, forms chyme and moves chyme to duodenum
hCl stomach
denatures proteins
pepsinogen stomach
hydrolyses peptide bonds
gastric lipase stomach
hydrolyses triglycerides
Goblet cells
protection and mucous production
COX-1 pathway
immune system, protects inside of stomach, mucous production
Parietal cell produces
hCl and intrinsic factor
Intrinsic factor absorbs
B12
Chief cells produce
pepsinogen and gastric lipase
G cells produce
gastrin
G cell function
stimulates parietal and chief cells, increases secretion and motility
Regulation of gastric activity under
CNS, ENS, hormones
3 phases of gastric activity
Cephalic phase, gastric phase, intestinal phase
cephalic phase
sight, smell, taste and thought of food. Increase gastrin
Gastric phase
arrival of food in stomach
Gastric phase triggered by
stretch receptors and chemoreceptors
Gastric phase pH
decreased pH in stomach
Gastric phase enhanced secretion
gastrin, pepsinogen and hCl
Intestinal phase
chyme enters duodenum
Intestinal phase enhanced secretion
secretin, cholecystokinin (CCK), gastric inhibitory peptide (GIP)
Secretin
reduces production of stomach acid
CCK
inhibits gastric emptying
GIP
inhibits gastric secretion and emptying
Chrelin
appetite stimulant
Leptin
appetite suppressant
Leptin secreted
by adipose tissue when fat stores increase
Leptin acts by
inhibiting appetite stimulant neuropeptide Y (NPY)
Insulin and CCK
acts as fullness signals to decrease hunger
Pancreas attached to
duodenum by pancreatic duct
Pancreas exocrine cell function
acinar gland secretes pancreatic juice, digestive cells and buffers
Pancreas exocrine cell function
pancreatic islet cells, secrete insulin and glucagon into blood stream
Daily pancreatic secretions per day
1000mL
Pancreatic secretions
water, salts, bicarbonate, phosphate, buffers, enzymes
Pancreas carbs
pancreatic alpha amylase
Pancreas proteins
proteolytic enzymes (tripsin) and proteases
Pancreas triglycerides
pancreatic lipases
Pancreas DNA and RNA
nucleases
Liver weight
1.5kg
Liver location
rights hypochondriac and epigastric region
4 liver lobes
right lobe, left lobe, caudate lobe, quadrate lobe
Lobule components
Hepatocytes, sinusoids, satellite macrophages (Kupffer cells)
Hepatocyte location
around sinusoids and hepatic vein
Hepatocytes function
adjust levels of circulating nutrients
Blood passes
through sinusoids and hepatic vein
Kupffer cell function
phagocytic, engulf pathogens, cell debris and damaged RBC
Hepatic artery
delivers oxygenated blood
Hepatic portal circulation
delivers nutrient rich blood from the intestines
Liver metabolic regulation
carb, lipid and protein metabolism
waste removal
vitamin and miner store
process drugs
Liver haematological function
removal of bacteria, old RBCs and WBCs
produce plasma proteins
removal of hormones and antibodies
removal and storage of toxins
activation of vitamin D
Bile function
digestion of lipids
Lipid digestion
stomach processing creates large drops containing lipids
bile salts break droplets apart
tiny emulsification droplets able to be absorbed by epithelium
Gallbladder
stores and concentrates bile, releases bile in duodenum
bile release stimulated by
CCK
Small intestine length
6m
Plicae Circularis
circular folds in small intestine
Plicae Circularis function
mix chyme
Villi in small intestine
capillaries and lacteals
Microvilli in small intestine
brush border
3 parts of small intestine
duodenum, jejunum, ileum
Duodenum function
receives chyme from stomach, mixes with pancreatic enzymes, neutralises acid
Jejunum function
chemical digestion and nutrient absorption
Ileum function
nutrient absorption, vit B12 synthesis
Carbohydrases function
breaks bonds between simple sugars and
Proteases and peptidases
break bonds between amino acids
Lipases
seperate fatty acids from glycerides