Digestive System Flashcards
Type of nutrients
- Carbohydrates
- Lipid
- Protein
- Vitamin
- Minerals
- Water
Carbohydrates
1g = 4kcal energy
Can add into
protein (glycoproteins)
Lipid (glycolipids)
Types of carbohydrates
Monosaccharides ( glucose, fructose)
Simplest structure
Disaccharide (maltose, lactose)
Two monosaccharide linked together
Polysaccharide（starch/ glycogen)
More than 2 monosaccharide connect
Non-digestible polysaccharide from plants = cellulose
Soluble vs insoluble
Soluble:
1. Bind intestinal fat to prevent over absorption
2, reduce body cholesterol
3. Stabilise blood glucose
Insoluble:
1. Add bulk to feces
2. Stimulate faeces movement
Four types of lipid
- Triglyceride ( fats)
2nd choice of energy
Keep warm - Phospholipid
Structural component of cell membrane - Steroids
Cholesterol in animal & plant
Structural component of cell membrane - Saturated fat
Carbon-carbon single bond
Animal fat
increased risk of cardiovascular diseases
Lipid in blood
Density of lipoprotein
Is not soluble -) triglyceride circulate as lipoprotein
LDL-) transport cholesterol from liver to cell
HDL-) removing extra cholesterol, transporting cholesterol from lining to glands for hormone synthesis or bile excretion
Proteins functions
Build block of body tissue
Enzyme
Receptor
Transport agent
Hormone
pH buffer
Energy source
Vitamins- essentials vs non-essentials
Water soluble vs fat soluble
Essentials
A
B
C
E
Non-essentials
D
K
Water soluble: B & C
Cannot store in body, excrete by urine, quick deficiency
Fat soluble: A D E K
Minerals sources, 7 major & minor
Source: beef, liver
Major minerals: calcium, potassium, magnesium, sodium, chloride
Trace mineral: copper, zinc, iron
Water functions
As a transport medium
• As a solvent
• As a lubricant
• Regulate body temperature
• Help in digestion, absorption and excretion
• Help in maintaining the homeostasis of ion
Metabolism-) anabolism & catabolism
Anabolism-) system to build up molecules
Catabolism-) system to break down molecules
-) slowly releasing energy
Stage of digestion
- Ingestion
- Secretion
- Mobility
- Digestion
- Absorption
- Defaecation
Parts of GI tract & Accessory digestive organs
Mouth
Pharynx
Oesophagus
Stomach
Small intestine
Large intestine
Teth
Tongue
Salivary glands
Liver
Galbladder
Pancrease
Peritoneum & mesentery
Parietal wall-) outside, connect to abdominal wall
Visceral peritoneum-) cover organ
Mesentery-) double layer of visceral pitoneum
Four layers of tissue in GI tract
- Epithelial
Most inner
Goblet cell-) secrete mucus for protection and lubricate - Submucosa
Connective tissue - Muscularis extrema
Skeletal / smooth muscle
Outer circular, inner longitudinal muscle - Serosa
Outer: visceral pertoneum
2 actions of gi tract
Peristalsis向前推
Segmentation前後前後撈
Small intestine ✅
Mouth
For chewing food
Convert food into bolis
Carbohydrate digestion
Teeth
Hild 20
Grown 32
Incision
Tear
Tear & crush
Grinning
Salivary glands
Secrete saliva
1. Water to dissolve food
2. IgA antibody & lysozyme for bacteria killing
Oesophagus
25cm
Skeletal muscle-) mix -) smooth muscle
Push food with peristalsis down to stomach
Stomach
2L, mix & churn food
Mainly protein digestion, no absorption.
Swallowing steps
- Food bolus push by tongue from oral cavity to orolarynx
- Initial reflex contraction of pharyngeal muscle to propel food into laryngopharynx
- Soft platelet rise to block food from entering nasopharynx
- Epiglottis prevent food entering airway
- Relax upper oesopharyngeal sphincter
- Food pass thru by peristalsis
- Relax of lower oesophageal sphincter to allow food entering stomach
Stomach 4 parts
Cardia ( near oesophagus)
Fundus
Body
Pylorus ( funnel shape, connect to dudenum
4 layers of stomach
Mucosa
Submucosa
Muscularis externa
Gastric pit
1. Surface cell: form mucus layer muon top
2. Neck cell: secrete mucus to protect stomacch
Small intestine
Duodenum( chemical digestion
Jejunum (nutrient asorption
Illeum (absorp nutrient & bile salt)
Villi 絨毛 2 deviations
With capillaries-) absorb non-lipid substance
With lacteal- )absorb lipid substance
Type of digestive juice in intestine
1 Intestinal juice
2. Pancreatic juice
3. Bile
Pancreas- location, component
Pancreatic juice
Location: at epigastric & umbilical region posterior to stomach & liver
Pancreatic acini
Release pancreatic enzyme to duodenum to digest sugar, peptide, lipid
Pancreatic islet
Secrete Insulin & glucagon
Component of pancreatic jucie
1 water with bicarbonate-) alkaline, neutralise acidic chyme
2. Pancreatic amylase
4. Protease
3. Pancreatic lipase
Liver location, function
At hypochondriac & epigastric region
Function
1. Production of cholesterol (vit D
2. Storage of micro nutrient (copper, zinc
3. Blood sugar balance
4. Produce of bile
5. Protein synthesis( globulin
6. Immune system
7. Metabolism
8. Detoxification
Liver function ( shorter)
- Site for metabolism
- Bile synthesis
- Storage of nutrient
- Activate vit D to calcitriol
Gallbladdar 膽囊
Store up to 50 mL bile
Bile & related
Bile contain water, bile salt & bilirubin
Bile salt: emulsify fat into droplet
Bilirubin: form after rbc breakdown
Mechanical digestion in small intestine
Step
- Initiate with chyme entering
- Regular contraction / relaxation of circular muscle
- Mix chyme with digestive juivce
- Slow down chyme movement to facilitate nutrition absorption
Absorption in small intestine
