Module 4 Digestive System 1 Flashcards
Digestive System Components (6)
Mouth Pharynx Oesophagus Stomach Small Intestine Large Intestine (inc Rectum & Anal canal)
Digestive Processes (6)
Ingestion Secretion Mixing & Propulsion Digestion Absorption Elimination
GIT Layers
Mucosa
Submucosa
Muscularis
Serosa (Peritoneum)
Mucosa Layer 1 - Epithelium Information
Mouth, pharynx, oesophogus, anus = Epithelium for Protection
Stomach & Intestines = Columnar Epithelium
1- Microvilli - Surface Area/Absorption
2- Goblet Cells - Secretion of Mucus
3- Enteroendocrine Cells- Secret hormones
Mucosa Layer 2 - Lamina Propria Information
Connective Tissue - BV & Lymphatic Tissue = Absorption of nutrients
MALT - prevalent in tonsils, oesophagus, small/large intestine
GALT(Gut)- Contains 70% bodys immune Cells
First Line defence
Mucosa Layer 3 - Muscularis Mucosa Information
Thin Smooth Muscle
Villi - surface area = absorption & digestion
Mucosa Layers (3) Recap
Epithelium - Protection
Lamina Propria - GALT
Muscularis Mucosa - Villi
Submucosa Information
Connective tissue
Blood & Lymph
Submucosal Plexus (secretions)
Muscularis Externa Information
Mouth, pharynx, Upper oesophagus, anal sphincter = skeletal muscle (voluntary)
Rest GIT = smooth muscle (involuntary)
- 2 layers - Inner Circular & Outer longitudal
- Myenteric Plexus (between layers) - for Motility
- Aids - Mixing (digestive juices) & Propulsion (peristalsis)
Peritoneum
Barrier to the spread of infection
- Parietal - external layer
- Visceral - Internal Layer
- Serous Fluid - between layers
Peritoneum Pathologies
- Ascites ( accumulation fluid in peritoneal cavity)
2. Peritonitis (acute inflammation peritoneum)
Greater Omentum
Apron - Largest Fold of Peritoneum (4 layers)
- Stores fat
- Lymph nodes - macrophages & plasma cells (antibodies - GIT)
Lesser Omentum
Suspends stomach & duodenum from Liver
Pathway BV entering liver
Contains - hepatic portal vein, hepatic artery, bile duct, lymph nodes
Enteric Nervous System - Details
Brain of Gut - Oesophagus to anus
100 million neurons
Regulated by autonomic NS
ENS
Parasympathetic - Rest & Digest
Increases muscular activity (myenteric plexus) & secretion submucosal plexus)
Sympathetic - Fight or Flight
Decreases muscular activity (myenteric plexus) & secretion submucosal plexus)
ENS - Myenteric Plexus
M = Motility (between fibres of Muscularis Externa)
Controls strength & frequency of muscle contraction
ENS - Submucosal Plexus
S = Secretions (Submucosa)
Controls digestive secretions
ENS - Neurons
1- Motor (myenteric plexus- control peristalsis. Submucosal plexus - control secretions)
2-Sensory (receive mucosal info - chemo/stretch receptors)
3- Inter (connect 2 plexus)
GIT - Blood Supply
GIT supplied by Arterial Blood via Abdominal Aorta
Nutrient rich venus blood returned via liver (Portal System/Iliac Veins) > Liver filters blood > returned to systemic circulation
*Portal Vein Drains GIT components (except rectum/anal canal = ilium vein) > Liver
*
Oral Cavity
Lined with mucous membranes Hard palate Soft Palate Uvula Tongue (Papillae)
Oral Cavity Functions (4)
Mastication
Speech
Taste
Swallowing
Teeth - Information
32 (Adult) Crown,Neck,Root Dentin - Internal bulk of tooth Covered by enamel Sit in gingiva (gum) Function = Mastication
Saliva - Information
Produced by 3 glands (Parotid, Submandibular, Sublingual)
Parasympathetic NS > continuous lubrication
Reabsorbed
Sympathetic NS (stress) = dryness/dehydration/thirst
PH 6.35 -6.85 - mildly acidic
Saliva - Composition (6)
Water (95%) Mineral salts Enzymes Mucus IgA Blood Clotting factors
Saliva Functions (7)
Digestion Taste Cleansing (oral cavity/teeth) Defence (IgA/Lysozomes) Lubrication Buffer (acidic foodO Waste removal (Urea/Uric)
Oesophagus - Information
25cm muscular tube Lined with Epithelium Superior/middle = skeletal muscle Lower = smooth muscle Food travels via peristalsis Epiglottis - stops food entering trachea Lower Oesophageal sphincter - prevents stomach reflux
Oesophagus - Location
Attached to Larynx
Posterior to trachea
Passes through diaphragm
Stomach - Regions (4)
Cardia
Fundus
Body
Pyloric
Stomach - Overview & Function
J shaped
Lesser & greater curvatures
Same layers as GIT EXCEPT 3 layers of muscle
2 sphincters - cardiac (top) Pyloric (bottom)
Simple Epithelial cells - replace lining approx 3 days Highly acidic (ph2-3)
Function - Churn & Mix food
Hormones - Ghrelin (Hunger) Gastrin (Secretion)
Stomach - Cells (3)
Parietal -
IF (B12)
HCI (Activate Pepsin & assist activate bile/pancreatic juices. Iron conversion. Microbial)
Chief -
Pepsinogen (protein digestion)Gastric lipase (lipid digestion)
Goblet - (Mucus - protects from acidity)
Pancreas (Accessory) - Exocrine Functions
Exocrine : Pancreatic juice Sodium Bicarbonate/water Protease enzymes - 4 (Trypsin/Chymotrypsin > Protein, Ribonuclease >RNA, Deoxyribonuclease > DNA) Pancreatic Lipase (Fat) Pancreatic Amylase (Starch >Sugar )
Pancreas (Accessory) - Endocrine Functions
Endocrine:
Hormones>Blood
Insulin & Glucose
Somatostatin (Growth/inhibiting hormone)
Location = Connected to duodenum via pancreatic duct
Gallbladder (Accessory) - Information
Ejects bile > emulsifies fats
Emulsification breaks down lipids (Increases surface area for enzymes to work)
Bile (Gallbladder)
Produced by hepatocytes > GB > storage
Bile = salts/cholesterol/bilirubin
90-95% bile transported back to liver from Ileum
Produced by hepatocytes (liver)
Contacts and ejects bile on stimulation
Gallbladder > Bile> Cystic duct >Common bile duct
Pancreas > Pancreatic enzymes>Pancreatic duct joins common bile duct > forms Ampullar of vater’ > Duodenum
Small Intestine - Regions (3) & Functions
Duodenum - Emulsification & Digestion (30cm)
Jejunum - absorption (2.5m)
Ileum - B12 absorption (3.5m)
Peristalsis Digestion Absorption Hunger/saiety Immunity - Peyers patches
Small Intestine - Information
Chyme enters via Phyloric sphincter
Most digestion & absorption occurs
Villi maximise SA
Variety of cells (Goblet, endocrine, absorptive)
Absorption ——90% Absorption occurs in SI
Large Intestine - Regions (4)
Caecum
Colon (A,T,D)
Rectum
Anus (2 Sphincters)
Deification
Motion of passing a stool
Peristalsis > fecal matter > rectum>Stretch receptors>Vol relax external sphincter
Large Intestine - Microbes (functions)
Final stages nutrient extraction - fermentation
Support Immunity
Ferment residual AA (Fecal odor)
Ferment Fibre >SCFA> support tight cell junctions
Produce B12,K2 FA
Keep pathogenic bacteria/fungus at bay
Biriruben - make into smaller molecules for excretion (fecal colour)
ABSORBTION Water, vitamins, minerals, some drugs
Some toxins reabsorbed > liver>excreted urine
Mostly symbiotic
Pancreatic Enzymes
Secreted into Duodenum ( Protese inactive form)
Pancreatic Amylase - Starches >Sugars Pancreatic Lipase - Lipid/Fat Dig Trypsin - Protein Dig Chymotrypsin - Protein Dig Riboneouclease - Dig RNA Oxyroboneuclease - Dig DNA
CCK (Peptide Hormone)
Stimulates pancreatic juices & enzymes ( Dig carb, Protein, fat)
Stimulates bile production (hepatic) & secretion by contraction of GB
mediates Satiety
Villi & Microvilli - function
Increase surface area of small intestine for absorption
Villi folds created by Muscularis Mucosa = increase SA
Microvilli contain brush border enzymes
Brush Border Enzymes
Attach to intestinal lining (not free)
Maltase, Sucrase, Lactase > break down sugars to glucose, fructose, galactose etc.
Dipetidase - break down proteins to AA
Nucleosides & Phosphatases - Digest RNA & DNA
Liver - functions (H Cleanse De 2HO ss Met)
Heat - regulation Cleanse blood of microbes Detoxification - Toxins, Alcohol, drugs Hormone deactivation Hemolysis Synthesis - Activate D3, Vit A, AA Storage - Vitamins, Iron, Copper, magnesium Metabolism - Fats, glycogen, AA
Liver Detoxification - Classifications
High ATP
Hydrophillic > H20 Soluble > Excreted
Lipophillic > Chemically altered > H20 soluble > excreted
Liver Detoxification - 2 Phases
Phase 1 - Bioactivation
CYP450 enzymes
>convert H20 soluble toxins >H20 substance > excretion kidney
> convert toxins > more reactive substance > dealt with phase 2
Phase 2 - Conjigation
Molecules attach > neutralise/stabilise > H20 soluble substance > excreted
Neurons (3 Types)
1- Motor - outgoing action/signal. Myenteric> control peristalsis & Submucosal > control secretions.
2- Sensory - info from mucal environment - Chemo receptors & stretch receptors
3- Inter - connect the 2 plexus’s
Plexus Networks
Myenteric > controls strength and frequency of muscle contraction - MOTILITY
Submucusal > controls digestive secretions & detects sensort info
both contain para & sympathetic nerve fibres
Abdominal Quadrants (9 quadrants - 3 regions)
R/L Hypochrondrium , epigastric region
R/L flank, umbilical region
R/L groin, pubic region
Dietary Carbs (3)
Mono - sac > 1 sugar unit > Glucose, fructose,Galactose
Di - sac > 2 sugar units
> Maltose - Dig Glucose x2
> Sucrose - Dig Glucose & Fructose
> Maltose - Dig Glucose & Lactose
Poly - sac > many sugar units
> Starch - Dig Glucose (pots, wheat, rice etc)
> Glycogen - Dig Glucose
> Cellulose - Indigestable
Dietary Lipids (3)
Triglycerides - predominant
Composed > Glycerol and 3 FA chains
FA are un/saturated
saturated - no double bonds - rigid
unstaurated - one or more double bonds between Carbon atoms
Phospholipids
2 FA tails and phosphate head
Dig - free FA & absorbed
Cholesterol
steriod in animal food
vital for cell membrane, vit d synthesis & sex hormone synthesis
Cis/Trans FA
Presence of a double bond
CIS > H on SAME side of bond
TRANS > H OPP side of bond
Proteins - Information
Long molecules AA
each protein has unique 3D structure (lock and key model)
need to be denatured before proteses enzymes can cleave apart
Body temp regulation > keep 3D shape
AA absorbed in SI
Proteins - Functions
Immunity (Iga & antibodies) Structures (muscle, collagen) Enzymes Hormones Neurotransmitters Energy
Denatured by Body temp/Ph changes
Enzymes
Biological catalysts
Not consumed in reaction - van preform reaction many times
Specific reactions - lock and key
names based on reactive ability - ie ase > lactase = lactose enzyme
Protein digestion = ie in > Pepsin
Liver Metabolism
Carbs - Excess glucose> converted glycogen> stored for use
Fat - Metabolise from storage as needed. Synthesis of cholesterol & Tricycerides
Protein
Convert essentail AA > Non ES AA
remove nitrogen from AA > Urea>excretion
break doen nucleotides > Uric acid > excretion
