Digestive System Flashcards
6 Functions of Digestive System
Ingestion
Mechanical Processing
Digestion
Secretion
Absoprtion
Excretion
6 Subdivisions of Digestion Tract
Oral Cavity (+Teeth/Tongue)
Pharynx
Oesophagus
Stomach
Small Intestine
Large Intestine
Oral Cavity Digestive Function
Mechanical Processing
Moistening
Salivary Secretions
Pharynx Digestive Function
Propulsion
Oesophagus Digestive Function
Transport of materials to Stomach
Stomach Digestive Function
Chemical Breakdown
Mechanical Processing
Small/Large Intestine Digestive Function
Enzymatic Digestion
Absorption
4 Accessory Organs of Digestive System
Salivary Glands
Liver
Gallbladder
Pancreas
Salivary Gland Digestive Function
Secretion of Saliva
Liver Digestive Function
Secretion of Bile
Gallbladder Digestive Function
Storage of Bile
Pancreas Digestive Function
Secretion of Buffers and Enzymes
Peritoneum Definition
Cavity holding DIgestive Organs
Lined by Serous Parietal Membrane
Function of Peritoneal Fluid
Found in Peritoneum
Lubrication of organs during contraction/expansion
Allows organs to slide over each other
Mesentery Definition/Function
Attaches portions of digestive tract to peritoneum.
Allows for passage of blood vessels, nerves and lymphatic vessels
Function of Digestive Tract
Protection against Digestive Acids/Enzymes, Mechanical Stress and Bacteria
4 Major Layers of Digestive Tract
Mucosa
Submucosa
Muscularis Externa
Serosa
Plica Circulares Definition/Function
Microvilli lining the Digestive Tract
Increases SA on digestive tract
3 Structures of Mucosa
Mucosal Epithelium - Simple Columnar for faster absoprtion
Lamina Propria - Areolar Tissue with blood/lymphatic vessels
Muscularis Muscosae - Smooth muscle changing shape of Plica
Contraction of Muscularis Muscosae/Externa
Inner Circular Layer contraction decreases diameter of Plica
Outer Longitudinal Layer contraction decreases length of Plica
Submucosa Definition/Function
Layer of dense irregular connective tissue
Contains large blood vessels and lymphatic vessels
Acts as service corridor
Muscularis Externa Definition/Function
Smooth Muscle controlling shape of GI tract
2 Layers, similar to Muscularis Mucosa
Structure similar to Serous Membrane
Adventitia
Dense sheath of collagen fibres
In Oral Cavity, Pharynx, Oesophagus, Rectum
Cells controlling smooth muscle activity
Pacesetter Cells - Similar to Pacemaker Cells in Heart
Cells undergo spontaneous depolarization in waves
Peristalsis Definition
Involuntary Contraction/Relaxation of Smooth Muscle in Digestive Tract to move food
3 Steps of Peristalsis
Circular Muscle Contracts behind bolus
Longitudinal Muscle Contracts ahead of bolus
Circular Muscle Contracts to force bolus forward
Functions of Oral Cavity
Sensory Analysis
Mechanical Processing
Lubrication
Limited Digestion (carbs+lipids)
Passageway for air,food and liquids
Functions of Saliva
Lubricates mouth and contents
Dissolves chemicals
Initiating digestion of complex carbs via salivary amylase
4 Steps of Swallowing
Buccal Phase - Bolus is pushed to back of mouth by tongue
Pharyngeal Phase - Food pushes back epiglottos cartilage, closing the trachea
Oesophageal Phase - Food travels down oesophagus
Food enters stomach
4 Features of Oesophagus
Contains Stratified Squamous Epithelium
Resting muscle tone prevents air from entering
Conveys food and liquid to stomach
Contains Adventitia