Week 2 - Digestive System Flashcards
Digestive Tract
Tube from the mouth to the anus and Accessory organs
Gastrointestinal tract
Only the stomach and the intestines
Digestive system components in order
Oral cavity (mouth)
Accessory organs - tonsils and salivary glands
Pharynx (throat)
Oesophagus
Stomach
Small intestine - Duodenum, Jejunum and Ileum
Accessory organs - Liver, Gallbladder and Pancreas
Large Intestine - Cecum, Colon, Rectum and Anal canal
Digestive System Functions
Ingestion, mastication, propulsion, mixing, secretion, digestion, absorption, elimination
Mastication
food is mechanically broken down. Increases the total
surface area to allow digestive enzymes access
Propulsion
the movement of food through the digestive tract
Three types of propulsion
Swallowing - Moves bolus from oral cavity into oesophagus
Peristalsis - wave of smooth muscle relaxes in front of bolus and wave of smooth muscle contracts behind bolus which pushes it through the oesophagus and small intestine
Mass movements - contractions that move material in the large intestine
Mixing
Segmental contractions to mix food with digestive secretions in the small intestine
What type of secretion occurs in the digestive tract
Mucus secreted by the digestive tract and enzymes secreted from pancreas, small intestine, stomach and oral cavity help break down food
Water also helps this
Digestion (2 types)
Mechanical - mastication and mixing
Chemical - digestive enzymes
Describe an enzyme
A substance that increases the speed of a reaction without being changed or used up in the process - is usually always a protein
Two mechanisms that describe the action of enzymes
Lock and key hypothesis - enzyme + substrate enter an active site and combine (COMBINE)
Induced fit model - substrate enters active site of enzyme and it breaks the substrate down (BREAKS DOWN)
Name the 3 Carbohydrate (saccharides)
Polysaccharide, Disaccharide, Monosaccharide
What are proteins composed of and how are they held together
Amino Acid and held together by Peptide bonds
Name the 3 Lipids
Fatty Acids, Triglyceride, Glycerol
Types of digestive enzymes
Amylase breaks down sugars (carbs), Lipase breaks down fat, Protease breaks down protein
What affects enzyme function
Temperature and pH
Amylase
Break down carbs
Lipase
Break down lipids (fats)
Protease
Break down proteins
What occurs in the large intestine turning bolus into feces
It absorbs water and salts
4 layers of digestive tract
Mucosa
Submucosa
Muscularis
Serosa
Mucosa contain 2 receptors
Mechanoreceptors
Chemoreceptors
Submucosa contains
Nerves, lymphatic and blood vessels and small glands
What type of muscle is the Muscularis of the digestive tract
Smooth muscle
Serosa
Smooth layer that covers the digestive tract organs
Enteric Nervous System (ENS)
A division of the ANS located within the digestive tract walls and can work independently to ANS
What does the PNS do to digestion
Increases motility, salivary and gastric acid secretions
What does the SNS do to digestion
Decreases motility
3 endocrine secretions
Gastrin (tells the stomach to release gastric acid), Secretin (regulated water homeostasis throughout the body and influences the environment in the duodenum by regulating secretions in the stomach, pancreas and liver, Cholecystokinin (tells gallbladder to secrete bile when the upper small intestine becomes acidic)
