Digestive System - Functions Flashcards
List the components of the digestive tract, in order.
Oral cavity, pharynx, oesophagus, stomach, small intestine, large intestine, rectum, anus
Name the three portions of the pharynx.
Nasopharynx, oropharynx, laryngopharynx
Name the functions of the digestive tract.
Ingestion, mastication, propulsion, mixing, secretion, absorption, elimination
What is Mastication?
Process of mechanically breaking down food to increase total surface area to allow digestive enzymes to break down food.
What is Propulsion and name the characteristics of this movement?
Movement of food through digestive tract, which takes approximately 24-36 hours.
Swallowing, peristalsis and mass-movement.
Describe Swallowing [Propulsion].
Moves liquids or soft mass of foods/liquids, called a bolus, from oral cavity into oesophagus.
Describe Peristalsis [Propulsion].
Move material through digestive tract.
What are Peristaltic waves?
They are muscular contractions made up of a wave of relaxation of circular muscles in front of the bolus, followed by wave of strong contraction of circular muscles in front of bolus. This moves the bolus along the digestive tube.
Describe Mass-movements [Propulsion]?
Contractions that move material in distal parts of large intestine to the anus.
Describe Mixing.
Contractions that move food back and forth in digestive tract to mix it with digestive secretions to help break food into smaller pieces.
What are Segmental contractions [Mixing]?
Mixing contractions that occur in the small intestine.
Describe Secretion.
Help to lubricate, liquefy, buffer, and digest food.
What are the types of secretions?
Mucus, water and enzymes
What is the function of Mucus during digestion [Secretion]?
Lubricates lining of tract and protects epithelial cells from abrasion, stomach acid and digestive enzymes.
What is the function of Water during digestion [Secretion]?
Liquefies food making it easier to digest and absorb.
What is the function of Enzymes and where is it secreted [Secretion]?
Breaks down complex food molecules to smaller molecules.
Secreted from pancreas, small intestine, stomach and oral cavity.
What is an Enzyme?
A protein catalyst that speeds up the rate of a chemical reaction.
Describe Digestion.
The breakdown of large organic molecules into their component parts:
carbs -> mono
proteins -> amino
triglycerides -> fatty acids and glycerol
What are the components of Digestion?
Mechanical digestion: involves mastication and mixing
Chemical digestion: achieved by digestive enzymes secreted along tract
Describe Absorption.
Movement of molecules out of digestive tract and into circulatory or lymphatic system.
Achieved via Diffusion, Facilitated diffusion, Active transport, Osmosis, Symport, or Endocytosis.
Describe Elimination.
Waste products removed from body via defecation. Occurs in large intestine, where material changed from liquefied to semi-solid by absorbing water and salts.
