BIO001 – Digestive System & Biological
Molecules Glossary – Complete Definitions List
Absorption - Process that takes useful products of digestion from the gut into blood or lymphatic
system
Active transport - Uptake of substances into a cell against a concentration gradient. Requires
energy
Amino acids - Nitrogen containing substances that form the building blocks of proteins
Amylase - Enzyme that is responsible for the break down of starch molecules. Found in
saliva.
Anus - The end of the gut from which faeces is eliminated by egestion.
Assimilation - Using the molecules produced by digestion for other purposes, e.g. for building new
cells
ATP - Chemical in cells that is used to transfer energy from respiration to reactions that require
it.
Bile - An alkaline fluid containing bile salts that is produced in the liver and stored in the gall bladder.
Neutralises stomach acid and emulsifies fats.
Blood - Liquid tissue that is the main transport medium in animals.
Bolus - A small ball of food that passes into the oesophagus
Capillary - The very fine blood vessels that permeate all the tissues in the body to supply oxygen and
nutrients as well as remove waste products.
, Carbohydrase - An enzyme that breaks down large carbohydrate molecules into simple
sugars.
Carbohydrate - A biological molecule containing carbon hydrogen and oxygen, usually with the
formula (CH2O)n
Cardiac sphincter - The ring of muscle at the top of the stomach
Chemical digestion - The process by which large insoluble nutrient molecules are broken down into
small soluble molecules by enzymes.
Chymotrypsin - Protease secreted by the pancreas that digests proteins in the duodenum. Like
trypsin, works best at slightly alkaline pH.
Circular - Rings of muscle fibres running round the gut to help in peristalsis - the movement of food
along the gut.
Circular muscles - Muscle fibres that form a ring around the iris. They contract to shut the pupil in
bright light.
Colon - First part of the large intestine. Site of water absorption from waste material.
Concentration gradient - This exists wherever there is more of a substance in one area compared to
another.
Diffusion - The net movement of a substance from an area of high concentration to one of lower
concentration.
Digestion - The process of breaking large insoluble food molecules into small soluble molecules that
can be absorbed
Digestive system - The gut: the site of digestion and absorption.
Molecules Glossary – Complete Definitions List
Absorption - Process that takes useful products of digestion from the gut into blood or lymphatic
system
Active transport - Uptake of substances into a cell against a concentration gradient. Requires
energy
Amino acids - Nitrogen containing substances that form the building blocks of proteins
Amylase - Enzyme that is responsible for the break down of starch molecules. Found in
saliva.
Anus - The end of the gut from which faeces is eliminated by egestion.
Assimilation - Using the molecules produced by digestion for other purposes, e.g. for building new
cells
ATP - Chemical in cells that is used to transfer energy from respiration to reactions that require
it.
Bile - An alkaline fluid containing bile salts that is produced in the liver and stored in the gall bladder.
Neutralises stomach acid and emulsifies fats.
Blood - Liquid tissue that is the main transport medium in animals.
Bolus - A small ball of food that passes into the oesophagus
Capillary - The very fine blood vessels that permeate all the tissues in the body to supply oxygen and
nutrients as well as remove waste products.
, Carbohydrase - An enzyme that breaks down large carbohydrate molecules into simple
sugars.
Carbohydrate - A biological molecule containing carbon hydrogen and oxygen, usually with the
formula (CH2O)n
Cardiac sphincter - The ring of muscle at the top of the stomach
Chemical digestion - The process by which large insoluble nutrient molecules are broken down into
small soluble molecules by enzymes.
Chymotrypsin - Protease secreted by the pancreas that digests proteins in the duodenum. Like
trypsin, works best at slightly alkaline pH.
Circular - Rings of muscle fibres running round the gut to help in peristalsis - the movement of food
along the gut.
Circular muscles - Muscle fibres that form a ring around the iris. They contract to shut the pupil in
bright light.
Colon - First part of the large intestine. Site of water absorption from waste material.
Concentration gradient - This exists wherever there is more of a substance in one area compared to
another.
Diffusion - The net movement of a substance from an area of high concentration to one of lower
concentration.
Digestion - The process of breaking large insoluble food molecules into small soluble molecules that
can be absorbed
Digestive system - The gut: the site of digestion and absorption.
