Human Nutrition Flashcards
Nutrition
The way an organism obtains and uses food
Autotrophic (eg)
Organism that makes its own food (e.g. plants - photosynthesis)
Heterotrophic (eg)
Organism that can’t make its own food
Digestion
The physical and chemical breakdown of food
need for digestion
Breakdown large food particles until they’re small enough to pass into body cells
need for digestive system
digest food in single location, individual cells don’t have to contain full range of digestive enzymes
main stages of digestion
ingestion
digestion
absorption
egestion
ingestion
Food taken into alimentary canal
digestion
Food broken down into smaller soluble pieces
absorption
Movement of digested food from alimentary canal into blood system
egestion
Removal of unabsorbed material as faeces
methods for mechanical breakdown of food
teeth
contractions in stomach wall
peristalsis
peristalsis
waves of muscular action in walls of alimentary canal moving contents along
what stimulates peristalsis
fibre
teeth & use
incisors - cutting
canines - tearing
pre molars & molars - crushing/grinding
dental formula
2(I 2/2 - C 1/1 - PM 2/2 - M 3/3)
amount of teeth in child and adult
adult - 32
child - 20
length of oesophagus
muscular tube 25cm long
location of oesophagus
connects pharynx to stomach
Function of oesophagus
Food moves down the oesophagus by peristalsis
Stomach shape
J shape muscular bag
Functions of stomach
-Stores food for about four hours -churns and mixes food with gastric juice forming chyme
-digests food
Mechanical digestion in the stomach
peristalsis
Chemical digestion in the stomach
Use of gastric juice containing: mucus, HCL & pepsinogen
Mucus
Lines and protects stomach wall
Hydrochloric acid
-Kills bacteria
-activates pepsinogen (i.e. pepsin)
Pepsinogen
-activates enzyme pepsin due to hydrochloric acid
-pepsin converts proteins into peptides
Cardiac sphincter muscle
Circular muscle which contracts to close entry from oesophagus to stomach