Nutrition Flashcards
What are the 3 importances of food
- Source of energy provides fuel for the cell ( mainly from lipids and carbs)
- Provides material for growth and repair of tissues ( mainly from proteins and minerals)
- Contains regulating substances ( vitamins; mineral salts; water) to control various body functions
What is nutrition
The process of taking in and using food
Explain the stages of nutrition fully
1) Ingestion
- Mouth; intake of large complex foods
2) Digestion
- mouth; stomach; small intestine; breaking down of food into soluble substances inside body
3) Absorption
- Small intestine; taking in of soluble substances into the blood system
4) Assimilation
- Body cells; soluble substances taken into the cells from the blood stream to be used for various purposes
5) Egestion
- Anus; elimination of undigested food and indigestible materials
- What is the alimentary canal made up of
- What are the associated organs
- mouth cavity; pharnyx; oesophagus; stomach; small intestine; large intestine and anus
- tongue; teeth; salivary glands; liver; pancreas; gall bladder
Explain the mouth cavity fully
- Lips; cheeks; tongue = keep food between teeth ensuring proper mastication and uniform chewing
- Teeth and tongue = mechanical digestion
- Teeth = 32 adult teeth
- Tongue = muscular organ of taste; moves food around the mouth; forms ball of food
- Salivary glands = 3 pairs; chemical digestion; contains water; enzymes and mucin
Types of teeth:
- Incisors = biting and cutting
- Canines = gripping and tearing
- Premolars = crushing and chewing
- Molars = crushing and chewing
Explain the pharynx fully
- Area at the back of the mouth cavity leading to the oesophagus and trachea ( repiratory pasage)
- Allows food into oesophagus during swallowing
- Epiglottis closes entrance to trachea when swallowing
Explain the oesophagus fully
- Narrow; muscular tube ( links pharynx to stomach)
- Behind trachea
- Forces bolus down into stomach by a muscular wave - like motion ( peristalsis)
- Peristalsis = involuntary; throughout alimentary canal
- Assists with mixing food and digestive juices as well as moving food along alimentary canal
Explain the stomach fully
- Muscular; bag like organ; just below diaphragm
- Inner surface = many muscular fold called ruggae which cause a churning action
- Secretes gastric juice (stimulated by hormone gastrin) ; is composed of protease enzymes and hydrochloric acid ( provide optimum acidic pH for protease enzymes)
-Mucus = lines stomach; prevents damage by HCL or juices - Has a cardiac and pyloric sphincter
- Food = in stomach for 2-3hrs and forms chyme
Explain t he small intestine fully
- First part = duodenum
- liver; gall bladder and pancreas = closely associated with duod
- 2 ducts open into duodenum : bile and pancreatic duct
- Bile and pancreatic juice = released into duod
- Enzymes = on surface of columnar epithelial cells that cover the villi
- Final digestion of all food types
- Bulk of adsorption of soluble food occurs here
- Large absorptive surface due to length; villi; folded inner walls and microvilli
Villi incr SA for maximum absorption of nutrients - 6m long
Explain the small intestine fully
- Last part of small intestine to anus
- 3 parts : caecum ( digestion of cellulose)
colon ( ascending; transverse; descending)
rectum ( temporary storage of faeces b4 release into anus) - Absorption of H2O; vitamins and minerals from undigested remains
- Alkaline mucus = secreted from colon walls to move contents along slowly
- Roughage and water = important 4 efficient transp of material along dig canal
- incr volume of colon; stretching large intestine walls which stimulates peristalsis and reduces constipation
Explain the liver fully
Functions:
- Secrete bile ( stored in gall bladder)
- Stores vitamins
- Stores minerals
- Detoxifies harmful substances
Deaminates excess amino acids into urea ( excreted by kidneys)
- Converts excess glucose into fat and stores it
Bile:
- Provides alkaline medium which neutralises the acidic chyme allowing intestinal enzymes to function optimally
- Enables absorption of fat and fat soluble vitamins
Explain the gall bladder fully
- Pear shaped pouch found in a depression on the lower surface of the liver
- Stores and releases bile into duodenum ( release is stimulated by hormone secretin)
Explain the pancreas fully
- Gland below stomach in the loop of the duodenum
- Secretes hormones and pancreatic juice
- control blood sugar levels; secreted by endocrine cells Islets of Langerhans into bloodstream
- stimulated by secretin - Pancreatic juice = consists of enzymes and bicarbonate ions
- released into duod via pancreatic duct
- Contains bicarbonate ions ( provide alkaline pH to activate enzymes)
- Contains enzymes ( protease; carbohydrose; lipease) to digest proteins; carbs and lipids
Explain mechanical digestion fully
- Breaking large pieces of food into smaller pieces
- Physical process involving muscle action
- Incr SA for enzyme action
Explain chemical digestion fully
- Breaking insoluble particles of food into soluble molecules
-Uses enzyme action from various digestive juices:- Saliva
- Gastric
- Pancreatic juice
- Bile
- Intestinal juice
-Carbohydrose = digestion of carbs into simple sugars eg glucose
- Protease = digestion of proteins into amino acids
- Lipases = digestion of lipids into glycerol and fatty acids
- Monosaccharides = stored in liver and muscles as glycogen
