Human Biology (b) Flashcards
nutrition defn.
how an animal gets its food
different types of animals (how. they get food)
herbivores- feed mainly on plants
carnivores- feed mainly on other animals
omnivores- feed on both plants and animals
autotroph defn.
organism that produces complex organic compounds from simple substances present in its surroundings (generally using energy from photosynthesis or chemosynthesis)
heterotroph defn.
cannot manufacture its own food and must take it in from the environment
stages in human nutrition
ingestion- consumption through the mouth into GI tract (gastro intestinal or alimentary canal)
digestion- physical (chewing/churning) and chemical (enzymes) breakdown of food
absorption- passing of useful components of food from GI tract into the blood
Egestion- removal of unabsorbed wastes from the GI tract
what is the digestive system
long tube starting at the south and ending at the anus (associated glands, salivary glands, liver, pancreas, attached
enzymes, where they’re found and their pH
Salivary amylase- mouth- 7
protease- stomach- 1
intestinal amylase- duodenum (small intestine)- 8/9
lipase- duodenum (small intestine)- 8/9
human dental formula
(i2, c1, pm2, m3) x2= 32
what each tooth does
incisors cut food
canines grip food
premolars and molars cut and grind food
how the mouth takes part in digestion
mouth chews (physical) saliva contains water, salts and amylase(inhibited by acid in stomach) which breaks starch down into maltose (pH 7)
what chewing etc does
food formed into bolus and is pushed into pharynx, epiglottis closes over the trachea and food passes down the oesophagus by peristalsis
what is peristalsis
muscular action in the walls of the alimentary canal that moves content along, fibre stimulates peristalsis by absorbing water and expanding, the physical bulk stimulates the intestine
what is the oesophagus
muscular tube that moves food by peristalsis, has no direct digestive role but can aid mechanical digestion
glands for digestion
liver, gall blader, pancreas, salivary gland
about the stomach
muscular bag that holds and digests food, lining is heavily folded forming millions of gastric glands which produce gastric juice (mucus, pepsinogen and hydrochloric acid)
what does mucus do in the stomach
coats the stomach and prevents self-digestion
about pepsinogen
inactive enzyme (so it doesn’t digest the cells producing it), converted to protease pepsin by the acid in the stomach
what does the acid in the stomach do
- kills bacteria
- loosens fibrous and cellular foods
- activates pepsinogen
- denatures salivary amylase
what does the stomach turn food into
chyme
pancreas role
secretes insulin and pancreatic juice
what does pancreatic juice do
contains sodium hydrogen carbonate that neutralises chyme and contains enzymes (ie. amylase and lipase)
what does the liver do
- breaks down red blood cells
- makes bile
- detoxifies the blood
- forms urea out of excess amino acids and uric acid from excess nucleic acids
- converts glucose to glycogen for storage
- converts carbohydrates to fat
- stores vitamins and minerals ( ie. iron, copper and zinc)
- makes cholesterol
- produces heat
what is bile
formed in the liver and stored in the gall bladder, formed by the remains of red blood cells, yellow/green viscous fluid, composed of water, bile salts and bile pigments, enters duodenum through the bile duct
the role of bile
- emulsifies lipids for digestion
2. neutralises chyme
