nutrition in humans Flashcards
(10 cards)
the order
- feeding/ingestion
- digestion
- absorption
- assimilation
- egestion
mouth and buccal cavity
- teeth break up large pieces of food into smaller pieces of food which increases the surface area of the food for enzymes to digest the food faster (physical digestion)
- ingested old stimulates the salivary glands to secrete saliva, which is mixed with food to soften in. Saliva also contains salivary amylase that breaks down starch into maltose (chemical digestion)
- the tongue rolls the food into small, slippery round masses or boli (bolus for singular)
what is peristalsis?
rhythmic wave-like muscular contractions in the wall of the alimentary canal
muscles in the oesophagus
antagonistic circular and longitudinal muscles.
when circular muscles contract, longitudinal muscles relax and the lumen constricts. food is pushed and squeezed forward
when the circular muscles relax and the longitudinal muscles contract, the gut dilates and becomes wider and shorter, which allows food to enter
stomach (describe)
distensible muscular bag with thick and well-developed muscular walls. the inner surface of the stomach wall has numerous pits, the alls of which are lined with gastric glands that secrete gastric juice
stomach ( physical digestion)
peristalsis in the stomach wall churns and breaks up the food, and mixes the food well with the gastric juice
stomach (chemical digestion)
- the undigested food stimulates the gastric glands to secrete gastric juice
- gastric juice contains hydrochloric acid, pepsinogen and mucus
- the HCl activates the inactive pepsinogen to active pepsin. the HCl also provides an optimum pH environment of 2 for the pepsin, and denatures the salivary amylase
- pepsin digests proteins into polypeptides
what is the function of the mucus in the stomach
- protects the stomach from being digested by the enzymes it produces
- moistens the food to allow easy movement within the stomach
