Nutritions in Humans Flashcards
Why is digestion important?
- breaks down larger molecules into smaller, simpler soluble and diffusible molecules
- can be absorbed into the blood stream and transported to body cells to be utilised
Define physical digestion, its purpose, where in the alimentary canal it can be found.
- mechanical breakdown of food into smaller pieces
- increases the SA:V ration for digestive enzymes to act on food efficiently
Mouth and Stomach
Define chemical digestion
- enzymatuc reaction that breaks down large molecules to smaller, diffusible ones.
*digestive enzymes are released in mouth, stomach and SI
Tell me the pathway of food! (Hint: its not the pathway of the alimentary canal)
Ingestion - Digestion - Absorption - Assimilation - Egestion
What is digestion
the process where food is broken down from larger molecules into smaller, simpler soluble and diffusible molecules that can be absorbed by bodily cells
What is ingestion?
the intake of food
What is assimiliation?
digested food is converted into new protoplasm/used to provide energy
What is absorption
digested food diffuses into cells
3 enzymes and what reactions they catalyse:
1. lipases
2. amylase
3. proteases
- (fat digesting) Fat –(lipase)–> glycerol+fatty acid
- (starch digesting). starch – (amylase) –>sugars/maltose
- (protein digesting). Protein – (proteases)–> amino acids
What is egestion?
discharge of undigested materual
What occurs in moth/buccal cavity?
Physical digestion:
- When food enters the moth, teeth breaks up food into smaller pieces
- increase in SA:V ration for enzymatic action on food chewing
- muscular tongue mixes food with saliva and rolls it into compact masses called bolus
- push bolus to back of the moth where its swallowed
What is the purpose of salivary glands?
produces saliva which contains enzymes. flows into buccal cavity via sulivary duct.
SALIVARY AMYLASE:
hydrolyses starch -> maltose
LYSOZYME
1. kills bacteria, microorganism
2. is present in mucus - soften and lubricates food making swallowing easier
talk about the swallong process.
- food is pushed into the pharnyx (connects moth or gullet and larynx -> voice box)
- Epiglottis (small flap) is bent down because weight of food. windpipe is closed.
Function of oesaphagus
Movement through peristalsis.
define peristalsis and its functions.
Peristalsis is the rhythmic contractions of circular and longitudinal muscles along the digestive system that propels food in a wave-like, unidirectional motion that is independent of gravity. involves a pair of antagonistic muscles which alternate in contraction.