Human Nutrition Flashcards
Ingestion
is the taking of substances such as food and drink into the body through the mouth
PD, CD, ABS, ASS, EG
Physical digestion is the breakdown of food into smaller pieces without chemical change to the food
molecules
Chemical digestion is the breakdown of large insoluble molecules into small soluble molecules.
Absorption is the movement of small food molecules and ions through the wall of the intestine into the blood.
Assimilation is the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells.
Egestion is the passing out of food that has not been digested or absorbed, as faeces, through the anus.
What is the use of physical digestion
The goal of physical digestion is to increase the surface area of the food to help enzymes breaking it down.
The alimentary Canal
Tube running through the body in which food is digested, nutrients absorbed and undigested food egested.
Why do we need saliva
Saliva helps to lubricate the food and make the small pieces stick together for swallowing.
Saliva is produced by salivary glands and it
contains enzyme salivary amylase which acts on
starch to break it down in smaller sugars such
as maltose.
Stomach
Destruction of pathogens due to hydrochloric acid
● Breaking down of proteins into polypeptide by pepsin
● Turning food into a liquid called chyme to release in the small intestine.
● Physical digestion thanks to the contraction of muscles
The chyme is released into the duodenum part of the small intestine. The pyloric sphincter regulates how much is released and whe
Duodenum
The first part of the small intestine is called the duodenum.
Functions:
- Neutralise the acidity from the hydrochloric acid by receiving 2 alkaline fluids, the bile from the gallbladder (prod. By liver) and the pancreatic juice from the pancreas.
- Further breaking down of molecules (chemical digestion) which is carried on in the ileum. This is done thanks to the many enzymes secreted by the pancreas.
- protease (e.g. trypsin) acts on polypeptides to make a.a.
- maltase acts on maltose to make glucose
- lipase acts on fats to make fatty acids and
glycerol).
Assimilation
Absorbed products from intestine are carried around in the body bloodstream. The uptake and use of food by the cells is called assimilation
Reminder:
● Glucose —> respiration to produce ATP and perform metabolic processes
● Fat → cell membranes, stored energy
● Amino acid → plasma protein (clotting), antibodies, enzymes, structural
component of cells and muscle fibres etc.
Egestion
Undigested matter, largely cellulose and vegetable fibres (roughage)
Bacteria digest fibres in compounds that are used to form fatty acids absorbed in the colon.
The colon absorbs the remaining of water.
Semi-solid waste called faeces passed into the rectum by
peristalsis and egested through the anus.
The residues may spend 12-24 hours in the intestine.
Teeth structure
Ppt
Balanced diet
A balanced diet is a diet that contains all essential nutrients in the correct proportions to maintain good health. The nutrients needed carbohydrates, vitamins, minerals, fibre, water
Carbohydrates
Carbohydrates are the cheapest and most readily available source of energy
-cellulose is a carb
Fats
- milk, meat, cheese, butter
- used for cooking
- stored in the body as fat deposits (helps reduce heat loss, if it has limited blood supply)
Proteins
- supply amino acids to build new cells
- form part of the cytoplasm and enzymes of cells and tissues
-
Vitamin c
- prevents scurvy
- maintain healthy skin, and gums
