nutrients and energy Flashcards
what is a balanced diet
a diet that includes all 7 types of nutrients in the right amounts
what are the 7 types of nutrients
1.carbohydrates
2.proteins
3.fats
4.minerals
5.vitamins
6.water
7.dietary fibre
role of carbohydrates
1.source of energy
role of proteins
growth, repair, antibodies, haemoglobin
role of fats
source and store of energy, insulation
types of minerals
1.calcium:bones and teeth
2.iron:making haemoglobin
role of vitamins
vitamin A: night vision
vitamin D: absorption of calcium into bones
vitamin C: protect against scurvy
role of water
solvent for metabolic reactions, transport, and cooling of body
role of dietary fibre
1.stimulates peristalsis
2.prevents constipation
3.protects against colon cancer
examples of malnutrition
1.constipation
2.coronary heart disease
3.obesity
cause of constipation
insufficient fibre in the diet, diet lacking in fibre may lead to bowel cancer
cause of coronary heart disease
when animal fats and cholesterol form atheroma on the walls of the coronary artery
what is associated with obesity
high blood pressure
heart disease
what is scurvy disease
1.caused by lack of vitamin c
2.bleeding gums, wounds don’t heal properly
what is rickets disease
1.caused by lack of vitamin d
2.growing bones become soft, causing bow legs or knock knees
effect of diet lacking in calcium
1.bones of skeleton do not form properly
2.growth is stunted
3.bones become brittle
effect of diet lacking in iron
anemia
what is kwashiorkor disease
characterized by a swollen abdomen, caused by protein deficiency
immune system is affected as there is difficulty producing antibodies
stages of human nutrition
1.ingestion
2.digestion(mechanical and chemical)
3.absorption
4.assimilation
5.egestion
what is ingestion
the taking in of substances into the body through the mouth
what is digestion
the breakdown of large insoluble food molecules into small water soluble molecules using mechanical and chemical processess
what is mechanical digestion
breaking down food into smaller pieces to increase surface area for faster action of enzymes
what is chemical digestion
breakdown of large insoluble molecules into small soluble ones
what is absorption
movement of small food molecules and ions through the wall of the intestine into the blood
what is assimilation
movement of digested food molecules into the cells of the body where they are used, becoming part of the cell
what is egestion
passing out of undigested and unabsorbed food, as faeces through the anus
equation of BMI
mass in kg/(height in meters)^2
tooth structure
1.the part of the tooth which is embedded in the gum is called the root
2.the crown is covered with enamel
3.under the enamel is a layer of dentine
4.in the middle of the tooth is the pulp cavity which contains nerves and blood vessels
what are the four types of teeth
1.incisors
2.canines
3.premolars and molars
what are incisors
sharp edges, chisel shaped teeth at the front of the mouth, they are used for biting off pieces of food
what are canines
more pointed teeth at either side of the incisors, used to tear meat
what are premolars and molars
large teeth towards the back of the mouth, they are cusped and used to crush and grind food
tooth decay
1.bacteria forms a layer on teeth called dental plaque
2.if sugar is left on the teeth bacteria in the plaque will feed on it
3.they use it in respiration changing it into acid
3.the acid gradually dissolves the enamel covering the tooth, and works it’s way into the dentine
what happens in the mouth
1.the teeth grind the food into smaller pieces, increasing it’s surface area
2.amylase begins to digest starch in the food to maltose
what is the oesophagus
muscular tube that transports food from the mouth to the stomach
what happens in the oesophagus
food moves down the oesophagus by peristalsis which is alternative contraction and relaxation of longitudinal and circular muscles in the walls of the alimentary canal
what happens in the stomach
1.contains other cells which produce protease enzymes and others which make hydrochloric acid
2.the main protease enzyme in the stomach is pepsin, it begins to digest proteins by breaking them down into polypeptides. pepsin works best in acidic condition
3.acid helps to kill any bacteria in the food and provides the acidic conditions for the activity of the pepsin
parts of small intestine
first part nearest to the stomach is called duodenum
the last part nearest to the colon is the ileum
duodenum
both pancreatic and bile juice are secreted from the pancreas and the liver to the duodenum
what does pancreatic juice contain
1.amylase
2. trypsin
3.lipase
what does amylase do
break down starch to maltose
what does trypsin do
a protease, which breaks down proteins to polypeptides
what does lipase do
breaks down fats to fatty acids and glycerol
bile juice
bile helps digest fat, by emulsifying large drops of fat into very small ones increasing their surface area to make it easier for lipase in the pancreatic juice to digest them into fatty acids and glycerol.
what are the enzymes that iluem produce
1.maltase
2.peptidase
3.lipase
what does maltase do
1.breaks down maltose to glucose.
what does peptidase do
breaks down any polypeptides into amino acids.
what does lipase do
completes the breakdown of fats to fatty acids and glycerol
adaption of villi for absorption
1.They are extremely numerous increasing the surface area for faster absorption
2.Their walls are very thin (single layer of cells) for faster absorption.
3.The epithelial cells of the villi have microvilli for further increase in surface area for faster absorption.
4.They have large network of blood capillaries.
5. They have lacteal vessels for absorption of fatty acids and glycerol.
6.Their cells have large number of mitochondria to
release energy for active transport.
what happens in the large intestine
In the colon, more water and salt are absorbed. However, the colon absorbs much less water than the small intestine.
