Chapter 7: human Nutrition Flashcards
What is a balanced diet?
A diet that contains all essential nutrients (carbohydrates, fats, proteins, vitamins, mineral salts, fibre and water) in the correct amounts for growth, repair and as an energy source.
Importance of carbohydrate and source
Used as a source of energy in respiration in cells.
Pasta, rice and potatoes
Importance of protein and source
Fish, meat and lentils
to build and repair muscles and bones and to make hormones and enzymes.
Importance of fat and source
insulation, storing energy, waterproofing, structure and protection around delicate organs
full-fat milk, cheese, butter, cream
Importance of vitamin C and D and source
Vitamin D is found in dairy products, eggs and fish oil. It helps the uptake of calcium during digestion and is also a factor in maintaining healthy bones.
Vitamins C citric fruits. protect cells and maintain healthy connective tissue, blood vessels, bones and cartilage.
Importance of calcium and iron and source
Calcium is needed for healthy bones and teeth and is found in dairy products and fish.
Iron is required to make the protein haemoglobin found in red blood cells. Iron is found in red meat and some green vegetables.
Importance of fiber and source
fibre is important for health as it aids digestion, helps control blood sugar levels, and reduces cholesterol levels.
Found in vegetables, fruit and whole grains
Importance of water
Water is important for all living organisms as many substances are able to dissolve in it (it is a solvent)
Vitamin D deficiency
Cause rickets
Vitamin c deficiency
Scurvy
main organs of the digestive system
alimentary canal: mouth, oesophagus, stomach, small intestine (duodenum and ileum) and large intestine (colon, rectum, anus)
associated organs: salivary glands, pancreas, liver and gall bladder
Ingestion
the taking of substances, e.g. food and drink, into the body
digestion
the breakdown of food
absorption
the movement of nutrients from the intestines into the blood
assimilation
uptake and use of nutrients by cells
egestion
the removal of undigested food from the body as faeces
Describe physical digestion
the breakdown of food into smaller pieces without chemical change to the food molecules
What does physical digestion do?
physical digestion increases the surface area of food for the action of enzymes in chemical digestion
Types of human teeth
incisors, canines, premolars and molars
structure of human teeth
https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/01/Structure-of-a-typical-tooth.png
enamel, dentine, pulp, nerves, blood vessels and cement, and understand that teeth are embedded in bone and the gums
Describe the function of the stomach in physical digestion
The stomach’s muscular walls contract to mechanically break down food
Role of bile
Bile emulsifies fatty acids and lipids, breaking large chains into smaller droplets. This increases the surface area for enzymes (lipase) to act on, therefore increasing the rate of digestion/the breakdown of fats.
Describe chemical digestion
the break down of large insoluble molecules into small soluble molecules
the role of chemical digestion
producing small soluble molecules that can be absorbed
Describe the digestion of starch in the digestive system:
(a) amylase breaks down starch to maltose
(b) maltase breaks down maltose to glucose on the membranes of the epithelium lining the small intestine
Break down of protein and lipids
proteases break down protein to amino acids
lipase breaks down fats and oils to fatty acids and glycerol
Describe the digestion of protein by proteases in the digestive system:
(a) pepsin breaks down protein in the acidic conditions of the stomach
(b) trypsin breaks down protein in the alkaline conditions of the small intestine
Where is amylase secreted and act?
Secreted
the salivary glands and the pancreas
Act
Small intestine and mouth
Where are protease and lipase secreted and act?
Secreted
Protease- stomach, pancreas and small intestine
Lipase- pancreas
Act
Protease- stomach and duodenum
Lipase- duodenum ( first part of small intestine)
Function of Hydrochloric Acid in gastric juice
killing harmful microorganisms in food and providing an acidic pH for optimum enzyme activity
What is bile?
is an alkaline mixture that neutralises the acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme action
Where are nutrients absorbed?
the small intestine is the region where nutrients are absorbed
Importance of villi and microvilli
increasing the internal surface area of the small intestine so they can absorb the maximum amount of nutrients.
Describe the structure of a villus
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQnXRIqJ64McrRfzLYeAxMjg2ZQI99CIX-xXfGwLe5cJMV92eySvwOuG9qc&s=10
Describe the structure of a villus
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQnXRIqJ64McrRfzLYeAxMjg2ZQI99CIX-xXfGwLe5cJMV92eySvwOuG9qc&s=10
Describe the roles of capillaries and lacteals in villi
The capillaries within the villi absorb most nutrients, while the lacteals, a part of the lymphatic system, absorb fatty acids and glycerol from dietary fats.
Where is water absorbed?
most water is absorbed from the small intestine but that some is also absorbed from the colon
