Nutrition (Humans) Flashcards
What is a Balanced diet?
- A diet consisting of all the food groups in correct proportions
What are the key food groups?
- Carbs
- Proteins
- Lipids
- Dietary fibre
- Vitamins
- Mineral ions
- Water
What is Malnutrition?
- Having an unbalanced diet
- Can cause problems such as starvation, CHD and constipation
Function and sources of Carbs
- Function: Source of Energy
- Sources: Breads, Cereals, Potatoes
Function and sources of Proteins
- Function: Growth and Repair
- Sources: Meat, Fish, Eggs, Nuts
Function and sources of Lipids
- Function: Insulation and Energy Storage
- Source: Butter, Oils, Nuts
Function and sources of Fibre
- Function: Provides bulk for the intestine to push food through it
- Source: Vegetables, Whole Grains
Function and sources of Vitamins
- Functions: Needed in small quantities to maintain health
- Sources: Fruit and Veg
Function and sources of Minerals
- Functions: Needed in small quantities to maintain health
- Sources: Fruit, Veg, Meat, Dairy
Function and sources of Water
- Function: Needed for chemical reactions in cells
- Sources: Water, Juice, Milk, Fruit, Veg
Function and sources of Calcium
- Function: Needed for strong teeth and bones
- Sources: Milk, Cheese, Eggs
Function and sources of Vitamin D
- Function: Helps to absorb calcium
- Sources: Oily fish, dairy, sunlight
Function and sources of Vitamin C
- Function: Essential part of collagen which makes up hair, skin, gums and bones
- Sources: Citrus fruit, strawberries, Green Veg
Function and sources of Vitamin A
- Function: Makes pigment in the retina for vision
- Sources: Meat, liver, dairy, spinach, eggs
Function and sources of Iron
- Function: Needed to make haemoglobin
- Sources: red meat, liver, spinach
Which factors can effect dietary needs?
- age
- height
- sex
- activity
- pregnancy
- breastfeeding
How does age affect dietary requirements?
- As children grow they need more energy and protein
- As adults age, they need less energy
How does Activity affect dietary requirements?
- ↑ activity = ↑ energy required
How does Pregnancy affect dietary requirements?
- During pregnancy, energy needed increases to support the growth of a foetus
- extra calcium is also needed to help build bones and teeth
How does Breastfeeding affect dietary requirements?
- Energy and Calcium requirements increase in order to make good milk
How does Sex affect dietary requirements?
- Male energy requirements usually exceed that of females
Chemical elements in Carbs, proteins and lipids
- Carbs: Carbon, oxygen and hydrogen
- Proteins: Carbon, oxygen, hydrogen, nitrogen and some contain others like sulfur
- Lipid: Carbon, oxygen and hydrogen
Structure of Carbs
- Contains C, H and O
- Made up of simple sugars
- A monosaccharide is a simple sugar e.g. glucose which contains lots of energy
- A disaccharide is two Monosaccharides joined together e.g. sucrose from one glucose and one fructose
- A polysaccharide is lots of monosaccharides e.g. starch or cellulose. They are insoluble and so are used as storage
Structure of Lipids
- Made up of triglycerides (fatty acids and glycerol)
- Divided into fats and oils depending on state at room temp
Structure of Proteins
- Made up of amino acids, of which there are 20
- When amino acids join, they make proteins
- They can be organised in any order, resulting in hundreds of thousands of proteins
What is Digestion?
Digestion is a process in which relatively large, insoluble molecules in food (such as starch, proteins) are broken down into smaller, soluble molecules that can be absorbed into the bloodstream and delivered to cells in the body
What is the digestive system made out of?
- The human digestive system is made up of the organs that form the alimentary canal and accessory organs
- The alimentary canal is the channel or passage through which food flows through the body, starting at the mouth and ending at the anus
- Digestion occurs within the alimentary canal
- Accessory organs produce substances that are needed for digestion to occur (such as enzymes and bile) but food does not pass directly through these organs
Parts of the Alimentary Canal
- Mouth
- Oesophagus
- Stomach
- Small intestine
- Large intestine
- Rectum
- Anus
Function of Mouth
- Performs mechanical digestion by chewing
- Amylase enzymes in saliva perform chemical digestion
Stomach
- Performs mechanical digestion by churning
- Protease enzymes perform chemical digestion
Small intestine
- First section - Duodenum completes chemical digestion
- Second section - Ileum is where absorption of digested molecules takes place
Large intestine
Water is absorbed and the faeces is stored in the rectum
Pancreas
Produces amylase, protease and lipase
liver
produces bile to emulsify fats
gall baldder
stores bile
Ingestion
Taking of substances into mouth
Mechanical digestion
the breakdown of food into smaller pieces without chemical change to the food molecules
Chemical digestion
the breakdown of large, insoluble molecules into small, soluble molecules
Absorption
the movement of small food molecules and ions through the wall of the intestine into the blood
Assimilation
the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells
Egestion
the passing out of food that has not been digested or absorbed (as faeces) through the anus
Peristalsis
- The process by which a food bolus is moved through the oesophagus and intestines
- A wave of contractions controlled by circular and longitudinal muscles
What is the role of digestive enzymes?
- Enzymes are biological catalysts – they speed up chemical reactions without themselves being used up or changed in the reaction
- There are three main types of digestive enzymes – carbohydrases, proteases and lipases
Carbohydrases
- Carbohydrases are enzymes that break down carbohydrates to simple sugars such as glucose
- Amylase is a carbohydrase which is made in the salivary glands, the pancreas and the small intestine
- Amylase breaks down starch into maltose
- Maltase then breaks down maltose into glucose
Proteases
- Proteases are a group of enzymes that break down proteins into amino acids
- Pepsin is an enzyme made in the stomach which breaks down proteins into smaller polypeptide chains
- Proteases made in the pancreas and small intestine break the peptides into amino acids
Lipases
- Lipases are enzymes that break down lipids (fats) to glycerol and fatty acids
- Lipase enzymes are produced in the pancreas and secreted into the small intestine
Where is bile produced?
Bile is an alkaline substance produced by cells in the liver
Where is bile stored and released?
Before being released into the small intestine bile is stored in the gallbladder
What are the two main roles of Bile?
- Neutralising the hydrochloric acid from the stomach
(This is essential as enzymes in the small intestine have a higher (more alkaline) optimum pH than those in the stomach) - Breaking apart large drops of fat into smaller ones (and so increasing their surface area)
This is known as emulsification
Adaptations of the small intestine for absorption
- Very long and has a highly folded surface with millions of villi (tiny, finger-like projections)
- These adaptations massively increase the surface area of the small intestine, allowing absorption to take place faster and more efficiently
adaptations of Villi in small intestine
- Large surface area
- short diffusion distance
- steep concentration gradient
