B6 - Human Nutrition T9 Flashcards
Why do we need digestive enzymes?
larger food molecules need to be digested into smaller soluble molecules so it can diffuse into cell membranes so body can use
What does protease do
breaks down proteins into amino acids
Source of protease
stomach + pancreas
Where protease acts
stomach + small intestine
Source of amylase
salivary glands + pancreas
Where amylase acts
mouth + small intestine
What does amylase do
breaks down starch into maltose
What does maltase do
breaks down maltose into glucose
Source of maltase
small intestine wall
Where does maltase act
small intestine
Source of lipase
pancreas
Where does lipase act
small intestine
What does lipase do
breaks fat molecule down into 3 fatty acids + 1 glycerol
What enzyme group do pepsin and trypsin belong to?
protease
Source of carbohydrates
Function of carbohydrates
Bread, cereals, pasta, rice,
potatoes
high energy source
Source of proteins
Function of proteins
Meat, fish, eggs, pulses
cell growth and repair
Source of lipids
Function of lipids
dairy, oil, nuts
high energy source and for insulation
Source of fibre
Function of fibre
fruit, vegetables, bran
provide bulk to help intestine walls to move food and faeces along gut
Source of Vitamin A
Function of Vitamin A
carrots, green vegeatbles, oily fish
needed for vision, strong immunity, growth
Source of Vitamin C
Fucntion of Vitamin C
citrus fruits, broccoli
helps absorb iron, maitains healthy tissue, heals wounds
Source of Vitamin D
Fucntion of Vitamin D
oily fish, margarine
helps absorb calcium = healthy bones + teeth
Mineral
Source of Calcium
Fucntion of Calcium
dairy, leafy greens
bone and teeth strength (deficieny can cause ricktes),
normal blood clotting
Mineral
Source of Iron
Fucntion of Iron
red meat, beans and nuts
produces haemoglobin in red blodd cells (deficiency causes anaemia)
Source of Water
Fucntion of Water
water, juice, milk
so cell reactions take place
Deficiency symptoms of low water/fibre
constipation
irregular bowel movements
3 factors affecting energy requirements
- age
- activity
- pregnancy
How age affects energy requirements
amount of energy needed decreases as you go into adulthood
children need more energy as they are growing, compared to adults
How activity affects energy requirements
If you are more active then you will need more energy for movement and muscle contractions
How pregnancy affects energy requirements
energy requirements will increase in order to support growth of the foetus
energy needs also increase due to the extra mass of the baby
Risks of having more energy in your diet than you use
body stores excess energy as body fat
can lead to :
obesity
increase risk of heart disease, type 2 diabetes, stroke and some cancer
Order of digestive system
(human alimentary canal)
mouth
oesophagus
pancreas
stomach
small intestine(duodenum->ileum)
large intestine
rectum
anus
What happens in the mouth
- teeth break up large food pieces into
smaller pieces with larger surface area to volume ratio (food
bolus - salivary amylase breaks down starch into glucose
- saliva lubricates food bolus - swallowed easily
What happens in the oesophagus?
- tube from the mouth to the stomach
- food bolus moves down due to unidirectional wave-like contractions** (peristalsis)** created by circular muscles and longitudinal muscles that create a squeezing action
What happens in the pancreas?
- Produces carbohydrase, protease and lipase enzymes
- secretes enzymes into the stomach and small intestine
What happens in the stomach?
Gastric juice is released from stomach lining when it detects food in the stomach
● Gastric juice is made of
○ Pepsin: enzyme breaking down proteins
○ Hydrochloric acid: makes stomach acidic in order for pepsin to work and to kill any
ingested bacteria
● Peristalsis also occurs here
What happens in the small intestine - duodenum?
The first part of the small intestine
● Carbohydrases, proteases and lipases digest food here
● Bile is released into the duodenum
● Peristalsis also occurs here
What happens in the small intestine - ileum?
Lined with villi (finger-like projections) to maximise absorption of digested soluble molecules into blood
How is the small intestine adapted for efficient absorption of the products of digestion?
1.long villi and micro villi - creates larger SA:V, quicker rate of diffusion
2.blood capiallaries and lacteal - maintain concentration gradient, speeds up rate of diffusion
3.thin wall (1 cell thick) - shorter diffusion distance, speeds up rate of diffusion
What happens in the large intestine?
Water is absorbed here, to produce faeces
● Faeces is stored in the rectum and the removed through the anus
Where is bile produced and stored?
produced in liver
stored in gallbladder
(2 points)
What are the roles of bile?
- neutralises HCl (stomach acid) so pancreas enzymes can work at optimum pH
- emulsifies large fat globules so larger SA:V -> lipase can break down fat molecules into fatty acids and glycerol quicker
