structure and function (human nutrition)

balanced diet is made up of (7)

• Carbohydrates

• Proteins

• Lipids

• Dietary Fibre

• Vitamins

• Minerals

• Water

	cause	effect
starvation
CHD
constipation
obesity

	function	source
carbohydrate
protein
lipid
fibre
minerals
vitamin
water

	function + deficiency?	source
Calcium
vitamin D
vitamin C
vitamin A
Iron

	energy requirement
age
activity levels
pregnancy
breastfeeding
sex

label body diagram

5 stages of digestion (IDAAE)

Ingestion - food enters mouth

digestion - break down large food molecules into smaller molecules

Absorption - small molecules absorbed through small intestine walls into blood

Assimilation - small food molecules are used to build large molecules in body cells

Egestion - removal of undigested food/waste/faeces through anus

what is mechanical digestion vs chemical digestion:

and what it does that for

mechanical - physical break down of food particles into smaller pieces (so enzymes have a bigger surface area to work on)

chemical - chemical break down of food molecules into smaller particles by enzymes, for absorption into bloodstream through small intestine walls

define digestion

… SO THAT

the breaking down of large, insoluble molecules in food into smaller, soluble molecules that can be absorbed into the bloodstream/delivered to cells in the body

mouth:
what kind of digestion/how it happens and why

any enzymes? - where produced/what do they do

in what form does the food leave

mechanical digestion - teeth chew food to break it into smaller pieces to increase its surface area for enzymes to work on it

amylase - from salivary glands starts digesting starch into maltose

food shaped into bolus (ball) by the tongue and lubricated in saliva to be swallowed easily

oesphagus:
what is it

how does food move down it

without relying on _______

tube that connects mouth to the stomach

wave-like contractions (peristalsis) take place to push food bolus down without relying on gravity

stomach:
mechanical vs chemical

enzymes/other substances? why produced

in what form does the food leave

mechanical digestion - churns/pummels food with its muscular walls

chemical digestion

- produces protease PEPSIN to break down proteins

- produces hydrochloric acid to kill bacteria and give optimum pH for protease enzymes to work (pH2 - acidic)

food leaves stomach as chyme

what is the alimentary canal

long channel through which food is digested - starts from mouth, ends at anus

small intestine:

what kind of digestion/how

what enzymes produces

first part vs second part

chemical digestion - produces protease, amylase and lipase

also where nutrients are absorbed out of alimentary canal into body

first part - duodenum, second part - ileum

large intestine:
type of digestion, what happens

first part vs second part

no chemical digestion - no digestive enzymes

excess water is absorbed from remaining food stuff, produces faeces

stored in rectum, removed through anus

pancreas:

what enzymes does it produce

secretes enzymes in an a____ fluid into _____ ______ to…

produces amylase, protease, lipase

secretes enzymes in an alkali fluid into small intestine to lower pH coming out of stomach

liver:

what does it produce

produces bile (more on later)

gallbladder function

stores bile

what is peristalsis + draw diagram

a mechanism that helps moves food along the alimentary canal

waves of contractions

w

what are carbohydrases

break down ____ into ____ _____ (general name)

break down carbohydrates into simple sugars

amylase:

where produced (3)

and what does it do

produced in salivary glands, pancreas and small intestine

breaks down starch into maltose

what then breaks maltose into glucose

maltase breaks maltose into glucose

diagram of starch to glucose via enzyme break down draw

what are proteases, where made (3), what does it do

a group of enzymes that break down proteins into amino acids

made in pancreas, stomach, small intestine

what are lipases, where produced

enzymes that break down lipids (fats) to glycerol and fatty acids

produced in pancreas and small intestine

where is bile produced vs stored vs released

is an a____ substance

produced in the liver

stored in the gallbladder

released into small intestine

is an alkaline substance, high pH

bile function (2) and why it is important

1. Neutralising the hydrochloric acid from the stomach

   • The alkaline properties of bile allow for this to occur

   • This neutralisation is essential as enzymes in the small intestine have a higher (more alkaline) optimum pH than those in the stomach

2. Breaking apart large drops of fat into smaller ones (and so increasing their surface area)

   • This is known as emulsification

• The more alkaline conditions and larger surface area allows lipase to chemically break down the fat (lipids) molecules into glycerol and fatty acids at a faster rateglycerol and fatty acids at a faster rate

what kind of digestion does bile do

mechanical - big chunks into small chunks, has no enzymes

what is emulsification

Breaking apart large drops of fat into smaller ones, increasing their surface area

general adaptations of small intestine

very long

highly folded surface

with millions of villi

• increase surface area so absorption takes place faster and more efficiently

how specifically do villi help small intestine

• large surface area

  • microvilli on surface of villus further increase SA available for absorption

• wall of villus only one cell thick

  • short diffusion distance = faster diffusion

• network of capillaries

  • network of blood capillaries transport glucose/amino acids away from small intestine in the blood

  • has a lacteal (lymph) which runs through centre of villus, transports fatty acids and glycerol away

    • keeps a steep concentration gradient - faster diffusion

how to find Energy Content of a Food Sample, unofficial

use a MOUNTED NEEDLE to burn a piece of food under a boiling tube of water, record temperature of water after

the larger the increase in water temperature, the ______ energy

the larger the increase in water temperature, the more energy

energy transferred formula + units

what does the constant mean

4.2 - it takes 4.2J of energy to raise 1g of water by 1oc

(specific heat capacity of water)

limitations (2)

• incomplete burning

• heat energy lost to surroundings

energy in food sample CORMMS

C - change type of food in sample

O - n/a

R - repeat x3 for each food sample, take avgs.

M - measure change in temperature of water

M - in oC, once all food has been burnt

S - control volume of water, distance between food and boiling tube, food will be relit every time it goes out