Food and Digestion

Word Bank

________: Ingestion: intake of food via the mouth Egestion: excretion of waste via the anus Digestion: breaking down of food from large, insoluble (unable to dissolve in water) pieces to small, soluble pieces Absorption: the movement of food particles through the wall of the intestine into the blood Assimilation: the movement of digested food particles into body cells where they are used Mechanical digestion: breaking down of food by chewing and swallowing Chemical digestion: breaking down of food into smaller molecules using chemical energy* (extension: using enzymes such as carbohydrase, amylase, protease, and lipase, using hydrochloric acid in the stomach) Peristalsis: the longitudinal and circular muscle contractions throughout the entire digestive tract (alimentary canal) Parts of the Digestive System Mouth: breaks down food by mechanical digestion Salivary glands: produce saliva Esophagus: transports food molecules to the stomach Stomach: breaks down food by chemical digestion (using hydrochloric acid) Small intestine: breaks down food and absorbs nutrients Large intestine: reabsorbs remaining water and minerals, removes waste to the anus Pancreas: secretes enzymes for digestion Liver: secretes bile to digest fats /lipids Gallbladder: store bile Anus: excrete waste products.

Water water

________ is important for maintaining the bodys metabolism and allowing food to dissolve in a medium If a persons diet is not balanced, it can lead to deficiency diseases.

importance of food

growth, energy, immunity, and normal body functions

7 food groups

carbohydrates, proteins, fats, vitamins, minerals, fiber, water

carbohydrates

main source of energy; found in bread, sugars, and rice

proteins

repair and maintenance; found in eggs, poultry, and chicken

fats

insulation, second source of energy; found in fast food, avocados, and fish

vitamins and minerals

maintaining the body’s functions and can help reduce the risk of getting sick; found as vitamin C and vitamin A; found in milk and red meat

fibre

moving food down the digestive tract (alimentary canal); found in whole grains, oats, and seeds

water

responsible for maintaining metabolism, the body's main solvent

deficiency diseases

a disease caused by the long-term lack or insufficient intake of a nutreitn (any of the 7 food groups)

scurvy

deficiency of vitamin C

rickets

childhood disease when growing caused by deficiency of vitamin D

night blindness

deficiency of vitamin A, damaged cornea

anaemia

deficiency of iron

symptoms of scurvy

bleeding/swollen gums, loose teeth, bulging eyes, weak limbs

symptoms of rickets

delayed growth and motor skills, pain in the spine, pelvis, and legs, skeletal deformities

symptoms of anaemia

fatigue, cold extremities, dizziness, pale skin

ingestion

intake of food via the mouth

egestion

excretion of waste via the anus

digestion

breaking down of food from large, insoluble (unable to dissolve in water) pieces to small, soluble pieces

absorption

the movement of food particles through the wall of the intestine into the blood

assimilation

the movement of digested food particles into body cells where they are used

mechanical digestion

breaking down of food by chewing and swallowing

chemical digestion

breaking down of food into smaller molecules using chemical energy (enzymes)

peristalsis

the longitudinal and circular muscle contractions throughout the entire digestive tract (alimentary canal)

mouth

teeth breaks down food by mechanical digestion increasing the volume to surface area ratio

salivary glands

produces saliva to lubricate food so it can be swallowed easily

oesophagus

tube from mouth transports food molecules to the stomach, moves down by peristalsi

pancreas

secretes enzymes (amylase, protease, lipase) into stomach and small intestine for digestion

stomach

breaks down food by chemical digestion

* hydrochloric acid: makes it acidic in order for the pepsin to work at its optimum breaking down proteins

small intestine: duodenum

* breaks down food using various enzymes
* bile is released here

explain the role of bile

* neutralises the hydrochloric acid from the stomach as the enzymes in the duodenum have a higher optimum pH
* emulsifies large drops of fat into smaller ones, the larger surface area allows lipases to work faster

what are fats broken down into

lipases break down lipids into glycerol and fatty acids

small intestine: ileum

* absorbs food into bloodstream
* lined with villi maximising absorption of digested soluble molecules into blood

adaptations of villi

* have thin lining one cell thick meaning quick absorption
* a large network of capillaries
* micro-villi increasing surface area

large intestine

reabsorbs remaining water and minerals, removes waste to the anus

liver

produces bile to digest fats/lipids

gallbladder

stores bile

anus

excrete waste products

Test for glucose:

* in a test tube add drops of Benedict’s solution
* heat at 70 degrees for 5 minutes
* if glucose is present: brick red
* if glucose is not present: blue

Test for starch:

* add drops of iodine and leave for a minute
* if starch is present: blue/black
* if starch is not present: brown

Test for protein:

* add drops of Biuret solution and leave for a minute
* if protein is present: purple
* if protein is not present: blue

Test for fat:

* add 2cm3 of ethanol
* add 2cm3 of distilled water
* leave for 3 minutes
* if fat is present: milky white emulsion
* if fat is not present: colourless

longitudinal contraction =

wider gut

circular contraction =

narrow gut

what is the calculation for investigating the energy content in a food sample

temp increase x mass of water x 4.2 / mass of food sample

what are enzymes

biological catalysts (increases the rate of a reaction), protein molecules

explain the Lock and Key hypothesis

* the shape of the substrate is complimentary to the shape for the active sit so when they bond it forms and enzyme-substrate complex
* once bound, the reaction take place and the products are released

when investigating enzyme activity (pH) why do we keep the test tube in the water beaker

so that we keep it the same temperature so that it is a controlled variable

how to investigate the affects of temperature on enzyme activity

1. starch solution is heated to set temperature
2. amylase is added
3. place drops of iodine in each well on a tray
4. every 30 seconds for 10 minutes add a drop of starch + amylase mixture to a new well
5. measure the time it take until the iodine stops turning blue/black
6. repeat the test with different temperature between 20 and 60

what is the optimum pH for most enzymes

7 (but some like pepsin require acidic conditions which is why it works in the stomach)

what is the optimum temperature for most enzymes

37 degrees C (body temperature)

what happens if the Ph is too high

the forces that hold the amino acid chain that make up the protein will be affected changing the shape of the active sit so the substrate can no longer fit in

it is said to be denatured

what happens if the temperature is too high

the bonds in the structure will break changing the shape of the active site so the substrate can no longer fit in

it is said to be denatured