1.3- digestion, absorption & metabolism

Question 1

What is mechanical digestion?

Answer 1

Action of chewing and churning in the stomach
-provides enzymes with a larger SA to work on

Question 2

What is chemical digestion?

Answer 2

Action of digestive enzymes in the stomach, mouth and small intestine

Question 3

What happens in the small intestine?

Answer 3

Partly digetsed food (chyme) is chemically altered by secretions from liver and the pancreas. Most nutirents are absorbed.

Question 4

What happens in the gall bladder?

Answer 4

bile is stored

Question 5

What happens in the stomach?

Answer 5

Churns food and mixes it with hydrochloric acid and enzymes

Question 6

What happens in the large intestine?

Answer 6

Reabsorbs fluid and processes waste ready for elimination from the body

Question 7

What is the lleum?

Answer 7

Part of the small intestine where digestion and absorption of nutrients is completed

Question 8

Function of Amylase?(carbohydrase)

Answer 8

Breaks down starch (carbohydrates) into simple sugars

Question 9

Function of Protease?

Answer 9

breaks down proteins into amino acids

Question 9

Function of Protease?

Answer 9

breaks down proteins into amino acids

Question 10

Function of Lipases?

Answer 10

Breaks down lipids/ fats into fatty acids and glycerol

Question 11

Optimum temperature for Digestive enzymes?

Answer 11

Work best at 37c (body temp)

Question 12

What are enzymes and how are they formed?

Answer 12

are biological catalysts
- active site and substrate fit by lock and key action or induced fit

Question 13

What is the role of the liver in digestion?

Answer 13

Produces bile which is used in the small intestine to emulsify fats so enzymes can’t act on them. (Can also help neutralise chyme as it contains alkaline salts)

Question 14

What is the role of the pancreas in digestion?

Answer 14

Produces digestive enzymes which is converted to pancreatic juice, this lowers the stomachs pH, helping to digest fats.
It also helps neutralise acidity of chyme as it leaves stomach

Question 15

What is absorption?

Answer 15

When food passes through intestine walls into the bloodstream

Question 16

What is assimilation?

Answer 16

the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells

Question 17

Explain the process of Assimilation in the liver?

Answer 17

-excess glucose is stored as glycogen which may be used for respiration
-toxins are broken down eg.alcohol
-produces proteins such as hormones and proteins for blood clotting
-takes dying red blood cells and converts the haemoglobin to help form bile

Question 18

What is the difference between active and passive transport?

Answer 18

Active: Requires energy ATP,moves AGAINST gradient (low –> high) eg. Sodium potassium pump and proton pump
Passive: no energy required, moves ALONG concentration gradient (high –> low) eg. Diffusion and osmosis

Question 19

How are the walls of the small intestine adapted for absorption?

Answer 19

-one cell think villi allows for easy diffusion of substances into the bloodstream
-villi means SI has a large SA, increasing the speed and efficiency of absorption
-network of capillaries in each villi means there is a constant blood flow to push nutrients into

Question 20

Where do the products of digestion go?

Answer 20

-into the bloodstream (amino acids, water soluble minerals/ vitamins, glucose)
-into the lacteal (glycerol, fatty acids, fat soluble vitamins/ minerals)

Question 21

What is metabolism?

Answer 21

The sum of all chemical reactions in the body that keeps you alive and your organs functioning normally. This requires energy

Question 22

What are anabolic reactions?

Answer 22

They require energy and synthesise complex molecules from simpler ones. Eg. Synthesis of proteins from amino acids

Question 23

What are catabolic reactions?

Answer 23

The breaking down of larger molecules into smaller ones and takes place in all living organisms and cells. Eg. Glycolysis which is the breakdown of glucose while using O2 and CO2

Question 24

What are the methods of membrane transport?

Answer 24

-Diffusion
-facilitated diffusion (both are passive)
-osmosis
- active transport (both are active (require energy))

Question 25

What are villi?

Answer 25

Small finger-like structures that increase the surface area of the walls of the SI.
-they have very thin walls, allowing movement by diffusion
-also have good network of blood capillaries

Question 26

What is diffusion?

Answer 26

Movement of molecules from an area of high concentration to low concentration

Question 27

What is facilitated diffusion?

Answer 27

Movement of specific molecules across cell membranes through protein channels
-larger and polar molecules can’t get across membrane via simple diffusion (transmembrane proteins)

Question 28

What is osmosis?

Answer 28

Movement of water from a high water concentration to a low water concentration across a partially permeable membrane

Question 28

What is osmosis?

Answer 28

Movement of water from a high water concentration to a low water concentration across a partially permeable membrane

Question 29

What is active transport?

Answer 29

movement of molecules into or out of a cell against a concentration gradient

Question 30

function of salivary glands

Answer 30

produce saliva to soften food making it easier to swallow. 1

Question 31

Epiglottis function

Answer 31

Flap of cartilage covering the opening of the windpipe when swallowing which prevents food from entering the lungs. 2

Question 32

Oesophagus function

Answer 32

Muscular tube which food passes through by peristalsis. 3

Question 33

Rectum function

Answer 33

stores faeces.

Question 34

anus function

Answer 34

opening for elimination of faeces

Question 35

What is Elimination?

Answer 35

The removal of undigested waste from the body

Question 36

What is digestion?

Answer 36

The physical and chemical breakdown of food

Question 37

What is the lacteal?

Answer 37

A central vessel and is connected to the lymphatic system

Question 38

What is NSP and what foods is it found in?

Answer 38

non-starch polysaccharide/ dietary fibre
-found in the indigestable parts of cereals, fruits and vegetables

Question 39

What are the ways you can help food to pass through the colon?

Answer 39

-eating a fibre rich diet and drinking lots of water
- limiting intakes of meat (slows down transit time)
-physical activity (reduces time food takes)

Question 40

name 3 products found in gastric juice produced by cells in the walls of the stomach?

Answer 40

-hydrochloric acid
-pepsin
-rennin

Question 41

Affects of NSP/ dietary fibre on the transit time in the colon?

Answer 41

-too little dietary fibre increases the transit time resulting in the re absorption of water causing constipation
-too much fibre means the food passes through the colon too quickly with little reabsorption causing diarrhea

Question 42

health conditions linked to a lack of dietary fibre?

Answer 42

-constipation
-IBS
-heart disease
-bowel cancer
-diverticulitis (small pouches in the colon)

Question 43

benefits of fibre in the diet?

Answer 43

-helps maintain bowel health
-lowers cholesterol (by lowering low-density lipoprotein)
-helps control blood sugar levels (slows the absorption of sugar)
-helps prevent obesity (more filling so stay satisfied for longer)

Question 44

Name 3 parts of the digestive system where absorption of nutrients take place?

Answer 44

-SI- absorption of nutrients is completed
-mouth/stomach- partial digestion of carbohydrates and proteins
-lI- some minerals and most water is absorbed