24. Human Nutrition

Question 1

Nutrition def.

Answer 1

The way an organism obtains and uses its food

Question 2

The two types of nutrition

Answer 2

Autotroph- makes own food through photosynthesis

Heterotroph- Eats other organisms for food

Question 3

Digestion def.

Answer 3

The physical and chemical breakdown of food into soluble particles small enough to pass into the blood and to the body cells

Question 4

Alimentary canal diagram

Answer 4

Mouth (salivary gland)
Oesophagus
Stomach
Duodenum (Liver, gal bladder, bile duct, pancreas)
ileum
Appendix
Caecum
Colon
Rectum
Anus

Question 5

Steps in digestion (4)

Answer 5

Ingestion
Digestion
Absorption
Egestion

Question 6

Ingestion def. and where

Answer 6

def. Food is taken into the alimentary canal

where: the mouth

Question 7

Digestion def. and where

Answer 7

Def: The physical and chemical breakdown of food into soluble particles small enough to pass into the blood and to the body cells
Where: mouth, oesophagus, stomach, small intestine

Question 8

Absorption def. and where

Answer 8

Def: the movement of digested food into the blood.
Where: small intestine

Question 9

Egestion def and where

Answer 9

Def: Removal of undigested, unabsorbed food as faeces
Where: Anus

Question 10

Def. of peristalsis

Answer 10

Rhythmic muscular contraction and relaxation in the wall of the alimentary canal (oesophagus) causing the food to move along the canal and be broken down

Question 11

Where does mechanical digestion take place

Answer 11

teeth
peristalsis (oesophagus)
Contractions in stomach wall

Question 12

Mechanical Digestion in mouth
Function
Name teeth and function

Answer 12

Food is broken down by the teeth by chewing
this increases the surface area for the enzymes to work.
Teeth: Incisors (front- biting of a piece), Canines (side-tear), Premolars and Molars (back- chew and grind)

Question 13

Dental formula

Answer 13

32 teeth
I (2/2), C (1/1), P (2/2), M (3/3)
upper no.=teeth on top half of one side
lower no= teeth on bottom half of same side

Question 14

Structure of a tooth

Answer 14

Diagram in copy
Crown, Root, Gums
Out---> In
Enamel (protect), 
Dentine (typical tooth structure), 
Pulp Cavity (contains blood vessels and provides nutrients for tooth)

Question 15

Chemical digestion in the mouth
enzyme
role/substrate
product
production site
action site
optimum ph

Answer 15

Enzyme: amalyse
Role/Substrate: Digests starch
Product: Maltose
Production site: Salivary glands (mouth)
Action site: In the mouth
Optimum pH: pH 7/8

Question 16

Digestion in the oesophagus

Answer 16

Made up of a muscular tube

Role: Brings food to stomach. Food moves by peristalsis so digests the food

Question 17

Digestion in the stomach
muscles that allow food to enter leave
shape
types of digestion

Answer 17

Food enters the stomach from the oesophagus when the cardiac sphincter muscle opens.
Is a J shaped muscular bag.
Involved in chemical and mechanical digestion
food leaves when pyloric muscle opens

Question 18

Mechanical digestion in the stomach

Answer 18

Muscles contract which churns the food and makes chyme

Question 19

Chemical Digestion

Answer 19

Produces gastric juice containing Mucus, HCL, Pepsinogen

Question 20

Role of

1. Mucus
2. HCL
3. Pepsinogen

Answer 20

1. Mucus: lines and protects the stomach so it doesnt digest itself.
2. HCL: Hydrochloric acid: gives a pH of 1/2-the optimum pH for the enzyme. Kills bacteria present. Activates pepsinogen (pH 1/2). Denatures Amalyse (pH 7/8)
3. Pepsinogen: enzyme produced in stomach. Inactivates to prevent self digestion. Converted to active enzyme pepsin by HCL when it comes in contact with food.
   Digests proteins to peptides

Question 21

Pepsin
Role
Substrate
Product
Production site
Action site
Optimum pH

Answer 21

Role: Digests protein
Substrate: Proteins
Product: Peptides
Production site: Stomach in gastric glands
Action site: Stomach
Optimum pH: pH 1/2

Question 22

How does the stomach prevent self digestion?

Answer 22

Mucus lines the wall. It is an alkaline (pH 7-14) so protects against acid pH.

2. Cells in wall are tightly packed together and renewed at a rapid rate
3. Pepsinogen is inactive until it comes in contact with food.

Question 23

Small intestine
Main Parts
pH
What happens

Answer 23

Main parts: Duodenum and ileum
pH 7/8 (because we left the stomach)
What happens: Chemical digestion (duodenum) Absorption (ileum)

Question 24

How the duodenum digests the food

Answer 24

wall of duodenum: secretes intestinal juices containing different enzymes which break down food.
Pancreas and liver: produce juices that travel to the duodenum.

Question 25

Role of pancreas

Answer 25

Produces pancreatic juices

they travel to the duodenum via the pancreatic duct. Contains enzymes lipase (fats) and amalyse (starch)

Question 26

Lipase
role
substrate
product
production site
action site
pH

Answer 26

role: breaks down fats
substrate: Fats/ Lipids
product: Fatty acids and glycerol
production site: Pancreas
action site: duodenum
pH: 7/8

Question 27

Amalyse
role
substrate
product
production site
action site
pH

Answer 27

role: digests starch
substrate: starch
product: maltose
production site: Pancreas/ small intestine
action site: small intestine
pH: 6.7/7

Question 28

Liver functions

Answer 28

Makes bile
Breakdown of toxic substances, 
Regulates heat, 
Break down amino acids to urea,
Breakdown carbohydrates to fat, 
Stores minerals (iron and copper), vit D and glycerol.

Question 29

Bile
consists of
functions
more functions

Answer 29

Consists of: Water, bile salts, bile pigment

Functions: emulsifies fats (fats easier to digest-in fat droplets) and neutralises acidic chyme

Question 30

Absorption
def.
where

Answer 30

def. The movement of digested food into the bloodstream.

Where: The ileum

Question 31

Villi
what
function

Answer 31

What: finger like folds in the lining of the small intestine.
Function: increases surface area for absorption of digested food.

Question 32

What is absorbed by villi and where they go

Answer 32

Water, Glucose, Amino acids, Vitamins, Minerals- absorbed into capillaries, travel to liver via the hepatic portal vein, stored by liver, released and passed to heart via hepatic vein and then passed to body.

Fatty acids and glycerol- absorbed into lacteal and transported to the lymph vessel and up to the subclavian veins into the vena cava to the heart.

Question 33

Structure of villus

Answer 33

Lacteal in centre which goes to lymph vessels.
Network of capillaries- goes to hepatic portal vein.
Villus on outside

Question 34

Function of hepatic vein and artery

Answer 34

Artery: Brings blood to the liver from the heart
Vein: Brings food from the liver to the heart

Question 35

How the villus are adapted for absorption:

Answer 35

Walls 1 cell thick
Long so increases surface area
Large capillary supply for efficient absorption
lacteal present for digested fat absorption

Question 36

Parts of the large intestine and functions

Answer 36

Appendix, Caecum: Function unknown 
Colon: 
Reabsorbs water, 
Forms solid waste (faeces), 
Bacteria in colon produce vit. B and K, 
Digest cellulose
Rectum: Stores faeces
Anus: Egestes faeces

Question 37

Benefits and importance of Fibre

Sources

Answer 37

Stimulates peristalsis in colon: prevent constipation
Provides bulk so prevents overeating as takes longer to digest
Provides and promotes gut bacteria
Regulates blood sugar levels
Lowers cholesterol
Sources: Wholegrain foods, Fruit and veg, Porridge