Chapter 28 - Human Nutrition

Question 1

Name the two types of nutrition

Answer 1

Autotrophic

Heterotrophic

Question 2

What is digestion

Answer 2

The break down of food into particles that are small enough to pass into body cells

Question 3

What are the two types of digestion

Answer 3

Chemical - enzymes

Mechanical - physical

Question 4

What are the five sequence of events

Answer 4

1. Ingestion - food is take into the alimentary canal (mouth)
2. Digestion - food is broken into smaller, more soluble pieces by chemical and physical digestion (mouth, stomach, small intestine)
3. Absorption - food passes into the bloodstream and enters the body (small intestine)
4. Egestio. - removal of undigested, unabsorbed material (rectum, anus)

Question 5

Why does mechanical digestion occur in the mouth

Answer 5

Makes food easier to swallow

Creates a greater surface area for enzymes to act

Question 6

Why does chemical digestion occur in the mouth

Answer 6

Enzymes = amylase

Question 7

What are the four type of teeth

Answer 7

Incisors
Canines
Premolars
Molars

Question 8

What are incisors used for

Answer 8

Cutting, slicing, biting

Question 9

What are canines used for

Answer 9

Gripping, tearing, stabbing

Question 10

What are premolars and molars used for

Answer 10

Crushing, grinding, chewing

Question 11

What is the human dental formula

Answer 11

I = 2/2
C = 1/1 
PM = 2/2 
M = 3/3

Question 12

What chemical is found in the mouth

Answer 12

Amylase

Question 13

What does the chemical/enzyme in the mouth do

Answer 13

Breaks down starch to maltose

Question 14

What is saliva

Answer 14

Made by 3 pairs of salivary glands
Body makes 1 liter per day
Water, salts, mucous, amylase, lysozyme

Question 15

What does saliva do

Answer 15

Softens and dissolves food 
Causes food to form into a ball (bolus)
Food is pushed back towards the pharynx 
Epiglottis closes over the trachea
Bolus passes down the oesophagus

Question 16

What does the oesophagus do

Answer 16

Carries food by peristalsis to the stomach

Assisted by mucous and saliva from the lining of the oesophagus

Question 17

What is peristalsis

Answer 17

Muscular waves that force food through the alimentary canal

Question 18

What is the stomach

Answer 18

Muscular bag which stores and digests food
Has a sphincter muscle
Lining heavily folded with gastric glands

Question 19

What is the sphincter muscle

Answer 19

It allows food into stomach

Circular ring of muscle

Question 20

What is gastric juice

Answer 20

Made up of mucous which coats the stomach
Pepsinogen which is an inactive enzyme that is converted to pepsin by acid, pepsin breaks proteins into peptides
Hydrochloric Acid which has a ph of 1-2, kills bacteria, activates pepsinogen

Question 21

What is chyme

Answer 21

Thick soupy mixture
Made by churning of stomach
Leaves when pyloric sphincter opens

Question 22

What is the small intestine made up of

Answer 22

Duodenum

Ileum

Question 23

What happens in the duodenum

Answer 23

Digestion occurs - enzymes are produced

Inner lining has infoldings called villi which increases surface area

Question 24

What happens in the ileum

Answer 24

Food entering is fully digested

Nutrients are absorbed into capillaries in the ileum

Question 25

What are villi

Answer 25

Infoldings in the small intestine 
They have walls that are one cell thick 
Rich blood supply
In the duodenum - villi produce enzymes 
In the ileum - villi absorbs water and nutrients

Question 26

What do capillaries in the villi do

Answer 26

Carries nutrients to hepatic portal vein
They goes to liver
Stores or release nutrients
Deamination

Question 27

What is lacteal

Answer 27

Lymph fluid

Absorbed fatty acids and glycerol

Question 28

What is the adaptation of the small intestine

Answer 28

Very long 
Numerous villi and microvilli 
Villi walls are very thin 
Rich blood supply
Villi has lymph supply to carry away fats

Question 29

What is the pancreas

Answer 29

Secretes insulin and digestive materials into duodenum from the pancreatic duct
Pancreatic juice - sodium bicarbonate - neutralists chyme
Enzymes - amylase and lipase

Question 30

What is the liver

Answer 30

Makes bile - partly formed from remains of red blood cells, yellow/green liquid 
Functions of bile: 
Stores in the gall bladder
Emulsified lipids - increases surface area for enzymes 
Neutralizes chyme 
Functions of the liver: 
Detoxifies the body - alcohol / drugs
Deamination - breaks down amino acids

Question 31

What is the large intestine

Answer 31

About 1.5. meters long
6cm in diameter
Food stays for 10 hrs to a few days
Consists of the caecum and appendix

Question 32

What is the function of the caecum and appendix in both humans and herbivores

Answer 32

Humans - vestigial organ, functions unknown

Herbivore - bacteria to digest cellulose

Question 33

What is the colon

Answer 33

Reabsorbs water - constipation / diarrhea

Makes faeces

Question 34

What is symbiotic bacteria

Answer 34

Bacteria which lives in humans and benefits humans

1. Produces some B group vitamins and vitamin K in the colon
2. Bacteria in colon helps break down food - cellulose
3. Presence prevents pathogenic bacteria and fungi growing

Question 35

Describe amylase

Answer 35

Role - digests starch 
Production site - salivary glands
Where it acts -  mouth
Ph - 8 
Product - maltose

Question 36

Describe pepsin

Answer 36

Role - digests proteins 
Production site - gastric glands 
Where it acts - stomach
Ph - 2
Product - peptides

Question 37

Describe lipase

Answer 37

Role - digests fats
Production site - pancreas
Where it acts - duodenum 
Ph - 8 
Product - glycerol and fatty acids

Question 38

What is dietary fiber

Answer 38

Consists of cellulose - humans can’t digest it
Prevents constipation - undigested material passes through the colon too slowly / too much water reabsorbed
Absorbs and stores water - unabsorbed material expands in large intestine, stimulates the muscle of the large intestine which stimulates persa