digestive system

Question 1

define nutrition?

Answer 1

the process by which an organism obtains and uses it’s food

Question 2

define digestion?

Answer 2

the physical and chemical breakdown of food into small soluble particles that can be absorbed and transported

Question 3

explain physical vs chemical digestion?

Answer 3

physical= the mechanical breakdown of food. It involves the teeth

chemical= involves enzymes breaking down the food. mouth, stomach, intestines

Question 4

what does each digest:
amylase
protease
lipase

Answer 4

starch
protein
lipids or fats

Question 5

explain the stages in human nutrition?

Answer 5

ingestion= food is taken into the alimentary canal

digestion= food is broken down into smaller soluble pieces

absorption= the movement of digested from the alimentary canal into the blood system

assimilation= absorbed food is converted to new cell substances or used to provide energy

egestion= removal of unabsorbed material from digestive system as faeces

Question 6

explain 3 ways food can be mechanically broken down?

Answer 6

1) teeth
2) contractions in stomach wall
3) peristalsis

Question 7

define peristalsis?

Answer 7

Involuntary muscular contraction in the wall of the alimentary canal, that causes food to move along the canal

Question 8

name and explain the four types of teeth?

Answer 8

incisors= chisel shaped with sharp edges- cut, slice and bite

canines= long, pointed teeth. grip, stab and tear

premolars= contain cusps. crush and chew

molars= large teeth located in the back of the mouth. crush and chew

Question 9

name the dental formula

Answer 9

2 (I 2/2 C 1/1 PM 2/2 M 3/3)

Question 10

what does saliva consist of?

Answer 10

water, salt , amylase, lysozyme
PH of 7, it is destroyed when it reaches the stomach as the PH here is lower

Question 11

what is the function of lysozyme?

Answer 11

helps kill micro-organisms

Question 12

function of oesophagus?

Answer 12

muscular tube, 25 cm long
connects the pharynx to the stomach
moves down by peristalsis

Question 13

function of stomach?

Answer 13

J shaped muscular bag
stores and digests food
churns and mixes food with gastric juice forming chyme

Question 14

what are the roles of the cardiac sphincter muscle and the pyloric sphincter muscle?

Answer 14

cardiac sphincter= circular muscle which contracts to close entry from oesophagus to the stomach

pyloric sphincter muscle= circular muscle which contracts to close the entry to duodenum from the stomach

Question 15

what is the stomach lining called?

Answer 15

mucosa
mucosa has many folds in it forming millions of gastric glands which secrete gastric juice

Question 16

what does gastric juice consist of?

Answer 16

mucous
pepsinogen
hydrochloric acid

Question 17

explain what mucous is?

Answer 17

produced by goblet cells
they are alkaline to prevent the stomach from digesting itself

Question 18

explain what pepsinogen is?

Answer 18

produced by chief cells
inactive enzyme made active when converted into pepsin by acid in the stomach.
pepsin digests protein to peptides

Question 19

explain what hydrochloric acid is?

Answer 19

PH of 1/2
kills many bacteria, loosens food, converts pepsinogen to pepsin

Question 20

what is the function of the small intestine?

Answer 20

muscular tube 5-6m long
function: digestion and absorption
has 3 main parts: duodenum, jejunum, ileum

Question 21

explain the duodenum?

Answer 21

most digestion takes place here as the chyme from the stomach is mixed with enzymes from the duodenum and the pancreas and bile from the liver

Question 22

function of ileum and jejunum?

Answer 22

to absorb the end products of digestion: amino acids, simple sugars and fats.
these end products pass into blood capillaries and then the hepatic portal vein brings these nutrients directly to the liver

Question 23

adaptions of small intestine?

Answer 23

1) long: provides sufficient time for digestion and absorption
2) presence of microvilli: increases surface area for absorption
3) villi walls are 1 cell thick: allows for food nutrients to diffuse quickly

Question 24

describe the function of a single villus?

Answer 24

fatty acids and glycerol are absorbed into the lacteal, all others are absorbed into blood vessels

Question 25

Outline the role of the large intestine in absorbing water and eliminating faeces?

Answer 25

the colon reabsorbs water from the remaining food.
the faeces are stored in the rectum and egested through the anus.

Question 26

define symbiotic bacteria?

Answer 26

extremely important. The bacteria obtain nourishment and we obtain vitamins and digested food.
produces K and B vitamins, digests cellulose.

Question 27

how does the blood transport nutrients?

Answer 27

small intestine is connected to the liver by the hepatic portal vein. Nutrients such as glucose and amino acids pass into the blood capillaries and are transported from small intestine to liver.
The liver stores the nutrients and releases them when needed by the body.

Question 28

can you describe how fats are absorbed from small intestine into the blood?

Answer 28

fatty acids are absorbed from the small intestine into the lymphatic system

Question 29

name functions of the liver?

Answer 29

• produces bile

Question 30

what is in bile and what’s it function?

Answer 30

water, bile salts, bile pigments.
1) emulsifies fat
2) neutralises chyme from the stomach
3) excretes pigments

Question 31

role, production site, where it acts, optimum PH and digestion product of amylase?

Answer 31

role: digests starch
production site: pancreas
where it acts: mouth
PH: 7
digestion product: maltose

Question 32

role, production site, where it acts, optimum PH and digestion product of pepsin?

Answer 32

role: digests protein
production site: gastric glands in stomach wall
where it acts: stomach
PH: 2
digestion product: peptides

Question 33

role, production site, where it acts, optimum PH and digestion product of lipase?

Answer 33

role: digest fat
production site: pancreas
where it acts: duodenum
optimum PH: 8
digestion product: fatty acids and glycerol

Question 34

what is the role of fibre?

Answer 34

fibre stimulates peristalsis in the colon which helps prevent constipation and reduces risk of colon cancer.

Question 35

define balanced diet?

Answer 35

taking the correct components of all the 7 essential components in the diet

Question 36

can you give 2 aspects of a person’s diet that usually leads them to have a balanced diet?

Answer 36

eat a variety of food
eat each type of food in moderation

Question 37

list 5 food groups?

Answer 37

grain, vegetable, fruit, dairy, protein and fats