The digestive system

Question 1

what are the for types of tissues in animals

Answer 1

muscle tissue, nervous tissue, connective tissue and epithelial tissue

Question 2

what is the purpose of the digestive system

Answer 2

cells of an organism require nutrients and for vertebrates digestion of food is the first important step that must occur. some nutrients can dissolve in water and redily enter cells but some are too large and must be broken down into smaller units

Question 3

definition of digestion

Answer 3

the chemical process of breaking down large organic molecules into a size that can pass across plasma membranes and around the body

Question 4

what are the four main specialised functions in the digestive system

Answer 4

ingestion, digestion, absorption and egestion

Question 5

function of ingestion

Answer 5

the taking in of nutrients

Question 6

the function of digestion

Answer 6

the breakdown of complex organic molecules into smaller components by mechanical and chemical means

Question 7

the function of absorption

Answer 7

the taking up of digested molecules into the cells of the digestive tract through the cell membrane

Question 8

the function of egestion

Answer 8

the removal of waste food materials (unabsorbed food) from the body

Question 9

what is mechanical or physical digestion

Answer 9

when large pieces of food are broken down into smaller pieces of the same food, chemically the food stays the exact same

Question 10

when does mechanical/physical digestion occur

Answer 10

chewing, the cutting up of food. peristalsis, the muscular contractions of the stomach and bile which is produced in the liver and emulsifiers lipids, breaking up fatty masses into smaller droplets

Question 11

what is the aim of mechanical/physical digestion

Answer 11

to increase surface area of the food so chemical digestion can happen at a faster rate

Question 12

what is chemical digestion

Answer 12

when enzymes break down complex structures into their simplest forms, they go from polymers to monomers

Question 13

what is the alimentary tract

Answer 13

the tube from the top to the bottom of the digestive system

Question 14

what does the alimentary tract include

Answer 14

the mouth, oesophagus, stomach, small intestine, large intestine, rectum and anus

Question 15

what are the accessory glands of the digestive system

Answer 15

salivary glands, gall bladder, liver and pancreas and others which contribute vital subtstancea to the functions of the system

Question 16

what happens in the mouth

Answer 16

teeth mechanically break down food, saliva contains amylase which digests starch into maltose, saliva lubricates food which makes it easier to swallow. the epiglottis closes off the trachea so food bolus goes down the oesophagus

Question 17

what is peristalsis

Answer 17

undirectional muscular contractions which allow fod to move along the digestive system and break it down further

Question 18

what happens in the stomach

Answer 18

mechanical digestion occurs as the muscles of the stomach wall relax and contract (peristalsis), the food is now called chyme. gastric juice is secreted from the cells lining the stomach walls.

Question 19

what is pepsinogen and its purpose

Answer 19

it is converted into the active enzyme pepsin where it then acts on the peptide bonds between amino acids, breaking down the long protein chains into smaller amino acids

Question 20

what are the three regions of the small intestine

Answer 20

the duodenum, jejunum and ileum

Question 21

what are the two functions of the small intestine

Answer 21

digestion - further and final digestion of all organic molecules including carbohydrates, proteins and lipids. absorption - of digested molecules into the bloodstream

Question 22

what happens in the small intestine

Answer 22

pancreatic enzymes and intestinal enzymes enter the duodenum at the top of the small intestine which contain enzymes

Question 23

what is pancreatic juice

Answer 23

contains a mixture of amylase, trypsin, lipase and bicarbonate. the bicarbonate neutralises the acidity of the digested food which stops the action of pepsin

Question 24

what is bile, where is it produced and stored?

Answer 24

its produced in the liver and passes down the bile duct and into the duodenum but is stored in the gall bladder if there is no food to digest. its involved in the mechanical digestion of fats by emulsifing them into smaller pieces

Question 25

what do lipases do

Answer 25

they are enzymes that are produced in the pancreas and chemically break down fat into fatty acids and glycerol

Question 26

what happens to amino acids, simple sugars, vitamins and minerals digestive system

Answer 26

they are absorbed into the blood capillaries via active transport

Question 27

what happens to fatty acids and glycerol

Answer 27

they are lipid soluble so can easily diffuse through the membranes of the intestinal walls

Question 28

what happens to water once it reaches the intestines

Answer 28

90-95% of water is absorbed by osmosis, the rest is disposed of

Question 29

what happens to carbs, starch, proteins and lipids in the digestive system

Answer 29

if they are too large of a molecule to directly cross the plasma membrane, the are broken down into their simplest forms by enzymes

Question 30

how to enzymes break down food molecules

Answer 30

by the process of hydrolysis - where a molecule of water breaks down one or more chemical bonds

Question 31

what enzyme breaks down and what is the smallest unit of carbs

Answer 31

carbohydrase, smallest unit is monosaccharides

Question 32

what enzyme breaks down and what is the smallest unit of starch

Answer 32

amylase and peptidase, smallest unit is maltose

Question 33

what enzyme breaks down and what is the smallest unit of protein

Answer 33

protease, smallest unit is amino acids

Question 34

what enzyme breaks down and what is the smallest unit lipids

Answer 34

lipase, smallest unit is fatty acids and glycerol

Question 35

what is the main function of the large intestine

Answer 35

compact undigested food and to absorb water and some salts back into the body

Question 36

what are the two non-primary functions of the large intestine

Answer 36

bacteria in the colon act on undigested matter, producing vitamin a and k. and peristalsis including in the rectum

Question 37

what is in gastric juice

Answer 37

this substance contains, mucus,water, hydrochloric acid and pepsinogen