b2 Flashcards
order the following: organism, tissue, cell, organ system, organ
cell, tissue, organ, organ system, organism
state the 3 nutrients found in food
- carbohydrates
- protein
- lipids
define digestion
- when large food molecules are broken down into small molecules
state 6 parts of the disgestive system
- mouth
- oesophagus
- stomach
- small intestine
- liver and pancreas
- large intestine
state the function of the mouth
- the food is chewed in the mouth.
- enzymes in the saliva begin to digest
starch into smaller sugar molecules.
state the function of the oesophagus
- the food passes down the oesophagus
state the function of the stomach
- The churning action of the
stomach muscles turns the
food into a fluid increasing the surface area for enzymes to digest. - The food spends several hours in the stomach.
- The stomach also contains hydrochloric acid which helps the enzymes to digest protein.
state the function of the small intestine
the small food molecules are absorbed into the bloodstream by diffusion or active transport
state the function of the liver and pancreas
The liver releases bile which helps to speed up digestion of lipids.
The pancreas releases enzymes.
state the function of the large intestine
the fluid travels through the large intestine, where water is absorbed in the bloodstream
what is an enzyme?
- a large protein molecule and a biological catalyst
what is a biological catalyst?
- it speeds up the reaction without being used up
describe the lock and key model
- the enzyme’s active site has a specific shape.
- only a substrate with a complimentary shape can attach to the specific enzyme.
state the three digestive enzymes
- protease
- carbohydrase
- lipase
describe the enzyme protease
- made in the small intestine and pancreas
- breaks down protein into amino acids
describe the enzyme carbohydrase
- made in the small intestine and pancreas
- breaks down starch (amylase), into a chain of glucose molecules
describe the enzyme lipase
- made in the small intestine and pancreas
- breaks down lipids into glycerol and fatty acids
what is bile?
- an alkaline which neutralises stomach acid
what 2 factors affect enzyme activity?
- temperature
- PH
what does bile do?
- converts large lipid droplets into smaller droplets
- emulsifies the lipids
- increases the rate of lipid breakdown
how is the small intestine adapted for digestion?
- villi provide a large SA
- capillaries are thin for shorter diffusion distance
- the small intestine is very long increasing time for absorption
- good blood supply to maintain concentration gradient
how does temperature and PH affect enzyme activity?
- at high temperature, the enzyme molecule vibrates and the shape of the active site changes.
- the substrate no longer fits into the active site, so it denatures.
- the enzyme has an optimum PH, where the activity is maximum.
- the enzyme activity drops to zero if the PH is more acidic/alkaline.
what is a single circulatory system?
- Deoxygenated blood is pumped from the heart to
the gills where it collects oxygen and becomes
oxygenated. - The oxygenated blood now passes straight from the gills to the organs
where the oxygen diffuses out of the blood into the body cells. - The blood now returns to the heart.
what is the problem with a single circulatory system?
- the blood loses pressure, so it travels slowly.
what is a double circulatory system?
- The blood enters the heart twice
- The right side of the heart pumps deoxygenated
blood to the lungs - The left side of the heart pumps oxygenated blood to
the rest of the body
what is the benefit of a double circulatory system?
- the blood enters the heart twice, so it delivers oxygen rapidly.
why does the left ventricle have a thicker muscle than the right?
- to pump blood at a high pressure
where are coronary arteries found?
- they branch from the aorta and into/out of the heart
what is the purpose of coronary arteries?
- they provide oxygen to the muscle cells of the heart
what is the job of pacemaker cells?
it regulates the heartbeat
where are the pacemaker cells found in the heart?
right atrium
what is the job of an artificial pacemaker?
- it corrects the irregularities of the heartbeat
name the 3 blood vessels
- artery
- vein
- capillary
state the adaptations of an artery
- Thick muscular walls allow them to withstand high pressure.
- Elastic fibres stretch when the surge of blood passes through and then recoils between surges
which keeps the blood moving.
state the adaptations of a vein
- Many veins contain valves, which stop blood flowing backwards.
- Thin walls shorten the diffusion pathway
- Large lumen allows more blood to flow