paper1- topic 2 Flashcards
what is a tissue
a group of cells with a similar structure and function
what is an organ
a group of tissues working together for a specific function
what is an organ system
work together to from organisms
digestion
large food molecules are broken down into small molecules by enzymes .
the small molecules can then be absorbed into the bloodstream
digestive system
1) food chewed in mouth- enzymes in saliva begin to digest the starch into smaller sugar molecules
2) food passes down oesophagus into stomach- enzymes begin the digestion of proteins. stomach contains acid to help digest the proteins
3) food spends hours in stomach- churning action of the stomach muscles turns the food into fluid- increasing the surface area for enzymes to digest
4) food passes into small intestine- chemicals are then released into small intestine by liver and pancreas
liver releases bile which helps speed up digestion of lips and neutralises the acid released from the stomach
5) fluid makes its way to large intestine where water is absorbed into bloodstream
6) faeces is released from body
bile
neutralises stomach acid
increases rate of lipid digestion by lipase
effect of temp on enzymes
as temp increases - reaction gets faster as there are more collisions between substrate and active site
optimum temperature- maximum frequency of successful collisions
as temp increases past optimum- enzyme vibratres and shape of active site changes so substrate no longer fits (denatured)
effect of pH on enzyme
active site dentaures if conditions are too alkaline or acidic
food tests method
1) take food sample and grind using pestle and mortar
2) transfer paste to beaker and add more distilled water and stir so chemicals in the food dissolve in the water
3) filter the solution to remove suspended food particles
4) use different tests
food tests
starch- add iodine - orange and turns blue/black if starch is present
sugars- add benedicts solution- add to water bath - blue and turns green/yellow/red depending on how much sugar is present
protein- add biuret solution - blue and turns purple/pink if protein is present
lipids- add sudan III- shake gently- red stained oil layer if lipids are present
effect of pH on amylase practical
1) place one drop of iodine solution into each well of spotting tile
2) add 2cm^3 of starch solution to first test tube
3) add 2cm^3 of amylase solution into second tube
4) add 2cm^3 of pH 5 buffer solution to third tube
5) place all three test tubes in water bath at 30 degrees and leave for 10 mins
6) combine three solutions into one and mix
7) return to water bath and start stopwatch
8) after 30s, transfer one drop of solution to well in spotting tile
9) iodine should turn blue/black
10) take sample every 30s and continue until iodine remains orange as this tells us starch is no longer present and the reaction has completed
11) record time
12) repeat using different pH buffers
problems with effect of pH practical
only taking samples every 30s - only have an approximate time for the reaction to complete
looking for time when iodine does not go blue/black- colour change is usually gradual and will not always be obvious
absorption in the small intestine
length gives a large surface area for absorption
interior is covered in villi - increasing surface area
villi have good blood supply increasing concentration gradient
villi have thin membrane which ensures a short diffusion path
structure of heart
four chambers - right and left atrium and ventricle
atria and ventricles are separated by valves
vena cava
brings in deoxygenated blood from the body
pulmonary artery
blood passes from heart to lungs collecting oxygen
pulmonary vein
oxygenated blood passes from lungs to heart
aorta
oxygenated blood is pumped from heart to body
how blood flows through the heart
blood enters left and right atrium
atria contracts and blood is forced into ventricles
ventricles contract and force blood out of heart
valves prevent blood flowing back into atria
coronary arteries
provide oxygen to muscle cells of the heart
oxygen is used in respiration for contraction
artificial pacemaker
small electrical device and it corrects irregularities in heart rate
arteries
carry high pressure blood from heart to organs in the body
thick muscular walls which allows them to withstand high pressure
elastic fibres stretch when the surge of blood passes through and recoil in between the surges which keeps the blood moving
capillaries
when blood passes through capillaries substances such as glucose diffuse from the blood to the cells
have thin walls so diffusion pathway is short
veins
towards the heart
thin walls as blood pressure is low
contain valves to stop blood flowing backwards
