2: Organisation Flashcards
definition of a cell
basic functional & structural units in a living organism
definition of a tissue
a group of cells of similar structure working together to perform a particular function
definition of an organ
made from a group of different tissues working together to perform a particular function
definition of an organ system
made from a group of organs with related functions, working together to perform body functions within the organism
what is digestion?
the process where large, insoluble molecules in food are broken down into smaller, soluble molecules that can be absorbed into the bloodstream & delivered to cells in the body
what is the function of the mouth/salivary glands?
mechanical digestion occurs here - teeth break food down to increase it s.a. to v ratio; amylase enzymes in saliva start to digest starch into maltose
what is the function of the oesophagus?
tube that connects mouth to stomach
what is the function of the stomach
food is mechanically digested by churning actions; protease enzymes start to chemically digest proteins; HCl is present to allow for optimum pH of enzymes and to kill bacteria
what is the function of the small intestine?
enzymes are produced here; slightly alkaline pH; digested molecules are absorbed through walls, lined w villi to increase s.a.
what is the function of the large intestine?
water is absorbed from remaining material in the colon to produce faeces (this is then stored in the rectum and removed through the anus)
what is the function of the pancreas?
produces all three types of digestive enzyme, amylase, protease, lipase; secretes enzymes in alkaline fluid to raise pH of fluid coming out of stomach
what is the function of the liver?
produces bile to emulsify fat, amino acids not used are broken down here to produce urea
what is the function of the gall bladder?
stores bile
why is bacteria important for digestion?
they form a microbial ecosystem; break down substances we can’t digest e.g. cellulose; supply essential nutrients; synthesise vitamin K; provide competition with any harmful bacteria to restrict their growth
what is metabolism? what is metabolic rate?
sum of all the reactions happening in a cell or organism; m.r. is the rate at which this happens
what do enzymes do?
speed up chemical reactions in cells, allowing reactions to occur at much faster speeds than they would without enzymes at relatively low temps.
how do enzymes work?
enzymes and substrates randomly move about in solution; when an enzyme and its complementary substrate randomly collide – with the substrate fitting into the active site of the enzyme – an enzyme-substrate complex forms, and the reaction occurs; product/s forms from substrate/s, are then released from the active site; enzyme is unchanged and will go on to catalyse further reactions
what is the induced-fit model?
when a substrate(s) binds to the active site of the enzyme, the active site and substrate change shape slightly to fit more perfectly together - makes it easier for bonds within the substrate to break and new bonds to form, producing product(s)
what is the effect of temp on enzymes?
they work fastest at their ‘optimum temperature’ – in the human body, it’s around 37⁰C; heating beyond the optimum will start to break the bonds that hold the enzyme together, enzyme will start to lose its shape -this reduces the effectiveness of substrate binding to the active site reducing the activity; eventually, the shape of the active site is lost completely, it is ‘denatured’ - substrates cannot fit as specific shape of their active site has been lost
low temperatures do not denature enzymes, enzymes and their substrates collide at a lower rate - less ke
what is the effect of pH on enzymes?
If pH is too high or too low, bonds that hold the amino acid chain together can be destroyed; this changes the shape of the active site, so substrate can no longer fit into it, reducing the rate of activity, until enzyme is denatured
describe the practical to investigate the effect of pH on the rate of reaction of amylase enzyme
- place single drops of iodine solution in rows on tile
- use the syringe to place 2cm3 of amylase in a test tube
- add 1cm3 buffer solution to test tube using syringe
- add 2cm3 starch solution to amylase & buffer solution, start the stopwatch whilst mixing using a pipette
- after 10 seconds, use pipette to place one drop of mixture on first drop of iodine, should turn blue-black
- wait another 10 seconds and place another drop of the mixture on the second drop of iodine
- repeat every 10 seconds until iodine solution remains orange-brown
- repeat experiment at different pH values – the less time the iodine solution takes to remain orange-brown, the quicker all the starch has been digested and so the better the enzyme works at that pH
how can the practical to investigate the effect of pH on the rate of reaction of amylase enzyme be improved?
temperature could be controlled by using a water bath at 35℃; all solutions that need to be used (starch etc.) should be placed in a water bath and allowed to reach the temperature (using a thermometer to check) before being used; a colorimeter can be used to measure the progress of the reaction more accurately; makes colour change more prominent
what enzyme breaks down starch? what is the product? where is the enzyme made?
amylase; produces glucose; made in salivary glands, pancreas and small intestine
what enzyme breaks down proteins? what is the product? where is the enzyme made?
protease; produces amino acid; made in stomach, pancreas and small intestine
what enzyme breaks down lipids/fats? what is the product? where is the enzyme made?
lipase; produces fatty acids and glycerol; made in pancreas and small intestine
where is bile produced, what does it do?
produced in the liver, stored in gall bladder; it is alkaline to neutralise HCl from stomach, and enzymes in the small intestine have a higher optimum pH than those in the stomach; also breaks down large drops of fat into smaller ones, increasing surface area - aka emulsification; alkaline conditions and larger surface area allows lipase to chemically break down fat (lipids) into glycerol and fatty acids faster (the rate of fat breakdown is increased)
what are the products of digestion used for?
used to build new carbohydrates, lipids and proteins required for function and growth; some glucose is used in respiration to release energy; amino acids are used to build proteins like enzymes and antibodies; products of lipid digestion can be used to build new cell membranes and hormones
what is the food test for starch? what is the colour change for a positive test?
iodine test; will change from orange/brown to blue/black
what is the food test for sugar? what is the colour change for a positive test?
benedict’s solution and heat (water bath); change from blue to brick red (any colour change away from blue)
what is the food test for protein? what is the colour change for a positive test?
biuret solution; change from blue to purple/lilac
what is the food test for fat? what is the colour change for a positive test?
first add ethanol and shake, then add water and shake, it will change from clear/colourless to cloudy (white emulsion formed)
what is coronary heart disease?
when layers of fatty material build up inside the coronary arteries, preventing oxygen getting to heart
how can different diseases interact?
defects in the immune system mean that one is more likely to suffer from infectious diseases; viruses living in cells can trigger cancers; immune reactions initially caused by a pathogen can trigger allergies e.g. skin rashes and asthma; severe physical ill health can lead to depression and other mental illness
how does poor diet increase the risk of what non-communicable diseases?
poor diet = obesity = type 2 diabetes
excess sugar consumption leads to a reduction in the body’s sensitivity to insulin
how does smoking increase the risk of what non-communicable diseases?
lung disease, lung cancer, cardiovascular disease
chemicals in cigarettes damage the bronchioles, destroy many of the alveoli in the lungs; damage the lining of the arteries, including the coronary arteries - encourages the build-up of fatty material in the arteries, CO in smoke reduces the amount of oxygen carried by the blood, nicotine in smoke increases heart rate, putting strain on heart
how does alcohol consumption increase the risk of what non-communicable diseases?
liver disease, impaired brain function
causes lipids to build up in the liver which is called fatty liver disease; neurones of brain can be damaged can e.g. slow reaction time, impair memory; cause brain shrinkage; lead to memory problems
how does exposure to carcinogens increase the risk of what non-communicable diseases?
cancer
exposure to ionising radiation can damage DNA of cells
how can the incidence of non-communicable disease impact all levels in society (from the individual to national and globally)?
non-communicable disease = treatment, hospitalisation and access to the right medication =
costs time and money at both a local and national level (and a personal level if healthcare is self-funded) = while receiving treatment, one may not be able to work = reduction their income and loss of work, can also have a profound effect on mental health = effects of the national economy (less people can work)
