B3 organisation and the digestive system and part of B4 Flashcards Preview

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Flashcards in B3 organisation and the digestive system and part of B4 Deck (69):

what is a tissue

a group of cells with similar structure and function working together


what is an organ

a collection of tissues working together to perform a specific function


what is an organ system

groups of organs that work together to carry out specific functions e.g. digestive system, circulatory system, gas exchange system


how long is the digestive system



what is the function of the digestive system

to break down large insoluble food molecules that the body can't absorb and create smaller soluble molecules that can be absorbed and used by cells


what does pancreas and salivary glands release

digestive juices containing enzymes to break down food


what happens in small intestine

soluble food molecules are absorbed into blood and then bloodstream


how is the small intestine adapted

has villi which creates a large surface area

has good blood supply

short diffusion distance to blood vessels


what is the function of the liver in the digestive system

produces bile


what is the function of bile and where is it stored

helps in the digestion of lipids, stored in the gall bladder, turns acidic liquid from stomach into alkaline for small intestine.
also emulsifies fats in food as not broken down in stomach by breaking them up which creates a bigger surface area of fats for lipase enzymes to act upon


what is the function of carbohydrates

provide energy for all the chemical reactions that take place in the body


what is the structure of carbohydrates

long chains of simple sugars e.g. glucose


what is the structure of starch and cellulose

long chains of simple sugars bonded together


how do amino acids form protein molecules

by forming covalent bonds in specific orders


what are lipids used for

used in cell membranes, also used for
storing energy
water proofing


what is a denatured protein

when the bonds that hold the proteins in these 3D shapes are broken and the shape of the protein is lost meaning it may not function anymore in the cells


what is a catalyst

something that speeds up a chemical reaction but doesn't affect the product can be used repeatedly


what are enzymes made up of

hey are proteins (made up of amino acid chains) folded to from the active site


what is metabolism

the sum of all the reactions in a cell or the body


what do protease enzymes do and where are they produced

break down protein into amino acid. produced in small intestine, pancreas and stomach


what do carbohydrase enzymes do and where are they produced

break down carbohydrates into simple sugars. made in small intestine, pancreas and salivary gland


what does amylase do and where is it made

breaks down starch into glucose. made in salivary gland and pancreas


what do lipase enzymes do and where are they produced

break down lipids into fatty acids and glycerol. made in small intestine and pancreas


how does temperature affect enzyme action

the rate of enzyme controlled reactions increases as the temperature increases


what happens above 40 degrees in enzyme activity

the protein structure of the enzyme is affected and the long amino acid chains begin to unravel so the active site shape changes and can no longer act as a catalyst


how does pH affect the shape of the active site of an enzyme

a change in pH affects the forces between the different parts of the protein molecule so that they change shape and the enzyme can no longer be a catalyst


how many glands are there in the lining of the stomach

35 million


how does hcl acid produced by stomach help digestion

allows protease enzymes to work effectively and kills bacteria


how does the thick layer of mucus produced by stomach help digestion

thick layer of mucus coats stomach walls and protects them from being digested by acid and enzymes


what are platelets

small fragments of cells that have no nucleus but help the blood to clot at site of wound and then dries to form a scab


what is blood clotting

a series of enzyme controlled reactions that convert fibrinogen into fibrin


what is a capillary

the tiniest blood vessel in the circulatory system that links arteries and veins. narrow with thin walls and oxygen and glucose easily diffuse out of blood and into capillaries


what are arteries

they carry blood from the heart to organs. cause of a pulse. have thick walls containing muscle and elastic fibres


what are veins

carry blood that is low in oxygen to heart from
organs. they have thin walls and valves to prevent backflow of blood


what is the human circulatory system made up of

blood, blood vessels and the heart


what does the plasma carry

red blood cells, white blood cells, platelets

takes waste co2 from cells to lungs

takes urea from liver to kidney

takes soluble products of digestion from small intestine to cells


what is blood made up of and what %

55% plasma
1% white blood cells and platelets
45% red blood cells


what is haemoglobin and where is it found

found in red blood cells, binds to oxygen


what are 2 adaptations of red blood cells

concave on both sides to give a bigger surface area

no nucleus to provide more space for haemoglobin


what are the 2 types of white blood cells and what do they do

lymphocytes- form antibodies against harmful microorganisms

phagocytes- engulf and digest invading bacteria and viruses


what is thee function of phloem cells

transport sugars made by photosynthesis from leaves to the rest of the plant


what is the function of xylem cells

carry water and mineral ions from the soil around the plant to the stem and leaves


what are mineral ions needed for in plants

production of proteins and other molecules within cells


what is water needed for in plants

photosynthesis and keeping the plant upright


what is transpiration

when stomata are open and water vapour evaporates from the cells lining the air spaces and then passes through the stomata by diffusion


what factors affect transpiration rate


surface area



light intensity


why do plants wilt

when they lose water. it is a protection mechanism against further loss as leaves hang down which reduces available surface area for water loss by evaporation


what happens if plants lose water faster than it is being replaced


stomata may close which stops photosynthesis and risks overheating


what is a potometer

used to show the uptake of water by a plant in different conditions


what happens if the heart beat is too slow

not enough oxygen can be distributed


what happens if the heart beat is too fast

blood can't be pumped properly


what is an artificial heart used for

temporary whilst waiting for a transplant so it can support the heart

also used to give a diseased heart a rest so it can recover


how is ventilation of the lungs done

by contracting and relaxing the intercostal muscles between the ribs and the diaphragm which changes the pressure inside the chest cavity so air is forced in or out of the lungs


what is an adaptation of the alveoli

provide a large surface area and a rich supply of blood capillaries so gases can diffuse efficiently


what are the 2 parts of the double circulatory system

one carries blood from heart to lungs and back allowing o2 and co2 to be exchanged with the air in the lungs

the other carries blood from the heart to all the other organs and back again


what is the atria

the top chambers of the heart where blood enters


what is the vena cava

where deoxygenated blood that enters the right atrium comes from


what is the pulmonary vein

oxygenated blood (from lungs) comes from before entering left atrium


what are ventricles

where blood is forced down once atria contract


what is the right ventricle

forces deoxygenated blood to the lungs in the pulmonary artery


what is the left ventricle

pumps oxygenated blood around the body in a big artery called the aorta


what are stents

metal mesh that is placed in the artery, a balloon is inflated to hold stent and blood vessel open. it is then deflated and removed but the stent remains open so blood can flow freely


what is bypass surgery

replacing narrow or blocked artery with bits of veins from other parts of the body


what are statins

prescribed medication that reduce blood cholesterol levels which slows down the rate at which fatty material is deposited in coronary afteries


why would a heart valve need to be replaced

if they begin to leak or become stiff and not open properly


what are mechanical valves

made of titanium and polymers, they last a long time but medicine has to be taken to stop blood clotting around it


what are biological valves

taken from pigs cattle or human donors but only last 12-15 years


why is the small intestine long, have a good blood supply and a large surface area

long so that food stays in it long enough to come into contact with digestive enzymes, good blood supply so that soluble food substances can be transported into bloodstream so they can move around the body and large surface area to increase efficiency of absorption of food molecules into the blood


what is the ph of the stomach

1.5 to 3.5