B3 organisation and the digestive system and part of B4 Flashcards
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
6-9m
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 insulation protection
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
temperature
surface area
wind
humidity
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
wilting
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
