heart/human circulation Flashcards
2.67 what factors may increase the risk of developing coronary heart disease and how?
- diet: eating lots of saturated fats inc. blood cholesterol & inc. risk of fatty deposits
- smoking: inc. blood pressure & inc. risk of fatty deposits forming
- high blood pressure: damages artery lining & inc. risk of fatty deposits forming. high salt levels in diet inc risk of high blood pressure
- obesity: being obese will inc blood pressure & may be linked to poor diet
- lack of exercise: causes high blood pressure
2.68 how does the structure of arteries relate to their function?
- thick outer wall: can transport blood at high pressure w/o bursting
- thick layer of elastic tissue: allows artery to stretch & recoil to keep blood flowing at high pressure
- thick layer of muscular tissue: helps to control flow of blood by widening (dilating) and narrowing (constricting)
2.68 how does the structure of veins relate to their function?
- fairly thin outer wall: blood is flowing at lower pressure so thick wall not needed
- thin layer of muscle & elastic tissue: wall can contract to keep blood flowing
- semilunar valves: prevents blood flowing backwards
2.68 how does the structure of capillaries relate to their function?
wall is one cell thick: short distance for diffusion of substances from blood into tissues
explain how coronary heart disease works
- coronary arteries supply heart muscle w blood. this blood provides glucose & O needed for aerobic respiration & removes CO2 produced by aerobic respiration
- if fatty deposits build up in artery walls, they narrow the lumen (space) of artery. this restricts blood flow to the HMC
- this causes HMC to receive less blood, which means that HMC receive less O (and glucose) for aerobic respiration
- as result aerobic respiration reduces & anaerobic respiration inc in HMC
- lactic acid will build up due to inc in anaerobic respiration, poisoning HMC & causing heart attacks.
what is the function of the circulatory system?
to transport substances around the body
what is pulmonary circulation?
deoxygenated blood is pumped to the lungs and oxygenated
blood returns back to the heart
what is systemic circulation?
oxygenated blood is pumped to all the other organs of the
body and deoxygenated blood returns back to the heart
2.65 what are the 4 chambers that the heart is divided into?
2 atria (top of the heart), and 2 ventricles (below the atria)
2.65 what is the difference between the atria and the ventricles?
atria: top of heart, thinner muscular walls
ventricles: below atria, thicker muscular walls
2.65 what separates the left and right side of the heart?
the septum
2.65 what does the right side of the heart pump?
deoxygenated blood to the lungs
2.65 what does the left side of the heart pump?
oxygenated blood to the body
2.65 which ventricle wall is thicker, and why?
left ventricle; allows it to pump blood at higher pressures so blood can travel around whole body
2.65 how does the heart function/pump blood around the body?
- two sides of heart contract & relax at same time to pump blood
- atria contract, emptying blood into ventricles
- ventricles then contract, pushing blood into arteries
- valves close to ensure blood flows in correct direction (semi-lunar valves)
2.66 explain how the heart rate changes during exercise
if exercise, muscles need more glucose & oxygen for aerobic respiration; HR inc so more blood travels to muscles
- when exercise starts, muscles produce more CO2 in aerobic respiration
- sensors in aorta & carotid artery detect this inc
- they send nerve impulses to medulla
- medulla responds by sending nerve impulses along the accelerator nerve
- accelerator nerve inc HR
- more blood supplied to muscles to meet demands of inc aerobic respiration
2.66 explain how the heart rate changes under the influence of adrenaline
- during times of fear/stress, adrenaline produced by adrenal glands & secreted into bloodstream
- as result, liver cells convert glycogen into glucose to inc blood glucose levels
- also, breathing & HR inc to inc blood flow
- hence, inc in B & HR allows more glucose and oxygen to be transported in bloodstream to respiring cells for ‘fight or flight’ response to occur
2.66 what controls changes in heart rate?
changes in heart rate are controlled by nerve impulses from medulla (part of brain)
2.66 what nerve decreases heart rate at rest?
decelerator nerve sends electrical impulses to dec HR at rest
2.59 what is in blood?
plasma, platelets, red & white blood cells
2.59 & 2.60 what is plasma/its function?
- straw coloured liquid
- transports blood cells & many other substances, incl: dissolved nutrients e.g. glucose & amino acids; dissolved waste products incl urea & CO2; hormones; proteins; heat energy; digested food
2.59 what are red blood cells/their function?
small red cells, transport oxygen (bound to haemoglobin)
2.59 what are platelets/their function?
- cell fragments
- release chemicals when blood exposed to air, which cause soluble fibrinogen to be converted to insoluble fibrin
- fibrin forms a mesh, which traps platelets & red blood cells - this is a clot (scab)
2.59 what are phagocytes & lymphocytes/their function? (white blood cells)
phagocytes: larger cells w multi-lobed nucleus; engulf & digest pathogens
lymphocytes: cells w very large nucleus; make & release antibodies, which bind to and destroy pathogens
2.61 how are red blood cells specialised for their job?
- contain haemoglobin: protein which combines w oxygen to form oxyhaemoglobin, this transports oxygen to respiring cells
- no nucleus, meaning more haemoglobin can be packed into each cell so more oxygen transported
- biconcave: inc SA:vol ratio & dec distance to centre of cell; this inc rate of diffusion
2.62 how does the immune system respond to disease using white blood cells? (phagocytes)
- phagocyte recognises pathogen
- phagocyte engulfs pathogen in process known as phagocytosis
- the lysozymes containing enzymes move towards pathogen
- enzymes break down pathogen
- useful materials are absorbed
- waste products are removed from phagocyte
2.62 how does the immune system respond to disease using white blood cells? (lymphocytes)
- lymphocytes detect pathogen’s antigens
- lymphocyte identifies correct type of antibody to make, which is complementary to pathogen’s antigen
- lymphocyte releases large numbers of correct antibody
- pathogens either clump together resulting in death, or antibodies trigger phagocytes; some pathogens can even burst
- lymphocytes produce cells that produce lots of antibody v quickly if detect same pathogen again (memory cells)
2.62 what do lymphocytes produce?
- special Y shapes proteins called antibodies
- these attach to proteins on surface of pathogens called antigens
- each pathogen has different shaped antigen, so need to make specific complementary antibody
2.62 lymphocytes allows organisms to…
build up an immunity towards certain diseases
2.62 what are anti-toxins?
antibodies that are specialised to combat toxins (chemicals released by pathogen which cause cell damage)
2.63B how does vaccination work?
- body given vaccine (dose of pathogen), normally by injection
- this dose is either dead pathogen or parts of pathogen’s cell surface - this stops pathogen causing disease
- lymphocytes generate antibodies against pathogen & more importantly, make memory cells
- so when body next encounters same pathogen, memory cells react to it v quickly, producing lots of antibodies much earlier than 1st time
- this kills pathogen before we feel ill & so prevents us being infected twice by same pathogen - said to have gained immunity
2.64B how are platelets involved in blood clotting, and how does it help the body?
- platelets fragments of larger cells
- if platelets exposed to oxygen in air (bc of cut) release chemicals which start clotting process
- these chemicals cause soluble plasma protein fibrinogen to become insoluble fibrous protein fibrin
- fibrin forms network of fibres across cut, which trap platelets & red blood cells
- this forms clot, or scab, which prevents further loss of blood
- also acts as barrier to prevent entry of pathogens
