Mass transport (currently just 7.4)

structure of atrium

thin walled and elastic and stretches as it collects blood

structure of ventricles

thicker muscular wall as must contract strongly to pump distance

aorta

connected to left ventricle and carries oxygenated blood to all parts of body except lungs

vena cava

connected to right atrium and brings deoxygenated blood back from tissues of body

pulmonary artery

connected to right ventricle and carries deoxygenated blood to the lungs where its replenished and carbon dioxide removed

pulmonary vein

connected to left atrium and brings oxygenated blood back from the lungs

coronary arteries

supply oxygen to heart muscle

what are the valves that prevent backflow of blood into the atria when ventricles contract?

• left atrioventricular (bicuspid) valve

• right atrioventricular (tricuspid) valve

semi lunar valves

link ventricles to the pulmonary artery and aorta and stop blood flowing back into heart after ventricles contract

which side of the heart pumps oxygenated blood to whole body?

left

what are the risk factors associated with cardiovascular disease?

smoking, high blood pressure, blood cholesterol, diet

how can smoking increase likelihood of heart disease?

• carbon monoxide combines with haemoglobin reducing oxygen carrying capacity of the blood

• nicotine stimulates production of adrenaline increasing heart rate and blood pressure

haemoglobin

• quaternanry structure with 4 chains

• each chain has a haem group containing an iron ion

• high affinity for oxygen and is a reversible reaction

how does haemoglobins affinity for oxygen vary depending on partial pressure of oxygen?

oxygen loads onto haemoglobin to form oxyhaemoglobin where there’s a high pO2 and unloads its oxygen where theres a lower pO2

what does a dissociation curve show?

how saturated the haemoglobin is with oxygen at any given partial pressure

what happens where partial pressure of oxygen is high (eg in the lungs)?

haemoglobin has a high affinity for oxygen so it has a high saturation of oxygen

what does 100% saturation mean?

every haemoglobin molecule is carrying the maximum 4 molecules of oxygen

why is the graph S-shaped (sigmodial)?

when haemolglobin combiens wit the first O2 molecule its shape alters in a way that makes it easier for other molecules to join too but as it starts to become saturated it gets harder for more O2 to join

carbon dioxide effect on oxygen unloading? (dont fully understand)

• cells respire prducing co2 raising partial pressure of co2

• this increase the rate of oxygen unloading (rate that oxyhaemoglobin dissociates to form haemoglobin and oxygen) so dissociation curve ‘shifts’ right

• saturation of blood with oxygen is lower for given partial pressure of oxygen meaning more oxygen is released

• bohr effect

what’s different for organisms that live in environments with a low concentration of oxygen? (opposite for small animals)

have haemoglobin with a higher affinity for oxygen than human haemoglobin so dissociation curve is to the left of ours

why do mammals have a double circulatory system?

when blood is passed thrugh the lungs, its pressure is reduced so if it was to pass immediately to rest of the body its low pressure would make circulation very slow

cardiac output

heart rate x stroke volume

tissue fluid formation

• start of capillary bed (arteriole end) hydrostatic pressure inside capillaries is greater than hydrostatic pressure in tissue fluid

• difference in hydrostatic pressure means overall outward pressure forces fluid out of capillaries and into spaces around cells forming tissue fluid

• as fluid leaves hydrostatic pressure reduces in capillaires so pressure is much lower at venule end of capillary bed

• due to fluid loss and increasing concentration of plasma proteins (don’t leave capillaries) water potential at venule end of capillary is lower than water potential in tissue fluid

• means some water re-enters capillaries from tissue fluid at venule end by osmosis

arteries

thick, elastic muscular walls that stretch as bood is pumped in and msucle wall contracts to force blood along

deoxygenated blood from the body…

right atrium, atrioventricular valve, right ventricle, semi lunar valve, pulmonary artery, lungs, pulmonary vein, left atrium, AV valve, left ventricle, SL valve, aorta to body, vena cava back

what has thickest walls?

left ventricle as pumps blood around body not just to lung and more than atria as push further

late diastole

• atria and ventricles relaxed

• AV valves open and SL valves closed

• blood flows passively from atria through AV valves, passive filling

atrial systole

• contiunes until about 70% full

• vol presses against AV valves slowly closing

• atria contracts propelling blood into ventricles stretching for full capacity

ventricuar systole (isometric phase)

• AV and SL valves closed

• atria relaxed and ventricules systole

• ventricles contracting but load of blood prevents them from shortening

  • isometric ventricular contraction

ventricular systole (isotonic phase)

• same vol of blood so pressure builds up

• when rising pressure exceeds that in aorta and pulmonary arteries SL valves forced open and blood ejected from heart

  • ventricular ejection

• and muscles shorten as they contract

ventricular diastole

• semi lunar valves close as ventricles begin to relax

• pressure falls in ventricles to a very low value and the AV valves open

might be more xx