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Biology A level > 3.1.2 circulatory systems > Flashcards

3.1.2 circulatory systems Flashcards

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1
Q

why do multicellular organisms need transport systems

A

they have a low surface area to volume ratio and a higher metabolic rate so all cells cannot get everything they need

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2
Q

what is a single circulatory system

A

blood only passes through the heart once for each complete circuit of the body

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3
Q

what is a double circulatory system

A

blood passes through the heart twice for each complete circuit of the body
left side pumps to rest of the body, right to the lungs

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4
Q

what is a closed circulatory system

A

the blood is enclosed in blood vessels

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5
Q

what is an open circulatory system

A

blood can freely flow through body cavity at points

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6
Q

how does an insect’s circulatory system work

A

the heart is segmented and contacts in a wave from the back, pumping blood into a single main artery which opens up into the body cavity
blood flows around the organs making its way back into the heart through valves
does not supply oxygen

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7
Q

how does a fishes circulatory system work

A

the heart pumps blood through gills then to the rest of the body in a single circuit

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8
Q

how does an mammals circulatory system work

A

heart is divided down the middle
left pumps to the rest of the body and the right pumps to the lungs

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9
Q

what is the function of an artery

A

carry blood away from the heart to the rest of the body

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10
Q

what is the function of a vein

A

bring deoxygenated blood back towards the heart

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11
Q

what is the function of an capillary

A

exchange substances with cells such as oxygen and glucose

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12
Q

what is the structure of arteries

A

walls are thick and muscular and contain elastic tissue to withstand and maintain high pressure
the endothelium is folded so it can expand to maintain pressure
arterioles have less elastic tissue but have smooth muscle to control blood flow

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13
Q

what is the structure of veins

A

they have wide lumen with little elastic and smooth muscle tissue
also have valves to stop blood flowing backwards

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14
Q

what is tissue fluid

A

the fluid that surrounds cells in tissues. it is made from substances that leave the blood

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15
Q

how is tissue fluid formed

A

at the arteriole end hydrostatic pressure in capillaries is greater than the hydrostatic pressure in the tissue fluid so fluid is forced out
as fluid leaves hydrostatic pressure in the capillaries decreases so it is lower at the venule end
oncotic pressure generated by plasma proteins and it lowers the water potential
at the venule end water potential in capillaries is lower than water potential in fluid so some water reenters the capillaries

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16
Q

where does excess tissue fluid drain

A

into the lymphatic system which leads to the main lymph vessels in the thorax where it is returned to the blood

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17
Q

how do valves stop blood flowing backward

A

the valves only open one if there is a higher pressure behind a valve they’re forced open if there is a higher pressure in front it forced shut

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18
Q

what are the valves between the atria and ventricles called

A

atrioventricular valves

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19
Q

what valves link ventricles and to arteries

A

semi lunar valves

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20
Q

what blood vessel brings blood from the rest of the body to the heart

A

vena cava

21
Q

what blood vessel brings blood to the heart from the lungs

A

pulmonary vein

22
Q

what blood vessel brings blood to the rest of the body from the heart

A

aorta

23
Q

what blood vessel brings blood to the lungs from the heart

A

pulmonary artery

24
Q

what is the cardiac cycle

A

the ongoing sequence of contraction and relaxation of the atria and ventricles to keep blood continuously circulating

25
Q

what is atrial systole

A

ventricles are relaxed and atria contract which decreases their volume and increases their pressure. this pushes blood through atrioventricular valves

26
Q

what is ventricular systole

A

atria relax and ventricles contract increasing their pressure. pressure in ventricles increases so atrioventricular valves shut and opens the semi lunar valves and forces blood out

27
Q

what is diastole

A

the ventricles and atria relax. high pressure in arteries shuts the semi lunar valves
atria fill with blood and atrial ventricular valves to open

28
Q

what is cardiac output

A

volume of blood pumped by the heart per minute

29
Q

how do we calculate cardiac output

A

heart rate x stroke volume

30
Q

what is the stroke volume

A

volume of blood pumped during each heartbeat

31
Q

what does myogenic mean

A

it can contract and relax without receiving signals from nerves

32
Q

how is heart rhythm controlled

A

electrical impulse from SAN in the wall of right atrium cause atria to contract
non conducting collagen tissue prevents waves passing directly from atria to ventricles
electrical impulses reach AVN which delays it slightly so ventricles contract after atria have emptied
electrical impulse travels down bundle of his to the purkyne fibres causing ventricles to contract

33
Q

what can we use to record hearts electrical activity

A

an electrocardiograph

34
Q

what causes the p wave

A

contraction (depolarisation) of the atria

35
Q

what causes the QRS complex

A

contraction (depolarisation) of ventricles

36
Q

what causes the T wave

A

relaxation (repolarisation) of the ventricles

37
Q

what is tachycardia

A

heart beat is too fast (120bpm)

38
Q

what is bradycardia

A

heartbeat is too slow (<60bpm)

39
Q

what is an ectopic heartbeat

A

an extra heartbeat caused by early contraction of the atria

40
Q

what is fibrillation

A

atria and ventricles loose rhythm and stop contractions properly

41
Q

what is haemoglobin

A

a protein the contains an iron haem group which has a high affinity for oxygen and carries oxygen around in blood as oxyhaemoglobin

42
Q

when does the oxygen load onto the haemoglobin

A

at high partial pressures of oxygen

43
Q

when does the oxygen offload from the haemoglobin

A

at low partial pressures of oxygen

44
Q

why is an oxygen dissociation curve s shaped

A

when Hb combines with the first oxygen molecule its shape alters in a way that makes it easier for other molecules to join
as it becomes more saturated it becomes harder for oxygen molecules to join

45
Q

what is different about foetal and adult haemoglobin

A

foetal Hb has a higher affinity for oxygen

46
Q

why does foetal haemoglobin need a higher affinity for oxygen

A

the foetus gets blood from the mother but oxygen saturation has decreased by the time it reaches the placenta so it needs a higher affinity for oxygen so that it can take up enough

47
Q

how do high concentrations of carbon dioxide effect how easily haemoglobin gives up oxygen

A

in high partial pressures of carbon dioxide Hb offloads oxygen more readily.
this means active cells offload more oxygen which is needed for increased respiration

48
Q

what is the bohr effect

A

the dissociation curve shifts right when carbon dioxide levels increase showing how more oxygen is released from the blood

49
Q

how do high concentrations of carbon dioxide effect oxygen unloading

A

CO2 enters red blood cells and combines with water to form carbonic acid. (enzyme carbonic anhydrase is used to catalyse). around 10% is carried in Hb to the lungs
the carbonic acid dissociates into H+ and HCO- ions
the H+ causes HbO8 to unload oxygen so Hb can take up H+ ions. this forms haemoglobinic acid
the HCO- diffuse out of the cell and are transported in plasma. to maintain the charge Cl- ions diffuse in (chloride shift)
in the lungs the low pCO2 causes some H+ and HCO- to recombine into CO2 which leaves via alveoli

Biology A level (13 decks)

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