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biology unit 2 > the cardiac cycle > Flashcards

the cardiac cycle Flashcards

1
Q

what does the cardiac cycle describe?

A

-the sequence of events that occur during one heartbeat

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2
Q

how many times on average does the heart beat per minute?

A

-about 70 times

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3
Q

what are the three stages of the cardiac cycle?

A

-atrial systole (contraction of atria)
-ventricular systole (contraction of ventricles)
-diastole (relaxation)

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4
Q

what happens in the atria during diastole ?

A

-walls relax
-blood enters from the vena cava and pulmonary vein

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5
Q

what happens in the ventricles during diastole ?

A

-wall relax
-semilunar valves closed because arterial pressure is greater than ventricular pressure which prevents blood flowing back into the ventricles
-AV valves open blood enters ventricle from atria

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6
Q

what happens the atria during atrial systole ?

A

-walls of atria contract
-force blood into ventricles
-AV stay open because pressure in the atria still exceed pressure in ventricles
-blood continues to enter the atria from the vena cava and pulmonary vein

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7
Q

what happens in the ventricles during atrial systole?

A

-walls remain relaxed
-volume increases as they fill with blood
-semilunar valves remain closed

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8
Q

what happens in the atria during ventricular systole?

A

-walls of atria relax
-AV valves close as the pressure in the ventricles exceed pressure in the atria

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9
Q

what happens in the ventricles during ventricular systole?

A

-walls contract
-chordae tendiae prevent AV valves blowing inside out
-as ventricle pressure peaks semilunar valves are forced open, forcing blood into the arteries
-at the end of ventricular systole the ventricles are art their smallest volume

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10
Q

how are heart sounds made?

A

-the closing of the valves so there are 2 for every cycle of the heart
-the flaps of tissue bang together to make a sound

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11
Q

look at book for the cardiac cycle diagram learn the steps

A

hdhhsahsg

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12
Q

what does it mean by both sides of the heart working simultaneously?

A

-both sides of the heart contract at the same time with the same part of the cycle occurring simultaneously in each

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13
Q

how do the valves open and close in the heart?

A

-the valves do not control the cardia cycle instead they are opened and closed passively de to pressure changes from different parts of the heart filling with blood

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14
Q

how can heart sounds be shown?

A

-on a phonocardiogram

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15
Q

what does ECG stand for and what does it show?

A

-electrocardiogram
-shows the electrical activity of the heart

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16
Q

when the pressure in the atria exceeds pressure in the ventricles what happens to the valves?

A

-the AV valves open and blood flows from the atria into the ventricles

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17
Q

when the pressure in the ventricles exceeds pressure in the atria what happens to the valves?

A

-the AV valves close which is the first heart beat sound which prevents blood flowing back into the atria

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18
Q

when pressure in the ventricles exceed pressure in the arteries what happens the semilunar valves?

A

-semilunar valves open allowing blood to flow into the arteries

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19
Q

when pressure in the arteries exceed pressure in the ventricles what happens the semilunar valves?

A

-semilunar valves close which is the second heartbeat this prevents blood flowing back into the ventricles

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20
Q

how is the coordination of the cardiac cycle stimulated?

A

-by a wave of electrical excitation

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21
Q

cardiac muscle in myogenic, what does this mean?

A

-its rhythmical contractions arise from within the muscle tissue itself

22
Q

what is the first stage of the coordination of the heart ?

A

-the SAN also known as the sinoatrial node send out a wave of electrical activity over the right atria causing atrial systole
-this electrical activity travels rapidly causing the atria to contract simultaneously

23
Q

after SAN signal what is the next stage of the coordination of the heart ?

A

-between the atria and the ventricles is layer of non conductive tissue that do not allow the wave of excitation to pass through
-the wave passes through the atrioventricular node AV node that conducts very slowly
-this causes ventricular systole to begin after atrial systole is complete and the ventricles are filled with blood

24
Q

what happens after the wave of excitation reaches the AV node ?

A

-the electrical activity passes down the septum of the ventricles in the bundle of his to the apex of the ventricles
-the simulation then spreads to the purkinje fibres which are found in the walls of the ventricles this causes the ventricle walls to contract forcing blood up through the arteries

25
Q

the sinoatrial node is under the control of what and why is this important?

A

-the nervous system
-this means that the heartbeat can be increased or decreased in time of need through external nervous system control
-despite this the heart is still myogenic

26
Q

what is the the difference between the cardiac cycle and the coordination of the cardiac cycle?

A

-the cardiac cycle is associated with pressure changes causing the opening and closing of valves
-the coordination of the heart involves the electrical stimulation of the heart
-many get these mixed up so read the question carefully

27
Q

what is an ECG?

A

-a graphical representation of the electrical activity of the heart

28
Q

look at the ECG diagram and learn the points

A
29
Q

why are ECG machines used?

A

to allow doctors to identify irregularities in the heartbeat

30
Q

blood is the term used to describe what?

A

-used to describe a suspension of red and white blood cells in a pale yellow fluid known as the plasma

31
Q

what are the two roles of the blood?

A

-defence and transport

32
Q

what is another name for RBCs?

A

-erythrocytes

33
Q

what are the 4 main components of the blood?

A

-platelets
-erythrocytes
-plasma
-white blood cells

34
Q

what are platelets and what are their job?

A

-cell fragments which are involved in the blood clotting process and they also repair minor breaks in the blood vessels

35
Q

what is the job of the plasma ?

A

-transport of CO2, amino acids, oxygen, ions, blood cells etc.

36
Q

what are 5 ways that erythrocytes adapted for their job?

A

-large number per mm3
-small size so haemoglobin is close to cell surface which aids diffusion by creating a small surface area to volume ratio
-small so they can flow easily through capillaries
-biconcave shape increases surface area
-no organelles and contain haemoglobin

37
Q

what are 3 adaptations of white blood cells?

A

-3 types
-have a nucleus
-larger than RBC

38
Q

what are the three types of white blood cells?

A

-polymorphs
-monocytes
-lymphocytes

39
Q

what are polymorphs, what do they look like and what is their job?

A

-most common (70% of all WBC)
-multilobed nucleus and granular cytoplasm
-they pass through squamous endothelium capillary cells to destroy foreign bodies by phagocytosis at areas of infection

40
Q

what are monocytes, what do they look like and what are their job?

A

-largest but least common WBC (5%)
-bean shaped nucleus
-they move out of the blood at sites of infection and develop into phagocytic macrophage cells which destroy foreign bodies
-live longer than polymorphs

41
Q

what are lymphocytes, what do they look like and what is their job?

A

-20-25% of all WBC
-very large nucleus
-small amount of cytoplasm
-produce 2 types of cells= B-cells which are involved in antibody production and T-cells which are involved in (cell immunity) and destroying foreign bacteria

42
Q

what is tissue fluid?

A

-the fluid that lies immediately outside the capillaries and surround the cells of the tissues

43
Q

what are 2 functions of tissue fluid?

A

-the osmoregulation of cells
-transport of substances in e.g. oxygen and amino acids into the tissues and substances out e.g. carbon dioxide to diffuse back into the blood capillaries

44
Q

what does the term ultrafiltration describe in terms of capillaries and tissue fluid?

A

-blood vessels narrow and a hydrostatic pressure is created which forces liquid and small molecules out of the capillaries

45
Q

what two components cannot be filtered out of the capillaries during ultrafiltration?

A

-plasma proteins and RBCs

46
Q

what are the two forces that oppose hydrostatic pressure ?

A

-lower water potential in the blood due to the presence of plasma proteins (hydrophilic) which pulls tissue fluid back by osmosis
-hydrostatic pressure of the tissue fluid opposing the inward flow of liquid from the capillaries

47
Q

what happens to hydrostatic pressure at the end of arterioles?

A

-the hydrostatic pressure exceeds both of the opposing forces(lower water potential and the hydrostatic pressure of the tissue fluid) and the liquid is filtered out of the blood

48
Q

how does the tissue fluid get back into the capillaries ?

A

-the returning fluid transports carbon dioxide and other waste products to the capillary
-loss of fluid from the capillary results in a reduction of hydrostatic pressure in the blood and so the hydrostatic pressure of the tissue fluid is greater than the blood
-this causes the tissue fluid to return to the capillary this is also aided by the difference in water potential

49
Q

why is blood clotting necessary?

A

-reduces blood loss during injury and it repairs and seals wound to prevent the entry of pathogens

50
Q

what are the steps involved in blood clotting?

A

-damage to tissues/vessels
-plate lets activated which includes thromboplastin
-this then catalyses
-prothrombin which is a plasma protein is converted to thrombin
-this catalyses again
-fibrinogen is converted to fibrin which is a mesh that is used to trap blood cells to form a clot

51
Q

what is haemophilia?

A

-prevents blood from clotting due to part of the cascade missing

biology unit 2 (16 decks)

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