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A Level Biology > 8.5 - The Heart > Flashcards

8.5 - The Heart Flashcards

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1
Q

What muscle is the heart made from ?

A

Cardiac

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2
Q

What side does deoxygenated blood flow into ?

A

Right side

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3
Q

Where does the deoxygenated blood get pumped too ?

A

The lungs

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4
Q

Where does the oxygenated blood pump too?

A

To the body

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5
Q

What type of membranes surround the heart ?

A

Inelastic pericardial membranes

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6
Q

What do the the inelastic pericardial membranes help with ?

A

Help prevent the heart from over-distending with blood

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7
Q

What are the right atrio-ventricular valves called?

A

Tricuspid valve

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8
Q

What are the left atrioventricular valves called ?

A

Bicuspid valve

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9
Q

What are examples of closed systems?

A

Fish and mammal

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10
Q

What is a open system ?

A

Blood isn’t enclosed within blood vessels so it floats freely within the body cavity in the haemocoel

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11
Q

What has a open circulatory system ?

A

Insects

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12
Q

What is a closed system?

A

Enclosed within blood vessels

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13
Q

Explain the flow of deoxygenated blood

A

- enters the right atrium
- from the upper body and head in the superior vena cava
- from the lower body in the inferior vena cava —> at relatively low pressure

  • atria have thin walls
  • as blood flows in - slight pressure builds up until the atria-ventricular valve ( tricuspid Valve ) opens to let blood pass into the right ventricle
  • when both atrium and ventricle are filled with blood = atrium contracts - forcing all the blood into the right ventricle = stretching the ventricle walls
  • as the right ventricle contract = tricuspid valve closes - preventing any back flow of blood to the atrium
  • Tendinous cords = make sure the valves are not turned inside out by the pressures exerted when the ventricle contracts
  • right ventricle contacts fully and pumps deoxygenated blood through the semilunar valves into the pulmonary artery —> transports it to the capillary beds of the lungs
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14
Q

Explain the flow of oxygenated blood in the heart ?

A
  • enters the left atrium from the pulmonary vein
  • pressure in the atrium builds = biscuspid valve opens between the left atrium and left ventricle
  • ventricle fills with oxygenated blood
  • when both the atrium and ventricle are full the atrium contracts - forcing all the oxygenated blood into the left ventricle
  • left ventricle contracts + pumps oxygenated blood through semilunar valves into the AORTA and around the body
  • as the ventricle contracts - the tricuspid valve closes = preventing any back flow of blood
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15
Q

What is the inner dividing of the wall called ?

A

The septum

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16
Q

What is the role of the septum ?

A

Prevents the mixing of deoxygenated and oxygenated blood

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17
Q

What side of the heart has a thicker muscular wall and why ?

A

Left side

  • lungs are relatively close to the heart
  • lungs are also much smaller than the rest of the body
  • right hand side of the heart has to pump the blood a relatively short distance and only has to overcome the resistance of the pulmonary circulation
  • left side has to produce sufficient force to overcome the resistance of the aorta and the arterial systems of the whole body + move the blood under pressure to all the extremities of the body
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18
Q

What does the cardiac cycle describe ?

A

The events in a single heartbeat

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19
Q

Define diastole

A

in diastole the heart relaxes

  • atria and then ventricles fill with blood
  • the volume and pressure of the blood in the heart build as the heart fills
  • but the pressure In the arteries is at a minimum
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20
Q

Define systole

A
  • in systole the atria contract —> atrial systole followed by ventricular systole
  • pressure inside the heart increases dramatically
  • blood is forced out of the right hand side of the heart to the lungs and from the left side to the main body circulation
  • the volume and pressure of the blood in the heart are LOW at the END of systole
  • blood pressure in the arteries is at a maximum
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21
Q

Describe what happens when aortic pressure rises

A
  • rises when ventricles contract as blood is forced into the aorta
  • gradually forces but never below around 12 kPa because of the elasticity of its wall
    = creates a recoil action
  • this is essential if blood is to be constantly delivered to the tissues
  • the recoil produces a temporary rise In pressure at the start of the relaxation phase
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22
Q

Why is atrial pressure always relatively low ?

A
  • due to the thin walls of the atrium - cannot create much force
  • it is highest when they are contracting but drops when the bicuspid valve closes and it’s walls relax
  • atria fill with blood —> leads to gradual build up of pressure until a slight drop when the bicuspid valve opens and some blood moves into the ventricle
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23
Q

Why is ventricular pressure low at first ?

A
  • low at first but gradually increases as the ventricles fill with blood as the atria contract
  • bicuspid valves close and pressure rises dramatically as the thick muscular walls of the ventricle contract
  • as pressure rises above that of the aorta blood is forced into the aorta past the semilunar valves
  • pressure falls as the ventricles empty and the walls relax
24
Q

What happens when ventricular volume rises ?

A
  • ventricular volume rises when the atria contract and the ventricles fill with blood and then drops suddenly as blood is forced out into the aorta when the semilunar valve opens
  • volume increases again as the ventricles fill with blood
25
Q

Describe what happens during ventricular systole ?

A
  • ventricles contract
  • pressure increases - closing the atrioventricular valves to prevent back flow and opening the semilunar valves
  • blood flows into the arteries
26
Q

Define myogenic

A

The hearts contraction is initiated from within the muscles itself rather than by nerve Impulses

27
Q

What is the average resting heart rate of an adult ?

A

Around 70 bpm

28
Q

What is the basic rhythm of the heart maintained by ?

A

A wave of electrical excitation

29
Q

Explain the process of a wave of electrical excitation

A
  • begins in the pacemaker area called the SINO-ATRIAL NODE ( SAN )
  • causes the atria to contract and so initiating the heartbeat
  • electrical activity from the SAN is picked up by the ATRIO-VENTRICULAR NODE ( AVN )
  • AVN imposes a slight delay before stimulating the bundle of HIS - bundle of conducting tissue made up of PURKYNE FIBRES - which penetrate through the septum between the ventricles
  • bundle of his splits into 2 branches and conducts the wave of excitation to the apex of the heart
  • at the apex purkyne fibres spread out through the walls of the ventricles on both sides
  • the spread of excitation triggers the contraction of the ventricles starting at the apex
  • contraction starting at the apex allow more efficient emptying of the ventricles
30
Q

What prevents the excitation passing directly to the ventricles ?

A

A layer of non - conducting tissue

31
Q

What is an electrocardiogram ?

A
  • way of measuring the spread of electrical excitation through the heart as a way of recording what happens as it contracts
  • recording of the electrical activity of the heart is called an electrodiogram ( ECG )
32
Q

What does an ECG precisely measure ?

A

measures tiny electrical differences in your skin which result from the electrical activity of the heart

33
Q

How does a ECG measure these tiny electrical differences ?

A
  • electrodes are stuck painlessly to clean skin = to get good contacts needed for the reliable results
  • signal from each of the electrodes is fed into the machine = produces a ECG
34
Q

What do ECG help diagnose ?

A

Heart problems

35
Q

What is tachycardia ?

A
  • heartbeat is rapid - over 100 bpm
  • often normal for eg. When you exercise, have a fever or angry
  • if abnormal = caused by problems in the electrical control of the heart and may need to be treated by medication or surgery
36
Q

Define Bradycardia

A
  • heart rate slows down to below 60 bpm
  • training makes the heart beat more slowly and efficiently
  • severe bradycardia can be serious and may need an artificial pacemaker to keep the heart beating steadily
37
Q

Define ectopic heartbeat

A
  • extra heartbeats that are out of the normal rhythm
  • most people have one a day
  • usually normal but they can be linked to serious conditions
38
Q

Define atrial fibrillation

A
  • example of an arrhythmia
  • means an abnormal rhythm of the heart
  • rapid electrical impulses are generated in the atria
  • they contract very fast ( fibrillate ) up to 400 times a minute
    - don’t contract properly and only some of the impulses are passed on to the ventricles which contract much less often
  • as a result the heart does not pump blood very effectively
39
Q

What is a bundle of His ?

A

Group of muscle tissue goes from here to purkyne fibres

40
Q

What is a p wave ?

A

Contraction , depolarisation of the aria

41
Q

What is the QRS complex ?

A

Contraction depolarisation of ventricle

42
Q

What is the T wave ?

A

Relaxation , repolarise of ventricle

43
Q

What is stroke volume ?

A

Volume of blood pumped during each heartbeat

44
Q

How do you calculate cardiac output ?

A

Cardiac output = heart rate x stroke volume

45
Q

Explain why healthy coronary arteries are important for maintaining a regular heart rhythm ?

A
  • heart cardiac muscles needs good supply of oxygen and glucose to contract with a regular rhythm
  • coronary arteries supply blood carrying glucose and oxygen to the heart
  • healthy coronary arteries provide a good supply of blood to the heart muscle so it can continue to beat
46
Q

What causes the heart sounds ?

A

First heart sound = blood hitting against atrioventricular valves
Second heart sound = sound of semilunar valves as they close to prevent a back flow of blood

47
Q

Explain the relationship between the heart sounds and the events of the cardiac cycle ?

A
  • pressure difference between atria and ventricles as atria empty and ventricles start to contract means blood is forced against the atrioventricular valve which close to prevent back flow of blood into the atria
  • pressure difference between blood in the artery and ventricles as they empty means blood hits semilunar valves which are closed to prevent back flow of blood into heart
48
Q

Explain the following statement - Bradycardia is common in diving mammals such as whales and seals

A
  • bradycardia is the slowing of the heart
  • when animals dine they need to conserve their energy and food to last for the whole dive
  • they undergo bradycardia as part of slowing down metabolism to enable them to stay under water as long as possible
49
Q

Evaluate the following statement - many people experience Tachycardia when they travel to high altitudes

A
  • trachycardia is the speeding up of the heart
  • at altitude there is less oxygen available in air
  • this means there is less oxygen available in the blood
  • heart speeds up to compensate and carry more oxygen to tissues even if it isn’t effective because of low oxygen atmosphere
50
Q

What are bundle of His ?

A

Conducting tissue composed of purkyne fibres that passes through the septum of the heart

51
Q

What is meant by the term myogenic ?

A

A muscle which has its own intrinsic rhythm

52
Q

What is non conducting tissue ?

A

Prevent the excitation from spreading to the ventricles and so ensures that the atria and ventricles don’t contract at the same time

53
Q

What is the Lub-dub sound ?

A

The sounds of the heartbeat due to heart valves closing

54
Q

Where does the Lub sound occur ?

A

The beginning of ventricular systole

55
Q

What is happening when the Lub sound is heard ?

A

Atrio- ventricular valves are closing and blood is leaving the ventricles

56
Q

Why does diastole follow systole in a mammalian heart ?

A

Cardiac muscle takes a short time to repolarise after being stimulated

A Level Biology (54 decks)

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