The Human Heart

Question 1

The Cardiac Cycle 1/5

Answer 1

Cardiac muscle is relaxed (distole) the blood drains into the LA from the lungs along the PV

Question 2

The Cardiac Cycle 2/5

Answer 2

Raising of the blood pressure in the LA forces the left AV valve to open

Question 3

The Cardiac Cycle 3/5

Answer 3

Contraction (left atrial systole) of the left atrial muscle forces more blood through the valve

Question 4

The Cardiac Cycle 4/5

Answer 4

As soon as the left atriole systole is over the left ventricular muscles start to contract (left ventricular systole)

Question 5

The Cardiac Cycle 5/5

Answer 5

this forces the left AV valve closed and open the SL in the mouth of the aorta. Blood then leaves the LV along the aorta

Question 6

What are the purkyne fibres

Answer 6

special muscle fibres that don’t contract but conduct electrical impulses

Question 7

What are purkyne fibres responsible for

Answer 7

carrying the impulses from the atria to the ventricles

Question 8

What is the vagus nerve

Answer 8

Decreases heart rate

Question 9

What is the sympathetic cardiac nerves

Answer 9

Increase heart rate and force contraction

Question 10

What does a ECG measure

Answer 10

measures the electrical activity of the heart

Question 11

What does the P wave

Answer 11

Caused by the depolarisation of the atria, which results in atrial contraction (systole)

Question 12

What does QRS wave measure

Answer 12

Caused by the depolarisation of the ventricles, which results in ventricular contraction

This is the largest wave because the ventricles have the largest muscle mass

Question 13

What does the T wave

Answer 13

Caused by the repolarisation of the ventricles, which results in ventricular relaxation (diastole)

Question 14

What is the cardiac output equation

Answer 14

Cardiac O = stoke volume x Heart rate

Question 15

What does the cardiac output equation measure

Answer 15

Volume of the blood pumped out of the heart in 1 min

Question 16

What is Tachycardia

Answer 16

When the heart beats too fast it is tachycardic

Question 17

Explain the difference the thickness of the wall of the right atrium and the wall of the right ventricle

Answer 17

the the right ventricle has mare cardiac muscle to deal with the volume and pressure of the blood

the right atrium pumps blood to the right ventricle

the right ventricle pumps blood to the lungs

Question 18

Explain why a blood clot in an artery leading to the brain could cause a stroke

Answer 18

reduced blood flow which resulst in less oxygen reaching the brain

reulsting in no areboic respiration= no atp which produces lactic acid

Question 19

Bradycardia

Answer 19

When the heart beats too slow it is bradycardic

Question 20

Ectopic heartbeat

Answer 20

This condition is caused by an early heartbeat followed by a pause

Question 21

When do valves open

Answer 21

when the pressure is greater BEHIND them

Question 22

When do valves close?

Answer 22

When the pressure is greater in FRONT

Remember valves stop the backflow of blood

Question 23

Why do the AV valves open?

Answer 23

if you have a higher pressure in the atria compared to the ventricles that’ll cause the AV open

Question 24

Why do the AV vavles close?

Answer 24

If you have higher pressure in the ventricles compared to the atrria

Question 25

Why do the SLV open

Answer 25

when the pressure in the ventricles is much higher than the aorta

Question 26

Why do the SLV close

Answer 26

when the pressure is higher in the arteris (aorta) compared to in the ventricles

Question 27

Explain how a blood clot can cause a heart attack

Answer 27

. prevents oxygen reaching the heart cells

• This prevetns areboic respiration
• (cardiac) muscle { unable to contract / dies

Question 28

Explain what is meant by the term myogenic

Answer 28

idea that stimulation generated from within (muscle)

idea that this results in depolarisation

Question 29

Explain how an electrocardiogram (ECG) can be used to calculate a person’s heart rate

Answer 29

it shows electrical activity of the heart
-Identify one heart beat
-count the number of { these / peaks / eq } in a {set time /
stated time}
=obtain heart rate e.g. beats divided by
time ;

Question 30

describe the pressure changes that take place

in the left ventricle during each stage of this cardiac cycle

Answer 30

-Pressure increases during atrial styole and ventricukar dystole
-Pressures increases during ventricular systole
and then pressure decrease

Question 31

During this cardiac cycle, the changes in pressure that occur in the left atrium and
in the left ventricle are different.

Answer 31

pressure changes are smaller in the atrium than ventricle

• The atrium has less cardiac muscle than the ventricle
• The atrium does not have to push the blood as far as the ventricle has to
• the increase in pressure happens inthe atrium before the ventricle