Cardiac systems at rest and exercise

Question 1

define pulmonary circuit

Answer 1

the circulation of blood through pulmonary artery to the lungs and pulmonary vein back to the heart

Question 2

define systemic circuit

Answer 2

the circulation of blood through the aorta to the body and vena cava back to the heart

Question 3

Definition of stroke volume

Answer 3

The volume of blood leaving the left ventricle per contraction

Question 4

cardiac output definition and equation

Answer 4

The volume of blood leaving the left ventricle per minute.
Cardiac output = stroke volume x heart rate

Question 5

values of CO = SV x HR at rest

Answer 5

5 l/min = 70ml/min x 70 bpm

Question 6

values of CO = SV x HR at sub max exercise

Answer 6

15 l/min = 100ml x 150 bpm

Question 7

values of CO = SV x HR at max exercise

Answer 7

28 l/min = 140ml x 200 bpm

Question 8

Explain order of the conduction system (electrical impulse) of the heart

Answer 8

1. SA node releases electrical impulse, which
   causes both atria to contract
2. Impulse passes to AV node, which delays the
   impulse until the atria finish contracting,
   then
3. Impulse passes down Bundle of His
4. Impulse passes onto Purkinje fibres, which
   causes ventricles to contract

Question 9

what is the cardiac cycle?

Answer 9

the cardiac cycle describes the movement of blood through the heart
at rest one complete cycle lasts 0.8 - 1 s and is repeated 60 times per minute

Question 10

describe diastole

Answer 10

lasts 0.5 s
the relaxation phase
the heart fills with blood

Question 11

describe systole

Answer 11

lasts 0.3s
the contraction phase
contraction of atria/ventricles
blood ejected

Question 12

describe the stage1 of the cardiac cycle: diastole

Answer 12

the heart is relaxed, both atria fill with blood
atrial blood pressure rises which causes AV valves to open
blood moves passively from the atria into the ventricles

Question 13

describe stage 2 of the cardiac cycle: atrial systole

Answer 13

both atria contract, forcing the remaining blood into the atria to move actively into the ventricles

Question 14

describe stage 3 of the cardiac cycle: ventricular systole

Answer 14

Ventricular blood pressure rises, which forces SL valves to open
Both ventricles contract, forcing blood out of the ventricles (called stroke volume)
Only 50% of the blood in the ventricles is ejected at rest.

Question 15

what is the relationship between heart rate, stroke volume and cardiac output ?

Answer 15

Q = SV x HR
Cardiac Output = Stroke Volume x Heart Rate

Question 16

HR is controlled by the autonomic nervous system, which
has 2 parts:

Answer 16

The sympathetic nervous system which is stimulated when the body is energised / when HR increases
The parasympathetic nervous system which is stimulated when the body is relaxed / when HR decreases

Question 17

proprioceptors

Answer 17

a neural control in muscles and joints that detect increased movement during exercise

Question 18

chemoreceptors

Answer 18

a neural control in the brain and blood vessels that detect change in lactic acid and CO2 levels

Question 19

baroreceptors

Answer 19

a neural control that detect change in blood pressure

Question 20

adrenaline

Answer 20

a hormonal control that

Question 21

Explain the neural control of heart rate during exercise.

Answer 21

Proprioceptors detect increased movement during
exercise
chemoreceptors detect increased lactic acid
and CO2
baroreceptors detect an increase in BP of the
blood vessels
The receptors send this information to
the CCC which increases sympathetic nerve activity, via
the accelerator nerve, to the SA node
The number of impulses from the SA node is increased, and therefore HR increases.