HEART STRUCTURE AND REGUALTION OF HR

Question 1

Describe the flow of blood through the heart

Answer 1

Deoxygenated blood return through the inferior (from lower body) and superior (from above heart) vena cava then into the right atrium.
Then through a tricuspid valve 8th the right ventricle
Moved through a semilunar valve to the pulmonary artery transporting blood to the lungs to be oxygenated.
It then returns to the heart via the pulmonary vein into the left atrium. Through a bicuspid valve and into the left ventricle.
Through a atrioventricular Vance to the aorta when’re oxygenated blood is transported around the body before returning to the vena cava

Question 2

Name the 3 layers of the heart and their main function

Answer 2

Epicardium - Protective outer layer
Myocardium - muscular middle layer (layer that can undergo hypertrophy)
Endocardium - thin inner layer

Question 3

What is the muscle in the heart

Answer 3

Cardiac muscle

Question 4

What is the definition of maximal exercise

Answer 4

Physical activity performed at the highest intensity a individual can achieve
98% + intensity

Question 5

What are the characteristics of maximal exercise

Answer 5

98% + performers maximum effort and HR
Short duration
E.g. sprinting, HITT, strength training
Enhances max strength, speed, power
Improves anaerobic capacity and metabolic rate

Question 6

What is the definition for sub maximal exercise

Answer 6

Physical activity performed at below maximum intensity - doesn’t push the body to its absolute limit
60% intensity
The heart can keep up with the demand for O2

Question 7

What are the characteristics of sub maximal exercise

Answer 7

60-80% of maximum effort and HR
Longer duration
E.g. jogging, brisk walking
Improves cardiovascular health, endurance and overall fitness without placing too mush stress on the body

Question 8

What are the main components of the cardiovascular system

Answer 8

Heart
Blood vessels
Blood

Question 9

What is the main function of the cardiovascular system

Answer 9

To deliver oxygen and nutrients and excrete waste products from all cells of the body as well as regulating body temperature

Question 10

Why is the heart described as a dual action pump

Answer 10

It has 2 circuits, the pulmonary and systemic

Question 11

What is the pulmonary circuit

Answer 11

Carries deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart
Includes the pulmonary artery and vein

Question 12

What is the systemic circuit

Answer 12

Carries oxygenated blood to the body tissues and deoxygenated blood back to the heart
Includes the aorta and S/I vena cava

Question 13

Example exam question:
Describe how the heart works as a dual action pump when circulating blood during exercise. (6)

Answer 13

Thee heart is a dual action pump because it has 2 circuits, the pulmonary and systemic?
The pulmonary circuit carries deoxygenated blood from the heart to the lungs and back. The oxygen poor blood travels through the S/I vena cava, right atrium, tricuspid valve, right ventricle, semilunar valve, pulmonary artery, lungs, pulmonary vein, left ventricle.
The systemic circuit carries oxygen rich blood from the heart to the body tissues and back. It travels through the left atrium, bicuspid valve, into the left ventricle through the atrioventricular valve into the aorta to the body tissues returning to the vena cava.

Question 14

Explain how the conduction system works

Answer 14

The heart is myogenic, meaning it generates its own beat via the natural pacemaker, the sinoatrial node. The SA node (in the RV) generates an electrical signal which travels to the LV and atrioventricular node and signals the walls of the atrium to contract, forcing blood into the ventricles. The AV node delays the signal slightly allowing the ventricles to fill with more blood. The electrical signal then travels down the bundle of His (in the sternum) to the purkyne fibres, spreading up through the ventricles causing them to contract forcing blood blood out of the heart.

Question 15

What are the 2 phases of the cardiac cycle and what do they mean

Answer 15

Systolic phase - contraction
Diastolic phase - relaxation

Question 16

What is Heart rate

Answer 16

The number of times the heart beats per minute
Measured in BPM

Question 17

What is the difference between tachycardia and bradycardia

Answer 17

Tachycardia is the unusually fats beating of the heart
Bradycardia is the slow beating of the heart, below 60 bpm

Question 18

What is stroke volume

Answer 18

The volume of blood pumped out of the left ventricle ** per contraction **

Question 19

How to calculate stroke volume

Answer 19

End diastolic volume - end systolic volume

Question 20

What determines stroke volume

Answer 20

Venous return (vol of blood returning to the heart), the more blood that returns, the more that can be pumped out.
Starlings law - the higher the venous return the more the ventricles can fill. The more filling, the greater stretch on the cardiac muscles. This creates a greater force of contraction, pushing more blood out of the heart, increasing SV.
(Elasticity of cardiac fibres)
+ the 5 mechanisms of venous return

Question 21

list and explain the 5 mechanisms of venous return

Answer 21

pocket valves - prevent backflow and keep blood flowing in 1 direction
skeletal muscle pump - veins in between skeletal muscles are squeezed/compressed to open valves to get blood back to the heart (often used in a cool down)
respiratory pump - breathing depth increases, so pressure in the thoracic cavity increases, bringing more blood back to the heart
smooth muscle - thin layer of smooth muscle helps to squeeze blood back to the heart (due to vasodilation and vasoconstriction)
gravity - blood from the upper body is helped back to the heart by gravity.

Question 22

how is it calculated

Answer 22

Q (cardiac output) = SV X HR

Question 22

define cardiac output

Answer 22

the volume of blood pumped out of the left ventricle per minute
measured in ml/min or L/min

Question 23

explain why an untrained and trained performer will have similar resting cardiac output

Answer 23

the trained will have a higher SV but lower HR and the untrained will have a lower SV but a higher HR

Question 24

explain the HR response in maximal exercise

Answer 24

anticipatory rise - due to adrenaline secreted by adrenal gland, stimulating SA node
sharp rise as exercise starts - due the the higher demand for oxygen - exercise starts anaerobically.
HR continues to rise as exercise is MAXIMAL (90-100%)
rapid decline after exercise - demand for O2 isn’t as high
gradual recovery as body systems return to resting state (HR remains slightly elevated to remove waste products during exercise.

Question 25

explain the HR response in sub-maximal exercise

Answer 25

anticipatory rise - due to adrenaline secreted by adrenal gland, stimulating SA node
sharp rise as exercise starts - due the the higher demand for oxygen - exercise starts anaerobically.
steady state exercise as the athletes heart is able to meet the demand for oxygenated blood at the working muscles
rapid decline after exercise - demand for O2 isn’t as high
gradual recovery as body systems return to resting state (HR remains slightly elevated to remove waste products during exercise.

Question 26

what are the HR responses to exercise

Answer 26

HR increases directly proportionally to exercise intensity

Question 27

what are the SV changes during exercise

Answer 27

as intensity increases SV increases until 60%
it then decreases due to the increase in HR
this means that there is a shorter diastolic (filling) phase of the heart so there is less stretch on cardiac muscles, therefore a lower force of contraction - decreasing SV

Question 28

what are the changes in cardiac output

Answer 28

long term training - cardiac muscles under go cardiac hypertrophy (getting bigger) this means that they can pump more blood, more forcefully out of the left ventricle per beat - so more blood per minute.
overtime SV will increase and HR will decrease so Q will remain the same
during exercise - HR increases, SV increases so cardiac output increases

Question 29

summarise the Cardiac Control Centre

Answer 29

found in the medulla oblongata
part of the Autonomic Nervous System
2 sub divisions - sympathetic and parasympathetic

Question 30

what nerves are associated with each ANS division and what do they do

Answer 30

sympathetic - accelerator nerve - speeds up HR
parasympathetic - vagus nerve - slows down HR

Question 31

what are the 3 ways that the CCC can control HR

Answer 31

Neural control
hormonal control
intrinsic control

Question 32

what is neural control

Answer 32

receptors detecting changes in the body due to physical activity. they send signals the the the SA node to either speed up or slow down HR

Question 33

name the receptors and what they do

Answer 33

proprio receptors - pick up movements in joints and muscles
e.g. muscle spindle detects changes in muscle length and Golgi tendon organ detects changes in muscle tension
chemo receptors - pick up chemical changes e.g. blood pH or depleting O2 levels/increasing CO2 levels
baro receptors - pick up changes in blood pressure due to increased exercise intensity
thermo receptors - pick up changes in muscle and blood temperature due to increased exercise intensity

Question 34

explain hormonal control

Answer 34

before and during exercise adrenaline and noradrenaline are secreted from the adrenal gland. they stimulate SA node to increase HR and SV - explaining the anticipatory rise in HR. they also help with he redistribution of blood during exercise. and when intensity drops and recovery starts, acetylcholine takes over.

Question 35

explain intrinsic control

Answer 35

this is the heart controlling itself it depends on temperature - if the temperature of the cardiac muscles increases then impulse speed increases.
and starlings law of the heart - venous return increases so does SV

Question 36

which are external control mechanisms and which are internal control mechanisms

Answer 36

neural and hormonal are external
intrinsic is internal

Question 37

explain the neural regulation of HR

Answer 37

the receptors detect their respective changes and send them to the ccc. it sends a message to either the SNS or PNS, depending on the changes. the SNS will make the accelerator nerve stimulate the SA node increase HR. the PNS will make the vagus nerve stimulate the SA node to slow down HR.

Question 38

explain the hormonal control of HR

Answer 38

adrenaline secreted from the adrenal gland, stimulates the SNS in the CCC. the accelerator nerve then increases HR and force of contraction
acetylcholine is secreted from the T-Lymphocytes in high amounts to the PNS. the vagus nerve then stimulates the SA node to decrease HR and force of contraction

Question 39

explain intrinsic control

Answer 39

venous return increases - more blood back to the right atrium - greater stretch on the cardiac muscles - greater force of contraction - SV increases. due to the greater stretch, SA node is stimulates to increase HR
temperature increases - increased nerve transmission - more stimulation of the SA node - HR increases
heart also becomes warmer - increases HR and cardiac muscles ability to stretch whilst filling, so a greater force of contraction