Topic 1 – Applied Anatomy + Physiology: 3.1.1.2 - Cardiovascular System
CHD: the blockage of the coronary
Health: the complete Health Fitness arteries caused by fatty build up
state pf mental, physical, ↓ Blood pressure ↑ Gaseous Exchange
↓ Risk of coronary heart disease ↑ Lung volume
and social wellbeing ↓ Risk of stroke ↑ Oxygen available High BP: a raised force of blood
↓ Plaque accumulation ↑ Cardiac output against the wall of the blood vessel
Fitness: the ability to ↓ LDL cholesterol ↑ Stroke volume greater than 140/90 mmHG
cope with the demands ↑ HDL cholesterol ↑ Heart efficiency
of the environment ↑ Blood vessel width ↑ Capacity for exercise High levels of low-density
↑ Intensity of exercise lipoprotein can lead to the
Cardiac Control Centre = Medulla Oblongata formation of cholesterol plaques
and restrict the size of the arteries
Cardiac Conduction System: The cardiac muscle/ heart is myogenic so it can
generate its own impulses.
Sinoatrial Node (SA): pacemaker of the heart – produces an electrical stimulus,
resulting in the atria contracting Atrial Systole: impulse causes atria to
contract Atrioventricular Node (AV): enables the ventricles to fill with
blood by delaying the stimulus until after the AV valves shut Bundle of His:
group of conduction cells, which brand into the Purkinje Fibre Purkinje
Fibres: found in the ventricular wall, conduct the electrical impulse from the
bundle of His and cause ventricular contraction Ventricular Contraction
Systole: impulses causes ventricles to contract
Cardiac Output = Heart Rate x Stroke Volume
Cardiac Output: the volume of blood ejected by the heart per minute (ml/min)
Stroke Volume: the volume of blood ejected from the heart per beat (ml)
Trained Athlete: HIGH SV & LOW resting HR
Untrained Athlete: LOW SV & HIGH resting HR
Regulation of Heart Rate:
1) Hormonal
a. Anticipatory Rise: the rise in the HR prior to exercise to onset exercise caused by the release of
adrenaline
2) Neural
a. Vasomotor Centre:
Baroreceptors: detects the change in blood pressure
Chemoreceptors: detects the chemical changed within the blood (blood acidity and pH)
Proprioceptors: detects changes in body movement
b. Cardiac Control Centre in the medulla oblongata (impulses sent via SA node):
Parasympathetic (via vagus nerve): slows down HR
Sympathetic (acceleratory nerve): speeds up HR
3) Intrinsic
a. Higher temperature caused through exercise caused increased HR as heart works harder to get blood to the
skin so heat can be lost as radiation
i. Thermoreceptors: detects changes in temperature
,Venous Return: the amount of blood returning to heart Vascular System: Redistribution of blood
via veins
1) Coronary Vessels:
More blood = Higher SV a. At the heart
b. Allows the heart to beat with more power
1) Skeletal Muscle Pump: veins run between c. Increasing stroke volume
muscles when the muscle contracts it d. Increasing cardiac output
squeezes the blood back to the heart e. Increasing venous return
2) Pocket Valves: one way system - helps prevent 2) Skin:
the backflow of blood a. For temperature regulation
b. Get rid of heat via radiation and cool the
3) Smooth Muscle: at arterioles and veins body down
constriction occurs to aid in the pumping of
blood back to the heart 3) Muscle:
a. For increased oxygen delivery for
4) Respiratory Pump: increased breathing rate respiration
will later change sin pressure in thoracic b. Removal of waste products such as CO2
cavities greater breathing movement, and lactic acid
increase in pressure in thorax, compresses veins
to assist back flow to the heart 4) Away from stomach/ kidney:
a. Considered non-essential systems during
5) Suction pump of the heart: the more blood exercise
pumped out of the heart, so more is forced back b. Vasoconstriction occurs
Vascular System: Blood Pressure 5) The brain
a. The brain function must be maintained
Pulmonary: during exercise
- Deoxygenated blood from the hart to the lung b. oxygen and nutrients required
- Oxygenated blood back to the heart
Systemic: Starlings Law of the heart:
- Oxygenated blood to the body from the heart
- The return of deoxygenated blood to the heart Increase Venous Return = Increase Stroke
Volume
Arteries + Arterioles:
Highest pressure – more elastic outer layer to cope Elasticity of cardiac fibres:
Transport blood away from the heart - Stretched during the diastole phase
- The more blood in the heart, the greater the
Capillaries: stretch, the stronger the contraction
One cell thick – only allows one cell through at any given time
Increase rate of diffusion Contractility of cardiac tissue:
- Myocardium
Veins + Venules: - The greater the contractility of the tissues, the
Veins have valves to prevent the backflow of blood greater the force of contraction
Blood flows through small veins (venules) then into veins that
bring blood back to the heart Increase venous return greater diastolic
filling of the heart cardiac muscle stretched
Blood Pressure: the force exerted by the blood against the blood greater force of contraction increase
vessel wall ejection fraction
Blood Pressure = Blood Flow x Resistance Ejection Fraction: the percentage of blood
pumped out by the left ventricle per beat
Systolic Pressure: contraction of the heart
Diastolic Pressure: relaxation, filling of the heart
, How is blood redistributed?
Vasomotor center controls blood redistribution/ blood flow
The CV center, CCC and respiratory center regulates blood pressure
Sympathetic Nervous Activity:
- Increases in impulses from the medulla via the sympathetic nervous system
- Adrenaline is released
- Impact on the SA node
- Impact blood vessels for vasodilation
- Parasympathetic will cause vasoconstriction
Precapillary Sphincters:
- A band of smooth muscle that adjusts blood flow into capillaries
Non-essential organs sympathetic pathway increases due to constriction of blood vessels
Working Muscles sympathetic pathway decreases as constriction decreases and parasympathetic increases
Cardiovascular Drift:
CV Drift occurs 10-20mins after exercise
occurs faster in warm environmental conditions
increase in HR and a decrease in stroke volume despite working out at the same intensity
CV drift is caused by a reduction of fluid in the blood/ sweating increases
Blood viscosity increases / increased resistance of blood flow
Venous return decrease / stroke volume decreases / reduced atrial filling
Purpose of CV Drift
1) Aims to cool the body
2) Maintain cardiac output
= To maintain performance and reduce effects of CV drift rehydration is needed (eg: water / electrolytes)
Oxygen dissociation & Bohrs Drift:
During exercise:
CO2 levels increase (by product of aerobic respiration)
O2 level decrease
- Reducing PO2
- Shifting the curve to the right
= An increase in CO2, shift curve to the right, increase O2 delivery at the muscle
Bohrs Shift when the oxyhemoglobin dissociation curve shifts to the right
Causes of Bohr Shift:
1) Occurs because of increased CO2 in the blood
2) Increase in hydrogen ions (Hydrogen ion created when a hydrogen atom loses or gains an electron)
- By product of breaking down glucose
3) Increase temperature
Result of Bohr shift:
= increased unloading of oxygen
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