Anatomy and physiology Flashcards
How does blood flow through the right side of the heart?
(deoxygenated blood)
Vena cava / Right atrium / Tricuspid valve / Right ventricle / Pulmonary artery
How does blood flow through the left side of the heart?
(oxygenated blood)
Pulmonary vein / Left atrium / Bicuspid valve / Left ventricle / Semi lunar valve / Aorta
What side of the heart is larger and has thicker walls?
Left side as blood travels a further distance so has to be pumped with more force.
What are the heart’s main 3 roles?
- Deliver oxygen to working muscles
- Remove waste products
- Transports heat to the surface of the skin
What is the cardiac conduction system?
A group of specialised cells located in the wall of the heart which send electrical impulses to the cardiac muscle, causing it to contract.
How does current flow in the cardiac conduction system?
SAN / AVN / Bundle of His / Purkinje fibres /
What is the location and role of the SAN?
Located in the walls of atria
The heart’s pacemaker, creates wave of excitation.
What is the location and role of the AVN?
Located in the atrioventricular septum
Delays impulse for 0.1 seconds so atria can contract fully before ventricular systole.
What is the location and role of the Bundle of His?
Located in septum
Transmits electrical impulses through branches
What is the location and role of the Purkinje fibres?
Network of muscle fibres spread throughout ventricles
Cause ventricular systole.
State the 3 components of the nervous system:
- Central nervous system
- Peripheral nervous system
- Autonomic nervous system
What is the role of the autonomic nervous system?
Subconsciously alters timings of heart.
Sympathetic neurons…
Increase HR
Parasympathetic neurons…
Decrease HR
What is the role of the Medulla oblongata?
Regulates several basic functions of the autonomic nervous system.
Cardiac control centre in the medulla oblongata controls sympathetic and parasympathetic systems.
Where are baroreceptors located and what do they detect?
Located in arterial walls of heart.
Detect change in blood pressure.
If blood pressure is too high…
- Baroreceptors detect artery wall is stretched, impulse is sent to medulla oblongata, impulse is sent down parasympathetic neurones to SAN, HR decreases, BP decreases
Where are chemoreceptors located and what do they detect?
Located in the blood
Detect changes in blood pH
If CO₂ concentration is too high…
Chemoreceptors detect increase in blood acidity, impulse sent to medulla oblongata, impulse is sent to SAN down sympathetic neurones, HR increases, CO₂ concentration decreases
Where are proprioceptors located and what do they detect?
Located in skin, muscle spindles, and tendons.
Detect changes in movement in limbs, muscles and joints.
If movement increases…
Proprioceptors detect increase in movement, impulse sent to medulla oblongata, impulse sent to SAN down sympathetic neurones, HR increases, Cardiac output increases and more oxygen is delivered to working muscles.
What is adrenaline and what is it’s role?
A stress hormone
Increases arousal and causes an anticipatory rise in heart rate.
How does adrenaline work?
- Adrenaline is released by adrenal glands in time of stress, adrenaline stimulates the SAN, mimicking the sympathetic nervous system
What is stroke volume?
The volume of blood pumped out by the heart ventricles per contraction.
What is the average resting stroke volume?
70ml
What 3 things affect stroke volume?
- Venous return
- Elasticity of cardiac fibres during diastole phase.
- Contractility of cardiac tissue.
What is venous return?
The volume of blood that returns to the heart after each contraction.
What is ejection fraction?
The percentage of blood that is pumped out by the left ventricle per beat.
What is the average resting and working ejection fraction?
Resting = 60%
Working = 85%
What is cardiac output?
The volume of blood pumped out by the heart ventricles per minute.
How does stroke volume change during high intensity exercise?
- Initial increase
- Once athlete is working beyond 40-60% of max intensity, SV plateaus.
- Because high HR = short diastole phase = not enough time for ventricles to fill = lower venous return = less blood pumped out
What does Starling’s law state?
Increased venous return causes greater diastolic filling of the heart, increasing the elasticity of cardiac fibres. This causes a greater force of contraction, increasing ejection fraction and stroke volume.
How to calculate Cardiac output
Q = SV x HR
(Average = 70 x 72 = 5040ml)
What is cardiac hypertrophy?
The thickening of the muscular wall of the heart.
What is bradycardia?
A resting heart rate below 60bpm.
Why is bradycardia common in elite athletes?
Cardiac hypertrophy causes a greater stroke volume.
How does heart rate respond to exercise?
- Anticipatory rise prior exercise
- Sharp, anaerobic rise
- Further rise
- Steady state
- Rapid decline post exercise
- Slower recovery
What is heart disease?
Blockage in - or narrowing of -the the coronary arteries due to a gradual build up of atheroma (fatty deposits).
What is a build up of atheroma called?
Atherosclerosis
What is atherosclerosis caused by? (4)
- High BP
- High cholesterol
- Lack of exercise
- Smoking
What is angina?
Chest pain caused by the narrowing of the coronary arteries as the heart receives a lack of oxygen.
When do heart attacks occur?
When a piece of atheroma breaks off in the artery, causing a blood clot that blocks off the supply of oxygenated blood to the heart.
What is blood pressure?
The force exerted by the blood against the blood vessel wall.
How do you calculate blood pressure?
BP = blood flow x resistance
Impacts of high blood pressure
Excess strain on the arteries can increase the risk of heart attacks, heart failure, kidney disease, strokes, and dementia.
What is LDL cholesterol?
Low density lipoproteins - transport cholesterol in the blood to tissues. Bad as they cause arteries to narrow.
What is HDL cholesterol?
High density lipoproteins - transport excess cholesterol in the blood back to liver to be broken down. Good as they remove LDL from arteries.
When do strokes occur?
When blood supply to the brain is cut off, damaging the brain cells.
What are ischemic strokes?
Caused by a blood clot blocking flow of blood to brain (most common)
What are haemorragic strokes?
Caused when a blood vessel that supplies the brain bursts.
What is cardiovascular drift?
An increase in heart rate during prolonged exercise. Happens because fluid is lost as sweat, causing plasma volume and therefore stroke volume to decrease.
This causes venous return to decrease and cardiac output to increase as more energy is needed to cool the body.
How does blood move through the vascular system from and to the heart?
Heart - arteries - arterioles - capillaries - venules - veins - heart.
What is the pulmonary cycle?
Flow of deoxygenated blood from the heart to the lungs and oxygenated blood from the lungs back to the heart.