Physiology and Anatomy (Cardiovascular System) Flashcards
Starling’s Law
1) Increased venous return leads to greater diastolic filling
2) Improves elasticity of cardiac muscle and strengthens contraction of the heart
3) Increases ejection fraction of the heart which increases stroke volume
Cardiovascular Drift
Body warms and sweats during exercise which leads to water from plasma lost as sweat. Therefore it makes blood more viscous, lowering venous return which decreases stroke volume so your body increases heart rate to compensate.
Chemoreceptors
Sensors in your blood vessels that detect concentration of CO2/lactic acid.
Proprioceptors
In your tendons which detect movement.
Baroreceptors
Receptors in the wall of the aorta and arteries that detect changes of blood pressure
Sympathetic Nervous System
Increases heart rate and causes the redistribution of blood to the muscles.
Parasympathetic Nervous System
Decreases heart rate and causes redistribution of blood to internal systems.
How heart rate is increased
1) Receptors detect change
2) Impulse sent to the Medulla Oblongata (Cardiac Control Centre) via the peripheral nervous system and central nervous system
3) CCC decides action and relays to the SAN to control heart beat
Role of Adrenaline
Before a competition there is a anticipatory rise due to adrenaline which prepares the body for exercise and strengthens ventricular systole
Cardiac Conduction System
1) The SAN causes ATRIAL SYSTOLE
2) The impulse travels to AVN which repeats it with a delay
3) The impulse goes down the BUNDLE OF HIS and PURKINJE FIBRES down to the ventricles
4) This all leads to VENTRICULAR SYSTOLE
Active mechanisms in venous return
1) Skeletal Muscle Pump: Change of shape during muscle contraction causes muscle to press onto veins, pushing blood back to the heart
2) Respiratory Pump: Change of pressure in chest cavity during inhalation and exhalation compresses on vein
3) Pocket Valves: Ensures blood flows in one direction and back to the heart
Factors effecting blood flow
- Blood flow (cardiac output)
- Lumen size (vessel diameter)
- Viscosity
- Vessel length
Effects of training on the heart
- Cardiac Hypertrophy
- Increased Contractility / Ejection Fraction
- Increased stroke volume
- Bradycardia
- Greater diastolic filling
Effects of exercise on the vascular system
- Capable of creating more blood cells
- Increased capillarisation of muscles
- Increased ability to vasodilate and vasoconstrict
- Blood becomes less viscous
- Blood becomes more efficient at removing waste product (buffering)
Myoglobin
Store of oxygen in your mitochondria
Practical Pressure
High partial pressure means that it easier for oxygen to bind with haemoglobin (high affinity) while low partial pressure means it easier for oxygen to be released (low affinity)
The Bohr Shift
Oxyhaemoglobin disassociation curve shifts to right as increased affinity of carbon dioxide during exercise lowers affinity of oxygen
Vascular Shunt Mechanism
Blood is redirected to areas that need blood the most
How is blood flow controlled?
1) Chemoreceptors detect change in CO2 levels in your blood
2) Impulse then sent to your vasomotor centre in your medulla oblongata
3) Chosen sympathetic response increases blood flow by vasodilating or constricting
Pre-capillary Sphincters
Rings of muscle located at the opening of the capillary.
Contract = Vasoconstriction
Relax = Vasodilation
Arterio-venous Oxygen Difference
Difference between the oxygen concentration of arterial blood arriving at the muscles and venous blood leaving.
- Low difference at rest and high difference at exercise
