cardio vascular system Flashcards
What type of system is the CV system
Double circulatory
What is pulmonary circulation
The right side of the heart receives deoxygenated blood from the muscles and other tissues and pumps to lungs to be oxygenated
What is systemic circulation
The left side of the heart receives oxygenated blood from the lungs and pumps it to the muscles and other tissues of the body
What do arteries do
Take blood away from heart
Properties of arteries
Think muscular wall and small lumen to cope with pressure
Branch into smaller arterioles
What are capillaries
One cell thick to allow for gas diffusion
What do veins do
Bring blood to the heart
Properties of veins
Wide lumen, pocket valves to stop back flow
Branch into venules
How are capillaries used in systemic circuit
Blood reaches capillaries surrounding the active muscle where o2 is delivered and co2 removed via gaseous exchange
How are capillaries used in the pulmonary circuit
Surround lung tissue co2 is delivered and exchanged for o2 ready to go back to heart
What is vascular shunt
The redirection of blood to the working muscles
How is vascular shunt achieved
Blood vessels widen to increase blood flow to working muscles (vasodilation)
Non working muscles blood is limited by narrowing blood vessels (vasoconstriction)
Pre capillary sphincters can be opened or closed to control blood flow in specific areas
What is vasodilation
The widening of blood vessels to allow increased blood flow
What is vasoconstriction
The narrowing of blood vessels to restrict blood flow
What is myogenic
It can generate its own electrical impulses and doesn’t require brain stimulation
Is the heart myogenic
Yes
What 4 stages can a heartbeat be split into
Atrial diastole
Ventricular diastole
Atrial systole
Ventricular systole
What is diastole
The heart relaxes and fills with blood
What is systole
The heart is contracting and forcing blood around two circuits
How is the cardiac cycle initiated
And electrical impulse
What is the cardiac conduction system
Cardiac diastole
SA node fires
Impulse cause atrial systole
Impulse delayed at AV node (slows down to allow atrium and ventricle to contract)
Impulse passes bundle of his and bundle branches
Impulse passes purkinje fibres
Causing ventricular systole
What does the blood consist of
Red blood cells
White blood cells
Platelets
Plasma
Functions of blood
Transport of gases and nutrients
Regulation of body temp (thermoregulation)
Protection and healing
What is venous return
The flow of blood that returns to the heart via the venules and veins
Increases during exercise
65% total blood is stored in veins at rest
What are the 4 stages of venous return mechanisms
Skeletal muscle pump
Pocket valves
Respiratory pump
Cardiac suction
What is skeletal muscle pump
When skeletal muscles compress the veins during movements the force blood back towards heart
What are pocket valves
Pocket valves in the veins and venules assist venous return by stopping backflow
What is respiratory pump
During inhalation the pressure inside thorax decreases compared to rest of body so a small flow of blood with go towards the chest
During exercise ventilation increases so the pressure difference increases pulling more blood to the heart
What is cardiac suction
As ventricles contract the atrioventricular valves are pulled down increasing atrium size
This causes pressure difference between atria and veins so sucking of blood to the heart
What is stroke volume
The volume of blood ejected from the left ventricle every beat
What is cardiac output
The volume of blood pumped out of the heart per minute
Calculation for cardiac output
Stroke volume x heart rate
(Q= SV x HR)
When exercising does cardiac output increase
Yes
What does starlings law state
That cardiac output is dependent on the extensibility of cardiac muscle fibres
Blood enters heart during diastole the tissue stretches, the greater the stretch the greater force of contraction so more blood
So cardiac output increases during exercise not only due to heart rate but also venous return increases
What is ejection fraction
The percentage of blood pumped out of the left ventricle each beat
- humans are not efficient so not all blood comes out of the heart each beat (at rest 55%)
- during exersice starlings law explains why ejection fraction increases to 70% or more
What is cardiac hypertrophy
The heart getting bigger and stronger
What is cardio vascular drift
Drifting upwards of heart rate when exersicing at a constant work rate over prolonged period or in hot environment
- sweating causes a decrease in blood volume nd venous return as plasma contain lots of water
Heart rate increases to compensate for the lower SV and maintain cardiac output
What is blood pressure
The force exerted by the blood on the inside walls of the blood vessels
How is blood pressure measured
In the left brachial artery using a sphygmomanometer
How does bp fluctuate
Higher when heart is contracting
What do the two numbers on the heart rate machine mean
Systolic pressure
Diastolic pressure
Hypotension bp value
<80
<60
Normal bp value
80-120
60-80
prehypertension bp value
120-139
80-89
Hypertension stage 1 bp value
140-159
90-99
Hypertension stage 2 bp value
160+
100+
Hypertension crisis bp value
180+
110+
What are the main 2 factors that affect blood pressure
Blood flow (cardiac output)
Peripheral resistance
What factors go into peripheral resistance
Blood viscosity
Blood vessels and length
Blood vessels elasticity
Effects of aerobic exercise on blood pressure
Systolic pressure increase to up to 200
Diastolic pressure remains normal
Once at a steady pace bp returns to normal (slightly raised)
Effects of anaerobic exercise on blood pressure
Systolic and diastolic pressures increase dramatically softly due to athlete holding breath
