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The Cardiovascular System (ECG (Electrocardiogram) (Heartbeat (Normal,…
The Cardiovascular System
Functions
Delivery
Removal
Transport
Maintenance
Prevention
Structure
A pump (the heart)
Extrinsic Control of the Heart
Parasympathetic Nervous System
Vagus Nerve
Carries impulses to nodes
Slows HR
Sympathetic Nervous System
Increases HR & force of contraction
Endocrine System
Norepinephrine/epinephrine
Increases HR & force of contraction
Increase the time of sympathetic response
intrinsic control of the heart
A system of channels (blood vessels)
A fluid medium (blood)
Cardiac Conduction System
Sinoatrial (SA) node
Atrioventricular (AV) node
AV bundle
Purkinje Fibres
intrinsic control of the heart
Action potentials
Cardiac Function
Cardiac Cycle: all events that occur between two consecutive heart beats.
Relaxation phase (diastole) and a contraction phase (systole)
It takes 0.81secs to complete in a normal adult.
Stroke Volume
The volume of blood pumped per beat
The amount of blood in the left ventricle before contraction is the end diastolic volume
The amount of blood in the left ventricle after contraction is the end systolic volume
Ejection Fraction
The proportion of blood pumped out of the left ventricle per beat
Ejection fraction at rest is approx 60%
Cardiac Output
Heart Rate x Stroke Volume
Cardiac Output (Q): the total volume of blood pumped by the ventricle per minute
Stroke volume at rest = about 60-80ml blood
Q = between 4.8 and 6.4 litres of blood per minute
ECG (Electrocardiogram)
ECG used to record electrical activity of the heart
Used to check HR is normal and can uncover abnormalities in functioning.
Body fluid conducts electricity. Electrical impulses generated in the heart are transmitted via body fluids which the ECG picks up.
Heartbeat
Normal
Fast
Slow
Irregular
P Wave: Activation of the atria
QRS Complex: Activation of the ventricles
T Wave: Recovery wave
The Vascular System
Arteries
Aterioles
Capillaries
Venules
Veins
How does structure help function?
Blood
(Distribution of blood) During rest ~50% blood goes to metabolically active tissues (e.g. liver, kidneys) and resting skeletal muscles get about 15%
Blood Pressure
Pressure exerted by the blood on vessel walls
BP is expressed by two numbers: systolic pressure and diastolic pressure
Hypertension is the clinical term describing blood pressure which is elevated above normal.
PRESSURE-VOLUME RELATIONSHIP
Return of blood to the heart
We spend the majority of our time upright. Thus the heart requires assistance to overcome the force of gravity when blood is returning to the heart from the lower parts of the body.
Breathing, the "muscle pump and valves" assist in this process
Blood is responsible for transport of various materials between the cells and tissues of the body.
3 main functions
transportation
temp regulation
pH balance
Blood Volume
Varies depending on body size and training status. Larger blood volumes = larger body size and highly endurance trained.
Normally 5/6 litres in men; 4/5 litres in women
Blood is made up of plasma, red blood cells, white blood cells and platelets.