presentation 08 - human circulation
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Human CirculationA closer look
Contents1. Cardiac cycle2. Maintenance of heartbeat3. Principles governing blood
circulation4. Cardiovascular disease5. Lymphatic system6. Blood composition and function
Cardiac cycle complete sequence of pumping and filling
Electrical activity of the heart
1 - Sinoatrial node (Pacemaker)2 - Atrioventricular node3 - Atrioventricular Bundle (Bundle of His)4 - Left & Right Bundle branches5 - Bundle Branches 6 - Purkinje fibers
AV valves
SL valves
Cardiac outputTotal volume of
blood pumped by the left ventricle per minute◦ Heart rate (HR)
# beats per minute
◦ Stroke volume (SV) mL
◦ Product gives the cardiac output (Q)
◦ Average adultQ = HR x SV
= 70 beats/min x 75 mL/beat
= 5.25 L/min
Maximum HR = 200-your ageTraining heart rate is 75% MHR
e.g. 200-15 = 185 * 0.75 =
139 beats/min 20 minutes, 3x a
week
Pulse Stretching of
arteries as an effect of heartbeat
Pressure waves moving the artery walls when blood moves into aorta
Usually accurate measure of heart rate
Normal resting pulse is 60-100 bpm
Common pulse points1. Temporal artery
3. Carotid artery
4. Brachial artery
5. Radial artery
Blood vessel structure
Physical principles governing blood circulation Blood flow velocity
◦ Aorta (30 cm/s)
◦ Capillaries (0.026 cm/s)
Law of continuity◦ Volume of flow per second must be constant through the
entire pipe
◦ Total cross-sectional area of the capillaries determines flow rate
◦ Blood flow slows down in capillary beds
Osmotic pressure – amount of pressure required to prevent diffusion of water
Blood pressureForce exerted by
blood on walls of vessels
Determined by cardiac output and peripheral resistance by arterioles
Arterial pressure measured by a sphygmomanometer
Systolic/Diastolic (mmHg)
Factors◦ Heart rate◦ Blood volume◦ Resistance of
vessels◦ Viscosity
Blood composition and function
Lymphatic SystemFunctions
◦ Returns excess body fluid to blood◦ Transports fats from intestines to blood◦ Defense
Anatomy◦ Lymph nodes scattered throughout body
(thymus, spleen)◦ Vessels
Cardiovascular disease Cardiovascular
disease (>50% of all deaths)
Heart attack- death of cardiac tissue due to coronary blockage
Stroke- death of nervous tissue in brain due to arterial blockage
Atherosclerosis: arterial plaques deposit
Arteriosclerosis: plaque hardening by calcium deposits
Hypertension: high blood pressure
Hypercholesterolemia: LDL, HDL