1. Human Circulation
A closer look

2. Contents Cardiac cycle Maintenance of heartbeat
Principles governing blood circulation
Lymphatic system
Blood composition and function
Cardiovascular disease

3. Cardiac cycle – complete sequence of pumping and filling

4. Electrical activity of the heart
EKG or ECG (electrocardiogram)
P wave - spread of electrical activity over the atria, beginning of its contraction
QRS complex - spread of electrical activity over the ventricles, beginning of its contraction
T wave - recovery phase of the ventricles
Influenced by nerves (vagus nerve – acetylcholine, epinephrine), hormones, and body temp.
1 - Sinoatrial node (Pacemaker) 2 - Atrioventricular node 3 - Atrioventricular Bundle (Bundle of His) 4 - Left & Right Bundle branches 5 - Bundle Branches
6 - Purkinje fibers

5. Cardiac output
Total 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
Average adult
CO = HR x SV
= 70 beats/min x 75 mL/beat
= 5.25 L/min
Maximum HR = 200-your age
Training heart rate is 75% MHR
e.g = 185 * 0.75 = 139 beats/min
20 minutes, 3x a week

6. 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 bpm
Common pulse points
1. Temporal artery
3. Carotid artery
4. Brachial artery
5. Radial artery

7. Blood vessel structure

8. 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 pipes delivering the fluid
Slows down in capillary beds
Nerves, muscle, hormone control

9. Blood pressure Force exerted by blood on walls of vessels
Pressure decreases from arteries to veins
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

10. Blood composition and function

11. Negative feedback mechanism
Erythropoietin produced in liver (low O2) stimulates marrow cells

12. Lymphatic System Functions Anatomy Returns excess body fluid to blood
Transports fats from intestines to blood
Defense
Anatomy
Lymph nodes scattered throughout body (thymus, spleen)
Vessels

13. 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

14. Quiz: Modified true or false
Water moves from a region of lower solute concentration to a region of higher solute concentration through osmosis.
Vacuoles bud off the rough ER and transport proteins to the receiving end of the Golgi apparatus for further modification.
The sandwich model is currently the accepted model for the plasma membrane.

15. Quiz: Modified true or false
The planaria has an open circulatory system.
In insects, oxygen is not transported using the circulatory system.
Interstitial fluid and blood are separate in an earthworm.
One disadvantage of amphibian circulation is that some mixing occurs in the heart.

16. Quiz: Modified true or false
Turtles are the only reptiles with four- chambered hearts.
During atrial systole, the atrioventricular valves are closed.
The T wave in an ECG corresponds to ventricular diastole.
The stretching of arteries in response to heartbeat is called the cardiac output.

17. Quiz: Modified true or false
Valves and skeletal muscle contraction facilitate blood flow in veins.
Capillaries have the highest total cross- sectional area of the three types of vessels.
Blood pressure is equal to osmotic pressure at the arterial end of the capillary.
When the precapillary sphincters are relaxed, blood flows through the capillary beds.