1. Cardiovascular System

2. Cardiovascular System Components
Circulatory system
Pulmonary system
Purposes:
Transport O2 to tissues and remove waste
Transport nutrients to tissues
Regulation of body temperature

3. Circulatory System Heart Arteries and arterioles Capillaries
Pumps blood
Arteries and arterioles
Carry blood away from heart
Capillaries
Exchange nutrients with tissues
Veins and venules
Carry blood toward heart

7. Pulmonary and Systemic Circuits
Left side of heart
Pumps oxygenated blood to body via arteries
Returns deoxygenated blood to right heart via veins
Pulmonary Circuit
Right side of heart
Pumps deoxygenated blood to lungs via pulmonary arteries
Returns oxygenated blood to left heart via pulmonary veins

8. Cardiac Cycle Systole Diastole Contractile phase of heart
Electrical and mechanical changes
E.g. blood pressure changes
E.g. blood volume changes
Diastole
Relaxation phase of heart
Takes twice as long as systole
E.g. resting HR = 60
Systole = 0.3 s
Diastole = 0.6 s

9. Arterial Blood Pressure
Expressed as systolic/diastolic
Normal – 120/80 mmHg
High – 140/90 mmHg
Systolic pressure (top number)
Pressure generated during ventricular contraction
Diastolic pressure
Pressure during cardiac relaxation

10. Blood Pressure Pulse Pressure (PP) Mean Arterial Pressure (MAP)
Difference between systolic and diastolic
PP = systolic - diastolic
Mean Arterial Pressure (MAP)
Average pressure in arteries
MAP = diastolic + 1/3 (systolic – diastolic)

13. Electrical Activity of the Heart
Contraction of heart depends on electrical stimulation of myocardium
Impulse is initiated on right atrium and spreads throughout the heart
May be recorded on an ECG

15. Electrocardiogram Records electrical activity of the heart P wave
Atrial depolarization
QRS complex
Ventricular depolarization
T wave
Ventricular repolarization

17. Diagnostic use of the ECG
ECG abnormalities may indicate coronary heart disease
ST-segment depression may indicate myocardial ischemia

19. Heart Rate Range of normal at rest is 50 – 100 b.m
Increases in proportion to exercise intensity
Max. HR is 220 – age
Medications or upper body exercise may change normal response

20. Stroke Volume Range of normal at rest is 60 – 100 ml.b
During exercise, SV increases quickly, reaching max. around 40% of VO2 max.
Max. SV is 120 – 200 ml.b, depending on size, heredity, and conditioning.
Increased SV during rhythmic aerobic exercise is due to complete filling of ventricles during diastole and/or complete emptying of ventricles during systole.

22. Central Circulation Maintenance
Important for older or deconditioned adults
Moderate, continuous, rhythmic aerobic activity encourages venous return
Strenuous activity and held muscle contractions should be avoided
Taper or cool down should follow each activity session to encourage venous return

23. Frank-Starling Law of the Heart
The heart will pump all the blood returned to it by the venous system. Central circulation must be maintained and the veins must continuously return blood to the heart.

24. Features that Encourage Venous Return
One-way valves in veins
Vasoconstriction of blood flow to inactive body parts
Pumping action of skeletal muscles in arches of feet, calves, thighs, etc.
Pressure changes in chest and abdomen during breathing
Maintenance of blood volume by adequate fluid replacement
Siphon action of vascular system

25. Features that Inhibit Venous return
Heat stress requiring additional blood flow to the skin for core temp. maintenance
Dehydration from sweating or from limiting fluid intake (dieting, making weight)
Held muscle contractions that cause blood to pool in the extremities
A Valsalva maneuver which increases pressure in the chest to a high level
Changing from a horizontal to a vertical position abruptly

27. Autonomic Nervous System Control of Heart Rate
Sympathetic control
Stimulates “fight or flight” response
Speeds up heart rate and stroke volume
Sympathetic tone > 100 bpm
Parasympathetic control
Connected to vagus nerves
Slows down heart rate
Parasympathetic tone 60 – 100 bpm

29. Skeletal Muscle Pump
Rhythmic skeletal muscle contractions force blood in the extremities toward the heart
One-way valves in veins prevent backflow of blood

31. Components of Blood Plasma Cells Hematocrit Liquid portion of blood
Contains ions, proteins, hormones
Cells
Red blood cells
Contain hemoglobin to carry oxygen
White blood cells
Platelets
Important in blood clotting
Hematocrit
Percent of blood composed of cells

32. Oxygen Delivery During Exercise
Oxygen demand by muscles during exercise is many times greater than at rest
Increased oxygen delivery accomplished by:
Increased cardiac output
Redistribution of blood flow to skeletal muscle

33. Redistribution of Blood Flow
Increased blood flow to working skeletal muscle
Reduced blood flow to less active organs
Liver, kidneys, GI tract

34. Increased blood flow to skeletal muscle during exercise
Withdrawal of sympathetic vasoconstriction
Autoregulation
Blood flow increased to meet metabolic demands of tissue
O2 tension, CO2 tension, ph, potassium, adenosine, nitric oxide