Cardiovascular System 1

Components of
Cardiovascular System
Exercise Physiology
◦ Deliver oxygenated
blood to muscles;
1900 gals/day
◦ Aerate blood in
◦ Transport heat to
◦ Deliver nutrients to
◦ Transport hormones
Organization of Circulatory System
Heart Chambers
Two Pumps in One
Right heart to lungs
 Left heart to body
 Right and left
atrioventricular valves
prevent backflow into
atria: tricuspid-right,
bicuspid (mitral)-left
 Right and left semilunar
valves prevent backflow
into ventricles:
pulmonic-right, aorticleft
Circulatory System: Valves
Circulatory System: Heart
Heart wall composed
of 3 layers
◦ Epicardium
◦ Myocardium
◦ Endocardium
Differs from skeletal
◦ Intercalated discs
connect cells to permit
electrical transmission
◦ Homogenous muscle
fibers similar to slow
twitch fibers
Circulatory System: Myocardium
Cardiac Cycle
1. Ventricular Diastole
Ventricular filling and
Atrial contraction
A-V valve opens
Aortic valve closes
2. Beginning of Ventricular Systole
A-V valve closes,
Isovolumetric Ventricular contraction Aortic valve closed
3. Ventricular Systole
Ventricular ejection
A-V valve closed
Aortic valve opens
4. Beginning of Diastole
Isovolumetric Ventricular relaxation
A-V valve closed
Aortic valve closes
Circulatory System: Heart
 Arteries: highly
muscular, elastic
 Capillaries: thin,
porous single layer
◦ Capillary branching
increases cross section
◦ Flow velocity inversely
proportional to area, so
broad capillary beds
have slow blood flow
Circulatory System
 Veins
Thinner walls, less
Serve as blood
Venous return
facilitated by flaps
Active cool-down
facilitates blood flow
Circulatory System
Blood Pressure
Blood Pressure = cardiac output x total peripheral resistance
Systolic Blood Pressure: pressure in
blood vessel due to surge of blood in
aorta and subsequent recoil of aortic
wall propagates a wave of pressure
through circuit.
 Diastolic Blood Pressure: pressure in
blood vessel during diastole.
 DBP provides indication of peripheral
resistance or ease of flow from “a to c”.
 Normal systolic BP < _?_ mm Hg and
diastolic BP < _?_ mm Hg.
Blood Pressure at Rest
During RHYTHMIC exercise, increase in
blood flow and dilation of blood vessels in
active muscles cause SBP to __?__ and
DBP to __?___.
 During RESISTIVE exercise, sustained
muscular forces compress peripheral
arteries causing blood pressure __?__.
 Upper body exercise has ___ BP than
exercise with legs.
Blood Pressure during Exercise
A bout of light- to moderate-intensity
exercise decreases SBP for up to ___ hrs.
 Pooling of blood in visceral organs and
lower extremities reduces central blood
volume which contributes to hypotensive
recovery response.
Blood Pressure during Recovery
Openings for left
and right coronary
arteries are in aorta
just above the
aortic valve.
Aortic valve flaps
close coronary
arteries during
ejection phase.
Heart’s Blood Supply
Myocardial oxygen
utilization is 70% to
80% at rest,
contrast to 25%
other tissues.
In vigorous
exercise, coronary
blood flow increases
4-6x above normal.
Heart’s Blood Supply
Impaired coronary
blood flow: angina
pectoris (chest
Rate pressure
product: estimate
of myocardial work
(SBP x HR)
Myocardium almost
completely aerobic
Heart’s Blood Supply

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