Transcript Cardiovascular System 1

Components of
Cardiovascular System
Exercise Physiology

Functions
◦ Deliver oxygenated
blood to muscles;
1900 gals/day
◦ Aerate blood in
lungs
◦ Transport heat to
surface
◦ Deliver nutrients to
tissues
◦ 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
Vasculature
 Arteries: highly
muscular, elastic
 Capillaries: thin,
porous single layer
◦ Capillary branching
increases cross section
area
◦ Flow velocity inversely
proportional to area, so
broad capillary beds
have slow blood flow
Circulatory System
Vasculature
 Veins
Thinner walls, less
muscular
Serve as blood
reservoir
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
pain).
Rate pressure
product: estimate
of myocardial work
(SBP x HR)
Myocardium almost
completely aerobic
Heart’s Blood Supply