Components of Cardiovascular System

Components of Cardiovascular System

Exercise Physiology

Organization of Circulatory System

Functions◦Deliver oxygenated

blood to muscles; 1900 gals/day

◦Aerate blood in lungs

◦Transport heat to surface

◦Deliver nutrients to tissues

◦Transport hormones

Circulatory System: Valves

Heart Chambers Two Pumps in One

Right heart to lungsLeft heart to bodyRight and left

atrioventricular valves prevent backflow into atria: tricuspid-right, bicuspid (mitral)-left

Right and left semilunar valves prevent backflow into ventricles: pulmonic-right, aortic-left

Circulatory System: Heart

Circulatory System: Myocardium

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: Heart

1. Ventricular DiastoleVentricular filling andAtrial contraction

A-V valve opensAortic valve closes

2. Beginning of Ventricular SystoleIsovolumetric Ventricular contraction

A-V valve closes,Aortic valve closed

3. Ventricular SystoleVentricular ejection

A-V valve closedAortic valve opens

4. Beginning of DiastoleIsovolumetric Ventricular relaxation

A-V valve closedAortic valve closes

Cardiac Cycle

Circulatory System

VasculatureArteries: highly

muscular, elasticCapillaries: 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

VasculatureVeins

Thinner walls, less muscular

Serve as blood reservoir

Venous return facilitated by flaps

Active cool-down facilitates blood flow

Blood PressureBlood Pressure = cardiac output x total peripheral resistance

Blood Pressure at Rest

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 during Exercise

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 Recovery

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.

Heart’s Blood Supply

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