The Cardiovascular System Chapter 5

Learning Objectives Know the components of the cardiovascular system. Know the basic, general anatomy and physiology of the cardiovascular system. Understand the responses of the cardiovascular system during exercise. Understand the responses of the cardiovascular system to exercise training.

Cardiovascular System Composition and Primary Function Heart:  Pumps blood to lungs and systemic circulation Blood vessels:  Pipelines for carrying blood to and from the tissues Blood:  Transport mechanism to and from tissues

The Heart— Functions as Two Pumps On the right:  Pumps blood to the lungs, where the blood is oxygenated. On the left:  Pumps oxygenated blood to the systemic circulation.

Types of Blood Vessels Arteries Veins Pulmonary veins Arterioles Capillaries Venules

Basic Anatomy of the Heart

Conducting System of the Heart

The Cardiac Cycle Cyclical pattern:  Diastole (relaxation phase)  Systole (contraction phase) Valves allow for unidirectional blood flow (prevent backflow of blood) Atrial and ventricular contraction (continued)

The Cardiac Cycle, continued End diastolic volume (EDV)  Amount of blood in each ventricle at the end of diastole End systolic volume (ESV)  Amount of blood in each ventricle at the end of systole Stroke volume (SV)  The amount of blood ejected out of each ventricle with each cardiac contraction

Events of the Cardiac Cycle See the full-sized figure on the AESP Resource Site.AESP Resource Site

Cardiac Output The amount of blood ejected by the heart each minute: At rest, approximately 5 liters per minute For a well-trained athlete, can increase to more than 40 liters per minute To determine cardiac output: CO = HR  SV where CO is cardiac output, HR is heart rate, and SV is stroke volume.

Control of Heart Rate and Stroke Volume Heart rate is influenced by the effect of the autonomic nervous system on the SA node. Stroke volume: Determined by end diastolic volume, which is related to ventricular contraction force.  Frank-Starling law of the heart Cardiac contractility: The heart’s ability to produce force per unit of time (power).

Factors Affecting Heart Rate Age Gender Size Posture Ingestion of food Smoking Emotion Body temperature Heat and humidity

Factors Affecting Stroke Volume Gravity Muscular activity Size of the heart Nervous influences

One-Way Valves of the Veins

Clinical Application Heart Murmurs May be caused by irregularities in vessel walls or malformed cardiac valves. May result in regurgitation of blood or restricted blood flow—  Causes the heart to work harder. The heart increases contraction force and consumes more oxygen. In some cases, heart murmurs may severely limit exercise tolerance.

Your Perspective How would you counsel a patient with a heart murmur about engaging in strenuous exercise?  Recognizing that exercise programs can be beneficial for so many different health problems, but patients with heart murmurs may have damaged heart valves.

Heart Rate and Stroke Volume in Aerobic Exercise Stroke volume increases very little with increased metabolism, until the metabolic level reaches approximately eight times the resting level. Heart rate is proportional to the work load imposed. Heart rate is proportional to oxygen consumption during exercise.

Typical Heart Rate Response to Exercise As exercise begins, heart rate rises rapidly. During exercise:  If light/moderate, heart rate will plateau within the first minute.  If heavy, heart rate increases until exhaustion. At the end of the exercise, heart rate rapidly declines within the first 2–3 minutes. After the initial rapid decline, heart rate decreases more slowly.

Heart Rate Changes in a Moderately Conditioned, Middle-Aged Subject

Factors Affecting Heart Rate Responses to Exercise Static vs. dynamic exercise Intensity Duration

Changes in Cardiovascular Function After Endurance Training

Short-Term Changes During Continuous, Moderate-Intensity Exercise

Anatomy of Blood Vessels Aorta and large arteries  Allow vessels to distend and recoil Arterioles  Act as resistance vessels, protecting capillaries Venules and veins  Serve as collecting vessels, draining various tissues

Hemodynamics Principles Governing Blood Flow Pressure Flow Resistance

Distribution of Blood to Systemic Tissues

Microcirculation

Blood Distribution to the Tissues Controlled by changes in the diameter of small arteries and arterioles Two mechanisms: 1.Nervous regulation 2.Chemical regulation

Blood Pressure The driving force for moving blood through the circulatory system Plays a role in several health problems:  Heart attacks  Stroke  Kidney disease Affected by various factors:  Age  Gender  Emotional state  Time of day  Body position

Typical Time Course of the Arterial Blood Pressure Response in a Healthy Young Male

Where to Learn More Cardiovascular system:  American Heart Association:  The Heart.org Cardiology Online:  AACVPR–American Association of Cardiovascular and Pulmonary Rehabilitation: 

ACSM Certification Standards— Knowledge of the normal chronic physiologic adaptations associated with cardiovascular exercise.  What sort of cardiorespiratory response would you expect to see in someone who is cleaning his house?  What response would you expect to see in someone who has been pushing a heavy sofa?  What response would you expect to see in someone who has just run a marathon?