Chapter 12: The Circulatory System

Flashcards covering key concepts from Chapter 12: The Circulatory System.

What are the three principal components of the circulatory system?

The heart, blood vessels, and blood.

What is plasma primarily composed of?

Water (over 90%).

What are the components of plasma?

Electrolytes, nutrients, wastes, gases, hormones, and plasma proteins (like albumins, globulins, and fibrinogen).

Where are erythrocytes synthesized?

Red bone marrow.

What hormone triggers the differentiation of stem cells to erythrocytes?

Erythropoietin (from the kidney).

What is the role of transferrin?

An iron-transport plasma protein that delivers iron to the bone marrow.

What is the role of ferritin?

A protein that stores iron in the liver, spleen, and small intestines.

What are the major causes of anemia?

Dietary deficiencies of iron, vitamin B12, or folic acid; aplastic anemia; blood loss; inadequate erythropoietin secretion; hemolytic anemia.

What are the two categories of leukocytes?

Granulocytes and agranulocytes.

Name three types of granulocytes.

Neutrophils, eosinophils, and basophils.

Name two types of agranulocytes.

Lymphocytes and monocytes (macrophages).

What is the function of basophils at the site of infection?

Secrete heparin (anti-clotting factor) and secrete histamine to attract infection-fighting cells and proteins.

Where are platelets produced?

Produced when cytoplasmic portions of large bone marrow cells (megakaryocytes) pinch off and enter the circulation.

What are the two circuits of the circulatory system?

Systemic and pulmonary.

Which blood vessels carry blood away from the heart?

Arteries.

Which blood vessels carry blood to the heart?

Veins.

Hydrostatic Pressure

Force exerted by the blood and is measured in mmHg (millimeters of mercury).

What are the two main determinants of resistance in blood flow?

The inside radius of the tube (blood vessel) and blood viscosity.

What are the three layers of the heart?

Epicardium, myocardium, and endocardium.

Where do the coronary arteries originate?

Behind the aortic valve cusps in the very first part of the aorta.

What constitutes the conducting system of the heart?

Specialized cardiac cells in electrical contact with cardiac muscle cells via gap junctions.

What is the function of the conducting system of the heart?

Initiates the heartbeat and helps spread an action potential rapidly throughout the heart.

Which node is normally the pacemaker for the entire heart?

The sinoatrial (SA) node.

What is the pacemaker potential?

A slow depolarization in the SA node that brings the membrane potential to threshold, causing an action potential.

In the absence of nervous or hormonal influences, what is the inherent autonomous discharge rate of the SA node?

Approximately 100 beats/minute.

What is being measured in an electrocardiogram (ECG)?

A measure of the currents generated in the extracellular fluid by the changes occurring simultaneously in many cardiac cells.

In an ECG, what event does P wave correspond to?

Atrial depolarization.

In an ECG, what event does the QRS complex correspond to?

Ventricular depolarization.

In an ECG, what event does the T wave correspond to?

Ventricular repolarization.

What are the two major phases of the cardiac cycle?

Systole (ventricular contraction and blood ejection) and diastole (ventricular relaxation and blood filling).

What cardiac event is associated with the first heart sound (lub)?

Closure of the AV valves.

What cardiac event is associated with the second heart sound (dub)?

Closure of the pulmonary and aortic valves.

Define stroke volume (SV).

The volume of blood each ventricle ejects during each contraction. SV=EDV-ESV

Define cardiac output (CO).

The volume of blood pumped out of each ventricle per minute. CO = HR x SV

Describe the Frank-Starling mechanism.

The relationship between end-diastolic volume and stroke volume. The greater the end-diastolic volume, the greater the stretch and the more forceful the contraction.

Define ejection fraction (EF).

The ratio of stroke volume (SV) to end-diastolic volume (EDV); EF= SV/EDV

How is echocardiography useful in measuring cardiac function?

Can detect abnormal functioning of cardiac valves or contractions of the cardiac walls, and can also be used to measure ejection fraction.