Basic Cardiac Principles

Exam 2

Function of the Circulatory System

maintains blood flow and supply to the body

Function of the Circulatory System

is to transport oxygen, nutrients, and hormones to cells while removing waste products.

Atrioventricular Valves

are valves located between the atria and ventricles, preventing back-flow of blood into the atria during heart contraction.

Bicuspid Valves

The LEFT AV valve consists of two flaps, or cusps, of the endocardium that regulates blood flow from the left atrium to the left ventricle.

AKA: mitral valve

Tricuspid Valve

The RIGHT AV valve, located between the right atrium and right ventricle, also consists of three flaps that prevent backflow of blood during contraction.

Semilunar Valve

Guards the bases of the two large arteries leaving the ventricular chambers

Pulmonary and Aortic Valves

Phases of the Cardiac Cycle

Atriole Systole

Ventricular Systole first phase

Ventricular Systole second phase

Ventricular Diastole early

Ventricular Diastole late

Atriole Systole

The phase of the cardiac cycle where the atria contract, pushing blood into the ventricles.

Ventricular Systole first phase

Ventricular contraction pushes AV valves closed

Ventricular Systole second phase

Semilunar valves open and blood is ejected

Ventricular Diastole early

Semilunar valves close and blood flows into atria

Ventricular Diastole late

Chambers relax and blood fills ventricles passively

Cardiac Output

the amount of blood the heart pumps/ejects per minute

Stroke Volume

the amount of blood pumped by the ventricles with each heartbeat

Preload

Stretching

Left Ventricular End Diastolic Pressure or Preload

the pressure in the left ventricle at the end of diastole, reflecting the volume of blood returning to the heart.

Frank Starling’s Law

the principle that the heart will contract more forcefully when it is filled with more blood due to increased stretch of the cardiac muscle fibers.

Afterload

the amount of resistance the heart must pump against when ejecting blood

Afterload

think hose kink

When afterload is low

the heart can eject blood more easily, leading to better stroke volume and cardiac output.

When afterload is high

the heart must work harder to eject blood, leading to increased workload and potential heart failure.

High afterload

hypertension

vasoconstiction

Contractility

the ability of the heart muscle to contract forcefully, affecting stroke volume and cardiac output.

Positive inotropy

increased force of contraction

Negative inotropy

decreased force of contraction

Ejection fraction

stroke volume/preload

Normal: 55-65%

below 40% is abnormal

left Ventricular

Beta 1 Receoptors

kidney, heart, adipose tissue

Beta 2 Receptor

smooth muscle, blood vessels, liver

Aldosterone

A hormone produced by the adrenal glands that regulates sodium and potassium levels, influencing blood pressure and fluid balance.

Hypertension

A chronic condition characterized by elevated blood pressure in the arteries, which can lead to serious health issues such as heart disease and stroke.

Regulation of Blood Pressure

Maintain tissue perfusion and/or blood to the capillary beds

Regulation of Blood pressure

Arterial pressure is determined by cardiac output and systemic vascular resistance, affecting overall blood flow.

Normal BP

120mm/80mm

Pulse Pressure

Difference between systolic and diastolic

120-80=40

Mean Arterial Pressure

Average pressure during ventricular contraction and relaxation

Systolic Blood Pressure

The pressure in the arteries during ventricular contraction, typically the higher number in a blood pressure reading.

Diastolic Blood Pressure

The pressure in the arteries during ventricular relaxation, typically the lower number in a blood pressure reading.

Hypertension

Primary: no known cause

Secondary: Caused by another disease or factor

Isolated systolic HTN: elevated systolic BP

Metabolic Syndrome Characteristics

Hypertension, Obesity, Abnormal cholesterol levels, chronic inflammation, insulin resistance

Insulin Resistance

A condition where cells in the body do not respond effectively to insulin, leading to elevated blood sugar levels.

Insulin Resistance

Insulin is not able to reduce blood sugar, the compensatory insulin fails as well and the person remains hyperglycemic

Angina

A type of chest pain caused by reduced blood flow to the heart muscles, often triggered by physical exertion or stress.

Cardiac Cycle

The sequence of events in one heartbeat, including diastole and systole, during which the heart chambers fill with blood and pump it out.

One complete heartbeat

Frank-Starlings law

The more the heart muscles stretch during diastole the more forcefully it will contract at systole