Lab 3

Blood Flow

The volume of blood moving past a specific point (or through a vessel

organ

heart); usually measured in ml

min

Cardiac Output (CO)

The amount of blood (ml

min) pumped by the heart per minute (this equals blood flow through the entire body). Calculated by: heart rate X stroke volume. CO = HR x SV

Stroke volume (SV)

The volume of blood ejected by the left (or right) ventricle per beat (ml

beat)

Heart Rate (HR)

The number of times the heart contracts per minute (beats

min)

Blood Pressure

The force exerted on a vessel wall by the enclosed blood (mm Hg); unless otherwise stated, “blood pressure” usually refers to pressure in large systemic arteries near heart; blood pressure gradients create the driving force for blood flow

Total Peripheral Resistance

The amount friction encountered by blood as it flows through all of the blood vessels in the body; affected mostly by vessel diameter; the higher the resistance, the more difficult it is to move blood through the vessel

Systole

Contraction of the heart; can be used to describe atria or ventricles

Diastole

Relaxation of the heart; can be used to describe atria or ventricles

Systolic pressure

Maximum pressure in the arteries during a heart cycle; occurs during ventricular systole (mmHg)

Diastolic pressure

Minimum pressure in the arteries; occurs just before aortic semi-lunar valve opens (mmHg)

Pulse

The throbbing caused by the regular expansion and recoil of the arteries as the ventricles eject blood (or not) into the arteries. Can be felt through the skin in several places on the body. Counting the number of pulses

minute is a non-invasive way of determining heart rate.

Pulse pressure

The difference in blood pressure between systolic and diastolic pressure

Mean arterial pressure

The mean diastolic pressure plus one third of the pulse pressure; the mean force driving blood flow

Baroreceptors

Special cells that monitor pressure in the walls of the carotid arteries and aorta; associated with afferent neuron; respond to changes in mean arterial pressure

Baroreceptor reflex

A reflex initiated by stimulation of baroreceptors which has the purpose of maintaining a stable level of mean arterial pressure

Vascular Tone

The degree of blood vessel constriction that occurs during resting body states, is relative to vessel’s maximal dilated state.

P wave

Atrial depolarization

PR interval

Time from depolarization of the SA node to the onset of ventricular depolarization (normal

PR segment

Isoelectric time between atrial depolarization and ventricular depolarization. Includes the atrial contract and delay of signal conduction at AV node.

QRS complex

Ventricular depolarization, atrial repolarization hidden in this complex.

QT interval

Time from ventricular depolarization to ventricular repolarization. Prolongation of the QT interval can result from multiple medications, electrolyte abnormalities, and certain disease states.

ST segment

Isoelectric time between ventricular depolarization and repolarization.

T wave

Ventricular repolarization

Tunica intima (interna)

Innermost layer (closest to blood); Made of simple squamous epithelium, present in all vessel types; smooth, continuous to prevent sticking of cells

blood

Tunica media

Middle tunic, contains smooth muscle to create constriction or dilation; thicker in arteries, thinner in veins; absent in capillaries

Tunica externa (externata) also called adventia

Outermost tunic; made of loose & dense connective tissues to anchor vessels to other structures

Arteries, arterioles

Vessels that carry blood away from heart; thickest of all vessels, do not contain valves; contains all three tunics

Veins, venules

Vessels that carry blood back to heart; thin walled, big lumen, contain valves b

c low pressure to keep blood moving back towards heart; contains all three tunics

Capillaries

Exchange vessels, contains slits between cell of tunica intima; lacks tunica media & well-defined tunica extern