Lab #8: Cardiovascular System and Blood Pressure Measurement

Systole

The cycle of mechanical contraction of the ventricles.

Diastole

The cycle of mechanical relaxation of the ventricles.

Heart Sounds

Sounds produced by the vibration of surrounding structures during the contraction and relaxation of the heart.

First heart sound (S1)

Produced at the beginning of systole when the AV valves close and the SL valves open; sounds like 'lub.'

Second heart sound (S2)

Occurs at the end of systole when the SL valves close and the AV valves open; sounds like 'dub.'

Auscultation

The procedure of listening to heart sounds using a stethoscope.

Pressure Gradient

The difference in pressure that drives blood flow from higher pressure regions to lower pressure regions.

Driving Pressure

The ventricular pressure that drives blood through the blood vessels.

Systolic Blood Pressure (SBP)

The highest pressure in the artery, produced during the heart's contractile phase; normal SBP is around 120 mmHg.

Diastolic Blood Pressure (DBP)

The lowest pressure in the artery, produced during the heart's relaxation phase; normal DBP is around 80 mmHg.

Sphygmomanometer

An instrument used to measure blood pressure.

Peripheral Resistance

The resistance to blood flow through the arterioles, influencing blood pressure.

Cardiac Output

The amount of blood pumped by the heart per minute, directly affecting arterial blood pressure.

Blood Pressure

The pressure of circulating blood on the walls of blood vessels.

Vena Cava

The large vein that carries deoxygenated blood into the right atrium of the heart.

Aorta

The largest artery in the body, carrying oxygenated blood from the left ventricle to the systemic circulation.

Blood Vessel Dilation

The widening of blood vessels, which decreases blood pressure.

Blood Vessel Constriction

The narrowing of blood vessels, which increases blood pressure.

Intraventricular Pressure

The pressure within the ventricles during contraction.

AV Valves

The valves located between the atria and ventricles that prevent backflow of blood.

SL Valves

The semilunar valves that prevent backflow of blood from the aorta and pulmonary artery into the ventricles.

Auscultation Procedure

Listening to heart sounds in a 'Z' pattern using a stethoscope.

Auscultation

The act of listening to internal sounds of the body, typically using a stethoscope.

Systolic Pressure

The cuff pressure at which the first sound is heard during blood pressure measurement.

Diastolic Pressure

The cuff pressure at which the sound becomes muffled and disappears during blood pressure measurement.

Pulse Pressure

Calculated as the difference between systolic and diastolic pressures.

Mean Arterial Pressure (MAP)

Equal to diastolic pressure plus one-third of the pulse pressure.

Pulse Pressure Formula

PP = Systolic - Diastolic.

Mean Arterial Pressure Formula

MAP = Diastolic + [1/3 * PP].

Cardiac Output (CO)

Calculated as Heart rate (in bpm) multiplied by Stroke volume (mL).

MAP in terms of CO and TPR

MAP = Cardiac output (ml/sec) * Total peripheral resistance (TPR units).

Factors affecting Blood Pressure

Instruments used, anxiety of the subject, body position, age, weight, and sex.

Heart Sounds

Sounds produced by the heart during the cardiac cycle, specifically 'Lub' and 'Dub'.

First Heart Sound (S1)

Occurs when the AV valves (tricuspid & mitral) close, marking the start of systole.

Second Heart Sound (S2)

Occurs when the SL valves (aortic & pulmonary) close, marking the end of systole.

Systolic Blood Pressure (SBP)

The highest pressure in the arteries when the heart pumps, normal value ~120 mmHg.

Diastolic Blood Pressure (DBP)

The lowest pressure in the arteries when the heart relaxes, normal value ~80 mmHg.

Driving Pressure

The force pushing blood forward from high pressure (aorta) to low pressure (vena cava).

Cardiac Output Definition

How much blood is pumped per minute, calculated as Heart Rate × Stroke Volume.

Resistance in Blood Pressure

Blood pressure depends on how hard the heart pumps and how much resistance there is.

Measuring Blood Pressure with a Cuff

Inflate cuff above systolic pressure to hear no sound; deflate to hear SBP and DBP.