19.5 Principles of Pressue /

What is the flow of liquids governed by?

Pressure - impels fluids to move

Resistance - opposes flow

What measures pressure? And blood pressure?

Manometer - j shaped glass tube partially filled with mercury

Sphygmomanometer - attached to pressure cuff

What is a pressure gradient?

Fluids flow down their pressure gradients from highest pressure point to low pressure point

How are pressure gradients applicable to the heart?

When a ventricle expands, internal pressure falls

If AV valve is open, blood flows into the ventricle from the atrium

When the ventricle contracts, internal pressure rises

Opening and closing of valves are governed by pressure changes - no muscles just passively pushed open and closed by pressure

What is auscultation?

Listening to the heart sounds made by the body

What are normal heart sounds?

Lub S1 and Dub S2

S1 is longer and louder, S2 is softer and sharper

Sometimes in children and adolescence you can hear a S3, it is rarely heard in those older than 30 and can indicate a enlarged and failing heart

What happens if the right ventricle pumps more than the left?

It would result in blood accumulating in the lungs, causing pulmonary hypertension, edema (swelling due to trapped liquid), and risk of drowning

Signs can include shortness of breath and sensation of suffocating

What would happen if the left ventricle pumps more blood than the right?

Blood accumulates in in systemic circuit, causing hypertension and widespread systemic edema

Marked by enlargement of the liver, distension of the jugular veins in neck, swelling in fingers ankles and feet as well as ascites which is pooling of fluid in the abdominal cavity

Can lead to stroke or kidney failure

What is congestive heart failure?

Fluid accumulation in either circuit due to insufficient ventricular pumping

Can be caused by myocardial infraction (heart attack), chronic hypertension, valvular defects, congenital (birth) defects

How is the hearts pace monitored?

By signals coming from cardiac centers in the medulla oblongata in the brainsteam, from the cardioacceleratory center which communicates with the hear by the right and left cardiac nerves that are sympathetic postganglionic nerve fibers. The other is the cardioinhibitory cent, communicates with the heart via the right and left vagus nerves carrying parasympathetic preganglionic nerve fibers

How long does it take for a red blood cell leaving the left ventricle to arrive back to the left ventricle?

One minute

What is the average heart rate throughout ones life?

120 bpm in newborns

72 - 80 in adult females, 64 - 72 in adult males

Rises again in older adults

What is tachycardia?

Persistent resting adult heart rate above 100 bpm

Can be caused by stress, anxiety, stimulants, heart disease or fever

Heart ban also race when body has lost a significant amount of blood or damage to the myocardium

What is bradycardia?

Persistent resting heart rate below 60 bpm, common during sleep or endurance trained athletes

Endurance training enlarges the heart, increases stroke volume, enabling it to maintain same output with fewer beats

Hypothermia can cause bradycardia, and bradycardia can also be induced before undergoing cardiac surgery