The Heart/Circulatory System

The Pump - Heart (Briefly now - more later)

•pericardium

• 4 chambers

Valves:

• generally three cusps (1 bicuspid)

• anchored via chordae

 

Heart Blood Supply

coronary arteries and veins - become occluded (plaque of cholesterol)

--> heart attack

 

Circulation

Arteries - away from heart - usually high O2

1) damping of pressure fluctuations

2) pressure reservoir

Veins - usually low O2

• Trace blood cell from lungs and back

Capillaries:

• v small diameter

• v thin walled (1 µm) - THE place for diffusion

• varies among tissues:

• some bulk flow of fluids out of capillaries as well

Venules

Capillary Beds

• made up of arterioles, capillaries, and venules

Arterioles:

• smooth muscle

• vasomotor control

EX 1 - response to cold

EX 2 - Excercise

 

Heart Physiology

• electrically coupled cells - gap junctions

intercalated discs

pacemaker cells - right atrium (sinoatrial node)

from SA node

AV node

Bundle of His

Ionic basis of pacemaker cells

• Ca++ ions leak into cell

---> threshold --> typical AP (Na+ mediated)

EKG

P wave

QRS complex

T wave

DIAGNOSES

• incr P --> enlarged atrium

• higher Q --> heart attack

• incr R ---> enlarged ventricles

• Can be correlated w/ heart sounds

 

Blood Pressure

• systole

diastole

Regulation of Heart Action

• myogenic

• nervous and hormonal

• main center - medulla oblongata

receives info re:

Sympathetic stimulation -

Parasympathetic stimulation -

Effects of Exercise

1) stroke volume

2) heart rate

3) blood pressure

4) mass of heart

 

Artherosclerosis

• 50% deaths in U.S.

Risk Factors:

• cholesterol (a lipid) - carried in blood attached to proteins

Low Density Lipoprotein

HDL - "Good Cholesterol"