HEART PHYSIOLOGY(HOW THE HEART WORKS)

HEART SOUNDS

HEART SOUNDS Blood turbulence from closing valves 2 sounds:

Lubb (closing of valves between atria and ventricles)

Dupp (closing of valves after ventricles)

HEARTSOUNDS

Heart physiology

• Internal pacemaker regulates beating of heart by setting a rhythmic electrical excitation

1. Begins in (1) sinoatrial node (in right atrium)

2. to atrioventricular node (2)(between atria) to

3. bundle of His (3)to

4. right and left bundle branches (interventricular septum towards apex) (4) to

5. Purkinje fibers (from apex upward) (5)

This “wave” of activity is picked up by an

electrocardiogram (ECG)

ELECTROCARDIOGRAM(ECG or EKG)

Recorded electrical currents of heart Determine healthy heart

P wave: atrial depolarization (contraction follows)

QRS complex: ventricular depolarization T wave: ventricular repolarization (start

relaxing)

BLOOD FLOW

pulse• Alternating expansion

and recoil of an artery• Wrist pulse = radial

artery• Neck pulse = carotid

artery

Blood pressure • Generated by contraction of

ventricles• Pressure exerted by blood

on walls of a blood vessel• Highest in aorta; falls as

distance from left ventricle increases

• Bp, as a vital sign, measures pressure in aorta/large arteries

Blood pressure

• 2 measurements: systolic (heart contraction) and diastolic (relaxation) pressure. EX. 120/80

• Affected by cardiac output and peripheral resistance

Cardiac output

• Stroke volume x heart rate• Stroke volume (SV) = amount of blood

ejected from heart each minute.• HR = # of beats per min.

resistance

• Affected by– diameter of blood vessel: – Blood viscosity (ratio of rbc

to fluid): increase by dehydration, polycythemia; decrease to anemia, hemorrhage

– Total blood vessel length: obesity

• What does blood pressure measure?

• What factors can raise blood pressure?

SystolicDiastolic

FACTORS AFFECTING BLOOD

FLOW

Vol. of blood through any tissue for a given time period.

Factors: Cardiac output: heart rate x stroke volume

(amount of blood per minute) Blood pressure Resistance

Size of vessel diameter Blood viscosity Total blood vessel length

HYPERTENSION

High blood pressure Major cause of heart failure and stroke Causes:

Overweight Excessive alcohol Lack of exercise Diet:

high saturated fat (meat/butter)*****, high salt, low minerals (potassium, calcium)

Stress

******** newest science indicates processed food is to blame, not saturated fat