The Human Heart

Unit X

Heart Action• Controlled by ANS:

• Medulla

• Beats per minute:

• 70/80 (normal)

Heart Action Cont.• Blood cycle:

• One minute

• Blood loss:

• 35% Serious

• 50% Fatal

Heart Action Cont.• Factors that affect heart rate:

• Age

• Weight

• Physical condition

• Emotional State

• Gender

Heart Contractions• Four chambered heart

• Atria (atrium):

• Contract first

• Ventricle(s):

• Contract second

• “All or None Law”

Heart Contraction Cont.• Vagus nerve

• Sinoatrial node: “SA node”

• “Pacemaker of Heart”

• Regulates heartbeat

• Atrialventricular node: “AV node”

• “Bundle of His”

Atria

Ventricles

SA node

AV node

Bundle of His

Heart Contraction: Impulse Transmission

Heart Cont.• Composition:

• Cardiac muscle

• Location:

• Pericardial cavity

• Pericardium (membrane)

• Pericardial fluid

Heart Cont.• Heart structure*

• Blood flow* (Overhead)

Blood Vessels• Veins:• Carry blood to heart• High in CO2

• 3 tissue layers• One-way valves

Blood Vessels Cont.• Arteries:• Carry blood away from

heart• High in O2

• 3 tissue layers (much thicker)

Blood Vessels Cont.• Capillaries:• Connect arteries to veins

• Gas exchange

Blood Vessels Cont.• Coronary Arteries & Veins:• Supply the heart

Blood Pressure•Two types:• Systolic*

• Diastolic*

Systolic• Contraction of ventricles

• Range: 90-140 mmHg

• (120 average)

Diastolic• Ventricles relax (atria fill)

• Range: 60-90 mmHg

• (80 average)

Blood Pressure Cont.• Major causes of high blood

pressure:

• Heart attack

• Stroke (most common problem)

High Blood Pressure Factors

• Age

• Weight

• Emotions• Physical cond.

• Diet

• Arteriosclerosis

• Blood viscosity

• Blood volume

• Cardiac output

• Gender

General Review• 60,000-100,000 miles

• Heparin

• Hemophilia

• Streptokinase

• Epinephrine-serotonin

• Heart cells (size, not #)

That’s All Folks!!

Quiz Tomorrow