the heart

The Heart

The Location of the Heart in the Thoracic Cavity

Figure 20.2c

The pericardia

Echocardiogram

The cardiovascular system is divided into two circuits Pulmonary circuit

blood to and from the lungs System circuit

blood to and from the rest of the body

Vessels carry the blood through the circuits Arteries carry blood away from the

heart Veins carry blood to the heart Capillaries permit exchange

An Overview of the Cardiovascular System

Figure 20.1

Compare (what is the same) and Contrast (what is different) Pulmonary and Systemic Circuits1.Oxygenated

Deoxygenated2.Pressure3.Arteries Veins4.Color

Atria Thin walled chambers that receive blood

from the vena cavae Ventricles

Thick walled chambers separated from the atria by AV valves

Chordae tendineae Tendinous fibers attached to the AV

valves Papillary muscle and trabeculae

carneae Muscular projections on the inner wall of

ventricles

Internal Anatomy and Organization

1. Right atria Tricuspid valve

2. Right ventricle Pulmonary

valve3. Pulmonary

circuit4. Left atria

Bicuspid valve5. Left ventricle

Aortic valve6. Aorta and

systemic circuit

Blood flow through the heart

The Sectional Anatomy of the Heart

Figure 20.6a, b

Animation: Diagrammatic Frontal Section through the Heart

The Sectional Anatomy of the Heart

Figure 20.6c

Heart chambers and valves

Structure and Function Question:

Why does the human

heart have four chambers?

Structural Differences in heart chambers The left side of the heart is more

muscular than the right side

Functions of valves AV valves prevent backflow of blood from

the ventricles to the atria Semilunar valves prevent backflow into

the ventricles from the pulmonary trunk and aorta

Leaky valves????

Heart chambers and valves

Structural Differences between the Left and Right

Ventricles

Figure 20.7a-c

1. Volume

2. Thickness of wall

3. AV valve

4. Force of contraction

Valves of the Heart

Figure 20.8a

Valves of the Heart

Figure 20.8b

Organization of Heart Tissues

Components of the heart wall include Epicardiu

m Myocardiu

m Endocardi

um

The Heart Wall

Quiz Yourself- pg 453 in lab manual

The Heart Wall and Cardiac Muscle Cells

Figure 20.5a-c

The heart consists of four chambers Two atria and two ventricles

Major blood vessels of the heart include Inferior and superior vena cavae Aorta and pulmonary trunk

Superficial Anatomy of the Heart

The Superficial Anatomy of the Heart

Figure 20.3a

The Superficial Anatomy of the Heart

Figure 20.3b, c

Arteries: right/ left coronary arteries,

Veins: Great cardiac vein, anterior and posterior cardiac veins

Blood Supply to the Heart

Coronary Circulation

Figure 20.9c, d

By Pass Surgery- Video

Complete Activity 2, 3, 4 Lab 30

The conducting system includes: Sinoatrial (SA) node Atrioventricular (AV) node Conducting cells

Atrial conducting cells are found in internodal pathways

Ventricular conducting cells consist of the AV bundle, bundle branches, and Purkinje fibers

The Conducting System

SA node begins the action potential Stimulus spreads to the AV node Impulse is delayed at AV node Impulse then travels through

ventricular conducting cells Then distributed by Purkinje fibers

Impulse Conduction through the heart

Impulse Conduction through the Heart (figure

18.15)

Figure 20.13

Cardiac Cycle

Systole- contraction (ventricle) Diastole: relaxation (ventricle)

Key Idea: Both atria fill an contract at same time Both ventricles fill and contract at the same time

A Very efficient pump!

Pulmonary Edema

Regulation of Stroke Volume

More stretch = more forceful contraction

Think about rubber bands! High volume of venous return causes

more stretching of myocytes

Factors that increase venous return: 1. slow heart rate (why?) 2. exercise (why)

Regulation of Heart Rate

Normal heart rate is _____________?

Tachycardia and bradycardia……Medulla Oblongata (Brain stem) Sympathetic Parasympathetic Cardiaccelatory Cardioinhibitory Center (vagus nerve) center

SA/AV node SA/AV node

Regulation of Heart Rate

Sympathetic nervous system- speeds up heart rate

epinephrine (adrenaline) , norepinephrine Stress and exercise, high level of calcium

Parasympathetic nervous system- slows heart rate beta blockers, morphine- block epinephrine binding sites calcium channel blockers

Alcohol- decreases activity of the vagus nerve- and the caridoaccelratory center in the brain stem.