The Heart



Pathophysiology: Normal Heart Anatomy & Physiology

I. Heart Anatomy: Your Objectives:

← Determine the size & location of the heart.

← Determine the function/importance/description of each of the following parts.

← Determine the location of the parts on a heart diagram

Heart location and size

← Weight in lbs and grams _______________________________________

← Location in chest (give landmarks to describe)

Heart Structures:

← Heart Wall & Pericardial Cavity

o Parietal pericardium

▪ Lines pericardial cavity

o Pericardial cavity

▪ Contains serous fluid

▪ Reduce friction

o Visceral pericardium

▪ (aka. Epicardium)

▪ Lines heart

o Myocardium - pumps

o Endocardium – reduces friction

← Chambers & associated structures

o Atrium (atria = plural)

o Ventricles

o Septum

← Valves and associated structures

o Atrioventricular valves

▪ Tricuspid

▪ Bicuspid (aka. Mitral)

o Chordate tendinae & papillary muscles

▪ Anchor AV valves to prevent backflow

o Semilunar valves

▪ Pulmonary SL

▪ Aortic SL

o Know how valves open & close to prevent backflow of blood which is important in keeping oxygenated & deoxygenated blood from mixing and gets them to the right structures.

o What is the first heart sound caused by?

o What is the second heart sound caused by?

o What is a heart murmur caused by?

← Blood vessels (major)

o Superior vena cava

o Inferior vena cava

o Pulmonary trunk

o Pulmonary arteries (right and left)

o Pulmonary veins (right and left)

o Aorta (ascending, descending, arch)

← Fetal structures – what is the purpose of these 2 structures in a fetal heart?

o Foramen ovale

o Ductus arteriosus

1. Why are the circulatory system organs lined with endothelium?

2. Which chamber has thickest most muscular walls and why?

3. What is the purpose of the 4 valves?

Heart Diagram: Label the following parts on this diagram. Know these for your Quiz #1

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II. Pathway of circulation: Your Objectives

← Differentiate between pulmonary circuit and systemic circuit: which side of the heart is involved in each and what is the purpose of each?

← Determine the complete pathway a drop of blood would take beginning in the superior and inferior vena cava

Two events happen in a heart beat

1. electrical event which causes:

2. muscular event/contraction

Either event can have problems so doctors need the ability to check each one.

The Conduction system

I. Conduction System of the Heart - Know parts on diagram

Cardiac muscle needs organization/rhythm and speed control for maximum efficiency- So two controlling/coordinating systems are needed:

A. autonomic nervous system divisions

1. sympathetic NS - increase rate & force

2. parasympathetic NS - decrease heart rate & force

B. Intrinsic conduction system

a. sinoatrial (SA) node

b. atrioventricular (AV) node

c. AV bundle & bundle branches

d. Purkinje fibers

Electrical Event

A. electrical events caused by conducting system are recorded as deflection waves transmitted to entire body by means of electrolytes. The recording of heart electrical waves is called an ECG or EKG - electrocardiogram

B. ECG has 3 kinds of deflection waves

1. P wave

a. atrial depolarization (electricity)

2. QRS complex

a. ventricular depolarization (electricity)

c. atrial repolarization is hidden by QRS complex

3. T wave

a. ventricular repolarization (electricity)

C. healthy heart - consistant deflection waves

Be able to label the waves of an ECG and recognize normal and defective patterns.

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Muscular event – the Cardiac Cycle

I. alternate contraction and relaxation of heart

1. described in terms of ventricular events

2. systole - contraction

3. diastole – relaxation

. An echocardiogram is a sonogram of the heart and is used to

visualize the opening/closing of valves and working of muscles

II. Phases of cardiac cycle

A. mid to late diastole (heart is in complete relaxation) - ventricular filling

1. pressure in heart is low - blood flows passively into atria then ventricles

2. AV valves open - semilunar valves closed

3. 70% of ventricular filling occurs

4. atria begin to contract forcing remaining 30% of blood into ventricles

5. pressure in ventricles begins to close AV valves

B. ventricular systole

1. BP in ventricles rises sharply - closes AV valves

atrial begin filling again

2. isovolumetric contraction phase

a. while both sets of valves are closed - the muscle contracts which builds pressure for a very short time period

3. BP exceeds BP in aorta & pulmonary trunk and forces SL valves open

4. ventricular ejection phase

a. blood expelled into aorta and pulmonary trunk

b. normal aorta pressure is 120 mm Hg

C. Early diastole / isovolumetric relaxation phase

1. ventricles relax and pressure drops

2. blood backflow closes semilunar valves

1. atrial pressure will then force open AV valves

D. Cardiac cycle = 0.8 secs

1. atria systole = 0.1 secs

2. vent systole = 0.3 secs

3. total heart relaxation (quiescent period) = 0.4 secs

only time heart gets to relax

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Aorta

Label the diagram directly on the part without using leader lines: see example

Aorta

Aortic semilunar valve

Apex

Bicuspid valve

Descending Aorta

Inferior vena cava

Left Atrium

Left pulmonary artery

Left pulmonary veins

Left Ventricle

Pulmonary semilunar valve

Pulmonary trunk

Right Atrium

Right pulmonary artery

Right pulmonary veins

Right Ventricle

Septum

Superior vena cava

Tricuspid valve

Diagram #2 – Trace the pathway of blood flow

← Use blue arrows for deoxy blood

← Use red arrows for oxy blood

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