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Thoracic cavities:

1. R. & L. pleural cavities.2. Pericardial cavity.

3. Mediastinum

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Pericardium: (serous membranes that cover the heart):

1. Parietal pericardium: close to chest wall.

** Pericardial cavity: space between 2 pericardiums.

a. Containing pericardial fluid.

b. Acts as a lubricant to reduce friction between heart &

chest wall.

2. Visceral pericardium (= Epicardium): Surface membrane of the heart

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2. Four valves:

A. Tricuspid valve: R.A. R.V.

B. Pulmonary valve: R.V. pulmonary trunkC. Bicuspid (=mitral) valve: L.A. L.V.

D. Aortic valve: L.V. Aorta

Chordae tendineae:

connective tissues connected tricuspid valve& bicuspid valve to heart wall through papillary muscles.

* Papillary muscles:

* A-V valves: including tricuspid valve and bicuspid valve.

* Semilunar valves: including pulmonary valve and aortic valve

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Superficial Anatomy of the Heart

Sulci

Coronary sulcusdivides atria and ventricles

Anterior interventricular sulcusand

posterior interventricular sulcus

Separate left and right ventricles

Contain blood vessels of cardiac muscle

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3. Three layers of heart wall:

A. Epicardium: ( or visceral pericardium): outer layer

B. Myocardium: muscular wall , thickest layer

C. Endocardium: inner surfaces (including valves)

4. Base & Apex of heart:

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Right atrium:

1. Also called R. auricle(ear shape)

2. Receiving blood from:

a. Superior vena cava

b. Inferior vena cava

c. Coronary sinus

3. Fossa ovalis: a remnant site of foramen ovale in fetus

(a hole between RA & LA)

4. Containing SA node & AV node.

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Right ventricle:

1. Tricuspid valve (= right A-V valve): gate between RA & RV

2. Chordae tendineae and papillary muscles:

3. Moderator band: muscle ridge containing nerve fibers

for conducting system

4. Conus arteriosus: superior end of RV, leading to pulmonary valve

5. Pulmonary valve (= pulmonary semilunar valve)

6. Pulmonary trunk: branches into 2 R. & 2 L. pulmonary arteries.

7. Ligamentum arteriosum: remnant of ductus arteriosus in fetus.

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Trabeculae carneae

Muscular ridges on internal surface of right

and left ventricles

moderator band: (in RV only)

Ridge contains part of condu ct ing system

Coordinates contractions of cardiac muscle

cells

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Left atrium:

1. auricle

2. Collecting blood from: 2 R & 2 L pulmonary veins

3. Bicuspid valve (=mitral valve: bishops hat): LA --> LV

Left ventricle:

1. Wall is thicker than that of RV. (Larger pressure, 4-6 times, is needed

for systemic circulation.)

2. Only 1 pair of papillary muscle. Chordae tendineae are less than that of RV.

3. No moderator band on ventricular muscles

4. Aortic valve (= aortic semilunar v.): between LV and aorta.

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*** R. & L. A-V valves Semilunar valves

1. Pieces of cuspids: R=3, L=2 All 3

2. Chodae tendineae: yes no

3. Papillary muscles: yes no

4. Fibrous skeleton: yes yes

(=Cardiac skeleton)

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Valvular heart disease (VHD):

1.Reasons:a. Valves can not be closed completely due to damages of

papillary muscles, chordae tendineae or valves.

b. Inflammation of heart (carditis) is one of the major

factor (ex. rheumatic fever).

2.Symptoms:

a. Backflow (regurgitation) of blood from ventricle to

atrium, or aorta to L. ventricle, or pulmonary trunk to

R. ventricle. (Bicuspid valve damage is most common.)

b. Abnormal heart sound (murmur).

c. Short of breath (due to the lack of oxygen).

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Intercalated disc of cardiac muscles:

1. These discs interlock adjacent cells by desmosomes & gap junctions.

2. Function: propagate action potentials (AP).

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Cardiac muscles differ from skeletal muscles in:

1. Cardiac have smaller-size cells.

2. Only a single nucleus in one cardiac muscle cell.

3. Presence of intercalated discs.

4. Having branching interconnections

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Direction of blood flow in heart:

Superior vena cava

RA RV pulmonary trunkInferior vena cava

Lungs

2R & 2L Pulmonary veins

LA

LV

Aorta

Systemic Circulation

Coron ary arter ies

Coronary s inus

2R & 2L Pulmonary arteries

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Coronary circulation:

1.Coronary arteries:

A. Right coronary art.

a. Marginal art.

b. Posterior interventricular art.

(= posterior descending art. = PAD)

B. Left coronary art.

a. Circumflex art. Marginal art.

b. Anterior interventricular art.

(= Left anterior descending art. = LAD)

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Right Coronary Artery

Supplies blood to the following areas:

Right atrium

Portions of both ventricles

Cells of sinoatrial (SA) and atrioventricular

nodes

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Left Coronary Artery

Supplies blood to the following areas:

Left ventricle

Left atrium

Interventricular septum

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2. Cardiac veins:

A. Coronary sinus: collecting blood from the followings:

a. Great cardiac Vein:

b. Posterior cardiac V.

c. Middle cardiac V.

d. Small cardiac V.

B. Anterior cardiac veins (very small):

empty blood into R. atrium directly.

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Coronary circulation:

1. Originates at the base of the ascending aorta (= aortic sinuses)

R. coronary artery L. coronary artery

Circumflex artery

RA Anteriorinterventricular art.

RV

LA

Posterior interventricular art. LV

Small cardiac v. Middlecard. v. Posterior card. v. Greater card. v.

Coronary sinus

RA (chamber)

2. Arterial anastomoses: Multiple arteries supply one tissue area (ex. LV).

ex. Connection between anterior& posteriorinterventricular arteries.

wall

wall

wall

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Two types of cardiac muscles:1. Conducting system (1 % )

2. Contractile cells (99 %)

Conducting system:

1. Sinoatrial (SA) node: 1st. pacemaker (80-100 pulses/min)

2. Internodal pathways:

3. Atrioventricular (AV) node: 2nd pacemaker (40-60 pulses/min)

4. AV bundle (=Bundle of His)

5. Bundle branches:

a. L: to LV (Larger size)

b. R: to moderator band papillary muscle tricuspid valve

6. Purkinje fibers: to L & R ventricles.

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EKG, ECG (electrocardiogram):

1. P wave: depolarization of the atria (R & L)

2. QRS complex: depolarization of the ventricles

3. T wave: repolarization of ventricles

4. Two important factors of ECG:a. voltage (mV)

b. duration (m sec): interval:[including wave(s)]

and segment: [between waves]

5. Depolarization: causing muscle contraction (= systole).

6. Repolarization: causing muscle relaxation (= diastole).

Figure 20-13b An Electrocardiogram

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g g

800 msec

SQ

QRS interval

(ventricles depolarize)

Millivolts

R

PR segmentT wave

(ventricles repolarize)

R

P wave

(atria

depolarize)

ST

segment

ST

interval

QT

interval

PR

interval

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Cardiac cycle:

1. Two phases:

a. systole (contraction of atria & ventricles)

b. diastole (relaxation of atria & ventricles)

2. period between each heart beat (800 mSec/cycle = mSec/beat)

3. 1 min= 60 Sec = 60,000 mSec;

60000 mSec/min

= 75 beats/min.

800 mSec/beat

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Action potential (AP) in cardiac muscles:

1. Rapid depolarization: sodium entry by fast sodium channels

2. Plateau: calcium entry by slow calcium channels

3. Repolarization: potassium loss (move out of cells)

AP in skeletal muscles:

1. No plateau stage

2. AP: shorter duration

3. Muscle contraction: shorter duration.

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Blood pressure (BP):

1. Measuring by Sphygmomanometer.

2. Listen to the sound (Korotkoff Sound) by stethoscope

** The sound is due to the turbulence of blood flow.

3. It is written as: systolic P./ diastolic P.

(ex. 120 mmHg/80 mmHg = 120/80)

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Blood volumes in L. ventricle during cardiac cycle:

1. EDV: (end-diastolic volume)--- 130 ml

2. ESV: (end-systolic volume) ----- 50 ml

3. SV: (stroke volume = pump-out volume),

SV = EDV- ESV (ex. 130-50= 80 ml)

Cardiac output (CO):

CO = HR x SV = (heart rate) x (stroke volume)

= HR x (EDV-ESV)

(ml/min) = (beats/min) x (ml/beat)

Ex. CO= 75 (b/min) x 80 (ml/b)= 6000 (ml/min)

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Heart sounds:

1. Using instrument: stethoscope

2. First heart sound (S1): lubb, AV valves close (last longer)

3. Second HS (S2): dupp, semilunar valves close

4. S3 (blood flows to ventricles), S4 (atrial contraction): both are weak

5. Places to listen (fig. 20-18a)

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Factors affects cardiac output:

1. Cardiac reflexes:

a. By baroreceptors and chemoreceptors

b. Cardiac center: medulla oblongata(-) BP, (-) O2, (+) CO2 (+) HR

2. Autonomic tone:

a. Sympathetic N.: ---------- NE (+) HR

b. Parasympathetic N.: ---- Ach (-) HR (Nerves IX & X)

3. Hormones:

a. Epi, NE (norepinephrine): (+) HR

b. Thyroid hormones (T4, T3): (+) HR

c. Glucagon: (+) SV (+) CO

4. EDV:

5. ESV:

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4. EDV:

* Frank-Starling Principle = Starling Law

(+) EDV (+)SV (+) CO , (More blood in = More blood out)(More EDV More CO)

(More preload More CO)

5. ESV: (-) Afterload (-) ESV (+) SV (+) CO

(+) Afterload (+) ESV, (-) SV (-) CO

(Less afterload less ESV More CO)

** (ps) Afterload:

the amount of tension (or pressure) that ventricles

must produce to force open semilunar valves.

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Baroreceptors (for blood pressure):

1. R. & L. internal carotid sinuses

2. Aortic sinus: near the base of aortic arch

** When blood pressure is high at carotid & aortic sinuses:

increasing stretch of baroreceptors CNS

activating parasympathetic N.releasing Ach

(-) HR, (+) vasodilation

(-) blood pressure

3. Right atrial baroreceptors (atrium wall)

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Influences on Stroke Volume Preload(affect of stretching)

Frank-Starling Law of Heart

more muscle is stretched ( EDV),

greater force of contraction

more blood in, more force of contraction results

Contractility

autonomic nerves, hormones, Ca+2or K+levels

Afterload

amount of pressure (tension) created by

semilunar valves & arteries

high blood pressure creates high afterload

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Clinic terms:

1. CAD: coronary artery disease

2. Heart attack: blockage of coronary circulation &

death of some cardiac muscles.

3. Stroke: bleeding in brain due to clotted andbroken blood vessels

4. Bradycardia: slow HR

5. Tachycardia: fast HR

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Clinical Problems

MI = myocardial infarction = (heart attack)

death of area of heart muscles due to lack of O2

replaced with scar tissue

results depend on size & location of damage

Blood clot

use clot dissolving drugs streptokinase or t-PA

& heparin

balloon angioplasty

Angina pectoris----heart pain due to ischemia of

cardiac vessels & short of O2 in cardiac muscles.

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Myocardial infarction (MI), or heart attack

Pain does not always accompany a heartattack, therefore, the condition may goundiagnosed and may not be treatedbefore a fatal MI occurs

Damaged myocardial cells releaseenzymes into the blood circulation.

The enzymes include:

Cardiac troponin T,

Cardiac troponin I,

Creatinine phosphokinase, CK-MB

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Congestive Heart Failure

Causes of CHF coronary artery disease, hypertension, MI, valve

disorders, congenital defects

Left side heart failure

less effective pump so more blood remains inventricle

heart is overstretched & even more blood remains

blood backs up into lungs as pulmonary edema suffocation & lack of oxygen to the tissues

Right side failure

fluid builds up in tissues as peripheral edema

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Risk Factors for Heart Disease

Risk factors in heart disease: high blood cholesterol level

high blood pressure

cigarette smoking

obesity & lack of regular exercise.

Other factors include:

diabetes mellitus

genetic predisposition

male gender

high blood levels of fibrinogen

left ventricular hypertrophy

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Plasma Lipids and Heart Disease

Risk factor for developing heart disease ishigh blood cholesterol level.

Most lipids are transported as lipoproteins HDLs remove excess cholesterol from circulation

LDLs are associated with the formation of fattyplaques

VLDLs contribute to increased fatty plaqueformation

There are two sources of cholesterol in thebody: in foods we ingest

formed by liver

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Desirable Levels of Blood

Cholesterol for Adults

TC (total cholesterol) under 180 mg/dl

LDL under 100 mg/dl

HDL over 40 mg/dl

Triglycerides: 10-190 mg/dl.

Among the therapies used to reduce blood

cholesterol level are exercise, diet, and drugs.

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Total cholesterol

= LDL + HDL + (Triglyceride x 0.2)

Ex. 100 + 50 + (150 x 0.2)

= 100 + 50 + 30

= 180 (mg/dL)

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Exercise and the Heart

Sustained exercise increases oxygen demandin muscles.

Benefits of aerobic exercise (any activity that

works large body muscles for at least 20minutes, preferably 3-5 times per week) are;

increased cardiac output

increased HDL and decreased triglycerides

improved lung function

decreased blood pressure

weight control.