Anatomy & Physiology of Heart | Lecture notes Nursing

CIRCULATORY SYSTEM

⮚It is a fluid-filled network of tubes through

which materials move between the

environment and the cells of a multicellular

animal.

Major Components OF CIRCULATORY SYSTEM

⮚Heart

⮚Blood

⮚Blood vessels- veins, arteries, capillaries

Anatomy and Physiology of the Heart

Heart

⮚Primary function is to pump blood through the

arteries, capillaries and veins

⮚Pumps blood which creates blood pressure,

circulates oxygen nutrients and other

substances

LOCATION SIZE and the Shape of the Heart

⮚It weighs 300g and approximately the size of

the fist, 5 inches in length and 3 inches wide.

⮚The shape of the heart is somewhat cone like in

appearance.

⮚Mediastinum- the central section of the thorax

(chest cavity). It is in this area that the heart is

house, lying in front of the spinal column,

behind the sternum and between the lungs

⮚Two thirds of the heart lies to the left of the

midline, the apex of the heart just above the

diaphragm and the base of the heart lies at

approximately the level of the third rib

⮚The heart is enclosed by

pericardium/pericardial sac which consist of

two layers

1. Visceral pericardium- thin serous inner layer

which surrounds the heart.

2. Parietal pericardium- outer layer, consist of

tough, nonelastic, fibrous connective tissue and

serves to prevent over distension of the heart.

⮚In between the parietal and visceral

pericardium is a serous fluid (5-10ml) in the

pericardial sac, that prevents friction between

the two pericardial membranes as the heart

beats.

Layers of the heart are as follows:

a. Epicardium- outermost layer, a smooth outer

surface of the heart

b. Myocardium- thick middle layer composed

primarily of cardiac muscle cells heart where

the four chambers are made. Responsible for

the heart’s ability to contract

c. Endocardium

⮚Innermost layer of the heart composed of

thin connective tissue

⮚It lines the chambers and covers the heart

valves of the heart

⮚important characteristic is its smoothness

that prevents abnormal blood clotting

CHAMBERS OF THE HEART

⮚the four chambers of the hear are as follows:

⮚right atrium and right ventricle which are thin

and separated by the interatrial septum

⮚left atrium and left ventricle have thicker walls

and separated by interventricular septum

RIGHT ATRIUM

⮚receives deoxygenated blood from the body by

way of the Superior vena cava (SVC) and inferior

vena cava (IVC).

⮚From the RA, blood will flow to the right

atrioventricular valve or tricuspid valve into

the right Ventricle (RV)

⮚Tricuspid valve- prevents back flow of blood

from the RA to RV, when the RV contracts.

⮚Located between RA and RV

RIGHT VENTRICLE

⮚Receives blood from the RA and ejects this

blood into the lungs via Pulmonary artery.

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CIRCULATORY SYSTEM

⮚ It is a fluid-filled network of tubes through

which materials move between the

environment and the cells of a multicellular

animal.

Major Components OF CIRCULATORY SYSTEM

⮚ Heart

⮚ Blood

⮚ Blood vessels- veins, arteries, capillaries

Anatomy and Physiology of the Heart

Heart

⮚ Primary function is to pump blood through the

arteries, capillaries and veins

⮚ Pumps blood which creates blood pressure,

circulates oxygen nutrients and other

substances

LOCATION SIZE and the Shape of the Heart

⮚ It weighs 300g and approximately the size of

the fist, 5 inches in length and 3 inches wide.

⮚ The shape of the heart is somewhat cone like in

appearance.

⮚ Mediastinum- the central section of the thorax

(chest cavity). It is in this area that the heart is

house, lying in front of the spinal column,

behind the sternum and between the lungs

⮚ Two thirds of the heart lies to the left of the

midline, the apex of the heart just above the

diaphragm and the base of the heart lies at

approximately the level of the third rib

⮚ The heart is enclosed by

pericardium/pericardial sac which consist of

two layers

1. Visceral pericardium- thin serous inner layer

which surrounds the heart.

2. Parietal pericardium - outer layer, consist of

tough, nonelastic, fibrous connective tissue and

serves to prevent over distension of the heart.

⮚ In between the parietal and visceral

pericardium is a serous fluid (5-10ml) in the

pericardial sac, that prevents friction between

the two pericardial membranes as the heart

beats.

Layers of the heart are as follows:

a. Epicardium - outermost layer, a smooth outer

surface of the heart

b. Myocardium - thick middle layer composed

primarily of cardiac muscle cells heart where

the four chambers are made. Responsible for

the heart’s ability to contract

c. Endocardium

⮚ Innermost layer of the heart composed of

thin connective tissue

⮚ It lines the chambers and covers the heart

valves of the heart

⮚ important characteristic is its smoothness

that prevents abnormal blood clotting

CHAMBERS OF THE HEART

⮚ the four chambers of the hear are as follows:

⮚ right atrium and right ventricle which are thin

and separated by the interatrial septum

⮚ left atrium and left ventricle have thicker walls

and separated by interventricular septum

RIGHT ATRIUM

⮚ receives deoxygenated blood from the body by

way of the Superior vena cava (SVC) and inferior

vena cava (IVC).

⮚ From the RA , blood will flow to the right

atrioventricular valve or tricuspid valve into

the right Ventricle (RV)

⮚ Tricuspid valve- prevents back flow of blood

from the RA to RV, when the RV contracts.

⮚ Located between RA and RV

RIGHT VENTRICLE

⮚ Receives blood from the RA and ejects this

blood into the lungs via Pulmonary artery.

⮚ At the junction of this large artery and the RV is

the Pulmonary Semilunar valve

Pulmonary valve - prevents back flow of blood from the

pulmonary artery to the RV when RV relax.

LEFT ATRIUM

⮚ Receives oxygenated blood from the lungs by

way of four pulmonary veins.

⮚ This blood will flow into the left ventricle

through Mitral or Bicuspid valve.

Mitral/Bicuspid- it prevents back flow of blood

from LV to LA when LV contracts

⮚ Other function:

- Produce hormone involve in BP maintenance.

When the walls of the atria are stretched by

increase blood volume or blood pressure, the

cells produced Atrial natriuretic peptide.

LEFT VENTRICLE

⮚ Receives blood from the left atrium and ejects

blood into systemic arterial circulation.

⮚ Pumps blood to the body through the AORTA.

⮚ At the junction of aorta and LV is the Aortic

Semilunar valve/Aortic Valve.

- This valve is closed when the LV relaxes, to

prevent back flow of blood from the Aorta to

the Left Ventricle.

VALVES of the Heart

⮚ There are two set of valves: The atrioventricular

and semi lunar valves

ATRIOVENTRICULAR valves

- are tricuspid valve and bicuspid (mitral) valve,

located in between atria and ventricles

- allow blood to flow from the atria into the

ventricles

- Effective in preventing backflow of blood into

the ATRIA.

⮚ Tricuspid - name for its three cups, located

between RA and RV. Free edge of each of these

three cups extend into the ventricles where

they attach to the chordae tendineae.

⮚ Chordae tendeneae are fine chords of dense

connective tissue that attached to the papillary

muscles in the wall of the ventricles. The

chordae tendeneae supports the AV valves

during ventricular systole to prevent valvular

prolapse in the Atrium.

Papilliary muscles and chordae tendeneae - it prevents

inversion of the AV valves when the ventricles contract.

⮚ MITRAL/Bicuspid - located between LA and LV

SEMILUNAR VALVES

- are the aortic valve and pulmonic valve.

- Prevent backflow of blood into the ventricles

⮚ Aortic valve- lies between the LV and the aorta.

⮚ Pulmonic valve - lies between RV and

pulmonary artery.

During ventricular systole- the AV valves are close and

the semilunar valves are open.

During ventricular diastole- the semilunar valves are

close, and the AV are open.

CORONARY ARTERIES

● The coronary arteries originated from the aorta

just behind the aortic valve

● The two main coronary arteries are

Left Coronary Artery (LCA) and the Right

Coronary Artery (RCA) – supply blood to the

myocardium

● The LCA divides into two branches namely: the

Circumflex Coronary Artery (CCA) and Left

Anterior Descending Artery (LADA)

● CCA - supplies the LA, posterior lateral surface of

the LV.

● LADA - supplies the anterior wall of the LV, the

anterior interventricular septum, the anterior

papillary muscles and the apex of the heart.

● RCA - supplies the RA, RV, a portion of the

septum, SA node, AV node, and the inferior

portion of the ventricle.

⚫ It is determined by the amount of venous return ⚫ Increased Preload- fluids, SNS (vasoconstriction), Decreased Preload (Diuretics-Furosemide, Nitroglycerine (vasodilator) FRANK STARLING LAW ▪ Starling Law conceptualizes that the greater the myocardial stretch within physiologic limit, the more forceful the ventricular contraction resulting to increase Stroke volume. CONTRACTILITY ⚫ a change in inotropic state of the muscle without a change in myocardial fiber length or preload. ⚫ Strength of the cardiac cells to contract or shorten AFTERLOAD ⮚ The amount of tension in the ventricle during contraction to eject blood from the left ventricle into the aorta. ANS influences on Cardiac Activity SNS ⮚ responsible for preparation of the body for physical activity (Fight or Flight). ⮚ releases norepinephrine PNS ▪ regulates the calmer (Rest and Digest) functions ▪ Releases Acetylcholine CHEMORECEPTORS ⚫ Medulla Oblongata and special receptors are found in the carotid and aortic bodies which can regulate respiratory ACTIVITY. ⚫ are sensitive to changes in arterial carbon dioxide, oxygen, and pH. ⚫ A decrease pH or increase in paCO2 level causes a reflex SNS response that result in tachycardia, vasoconstriction and increased myocardial contractility ⚫ Decreased paCO2 and increased pH leads to vasodilation ⚫ A decrease pH or increase in paCO2 level leads to passive vasodilation Two Basic Myocardial Cell Groups

1. MYOCARDIAL WORKING CELLS ⮚ Are responsible for generating the physical contraction of the heart ⮚ The primary function of MWC include both CONTRACTION and RELAXATION 2. SPECIALIZED PEACEMAKER CELLS ⮚ Responsible for controlling the heart rate and the rhythm of the heart by coordinating regular depolarization ⮚ The primary function is for GENERATION and CONDUCTION of electrical impulses

Primary Cardiac Cell Characteristics

Automaticity

⮚ is the ability of the heart to initiate impulses

repetitively and spontaneously. Meaning the

cardiac muscle cells can generate their own

electrical impulses spontaneously without

external (nervous) stimulation. This intrinsic

spontaneous depolarization frequency produces

contraction of the myocardial cells.

Excitability -

⮚ the ability of the cardiac cells to respond to a

stimulus by initiating a cardiac impulse. It is

called irritability

Conductivity

⮚ the ability of the cardiac cells to receive to an

impulse by transmitting the impulse along cell

membranes.

Contractility

⮚ the ability of the cardiac cells to shorten and

cause cardiac muscle contraction in response to

electrical stimulus.

⮚ Known as rhythmicity.

⮚ Administration of epinephrine and dopamine

can enhance contractility

ELECTRICAL HEART CONDUCTION SYSTEM

⮚ The cardiac cycle is a sequence of mechanical

events that is regulated by the electrical activity

of the myocardium. The heart generates its

own beat, and the electrical impulses follow a

very specific route throughout the myocardium.

Sinoatrial (SA) Node

● Located in the upper portion of the Right Atrial

wall of the heart near the opening of SVC. SA

node receives its blood supply from SA artery.

● Made up of cluster of cells capable of

generating impulses travel throughout the

muscle fibers of both atria resulting in

DEPOLARIZATION

● the natural peacemaker of the heart is - has the

most rapid rate of contraction, it depolarizes

more rapidly than any other part of the

myocardium. The SA node triggers electrical

impulses at a firing rate of 60-100 beats per

minute.

● Furthermore, the SA node represents the P- wave (atrial contraction) on the EKG tracing.

INTERNODAL PATHWAYS

● distribute the electrical impulse from the SA

node throughout the ATRIA to the AV node

● The atria then depolarized and the impulse for

contraction is transmitted to the

atrioventricular (AV) node

● The transmission of impulses from the SA node

to the AV node and to the rest of atrial

myocardium brings ATRIAL SYSTOLE

AV (Atrioventricular) node

● Located on the floor of the right atrium just

above the tricuspid valve

● At the level of the AV node, the electrical

activity is delayed approximately 0.05sec.

● This delay allows for atrial contraction and a

complete filling of the ventricles. If there wasn’t

a delay the atriums would not fully empty into the ventricles which would cause problems.

● 3 regions: AV junctional tissue between the

atria and node, the nodal area , and AV

junctional tissue between the node and Bundle

of His

● The only pathway for conduction of atrial

impulse s to the VENTRICLES is the AV Bundle/

Bundle of His

● Slows impulse, intrinsic firing rate of 40-

60BPM

● The electrical impulses is transmitted into the

Bundle of His and travel into the Purkinje fibers

to the rest of the ventricular myocardium to

bring about VENTRICULAR systole.

AV JUNCTION

● Region where the AV node joins the Bundle of

His

● Similar to SA node, AV Junctional tissue contain

fibers that can depolarize spontaneously

forming an electrical impulse that can spread to

the heart chambers

● Therefore, if the SA node fails or slows below its

normal range, the AV junctional tissues can

initiate electrical activity to assume the role of

Secondary pacemaker

BUNDLE OF HIS

● The conduction pathway that leads out of the

AV node

● Approximately 15mm long and lies at the top of

the interventricular septum

● Called as Common Bundle- Two main branches

(left and right) that conduct electrical activity

from the Bundle of His down to Purkinje

Network

● Contains pacemaker cells that have the ability

to self initiate electrical activity at an intrinsic

firing rate of 40-60BPM

PURKINJE’S NETWORK

● Spread impulse throughout the ventricles

resulting to ventricular contraction

● Ventricular contraction is facilitated by the

rapid spread of electrical impulse through the

Left and Right Bundle branches and Purkinje

Fibers into the ventricular muscle

- Transportation-hormones, gasses, nutrients, ions, **heat

Regulation- pH, temperature, water balance in cells
Protection- clotting, white cells interferons,** complement Characteristics of BLOOD Volume ⮚ Female: 4-5 L ⮚ Male: 5-6 L Temperature ⮚ 38° C (100.4° F) pH: ⮚ 7.35 - 7. Viscosity ⮚ relative to water Formation of Blood Cells ⮚ Called hemopoiesis ⮚ Just before birth and throughout life occurs in red bone marrow ⮚ Contains pluripotent stem cells ⮚ **In response to specific hormones these develop through a series of changes to form all of the blood cells Composition/Component of the BLOOD

PLASMA** ⮚ Watery straw colored part of the blood ⮚ Made up of water, proteins, glucose, fats and gases ⮚ Transport nutrients ⮚ Maintain acid base balance ⮚ Transport waste from the tissues ⮚ ~91% water, 7% proteins, 1.5 % other solutes ⮚ Proteins: Albumin (54%)- osmosis and carriers; ⮚ Globulins (38%)- antibodies ⮚ Fibrinogen (7%)- clotting ⮚ Other: Electrolytes , nutrients, gases, hormones, vitamins & waste products 2. The Formed Elements **- (blood cells/cell fragments)
RBC/Erythrocytes** ⮚ Transport O2 and CO2 to and from tissues. ⮚ Contain Hemoglobin ⮚ **Has a lifespan of 90-120days
White Blood Cells (WBC)** ⮚ Defenses: phagocytes, antibody production and antibacterial action ⮚ Phagocytes: ⮚ Neutrophil- first responders ⮚ Monocytes 🡺macrophages (big eaters) ⮚ Eosinophil- phagocitize antibody-antigen complexes Involved in suppressing allergic responses ⮚ Basophil- intensify allergic reactions ⮚ Immune response- T-cells, B-cells& natural killer (NK) cells ⮚ Granulocytes- Neutrophils, Eosinophils, Basophils ⮚ Agranulocytes- Lymphocytes , Monocytes- that reside in your blood and tissues to find and destroy germs (viruses, bacteria, fungi and protozoa) and eliminate infected cells. Monocytes call on other white blood cells to help treat injury and prevent infection. ⮚ 4,000-11,000/μl WBC Life Span

5000-10,00 WBC /μl blood
Limited number of bacteria can be eaten
Life span is a few days
During active infection may be hours
Leukocytosis = increased WBC numbers 🡺response to stresses
Leukopenia = decreased WBC numbers 3. PLATELETS ⮚ Smallest cells in the blood ⮚ Essential for coagulation of blood ⮚ Plug damaged blood vessels ⮚ Promote blood clotting ⮚ Life span 5-9 days ⮚ 130,000-360,000/μl General Properties of Whole Blood Hematocrit ⮚ RBCs as percent of total blood volume ⮚ Female: 37%-48% ⮚ Male: 45%-52%

Hemoglobin ⮚ Female: 12-16 g/100 ml ⮚ Male: 13-18 g/100 ml DIAGNOSTIC TEST ECG ⮚ It is a graphical recording of the electrical activities of the heart. ⮚ It is the first diagnostic test done when cardiovascular disorder is suspected. ⮚ The procedure is PAINLESS. INDICATIONS OF ECG ⮚ MI and other CAD ⮚ Cardiac Dysrhythmias ⮚ Heart enlargement ⮚ Electrolytes imbalances- especially CA, NA and K levels ⮚ Inflammatory diseases of the heart ⮚ Effects of drugs on the heart ELECTRODE ⮚ An adhesive pad that contains conductive gel and designed to be attached to the patients skin LEADS

Electrodes connected to the monitor or EKG machine by wires ⮚ Wires are color coded. RHYTHM STRIP ⮚ The printed record of the electrical activity of the heart The standard ECG consist of 12 leads ⮚ (I, II, III, AVR, AVL, AVF, V1, V2, V3, V4, V5, V6) ⮚ Used in prehospital and clinics settings regularly to aid in screening patients who potential candidates for fibrinolytic therapy ⮚ 3 lead ECG - is use to detect life-threatening dysrhythmias Bipolar lead/Standard Limb Leads ⮚ Lead I II III - each have one positive electrode and one negative electrode ⮚ Current flows from the limbs through the heart ⮚ Lead II and modified chest lead are the most common leads used for cardiac monitoring because of their ability to visualized P waves. ⮚ LA Lead (Black lead) - Should be placed between the left shoulders and wrist away from the bony prominences as bone is a poor conductor of electricity ⮚ RA lead (white lead) should be placed at the Right shoulder and wrist ⮚ Left Leg Lead (red Lead) -between left leg and ankle ⮚ Right Leg Lead (Green Lead) - between the right hip and ankle, sometimes used as an additional ground lead. Lead Positive Electrode Negative Electrode Left arm Right arm Left leg Right arm III Left leg Left arm Augmented Leads ⮚ currents flows from the heart outward to the extremities ⮚ referred to as unipolar lead having one true pole. Augmented leads Position of flow aVR-Augmented voltage R arm Frm the heart to R arm aVL-Augmented voltage, Left arm Frm the heart to L arm aVF-Augmented Voltage-Left foot From the heart to the L foot CHEST LEADS ⮚ from V1-V ⮚ knows as Unipolar leads or Precordial leads ⮚ Ck=hest leads look at the heart via horizontal (transverse plane) ⮚ proper placement of the V leads is important to the correct interpretation of the 12 lead ECG strip V1- 4th^ ICS, R sternum V2-4th^ ICS, L sternum

⮚ Characterized by dip below the isoelectric line of 1- 2mm or 1-2 small boxes in the ECG strip ⮚ Immediate O2 administration ST segment Elevati on ⮚ Due to myocardial injury secondary to acute myocardial infarction ⮚ Other causes coronary artery spasm,pericarditis and ventricular aneurysm T wave-ventricles returns to resting state ⮚ Repolarization of the ventricles ; should exceed 5mm amplitude ⮚ Provides the resting state of the myocardial work / Resting phase of cardiac cycle/ ⮚ Represents the return of ions to the appropriate side of the cell membrane COMMON ECG changes Hypokalemia ⮚ U-wave ⮚ Depressed ST segment- ⮚ Short T-Wave HYPERKALEMIA ⮚ Prolonged QRS complex ⮚ Elevated ST segment- ACUTE MI ⮚ Peak T wave MI ⮚ Elevated ST segment- acute MI ⮚ Inverted T wave- myocardial ischemia ⮚ Pathologic Q wave QRS ⮚ Wide QRS- PVC ⮚ Prolonged QRS- Hyperkalemia Prolonged Q-T interval ⮚ Digitalis toxicity ⮚ Long term quinidine ⮚ Long term procainamide ⮚ hypoglycemia HEMODYNAMIC MONITORING ⮚ is the assessment of the patients circulatory status; it includes measurement of heart rate, PAP, PCWP, CVP, cardiac output and blood volume CVP ⮚ Monitors the pressures within the right atrium ⮚ Monitors the blood volume, adequacy of venous return to the heart, pump function of the right side of the heart ⮚ To serve as guide for fluid replacement ⮚ To administer blood products, TPN ⮚ To obtain venous access when peripheral vein sites are inadequate ⮚ To insert a temporary peacemaker ⮚ To obtain central venous sample ⮚ Requires the threading of a catheter into a large central vein (subclavian, internal jugular vein, median basilica, femoral). ⮚ The catheter tip is positioned in the RA, or upper portion of SVC ⮚ The level of water manometer should be placed at the right, mid axillary, 4th^ ICS. This is the approximate level of the RA when the client is in supine position ⮚ Position the client in SUPINE during the initial reading. To get accurate readings. Position can affect CVP readings ⮚ Strict asepsis. To prevent infection ⮚ Normal reading: ⮚ SVC= 0-12 cm H2O ⮚ RA= 5-12 cm H2O ⮚ CVP near zero- hypovolemia/ DHN- hypotension, oliguria and rapid, weak, thread pulse ⮚ High CVP (15-20cm H2O)- hypervolemia- hypertension. Polyuria, bounding pulse. PAP PCWP ⮚ Monitor pressure in the RA, RV, PA, and distal branches of pulmonary artery (PCWP) ⮚ It reflects pressure in the LEFT Atrium ⮚ Swan Ganz catheter is inserted via ante cubital vein into the right side of the heart and is floated into the pulmonary artery

⮚ Elevated PAP and PCWP-indicate LSHF ⮚ Normal range: ⮚ PAP= 4-12mmHg PCWP= 4-12mm Hg ⮚ PCWP reading above 25mm Hg indicate PULMONARY EDEMA Nursing Interventions ▪ Inflate balloon only for PCWP readings, deflate between reading ▪ Observe catheter insertion site; culture site q 48 hrs as ordered ▪ Assess extremity for color, temp, capillary filling and sensation COMPLICATIONS Pneumothorax, hemothorax, air embolism, hematoma, cardiac tamponade Cardiac CATHETERIZATION ⮚ To assess oxygen levels, pulmonary blood flow, CO, heart structures ⮚ Visualization of coronary artery Nursing Interventions (Before) ⮚ Provide psychosocial support ⮚ Assess for allergy to iodine/seafood ⮚ VS ⮚ Withheld meals before the procedure ⮚ Have the client to void. To promote comport ⮚ Administer sedative as order ⮚ Do cardiac monitoring ⮚ Tell client that warm or flushing sensation will be feel as the contrast medium is injected ⮚ Fluttering sensation is felt After the procedure ▪ Bed rest ▪ Monitor VS especially peripheral pulses ▪ Monitor EKG ▪ Apply pressure dressing/ice pack ▪ Immobilized affected extremity in extension ▪ Monitor extremities for color, temp, pulse and sensation COMPLICATIONS ⮚ Dysrhythmia ⮚ Pericardial tamponade ⮚ MI, pulmonary edema ⮚ Perforation of great vessels of the heart Angiography/Arteriography ▪ Involves introduction of contrast medium into the vascular system to outline the heart and blood vessels ▪ It may be done during cardiac catheterization ▪ Observe hypotension after the procedure

Anatomy & Physiology of Heart, Lecture notes of Nursing

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Partial preview of the text

Download Anatomy & Physiology of Heart and more Lecture notes Nursing in PDF only on Docsity!

CIRCULATORY SYSTEM

⮚ It is a fluid-filled network of tubes through

which materials move between the

environment and the cells of a multicellular

animal.

Major Components OF CIRCULATORY SYSTEM

⮚ Heart

⮚ Blood

⮚ Blood vessels- veins, arteries, capillaries

Anatomy and Physiology of the Heart

Heart

⮚ Primary function is to pump blood through the

arteries, capillaries and veins

⮚ Pumps blood which creates blood pressure,

circulates oxygen nutrients and other

substances

LOCATION SIZE and the Shape of the Heart

⮚ It weighs 300g and approximately the size of

the fist, 5 inches in length and 3 inches wide.

⮚ The shape of the heart is somewhat cone like in

appearance.

⮚ Mediastinum- the central section of the thorax

(chest cavity). It is in this area that the heart is

house, lying in front of the spinal column,

behind the sternum and between the lungs

⮚ Two thirds of the heart lies to the left of the

midline, the apex of the heart just above the

diaphragm and the base of the heart lies at

approximately the level of the third rib

⮚ The heart is enclosed by

pericardium/pericardial sac which consist of

two layers

1. Visceral pericardium- thin serous inner layer

which surrounds the heart.

2. Parietal pericardium - outer layer, consist of

tough, nonelastic, fibrous connective tissue and

serves to prevent over distension of the heart.

⮚ In between the parietal and visceral

pericardium is a serous fluid (5-10ml) in the

pericardial sac, that prevents friction between

the two pericardial membranes as the heart

beats.

Layers of the heart are as follows:

a. Epicardium - outermost layer, a smooth outer

surface of the heart

b. Myocardium - thick middle layer composed

primarily of cardiac muscle cells heart where

the four chambers are made. Responsible for

the heart’s ability to contract

c. Endocardium

⮚ Innermost layer of the heart composed of

thin connective tissue

⮚ It lines the chambers and covers the heart

valves of the heart

⮚ important characteristic is its smoothness

that prevents abnormal blood clotting

CHAMBERS OF THE HEART

⮚ the four chambers of the hear are as follows:

⮚ right atrium and right ventricle which are thin

and separated by the interatrial septum

⮚ left atrium and left ventricle have thicker walls

and separated by interventricular septum

RIGHT ATRIUM

⮚ receives deoxygenated blood from the body by

way of the Superior vena cava (SVC) and inferior

vena cava (IVC).

⮚ From the RA , blood will flow to the right

atrioventricular valve or tricuspid valve into

the right Ventricle (RV)

⮚ Tricuspid valve- prevents back flow of blood

from the RA to RV, when the RV contracts.

⮚ Located between RA and RV

RIGHT VENTRICLE

⮚ Receives blood from the RA and ejects this

blood into the lungs via Pulmonary artery.

⮚ At the junction of this large artery and the RV is