cardiovascular system

CARDIOVA

SCULAR

SYSTE

M

HEART Hollow, muscular organ 300 grams (size of a fist) 4 chambers Found in chest between lungs Surrounded by membrane called

pericardium Pericardial space is fluid-filled to

nourish and protect the heart.

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embe

r 2006

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POSITION OF THE HEART

Lies in the chest behind the sternum and between the lungs.

Coverings of the heart; Pericardium

• Pericardium-double layered sac composed of two parts: fibrous and serous membranes.

• The serous pericardium is two layers:1. Visceral pericardium form the inner layer that is on the

surface of the heart muscle.2. Parietal pericardium form the outer layer of the serous

membrane and secretes pericardial fluid

• Pericardial space is a potential space between the visceral and parietal layers of the serous membrane.

• Pericardial fluid- (serous fluid) prevents friction as the heart beats

Clinical Correlation

pericardial effusion: Inflammatory diseases can cause fluid to accumulate in the pericardial cavity.

Hemopericardium: Bleeding into the pericardial cavity.

may result from penetrating heart wounds or perforation of a weakened heart muscle following myocardial infarction.

Chambers of the heartRight Atrium• Thinner wall than ventricles• Receives deoxygenated blood from vena cava• Passes blood through tricuspid valve into right ventricleRight Ventricle• Thicker wall than atria• Comprises most of anterior surface of heart• Circulates deoxygenated blood to lungs through the pulmonary valve

into pulmonary arteryLeft Atrium• Receives freshly oxygenated blood from pulmonary vein Passes blood

to left ventricle through mitral valveLeft Ventricle• Receives blood from left atrium• Thickest myocardial wall• Forms apex of heart• Sends blood to systemic circulation via aorta

Valves of the heart

tricuspid

bicuspid(mitral)

aortic semilunar valvepulmonary semilunarvalve

posterior

Valves of the heart

posterior

aortic semilunar valvepulmonary semilunar

bicuspid(mitral) tricuspid

Layers of heart tissueEndocardium• Inner lining• Smooth surface that permits blood to move easily through the heart.

Myocardium• Middle layer made of cardiac muscle• Forms the bulk of the heart wall• Contains the septum- a thick muscular wall that completely

separates the blood in the right side of the heart from the blood in the left side.

Epicardium• Protective, outer layer of the hear• The coronary blood vessels that nourish the heart wall are located in

this layer.

The cardiac muscle (myocardium) Cardiac muscle is composed

of irregular branched cells.

Bound together longitudinally by intercalated disks.

Shows strong, involuntary contractions.

Atrioventricular Valves

• Chordae tendineae tiny collagen cords that connect cusps of valve to papillary muscles

• Atrioventricular Valves:

Left AV valve (Mitral, bicuspid)• Contains 2 cusps Right AV valve (Tricuspid)• Contains 3 cusps

CONDUCTING SYSTEM OF THE HEART

• Which initiates the electrical impulse for heart’s contraction (heartbeat) and spreads it through the ventricular myocardium.

• sinoatrial (sa) node (pacemaker) it lies in the wall of the right atrium it generate the nerve impulses

• atrioventricular (av) node lies in the lower part of the interatrial septum.

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Deoxygenated blood returns to the heart via the superior and inferior vena cava, enters the right atrium, passes into the right ventricle, and from here it is pumped to the pulmonary artery.

Oxygenated blood returning from the lungs enters the left atrium via the pulmonary veins, passes into the left ventricle, and is then pumped to the aorta.

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• The heart has two pumping chambers that work together, right ventricle (pulmonary) and left ventricle (systemic).

• Repetitive, sequential contraction is called systole and relaxation called diastole.

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• Artery - vessel that carries blood away from the heart. Usually oxygenated. All arteries carry oxygenated blood except pulmonary artery.

• Vein - vessel that carries blood towards the heart. Usually deoxygenated. All veins carry deoxygenated blood except pulmonary vein.

• Capillary - a small blood vessel that connect end of the arteries and beginning of the veins

Walls of blood vessels

• Consist of three layers: tunica intima, tunica media, and tunica externa (or adventitia).

• The artery has a thicker wall and narrow lumen. • The vein has thinner wall and large lumen .

• The veins has valves.

• Capillaries have only one layer called endothelium.

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Blood Vessels

• Systemic vessels– Transport blood through the body part from

left ventricle and back to right atrium

• Pulmonary vessels– Transport blood from right ventricle through

lungs and back to left atrium.

Blood vessels of the heart

Coronary Arteries supply the heart wall with oxygenated blood Cardiac Veins remove deoxygenated blood from the heart wall

LYMPHATIC SYSTEMS

Lymphoid organs include:

• Lymph nodes

• Spleen

• Thymus

• Tonsils

Function:Host defense; eliminates abnormal (sick, aged, or cancerous) cells and pathogens.

The Lymph

plasma from capillaries pass out to the space between the cells to supply the cells with oxygen and nutrient and remove carbon dioxide and waste products.

85% plasma that moved out of capillaries return back to the capillaries while the remaining 15% return to the blood circulation through the lymphatic vessels

Lymphatic organs and tissues are sites of lymphocyte maturation.

The Lymph lymphatic vessels pass through lymph nodes which filtrate the lymph and add lymphocytes

(B. lymphocytes & T. lymphocytes).

lymph (lymphatic fluid) = plasma – blood cells

lymph (lymphatic fluid) = plasma+ lymphocytes

lymph nodes scattered all over the body they contain B. lymphocytes T. lymphocytes macrophage

lymphatic capillary

lymphatic trunks

lymphatic collecting vessels

lymphatic ducts

Lymphatic vessels

lymphatic vessels begin from the spaces between the cells and end into the venous system (blood circulation)

lymphatic vessels like veins has valves

collect into two main trunks thoracic duct right lymphatic duct

Function of lymphatic system

absorption of fat immunity maintain blood volume