OVER VIEW OF CIRCULATORY SYSTEM HEART AND VESSELS
LEARNING OBJECTIVES
At the end of thelecture the student should be able to know
About organization of cardio vascular system
About Components of cardio vascular system
About location, external and internal structure of heart
About different chambers and valve of the heart
About two different circulatory circuits; he should understands the working of these circuits
About the structure of different vessels
CIRCULATORY SYSTEM
Known as cardiovascular system
A closed system of the heart and blood vessels
Circulates blood through out the body
Components
Heart -main pumping organ of body
Vessels - carry the blood towards and away from heart
Arteries
Veins
capillaries
lymphatics
FUNCTIONS OF CARDIOVASCULAR SYSTEM
•
Circulate blood throughout entire body for
–
Transport of oxygen to cells
–
Transport of CO2 away from cells
–
Transport of nutrients (glucose) to cells
–
Movement of immune system components (cells, antibodies)
–
Transport of endocrine gland secretions
ORGANIZATION OF CVS
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Heart is the central organ for pumping
•
The cardiovascular system is divided into two circuits
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Pulmonary circuit
–
•
Systemic circuit
–
•
blood to and from the lungs
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
OVER VIEW OF HEART
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Pumping station of the body
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Hollow muscular organ
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About the size of the fist
Location
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In middle mediastinum
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Within pericardial cavity
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Between lungs
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Posterior to sternum
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Anterior to vertebral column
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Pointed apex directed to left
OVER VIEW OF HEART
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Covered by pericardium
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Has 3 layers in wall
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Has 4 chambers
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Has four valves
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Supplied by coronary arteries
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Connected to pulmonary and systemic circuit by large vessels
•
Has specialized, autonomous conducting system
OVER VIEW OF PERICARDIUM
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A double-walled sac around the heart composed of:
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A superficial fibrous pericardium
–
A deep two-layer serous pericardium
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The parietal layer lines the internal surface of the fibrous pericardium
•
The visceral layer or epicardium lines the surface of the heart
•
They are separated by the fluid-filled pericardial cavity
OVER VIEW OF HEART WALL

Three layers



Epicardium

Outside layer

This layer is the parietal pericardium

Connective tissuelayer
Myocardium

Middle layer

Mostly cardiac muscle
Endocardium

Inner layer

Endothelium
EXTERNAL HEART ANATOMY
OVER VIEW OF HEART CHAMBERS

Right and left side act
as separate pumps

Four chambers
Atria

Receiving and upper

Right atrium
chambers
Left atrium
Ventricles

Discharging and lower
chambers

Right ventricle

Left ventricle
OVER VIEW OF ATRIA
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Receiving chambers of the heart
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Each atrium has a protruding auricle
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Pectinate muscles mark atrial walls
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Collect blood
•
Right atria from systemic circuit through
•
–
Superior and inferior venae cavae
–
Coronary sinus
Left atria from pulmonary circuit through
–
Pulmonary veins
OVER VIEW OF VENTRICLES
Discharging chambers of the heart
Papillary muscles and trabeculae carneae muscles mark ventricular walls
Pumps blood
Right ventricle into the pulmonary trunk
Left ventricle into the aorta
OVER VIEW OF HEART VALVES
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Allow blood to flow in only One direction
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Four valves
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Atrioventricular valves
– between atria and ventricles
•
•
Bicuspid valve (left)
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Tricuspid valve (right)
Semilunar valves
–
between ventricle and artery
•
Pulmonary between right ventricle and pulmonary trunk
•
Aortic between left ventricle and aorta
THE HEART: ASSOCIATED GREAT VESSELS

Aorta


Pulmonary arteries


Leaves left ventricle
Leave right ventricle
Vena cava

Enters right atrium

Pulmonary veins (four)

Enter left atrium
OVER VIEW OF CORONARY CIRCULATION

Blood in the heart chambers does not nourish the myocardium

The heart has its own nourishing circulatory system

Coronary arteries

Cardiac veins

Blood empties into the right atrium via the coronary sinus
OVER VIEW OF CONDUCTING SYSTEM

Intrinsic conduction system
(nodal system)

Heart muscle cells contract, without nerve impulses, in a regular, continuous
way

Special tissue sets the pace

Sinoatrial node (right atrium)


Pacemaker
Atrioventricular node

(junction of r&l atria and ventricles)

Atrioventricular bundle (Bundle of His)

Bundle branches (right and left)

Purkinje fibers
PULMONARY CIRCULATION PATHWAY
Deoxygenated blood from body  vena cava  Right atrium tricuspid valve  right
ventricle pulmonary semilunar valve  pulmonary arteries  lungs
SYSTEMIC CIRCULATION PATHWAY
Oxygenated blood from lungspulmonary veins  left atriumbicuspid valve  left ventricle
 aortic semilunar valve  aortastemic circulation
OVER VIEW OF VASCULAR SYSTEM
BLOOD VESSELS
LYMPHATICS
OVER VIEW OF BLOOD VESSELS
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Tubular structures that carry blood to and from the heart
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Arteries
–
Arterioles
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Capillaries
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Venules
–
Veins
LAYERS OF VESSEL WALL
•
•
•
•
Tunica externa
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Outermost layer
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CT w/elastin and collagen
–
Strengthens, Anchors
Tunica media
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Middle layer
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Circular Smooth Muscle
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Vaso-constriction/dilation
Tunica intima
–
Innermost layer
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Endothelium
–
Minimize friction
Lumen
DIFFERENCES BETWEEN BLOOD VESSEL TYPES
MOVEMENT OF BLOOD THROUGH VESSELS

Most arterial blood is pumped by the heart

Veins use the milking action of muscles to help move blood
CAPILLARIES
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Microscopic--one cell layer thick
•
Bathed in extracellular matrix of areolar tissue

Capillary beds consist of two types of vessels

Vascular shunt – directly connects an arteriole to a venule

True capillaries – exchange vessels

Oxygen and nutrients cross to cells

Carbon dioxide and metabolic waste products cross into blood
LYMPHATIC VESSELS : ANATOMY
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Lymph- clear fluid from loose areolar CT around capillaries
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Lymphatic capillaries (near blood capillaries) 
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Lymph collecting vessels (small, 3 tunicas, valves)
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Lymph nodes (sit along collecting vessels)-clean lymph of pathogens, they are NOT
glands
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Lymphatic trunks (convergence large collecting vessels)
–
•
Lumbar, intestinal, bronchomediastinal, subclavian, jugular
Lymphatic ducts  empty into veins of neck
LYMPHATIC VESSELS : FUNCTION
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Collect excess tissue fluid collecting at arteriole end
•
Return leaked blood proteins to blood (maintain osmotic pressure needed to take up
water into bloodstream)
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Lymph moved through vessels by
•
–
Pulse of nearby arteries
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Contraction of surrounding skeletal muscle
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Regular movement of body (wiggling legs)
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Muscle in tunica media
Lacteals-lymphatic capillaries w/unique function
–
In mucosa of small intestine, receive digested fat from intestine
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Fatty lymph becomes milky = chyle
Chyle goes to bloodstream