Over View of Circulatory System

OVER VIEW OF CIRCULATORY SYSTEM
HEART AND VESSELS

LEARNING OBJECTIVES

At the end of the lecture 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

–  Heart is the central organ for pumping

–  The cardiovascular system is divided into two circuits

–  Pulmonary circuit

–  blood to and from the lungs

–  Systemic circuit

–  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

–  Pumping station of the body

–  Hollow muscular organ

–  About the size of the fist

•  Location

–  In middle mediastinum

–  Within pericardial cavity

–  Between lungs

–  Posterior to sternum

–  Anterior to vertebral column

–  Pointed apex directed to left

•  Covered by pericardium

•  Has 3 layers in wall

•  Has 4 chambers

•  Has four valves

•  Supplied by coronary arteries

•  Connected to pulmonary and systemic circuit by large vessels

•  Has specialized, autonomous conducting system

OVER VIEW OF PERICARDIUM

•  A double-walled sac around the heart composed of:

•  A superficial fibrous pericardium

•  A deep two-layer serous pericardium

•  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

OVER VIEW OF HEART CHAMBERS

•  Right and left side act as separate pumps

•  Four chambers

Atria

•  Receiving and upper chambers

–  Right atrium

–  Left atrium

Ventricles

•  Discharging and lower

•  chambers

–  Right ventricle

–  Left ventricle

OVER VIEW OF ATRIA

•  Receiving chambers of the heart

•  Each atrium has a protruding auricle

•  Pectinate muscles mark atrial walls

•  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

•  Allow blood to flow in only One direction

•  Four valves

•  Atrioventricular valves

– between atria and ventricles

•  Bicuspid valve (left)

•  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

·  Leaves left ventricle

·  Pulmonary arteries

·  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 à vena cava à Right atriumà tricuspid valve à right ventricleà pulmonary semilunar valve àpulmonary arteries à lungs

SYSTEMIC CIRCULATION PATHWAY

•  Oxygenated blood from lungsàpulmonary veins à left atriumàbicuspid valve à left ventricle à aortic semilunar valve àaortaàstemic circulation

OVER VIEW OF VASCULAR SYSTEM

•  BLOOD VESSELS

•  LYMPHATICS

•  Tubular structures that carry blood to and from the heart

•  Arteries

•  Arterioles

•  Capillaries

•  Venules

•  Veins

OVER VIEW OF BLOOD VESSELS

LAYERS OF VESSEL WALL

•  Tunica externa

–  Outermost layer

–  CT w/elastin and collagen

–  Strengthens, Anchors

•  Tunica media

–  Middle layer

–  Circular Smooth Muscle

–  Vaso-constriction/dilation

•  Tunica intima

–  Innermost layer

–  Endothelium

–  Minimize friction

•  Lumen

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

•  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

•  Lymph- clear fluid from loose areolar CT around capillaries

•  Lymphatic capillaries (near blood capillaries) à

•  Lymph collecting vessels (small, 3 tunicas, valves)à

•  Lymph nodes (sit along collecting vessels)-clean lymph of pathogens, they are NOT glands

•  Lymphatic trunks à(convergence large collecting vessels)

–  Lumbar, intestinal, bronchomediastinal, subclavian, jugular

•  Lymphatic ducts à empty into veins of neck

LYMPHATIC VESSELS : FUNCTION

•  Collect excess tissue fluid collecting at arteriole end

•  Return leaked blood proteins to blood (maintain osmotic pressure needed to take up water into bloodstream)

•  Lymph moved through vessels by

–  Pulse of nearby arteries

–  Contraction of surrounding skeletal muscle

–  Regular movement of body (wiggling legs)

–  Muscle in tunica media

•  Lacteals-lymphatic capillaries w/unique function

–  In mucosa of small intestine, receive digested fat from intestine

–  Fatty lymph becomes milky = chyle

–  Chyle goes to bloodstream