Transcript Anatomy of the Cardiovascular System

Anatomy of the
Cardiovascular System
Cardiovascular System
• Also circulatory system
• Consists of: the heart, arteries, veins,
capillaries
Heart
• Four chamber muscular organ
• Comparable to the size of a closed fist
• Located in the mediastinum
– Behind sternum
– Between 2nd and 6th ribs
– Between T5-T8
• Apex – base of heart
– Located at the 5th intercostal space
Heart
Coverings of the Heart
• Pericardium – loose fitting sac
surrounding the heart
– Fibrous pericardium – tough, loose-fitting,
inelastic
– Serous pericardium
• Parietal layer: lines the inside of the fibrous
pericardium
• Visceral layer: adheres to outside of the heart
– Pericardial space: between parietal and
visceral layer
• Filled with 10-15mL of pericardial fluid
• Decreases friction
Walls of the Heart
• Epicardium – outer layer
– Epicardium = serous pericardium
• Myocardium – thick, contractile layer composed
of cardiac muscle cells
– Intercalated disks contain many gap junctions
– Allow cardiac muscle cells to function as a single unit
 syncytium
• Endocaridium – interior of cardiac wall
– Endothelial tissue
– Covers projections of myocardial tissue called
trabeculae
Walls of the
Heart
Chambers of the Heart
• Atria – two superior chambers
– “Receiving chambers”
– Blood from veins enters atria
• Ventricles – two inferior chambers
– “pumping chambers”
– Thick muscular walls to increase force of
pumping action
• Left > right
– Separated by interventricular septum
Valves of the Heart
• Permit blood flow in one direction during
circulation
• Atrioventricular valves (AV valves)
– Also cuspid valves
– Between atria and ventricles
• Semilunar (SL valves)
– Between R ventricle and pulmonary arteries
and L ventricle and aorta
Atrioventricular Valves
• Tricuspid valve
– Btwn R atrium and ventricle
– 3 flaps of endocardium
– Connected to ventricular papillary muscle
via chordae tendinae
• Bicuspid valve
– Btwn L atrium and ventricle
– Also called mitral valve
– Two flaps of endocardium
Semilunar Valves
• Pulmonary semilunar valve
– Btwn R ventricle and pulmonary trunk
• Aorta semilunar valve
– Btwn L ventricle and aorta
Chambers & Valves
Trace the blood flow through the heart
Blood Supply to the Heart
• Right and left coronary arteries
– First branches off aorta
– Right coronary artery  right marginal
artery & posterior interventricular artery
– Left coronary artery  circumflex artery
& anterior interventricular artery
– Most of the blood goes to the L ventricle
– In 50% of the population, the R coronary
artery is dominant
Blood Supply to the Heart
• Anastomosis: Connections between blood
vessels that allow for collateral circulation
• Few exist between large branches of coronary
arteries
• In presence of an obstruction in a large
artery ischemia will result to a large area of
tissue
– Myocardial infarction (MI) (aka heart attack)
• Anastomoses do exists between smaller
branches of the R and L coronary arteries
Blood Supply to the Heart
• After traveling through the capillaries
of the heart, blood empties into the R
atrium via the coronary sinus
Conduction System of the Heart
• Four structures composed of modified
cardiac muscle
• Sinoatrial Node (SA Node)
– Pacemaker of the heart
– 100s of cells in the R atrium near the
opening of the superior vena cava
• Atrioventricular Node (AV Node)
– Small mass of cardiac muscle tissue
– Left lower border of R atrium
Conduction System of the Heart
• Atrioventricular Bundle
– Also Bundle of His
– Bundle of specialized cardiac muscle fibers
originating in the AV node
– Branches into R and L branches eventually
becoming Purkinje fibers
– Extend into the walls of the ventricles and
papillary muscles
Types of Blood Vessels
• Artery – carries oxygenated blood away
from the heart
– “distributors”
– Arteriole: small artery
– Precapillary sphincters: regulate the blood
flow into capillaries
Types of Blood Vessels
• Vein – carries unoxygenated blood
towards the heart
– Great ability to stretch (capacitance)
– Function as reservoirs: blood pools in the
valves then is pushed forward from the
pumping pressure
– Venules: small vein
Types of Blood Vessels
Types of Blood Vessels
• Capillaries – arterial system switches to
venous system
– “primary exchange vessels”
– Transport materials to and from the cells
– Speed of blood flow decreases to increase
contact time
– Microcirculation: blood flow between
arterioles, capillaries and venules
Types of Blood Vessels
Structure of Blood Vessels
• Tunica adventitia - outermost layer
– Fibrous connective tissue
– Holds vessels open; prevents tearing of
vessels walls during body movements
– Larger in veins than arteries
• Tunica media – middle layer
– Smooth muscle and elastic CT
– Helps vessels constrict and dilate
– Larger in arteries
Structure of Blood Vessels
• Tunica intima – innermost layer
– Composed of endothelium
– Semilunar valves present in veins
– One cell thick in capillaries
Circulatory Routes
• Systemic Circulation – blood flow from
the L ventricle to the body & back to
the R atrium
• Pulmonary Circulation – blood flow from
the R ventricle to the lungs and back to
the L atrium
Circulatory Routes
Aorta
Systemic Arteries
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Arch of aorta
Subclavian (L and R)
Brachiocephalic
common carotid (L
and R)
Axillary (L and R)
Brachial (L and R)
Radial
Ulnar
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Abdominal aorta
Common iliac
External iliac
Femoral
Popliteal
Posterior tibial
Anterior tibial
Dorsal pedis
Systemic Veins
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Superior vena cava
Inferior vena cava
External jugular
Internal jugular
Brachiocephalic (L
and R)
• Subclavian (L and R)
• Cephalic
• axillary
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Basilic
Median basilic
Median cubital
Common iliac
External iliac
Femoral
Popliteal
Great saphenous
Small saphenous
Fetal Circulation
• Two umbilical arteries carry blood to the
placenta
• The placenta allows for exchange of oxygen
and nutrients from the mother. Maternal and
fetal blood do NOT mix.
• Umbilical vein returns oxygenated blood and
enters fetus via the umbilicus
• Foramen ovale – hole btwn the R and L atria
– Allows for blood to bypass the R ventricle and
pulmonary circulation
Fetal Circulation
• Ductus arteriosus – small vessel
connecting the pulmonary artery and
the aorta
– Allows for another bypass route from the
lungs
**Most of fetal blood is a mixture of
oxygenated and deoxygenated blood**
Fetal
Circulation
Changes After Birth
• Umbilical vein become round ligament
• Umbilical arteries become umbilical
ligaments
• Foramen ovale closes after first few
breaths
– Full closure may take up to 9 months
• Ductus arteriosus contracts as soon as
respirations begin
– Become fibrous cord
Changes After Birth
Pericardium Disorders
• Pericarditis – inflammation of the heart
– Causes: trauma, viral or bacteria infection, tumor
– Edema causes visceral and parietal layers to rub
together = chest pain
– Pus or blood build up in pericardial space
– S/S
• Pain with respirations or coughing, dyspnea, restlessness
– Complications: Pericardial Effusion, Cardiac
Tamponade
– Treatment:
• Antibiotics, pain meds, antiinflammatory meds,
pericardiocentesis (Cardiac Tamponade)
Cardiac Tamponade
Heart Valve Disorders
• General Principles:
– Congenital defect: decreased pumping
efficiency
– Incompetent valve leak: allows backflow
into previous chamber
– Stenosed valves: narrowed valve; slowing
blood from out of chamber
Heart Valve Disorders
• Mitral Valve Prolapse (MVP)
– Flaps of mitral valve extend back into L
atrium causes leaking
– Mostly genetic basis
– 1 in 20 people
– S/S: most asymptomatic; chest pain,
fatigue
– Treatment: valvuloplasty
Mitral Valve Prolapse
Heart Valve Disorders
• Aortic Regurgitation
– Blood leaks back into L ventricle during
ejection into the aorta
– Volume overload in L ventricle,
hypertrophy, dilation of L ventricle
– Complications: myocaridal ischemia
– Treatment: valvuloplasty
Myocardium Disorders
• Atherosclerosis
– Type of arteriosclerosis
– Lipids build up on the inside of vessel walls
 calcify  vessels hard & brittle
– Risk factors: cigarette smoking, high
fat/cholesterol diet, hypertension
Atherosclerosis
Myocardium Disorders
• Myocardial Infarction
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“Heart Attack”
Coronary thrombosis: clot
Coronary embolism: mobilized clot
Occlude coronary artery  heart tissue
deprived of oxygen  cell death
– S/S:
• Angina pectoris – severe chest pain resulting
from inadequate oxygen to myocardium
– Treatment: Coronary Bypass Surgery
• Veins are harvested from other areas of the
body and used to bypass obstructions
Myocardium Disorders
• Congestive Heart Failure (CHF)
– “Left-sided Heart Failure”
– Inability of the L ventricle to pump blood
efficiently
– Causes: myocardial infarction
– S/S: decreased pumping pressure in
systemic circulation; retained fluids
• Can lead to congestion in pulmonary circulation 
pulmonary edema  right-sided heart failure
– Treatment: heart transplant
Congestive Heart Failure
Myocardium Disorders
• Coronary Artery Disease (CAD)
– Leading cause of death in US
– General term to describe decreased blood
flow to myocardium & associated side
effects
Disorders of the Arteries
• Arteriosclerosis
– Arteries become occluded, weak and
hardened
– Complications: ischemia, necrosis, gangrene
– Risk factors: age, diabetes, high
fat/cholesterol diet, hypertension, smoking
– Treatment: vasodilators, angioplasty, stent
placement, bypass surgery
– Complications: aneurysm
Angioplasty
Disorders of Veins
• Varicose Veins
– Enlarged veins caused by pooling
– Results in varicosities or varices (“spider
veins”)
– Risk factors: standing for long periods
• Semilunar valves widen  more pooling
– Treatment: compression stockings, surgical
removal
Varicose Veins
Disorders of Veins
• Phlebitis – vein inflammation
– Causes: irritation by IV catheter
• Thrombophlebitis
– Deep vein thrombosis (DVT)
– Phlebitis caused by a clot
– S/S
• Pain, redness, swelling
– Complications
• Pulmonary embolism
DVT
Pulmonary Embolism
Venous Stasis Ulcers
• Result of chronic
vein insufficiency
• Lack of oxygen
to peripheral
tissues
• Elevate leg &
apply pressure
• Irregular edges
• “Aching” pain
Patent Ductus Arteriosus (PDA)
Atrial Septal Defect (ASD)
Ventricular Septal Defect (VSD)
Tetralogy of Fallot (TOF)