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Cardiovascular System- The Heart -
Give a detailed description of the superficial and internal anatomy of the heart, including the pericardium, the myocardium, and the cardiac muscle.
Explain the functioning of the valves of the heart and how they relate to the heart sounds.
Discuss the conductive pathway of the heart, and relate that to clinical uses of the ECG.
Goals
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Pulmonary & Systemic Circuits
artery
vein
capillaries
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Location of Heart within Thoracic Cavity
•Inside thoracic cavity
•In center of chest deep to sternum, apex tipped toward the left; base superior
•Inside mediastinum
•In pericardial spacewww.freelivedoctor.com
Pericardium - Covering1. Fibrous pericardium - tough, collagenous2. Serous parietal pericardium (lines fibrous pericardium)3. Pericardial space with 10-20 ml of pericardial fluid4. Serous visceral pericardium adheres to the heart surface
(also known as epicardium)
Structure of Heart Wall
• Epicardium = visceral Pericardium (serosa)• Myocardium: muscle tissue + c.t. + blood vessels + ?• Endocardium: simple squamous epithelium continuous
with endothelia of blood vessels
Cardiac Muscle
• Striated, aerobic, interwoven, autorhythmic
• Intercalated discs - gap junctions, strong desmosomes
• Functional syncytium
Fibrous Skeleton
• Internal c.t. network with lots of collagen and elastic fibers
Encircles bases of great vessels
Encircles bases of valves
functions:Isolate atria from ventricles elctrically
Reinforce myocardium itself
Surface Anatomy of Heart
• Auricle of atria (expandable)
• Coronary sulcus (between atria & ventricles)
• Ant. & post. interventricular sulcus
• Base (3rd costal cartilage) vs. apex (5th intercostal space)
• Vessels entering & leaving the heartwww.freelivedoctor.com
Sectional (Internal) Heart Anatomy
• Atria & ventricles
• Interatrial & interventricular septae
• Valves (fibrous tissue)
• Pectinate muscles (auricles & ant. atria)
• Trabeculae carneae (ventricles)
• Chordae tendinae & papillary muscles
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Left vs. Right Ventricle
Left: high pressure pump - Right: low pressure pump right chamber is thinner walled than left
Ventricles separated by interventricular septum
Structure and Function of Valves
= Mitral valve
4 sets of valves
Prevent backflow of blood
Close passively under blood pressure
Heart sounds produced by valve closurewww.freelivedoctor.com
picture taken from R ventricle, looking toward R atrium
Support for AV valves: Support for AV valves: valves are restrained by chordae tendinae which are in turn attached to papillary muscles (prevention of backflow!)
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Blood flow pattern through the heart
1. Blood enters right atrium2. Passes tricuspid valve into right ventricle3. Leaves by passing pulmonary semilunar valves into
pulmonary trunk and to the lungs to be oxygenated4. Returns from the lung by way of pulmonary veins into
the left atrium5. From left atrium past bicuspid valve into left ventricle6. Leaves left ventricle past aortic semilunar valves into
aorta7. Distributed to rest of the body
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Actual physical contraction pattern of the myocardium as determined by the conduction.
A.Contraction is systole
B. Relaxation is diastole
The two atria are in systole and diastole together as are the two ventricles.
Cardiac Cycle
Auscultation of Heart Sounds:
1st HS: at beginning of ventricular contraction, due to?2nd HS: at beginning of ventricular diastole, due to?
Coronary CirculationCoronary arteries: first branches off the ascending aorta.
coronary veins coronary sinus right atrium (inferior to opening of inferior vena cava)
posterior view www.freelivedoctor.com
Conducting System of the HeartSpecialized muscle cells (autorhythmic cells) conduct APs to time and
synchronize the action of the chambers
SA node -pacemaker, spontaneously depolarizes most rapidly and initiate heart beat, positioned on back wall of right atrium , transmits action potential to
AV node - (where the four chambers meet).
AV bundle (bundle of His) transmits down top of interventricular septum where it divides into two
Bundle branches, one of which supplies each ventricle where they branch into
Purkinje fibers reflect up external walls of ventricles and stimulate contraction of cardiac muscle cells as a unit.
Purkinje fibers extend into papillary muscles as well
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The Circuits
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Pulmonary Circuit:`Pulmonary Circuit:`
From the “Right Heart” to From the “Right Heart” to the Lungsthe Lungs
Systemic Circuit:Systemic Circuit:
From the “Left Heart” to From the “Left Heart” to Everywhere ElseEverywhere Else
65 -70% in veins (= blood 65 -70% in veins (= blood reservoir); lumen is larger reservoir); lumen is larger than in corresponding than in corresponding arteriesarteries
30-35% in heart, arteries and 30-35% in heart, arteries and capillariescapillaries
N.B. The chambers pump the N.B. The chambers pump the same VOLUMEsame VOLUME
elastic arterieselastic arteries
muscular arteriesmuscular arteries
arteriolesarterioles
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capillariescapillaries
large veinlarge vein
medium-sized medium-sized veinvein
venulesvenules
Arteries – ALWAYS carry blood away from heart Veins – ALWAYS return blood to heart,
contain about 2/3 body's blood at any given time
Capillaries
• The smallestThe smallest• Only vessels that allow Only vessels that allow
exchangeexchange– Diffusion or active transportDiffusion or active transport
• Precapillary SphinctersPrecapillary Sphincters regulate flow and blood regulate flow and blood pressurepressure
Normal Blood Flow: From artery to capillary bed to vein and back to heart
3 exceptions: 3 exceptions: from artery to from artery to capillary to artery (or venule) to capillary to artery (or venule) to capillary to veincapillary to vein
HypophysisHypophysis
LiverLiver
In kidney nephronsIn kidney nephrons
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Portal SystemsPortal Systems
Gross Anatomy of Gross Anatomy of Circulatory SystemCirculatory System
Pulmonary & Pulmonary & Systemic CirculationsSystemic Circulations
Right ventricle into pulmonary trunk to pulmonary arteries to lungs
Return by way of 4 pulmonary veins to left atrium
Pulmonary Circuit
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Arteries to the Head
Common carotid (2)Common carotid (2) Vertebral Artery (2)Vertebral Artery (2)
Through the transverse Through the transverse foraminaforamina
Basilar Artery (1)Basilar Artery (1) Through foramen Through foramen
magnummagnum
Circle of WillisCircle of Willis
Circle of Willis = Cerebral Arterial Circle
= Ring of vessels = Ring of vessels surrounding pituitary gland - surrounding pituitary gland - supplies cerebrum and supplies cerebrum and cerebellumcerebellum
Brain can receive blood from Brain can receive blood from carotid or vertebral or basilar carotid or vertebral or basilar aa. aa.
Collateral circulationCollateral circulation
(significance?)(significance?)
Circle of Willis
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Arteries of the Arm Difference Between Difference Between
Right and Left??Right and Left?? SubclavianSubclavian AxillaryAxillary BrachialBrachial
RadialRadial UlnarUlnar
Descending Aorta - Thoracic Area
Bronchial arteries - supply bronchi Bronchial arteries - supply bronchi and lungsand lungs
Pericardial arteries - supply Pericardial arteries - supply pericardiumpericardium
Mediastinal arteries - supply Mediastinal arteries - supply mediastinal structuresmediastinal structures
Esophageal arteries - supply Esophageal arteries - supply esophagusesophagus
Paired intercostal arteries- thoracic Paired intercostal arteries- thoracic wallwall
Superior phrenic arteries - supply Superior phrenic arteries - supply diaphragmdiaphragm
Descending Aorta: Abdominal Area
Celiac trunk - 3 branches – to liver, Celiac trunk - 3 branches – to liver, gallbladder, esophagus, stomach, gallbladder, esophagus, stomach, duodenum, pancreas, and spleenduodenum, pancreas, and spleen
Superior mesenteric– to pancreas and Superior mesenteric– to pancreas and duodenum, small intestine and duodenum, small intestine and coloncolon
Paired suprarenal - to adrenal glandsPaired suprarenal - to adrenal glands
Paired renal – to kidneysPaired renal – to kidneys
Paired gonadal – to testes or ovariesPaired gonadal – to testes or ovaries
Inferior mesenteric – to terminal colon Inferior mesenteric – to terminal colon and rectumand rectum
Paired lumbar – to body wallPaired lumbar – to body wall
Circulation of the Leg
Common Iliac A. and Common Iliac A. and V.V.
External Iliac A. & V.External Iliac A. & V. Femoral A. & V.Femoral A. & V. Popliteal A. & V.Popliteal A. & V.
Anterior TibialAnterior Tibial Posterior TibialPosterior Tibial
Dorsal Pedal A.Dorsal Pedal A. Pulse checkingPulse checking
Great Saphenous V.Great Saphenous V. Used for coronary Used for coronary
bypassesbypasses Longest vesselLongest vessel
Venous Circulation
Mostly parallels Mostly parallels arterial circulationarterial circulation
Veins are more Veins are more superficial in limbssuperficial in limbs
Major exception in the Major exception in the abdomenabdomen Portal CirculationPortal Circulation
Venous Circulation
Mostly parallels Mostly parallels arterial circulationarterial circulation
Veins are more Veins are more superficial in limbssuperficial in limbs
Major exception in the Major exception in the abdomenabdomen Portal CirculationPortal Circulation
Portal vein
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VEINS
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Postcapillary venulePostcapillary venule
VenuleVenule
VeinVein
Thin wallThin wall
Large lumenLarge lumen
Low pressureLow pressure
Low velocityLow velocity
ValvesValves
Fetal circulation
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During fetal life, all oxygen and During fetal life, all oxygen and nutrition comes not from the intestine nutrition comes not from the intestine and lungs, but from the placenta.and lungs, but from the placenta.
The fetus has different circulatory The fetus has different circulatory pathways to accommodate these pathways to accommodate these different needs.different needs.
These pathways must change AT the These pathways must change AT the time of birth.time of birth.
Circulation Changes Circulation Changes AT BirthAT Birth
No blood coming from placentaNo blood coming from placenta
Ductus venosus becomes Ductus venosus becomes ligamentum ligamentum venosusvenosus (=ligamentum teres) (=ligamentum teres)
Foramen ovale closes & becomes Foramen ovale closes & becomes fossa fossa ovaleovale
Ductus arteriosus closes and becomes Ductus arteriosus closes and becomes ligamentum arteriosumligamentum arteriosum
Umbilical vein and arteries degenerateUmbilical vein and arteries degenerate
Patent foramen ovale
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Distinguishing Arteries from Veins:
• Artery walls thicker (more muscle and elastic fibers)
• Additional: internal & external elastic membranes
Artefacts when fixing slides:
• Arterial walls contract; endothelium cannot contract: pleated appearance
• Veins collapse
Fig 22.1
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elastic arteries
muscular arteries
arterioles
capillaries
large veinlarge vein
medium-sized medium-sized veinvein
venulesvenules
Arteries – ALWAYS carry blood away from heart Veins – ALWAYS return blood to heart,
contain about 2/3 body's blood at any given timewww.freelivedoctor.com
Pulmonary trunk & aortaand their major branches
Superior & inferiorvena cava and theirtributaries
Largest, conducting arteries – lead directly from heart, subject to high pressures
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External and internal carotids, brachial & femoral arteries
External and internal jugular, brachial & femoral veins
2 - 9 mm ~ 4 mm
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~ 10-50 µm
~ 30 µm
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Capillaries Capillaries
Intestinal mucosa Choroid plexus,endocrine glands, kidneys
Most body regions
Only endothelium
Variably permeable
somewhat permeable
Characterized by circular fenestrae or pores that penetrate the endothelium -permit exchange of larger molecules.
~ 8 µm
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Sinusoids
• Resemble fenestrated capillaries, yet1. irregular shapes2. have longer pores3. thinner (or no) basement membranes
• Blood movement very slow
• Found in the liver, heart, etc. sometimes called sinusoidal capillary.
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Capillary Bed
= Capillary region supplying a body area
• Metarteriole – shunt - preferred channel through a capillary bed
• Precapillary sphincter - closes bed temporarily to redistribute blood flow
• Arteriovenous anastomosis: interconnections , alternative routes of supply
Fig 22.4
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Normal: From capillary bed into veins and back to heart
3 exceptions • Hypophysis
_________________
• Liver _________________
• In kidney nephrons
Fig 19.6
Fig 22.26
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The BloodThe BloodDiscuss the composition of blood including the functions of the
various components
Explain the anatomy and functions of the red blood cells, including a description of blood typing
Discuss the types of white blood cells found in the blood and give the functions of each
Give a brief accounting of the platelets
Review hemopoiesis, including RBC and leukocyte formation
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Functions of Blood
• Distribution - nutrients, wastes, hormones, gases, etc.
• Self-sealing – hemostasis
• Disease/ infection fighting
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Blood = connective tissue
extracellularmatrix:Plasma
specialized cells:
(= Formed elements)
RBCs
WBCs
Plateletscolor ?volume ?
Plasma CompositionPlasma Composition
• Water 92%
• Plasma proteins 7%• Other solutes
1%
Transports organic and inorganic molecules, formed elements, and heat
Plasma ProteinsPlasma Proteins
• Albumin (60%) Major contributor to osmotic concentration of plasma. Transport of lipids and steroid hormones
• Globulins (35%) Transport ions, hormones, lipids; immune function
• Fibrinogen (4%) Essential component of clotting system (conversion to insoluble fibrin)
• Regulatory proteins (< 1%) ????
Other Solutes
• Electrolytes: Normal extracellular fluid ion composition (????)
• Organic nutrients: glucose, FA, AA
• Organic wastes: urea, bilirubin
Difference between Plasma and Interstitial Fluid :
Plasma has more:Plasma has more:• Dissolved O2 O2 diffuses out into tissue
• Dissolved proteins (too big to cross caps.)– Albumins – Globulins
• globulins• and globulins
– Fibrinogen
Similar concentration: Salts & small molecules
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serum = plasma -serum = plasma -
Difference between
plasma and serum?
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. . . . 2 more things:
Most plasma proteins are made in liver. Exception: ?
Lipoproteins = particles containing lipids (cholesterol & triglycerids) and proteins (albumins & globulins)
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Formed ElementsFormed Elements
Red and White Blood Cells
Platelets
• Platelets• WBCs
• RBCs
.1%
99.9%www.freelivedoctor.com
Formed Elements cont.Formed Elements cont.Why whitewhite blood cells???
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RBCs = Erythrocytes
Measured by hematocrit or PCV
Most abundant blood cell: 1000 RBCs/1 WBC
Contain hemoglobin, carry O2
Very regular shape - biconcave discs
Anucleate: Lifespan ~ 120 days replacement rate ~ 3 mio RBCs / sec
Structure of Hemoglobin (Hb)Structure of Hemoglobin (Hb)
Fe ion in heme group reversibly binds O2
How many oxygen
molecules can 1
Hb molecule
carry?
ABO & Rh ABO & Rh Blood TypesBlood Types
• Blood groups (types) based on specific RBC Blood groups (types) based on specific RBC surface antigens (= proteins)surface antigens (= proteins)
• > 30 common varieties of antigens known. > 30 common varieties of antigens known. Most important ABO & RhMost important ABO & Rh
blood type ?
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ABO Blood typing: ABO Blood typing: 4 combinations possible4 combinations possible
• A surface antigen = blood type A• B surface antigen = blood type B• both surface antigens = type AB• neither surface antigen = type O
• Rh surface antigen = + blood type• no Rh antigen = negative blood type
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. . . 2 - 8 months after birth:
Anti-A and anti-B antibodies can be Anti-A and anti-B antibodies can be formed in plasma !formed in plasma !
normally NO anti Rh present
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Transfusion ReactionTransfusion of incompatible blood can be fatal!
Universal Donor vs. Universal Donor vs. Universal RecipientUniversal RecipientOnly for emergencies - must be given slowly !
Clinical Brief
Anemia:Reduced oxygen carrying ability of blood. Causes??
Polycythemia: Erythrocytosis: excessive increase in RBCsPolycythemia vera:
Blood Doping:Via direct transfusion, orEPO use
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WBCs = LeukocytesWBCs = Leukocytes
Quantity and type determined by differential WBC count
Circulating WBCs are only a small fraction of total WBCs. Most are located in ?
Diapedesis
Chemotaxis
Granulocytes and Agranulocytes
Neutrophil (= PMN)Neutrophil (= PMN)
Up to ~ 70% (~ 2/3) of circulating WBCsCytoplasm packed with pale granules containing
lysosomal enzymes
phagocytic
EosinophilEosinophil
~ 2% - 4% of circulating WBCsGranules stain with eosinIncreased in allergies and parasitic infections
BasophilBasophil
• < 1% of circulating WBCs
• Granules stain with basic dyes and contain histamine
• Discharge of histamine promotes inflammation at site of injury (Similar to mast cells)
MonocyteMonocyte
• ~ 2% - 8% of circulating WBCs• Large kidney shaped nucleus• In tissue called Macrophage
LymphocytesLymphocytes
• ~ 20% - 30% of circulating WBCs• Relatively small (slightly larger than RBCs)• Large round nucleus• B, T, NK
Platelets = ThrombocytesPlatelets = Thrombocytes
Cell fragments of Megakaryocytes (~ 4,000 thrombocytes per Megakaryocyte)
~ 160 mLifespan ~ 12 days involved in blood clotting
Abnormal Blood Cell Counts
Leukopenia < 2,500/ L (normal 6000 – 9000)Leukocytosis > 30,000/ L
Thrombocytopenia: < 80,000/ L (normal ~ 350,000)
Thrombocytosis: > 1,000,000/ L
Also Lymphopenia vs. _____________
_________vs. Neutrophilia
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Hemopoiesis = Blood Cell FormationHemopoiesis = Blood Cell Formation
Hemocytoblasts: One type of stem cell for all blood cells
In red bone marrowIn red bone marrow
. . . then differentiation into 4 types of progenitor stem cells:
Erythroblast
Myeloblast
Monoblast
Lymphoblast
Fig 20.8