cardiovascular system

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


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


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!)


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


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


The Circuits


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


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


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


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


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

Portal vein


VEINS


Postcapillary venulePostcapillary venule

VenuleVenule

VeinVein

Thin wallThin wall

Large lumenLarge lumen

Low pressureLow pressure

Low velocityLow velocity

ValvesValves

Fetal circulation


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


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


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


External and internal carotids, brachial & femoral arteries

External and internal jugular, brachial & femoral veins

2 - 9 mm ~ 4 mm


~ 10-50 µm

~ 30 µm


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


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.


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


Normal: From capillary bed into veins and back to heart

3 exceptions • Hypophysis

_________________

• Liver _________________

• In kidney nephrons

Fig 19.6

Fig 22.26


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


Functions of Blood

• Distribution - nutrients, wastes, hormones, gases, etc.

• Self-sealing – hemostasis

• Disease/ infection fighting


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


serum = plasma -serum = plasma -

Difference between

plasma and serum?


. . . . 2 more things:

Most plasma proteins are made in liver. Exception: ?

Lipoproteins = particles containing lipids (cholesterol & triglycerids) and proteins (albumins & globulins)


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???


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 ?


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


. . . 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


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


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

http://www.whfreeman.com/immunology/CH01/figure01-05.gif

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


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

cardiovascular system

Health & Medicine

heart blood

left heart

right heart

heart surface

location of heart

blood pressure heart

auscultation of heart

left ventricles