8/2/2019 11-Ch 18 Lecture A

1/33

The Cardiovascular System: TheHeart: Part A

Marieb and Hoehn, 8 th ed.

Dr. Saheba

1

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

2/33

Heart AnatomySize of a fistLocation

In the mediastinum

between second rib and fifth intercostal spacesuperior surface of diaphragmTwo-thirds to the left of the midsternal line Anterior to the vertebral column, posterior tothe sternum

Enclosed in pericardium, a double-walled sac

PLAY Animation: Rotatable heart

2

Dr. Saheba

http://rotatable_heart.mov/http://rotatable_heart.mov/

8/2/2019 11-Ch 18 Lecture A

3/33

Figure 18.1c

(c)

Superiorvena cava

Left lung

Aorta Parietalpleura (cut)

Pericardium(cut)

Pulmonarytrunk

Diaphragm

Apex ofheart

3

Pericardium Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

4/33

Pericardium1. Superficial fibrous pericardium Protects, anchors, and prevents overfilling2. Deep two-layered serous pericardium

Parietal layer - lines the internal surface of thefibrous pericardium Visceral layer (epicardium) on external surfaceof the heartSeparated by fluid-filled pericardial cavity todecreases friction

4

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

5/33

5

Layers of the Heart Wall1. Epicardium visceral layer of the serous pericardium

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

6/33

Layers of the Heart Wall2. Myocardium

Spiral bundles of cardiac muscle cellsFibrous skeleton of the heart connective

tissue1. Anchors - muscle fibers2. Supports - great vessels and valves

3. Limits - spread of action potentials3. Endocardium - continuous with

endothelial lining of blood vessels

6

Cardiacmusclebundles

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

7/33

Chambers4 chambers1. Two atria

Separated internally by the interatrial septumCoronary sulcus (atrioventricular groove)encircles the junction of the atria and ventricles Auricles increase atrial volume

2. Two ventricles

Separated by the interventricular septum Anterior and posterior interventricular sulcimark the position of the septum externally

7

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

8/33

Figure 18.4b

(b) Anterior view

Brachiocephalic trunk

Superior vena cava

Right pulmonaryarteryAscending aorta Pulmonary trunk

Right pulmonary

veins

Right atrium

Right coronary artery(in coronary sulcus) Anterior cardiac vein

Right ventricle Right marginal artery

Small cardiac vein

Inferior vena cava

Left common carotidarteryLeft subclavian artery

Ligamentum arteriosum

Left pulmonary artery

Left pulmonary veins

Circumflex artery

Left coronary artery(in coronary sulcus)

Left ventricle

Great cardiac vein Anterior interventricularartery (in anteriorinterventricular sulcus)

Apex

Aortic arch

Auricle of

left atrium

8

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

9/33

Atria: The Receiving Chambers Walls are ridged by pectinate muscles

A. Vessels entering right atrium1. Superior vena cava2. Inferior vena cava3. Coronary sinus

B. Vessels entering left atrium

1. Right and2. left pulmonary veins

9

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

10/33

Ventricles: Discharge Blood1. Walls are ridged by trabeculae carneae2. Papillary muscles project into the

ventricular cavities3. Vessel leaving the right ventricle

Pulmonary trunk

4. Vessel leaving the left ventricle Aorta

10

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

11/33

Aorta

Left pulmonary

artery Left atrium Left pulmonaryveins

Mitral (bicuspid)valve

Aortic valve

Pulmonary valve Left ventricle Papillary muscle Interventricularseptum Epicardium Myocardium Endocardium

(e) Frontal section

Superior vena cava

Right pulmonaryartery Pulmonary trunk Right atrium

Right pulmonary

veins Fossa ovalis Pectinate muscles

Tricuspid valve Right ventricle Chordae tendineae Trabeculae carneae Inferior vena cava

11

Dr. Saheba

Figure 18.4e

8/2/2019 11-Ch 18 Lecture A

12/33

Heart - Pathway of BloodThe heart is two side-by-side pumps

1. Right side - for the pulmonary circuitblood to and from the lungs

2. Left side - for the systemic circuitblood to and from all body tissues

12

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

13/33

Oxygen-rich,CO 2-poor blood Oxygen-poor,CO

2-rich blood

Capillary bedsof lungs wheregas exchangeoccurs

Capillary beds of allbody tissues wheregas exchange occurs

Pulmonary veins Pulmonary arteries

PulmonaryCircuit

SystemicCircuit

Aorta and branches

Left atrium

Heart

Left ventricle Right atrium

Right ventricle

Venae cavae

13

Dr. Saheba

Figure 18.5

8/2/2019 11-Ch 18 Lecture A

14/33

PLAY Animation: Rotatable heart (sectioned)

Blood Through the HeartRight atrium tricuspid valve right ventricleRight ventricle pulmonary semilunar valve pulmonary trunk pulmonary arteries lungs

Lungs pulmonary veins left atriumLeft atrium bicuspid valve left ventricleLeft ventricle aortic semilunar valve aorta Aorta systemic circulation

14

Dr. Saheba

http://rotatable_heart_sectioned.mov/http://rotatable_heart_sectioned.mov/

8/2/2019 11-Ch 18 Lecture A

15/33

Blood Through the HeartEqual volumes of blood - to the pulmonary andsystemic circuitsPulmonary circuit is:

a short,low-pressure circulationSystemic circuit blood

much resistance inthe long pathways

Anatomy of the ventricles reflects thesedifferences

15

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

16/33

Figure 18.6

Rightventricle

Leftventricle

Interventricularseptum

16

Dr. Saheba

h b

8/2/2019 11-Ch 18 Lecture A

17/33

Coronary CirculationSupply - to the heart muscle itself Arterial supply varies considerably andcontains many anastomoses (junctions)among branchesCollateral routes provide additional routesfor blood delivery

17

Dr. Saheba

D S h b

8/2/2019 11-Ch 18 Lecture A

18/33

Coronary Circulation Arteries

1. Right coronary and2. left coronary (in atrioventricular groove),3. marginal,4. circumflex, and5. anterior interventricular arteries

Veins1. Small cardiac,2. anterior cardiac, and3. great cardiac veins

18

Dr. Saheba

D S h b

8/2/2019 11-Ch 18 Lecture A

19/33

Figure 18.7a

Right

ventricle

Rightcoronaryartery

Right

atrium

Rightmarginalartery

Posterior interventricular artery

Anterior interventricular artery

Circumflexartery

Leftcoronaryartery

Aorta

Anastomosis(junction ofvessels)

Leftventricle

Superiorvena cava

(a) The major coronary arteries

Left atrium

Pulmonarytrunk

19

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

20/33

Dr Saheba

8/2/2019 11-Ch 18 Lecture A

21/33

Figure 18.4d

(d) Posterior surface view

Aorta Left pulmonaryartery Left pulmonaryveins Auricle of leftatrium Left atrium

Great cardiacvein

Posterior veinof left ventricle Left ventricle

Apex

Superior vena cava

Right pulmonary artery Right pulmonary veins

Right atrium

Inferior vena cava

Right coronary artery(in coronary sulcus)

Coronary sinus

Posterior

interventricularartery (in posteriorinterventricular sulcus) Middle cardiac vein Right ventricle

21

Dr. Saheba

Dr Saheba

8/2/2019 11-Ch 18 Lecture A

22/33

Homeostatic Imbalances Angina pectoris

Thoracic pain caused by a fleeting deficiency inblood delivery to the myocardium

Cells are weakenedMyocardial infarction (heart attack)

Prolonged coronary blockage

Areas of cell death are repaired withnoncontractile scar tissue

22

Dr. Saheba

Dr Saheba

8/2/2019 11-Ch 18 Lecture A

23/33

Heart ValvesEnsure unidirectional blood flow through the heart

1. Atrioventricular (AV) valvesPrevent backflow into the atria when ventricles contract

2. Tricuspid valve (right)

3. Mitral valve (left)Chordae tendineae anchor AV valve cusps to papillary muscles

4. Semilunar (SL) valvesPrevent backflow into the ventricles when ventricles relax

i. Aortic semilunar valveii. Pulmonary semilunar valve

23

Dr. Saheba

Dr Saheba

8/2/2019 11-Ch 18 Lecture A

24/33

Pulmonary valve Aortic valve Area of cutaway

Mitral valve Tricuspid valve

Myocardium

Tricuspid(right atrioventricular)valve Mitral(left atrioventricular)valve

Aorticvalve

Pulmonaryvalve

(b)

Pulmonary valve Aortic valve Area of cutaway

Mitral valve Tricuspid valve

Myocardium

Tricuspid(right atrioventricular)valve

(a)

Mitral(left atrioventricular)valve Aortic valve

Pulmonaryvalve Fibrous

skeleton Anterior

24

Dr. Saheba

Figure 18.8a

Dr Saheba

8/2/2019 11-Ch 18 Lecture A

25/33

Pulmonary valve Aortic valve Area of cutaway

Mitral valve Tricuspid valve

Myocardium

Tricuspid(right atrioventricular)valve Mitral(left atrioventricular)valve

Aorticvalve

Pulmonaryvalve

(b)

25

Dr. Saheba

Figure 18.8b

Dr Saheba

8/2/2019 11-Ch 18 Lecture A

26/33

Figure 18.8c

Pulmonaryvalve

AorticvalveArea ofcutaway Mitralvalve

Tricuspidvalve

Chordae tendineaeattached to tricuspid valve flap

Papillarymuscle

(c)

26

Dr. Saheba

Dr Saheba

8/2/2019 11-Ch 18 Lecture A

27/33

PulmonaryvalveAortic valve Area ofcutaway Mitral valve Tricuspidvalve

Mitral valve Chordaetendineae

Interventricularseptum

Myocardium

of left ventricle

Opening of inferiorvena cava

Tricuspid valve

Papillarymuscles

Myocardiumof rightventricle

(d) 27

Dr. Saheba

Figure 18.8d

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

28/33

Figure 18.9

1 Blood returning to theheart fills atria, puttingpressure againstatrioventricular valves;atrioventricular valves areforced open.

1 Ventricles contract, forcingblood against atrioventricularvalve cusps.

2 As ventricles fill,atrioventricular valve flapshang limply into ventricles.

2 Atrioventricular valvesclose.

3 Atria contract, forcingadditional blood into ventricles.

3 Papillary musclescontract and chordaetendineae tighten,preventing valve flapsfrom everting into atria.

(a) AV valves open; atrial pressure greater than ventricular pressure

(b) AV valves closed; atrial pressure less than ventricular pressure

Direction ofblood flow

Atrium

Ventricle

Cusp ofatrioventricularvalve (open)

Chordaetendineae

Papillarymuscle

Atrium

Blood inventricle

Cusps ofatrioventricularvalve (closed)

28

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

29/33

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

30/33

Microscopic Anatomy of

Cardiac MuscleCardiac muscle cells are - striated, short, fat,branched, and interconnected

Connective tissue (endomysium) connects to thefibrous skeletonT tubules are wide but less numerous; SR issimpler than in skeletal muscleNumerous large mitochondria (25 35% of cell volume)

30

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

31/33

Nucleus

Desmosomes Gap junctions

Intercalated discs Cardiac muscle cell

(a)

31

Figure 18.11a

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

32/33

Microscopic Anatomy of

Cardiac MuscleIntercalated discs: junctions between cellsanchor cardiac cells

Desmosomes prevent cells fromseparating during contractionGap junctions allow ions to pass;

electrically couple adjacent cellsHeart muscle behaves as a functionalsyncytium

32

Dr. Saheba

8/2/2019 11-Ch 18 Lecture A

33/33

Figure 18 11b

Nucleus

Nucleus

I band A band

Cardiacmuscle cell

Sarcolemma

Z disc

Mitochondrion

Mitochondrion

T tubule

Sarcoplasmicreticulum

I band

Intercalateddisc

(b)