4.2 heart.copeland.2010

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Section 4.2 The Heart

Chapter 18, pp. 661-687

Keep an eye on the Forum over the next few days for a new question


Heart Anatomy

Approximately the size of your fist

Two side-by-side pumps

Location

Superior surface of diaphragm

Left of the midline, from 2nd rib to 5th intercostal space

Anterior to the vertebral column, posterior to the sternum

“mediastinum”


Heart Anatomy

Figure 18.1

Broad, flat base points to rt. shoulderApex points to lt. hip


3 layers of the heart

Pericardium

Outer sac

Myocardium

Muscle, bulk of mass

Endocardium

Inner lining


Coverings of the Heart: Anatomy

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


Coverings of the Heart: Physiology

The pericardium:

Protects and anchors the heart

Prevents overfilling of the heart with blood

Allows for the heart to work in a relatively friction-free environment

Epicardium – visceral layer of the serous pericardium


Pericardial Layers of the Heart

Figure 18.2


Heart Wall

Myocardium – cardiac muscle layer forming the bulk of the heart

Branching muscle cells arranged in bundles

Provides support for great vessels and valves

Directs spread of action potentials across heart

Fibrous skeleton of the heart – crisscrossing, interlacing layer of connective tissue, insulation, supports great vessels

Endocardium – endothelial layer of the inner myocardial surface; continuous with vessels leaving and entering the heart


Cardiac Muscle Bundles

Figure 18.3


External Heart: Major Vessels of the Heart (Anterior View) Vessels returning blood to the heart include:

Superior and inferior venae cavae, meaning?

Right and left pulmonary veins

Vessels conveying blood away from the heart:

Pulmonary trunk, which splits into right and left pulmonary arteries

Ascending aorta (three branches) – brachiocephalic, left common carotid, and subclavian arteries


External Heart: Vessels that Supply/Drain the Heart (Anterior View)

Arteries – right and left coronary (in atrioventricular groove), marginal, circumflex, and anterior interventricular arteries

Veins – small cardiac, anterior cardiac, and great cardiac veins

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4b

Brachiocephalictrunk

Superiorvena cava

Rightpulmonary artery

Ascendingaorta

Pulmonary trunk

Rightpulmonary veins

Right atriumRight coronaryartery (in coronarysulcus)Anteriorcardiac veinRight ventricleMarginal arterySmall cardiac vein

Inferiorvena cava

Left commoncarotid arteryLeftsubclavian arteryAortic arch

Ligamentumarteriosum

Left pulmonary artery

Left atrium

Auricle

CircumflexarteryLeft coronaryartery (in coronarysulcus)

Anteriorinterventricular artery(in anteriorinterventricular sulcus)

Great cardiac vein

Apex

Left pulmonary veins

Left ventricle


External Heart: Major Vessels of the Heart (Posterior View) Vessels returning blood to the heart include:

Right and left pulmonary veins

Superior and inferior venae cavae

Vessels conveying blood away from the heart include:

Aorta

Right and left pulmonary arteries


External Heart: Vessels that Supply/Drain the Heart (Posterior View)

Arteries – right coronary artery (in atrioventricular groove) and the posterior interventricular artery (in interventricular groove)

Veins – great cardiac vein, posterior vein to left ventricle, coronary sinus, and middle cardiac vein

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4d

(d)

Superiorvena cavaRightpulmonary artery


Right atrium

Right coronaryartery (in coronarysulcus)

Right ventricle

Coronary sinus

Middle cardiac vein


Left atrium

Auricleof left atrium

Left ventricle

Posterior veinof left ventricle

Posteriorinterventricular artery(in posteriorinterventricular sulcus)

Great cardiac vein

Apex

Leftpulmonary veins

Inferiorvena cava

Aorta

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4e

(e)

Superior vena cava

Rightpulmonary arteryPulmonary trunk

Right atriumRightpulmonary veinsFossaovalisPectinatemuscles

TricuspidValve (3 flaps)Right ventricle

Chordaetendineae

TrabeculaecarneaeInferiorvena cava

Aorta

Leftpulmonary arteryLeft atriumLeftpulmonary veins

Pulmonaryvalve

Aorticvalve

Mitral (bicuspid-2 flaps) valve

Left ventricle

PapillarymuscleInterventricularseptumMyocardium

VisceralpericardiumEndocardium


Atria of the Heart

Atria are the receiving chambers of the heart

Each atrium has a protruding auricle

Pectinate muscles mark atrial walls

Blood enters right atria from superior and inferior venae cavae and coronary sinus

Blood enters left atria from pulmonary veins


Ventricles of the Heart

Ventricles are the discharging chambers of the heart

Papillary muscles and trabeculae carneae muscles mark ventricular walls

Right ventricle pumps blood into the pulmonary trunk

Left ventricle pumps blood into the aorta


Right and Left Ventricles

Figure 18.6


Pathway of Blood Through the Heart and Lungs Right atrium tricuspid valve right ventricle

Right ventricle pulmonary semilunar valve pulmonary arteries lungs

Lungs pulmonary veins left atrium

Left atrium bicuspid valve left ventricle

Left ventricle aortic semilunar valve aorta

Aorta systemic circulation

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4e

(e)

Superior vena cava

Rightpulmonary arteryPulmonary trunk

Right atriumRightpulmonary veinsFossaovalisPectinatemuscles

TricuspidvalveRight ventricle

ChordaetendineaeTrabeculaecarneaeInferiorvena cava

Aorta

Leftpulmonary arteryLeft atriumLeftpulmonary veins

Pulmonaryvalve

Aorticvalve

Mitral (bicuspid) valve

Left ventricle

PapillarymuscleInterventricularseptumMyocardium

VisceralpericardiumEndocardium

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.5

Pulmonary circuit:Shorter, low pressure

Systemic circuit:Long pathway, 5x pressure (more resistance)


2 side-by-side pumps


Coronary Circulation

Coronary circulation is the functional blood supply to the heart muscle itself

Collateral routes ensure blood delivery to heart even if major vessels are occluded

Left coronary artery Right coronary artery

anterior interventricular

artery

interventricular septum &

anterior walls of both

ventricles

circumflex artery

left atrium & posterior walls of left

ventricle

marginal artery

posterior interventricular

artery

posterior right ventricular

walls

lateral right side of heart (incl right atrium


Coronary Circulation: Arterial Supply

Figure 18.7a

Blockage results in:Angina pectorisMyocardial Infarction (MI)


Coronary circulation

• many anastomoses, which provide alternate routes for nourishment if a given artery begins to be occluded - but total occlusion means ????

(1) actively deliver blood when heart is relaxed

(2) largely ineffective when ventricles contracting because??

• heart ~1/200 of body but requires ~1/20 of blood supply (esp. left ventricle)

Coronary venous supply:

from capillaries cardiac veins (great, middle & small) coronary sinus right atrium

also some anterior cardiac veins directly into right atrium anteriorly


Coronary Circulation: Venous Supply

Figure 18.7b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4d

(d)

Superiorvena cavaRightpulmonary artery


Right atrium

Right coronaryartery (in coronarysulcus)

Right ventricle

Coronary sinus

Middle cardiac vein


Left atrium

Auricleof left atrium

Left ventricle

Posterior veinof left ventricle

Posteriorinterventricular artery(in posteriorinterventricular sulcus)

Great cardiac vein

Apex

Leftpulmonary veins

Inferiorvena cava

Aorta


Heart Valves

Heart valves ensure unidirectional blood flow through the heart

Atrioventricular (AV) valves lie between the atria and the ventricles

AV valves prevent backflow into the atria when ventricles contract

Chordae tendineae anchor AV valves to papillary muscles


Heart Valves

Aortic semilunar valve lies between the left ventricle and the aorta

Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk

Semilunar valves prevent backflow of blood into the ventricles

No valves for vena cavae and pulmonary veins!


Heart Valves

Figure 18.8a, b


Heart Valves

Figure 18.8c, d


Atrioventricular Valve Function

Figure 18.9


Semilunar Valve Function

Figure 18.10


Microscopic Anatomy of Heart Muscle

Cardiac muscle is striated, short, fat, branched, and interconnected

The connective tissue endomysium acts as both tendon and insertion

Intercalated discs anchor cardiac cells together and allow free passage of ions

Heart muscle behaves as a functional syncytium

PLAYPLAY InterActive Physiology ®: Anatomy Review: The Heart, pages 3–7


Microscopic Anatomy of Cardiac Muscle

Figure 18.11

•1 or 2 nuclei/cell

•full of mitochondria(25% vs 2% skeletal)

•Resist fatigue

4.2 heart.copeland.2010

Health & Medicine

Transcript of 4.2 heart.copeland.2010