Download Left Ventricle

19
PART 1
The Heart
Pages 562-580
PowerPoint® Lecture Presentations prepared by
Leslie Hendon
University of Alabama, Birmingham
© 2014 Pearson Education, Inc.
The Heart
• A muscular double pump
• Pulmonary circuit—takes blood to and from the
lungs
• Systemic circuit—vessels transport blood to
and from body tissues
• Atria—receive blood from the pulmonary and
systemic circuits
• Ventricles—the pumping chambers of the heart
© 2014 Pearson Education, Inc.
Figure 19.1 The heart as a double pump.
Pulmonary Circuit
Capillary beds
of lungs where
gas exchange
occurs
Aorta and
branches
Pulmonary
arteries
Left
atrium
Pulmonary
veins
Right
atrium
Heart
Right
ventricle
Venae
cavae
Oxygen-rich,
CO2-poor blood
Oxygen-poor,
CO2-rich blood
© 2014 Pearson Education, Inc.
Left
ventricle
Systemic Circuit
Capillary
beds of all
body tissues
where gas
exchange
occurs
Location and Orientation within the Thorax
• Heart—typically weighs 250–350 grams
(healthy heart)
• Largest organ of the mediastinum
• Located between the lungs
• Apex lies to the left of the midline
• Base is the broad posterior surface
© 2014 Pearson Education, Inc.
Location of the Heart in the Thorax
Midsternal line
Superior vena cava
Aorta
Parietal pleura (cut)
Pulmonary trunk
Left lung
Pericardium (cut)
Rib 2
Apex of heart
Diaphragm
Diaphragm
(c)
(a)
Mediastinum
Mediastinum
Superior
vena cava
Heart
Right lung
(b)
Posterior
Right
auricle
of right
atrium
Right
ventricle
(d)
© 2014 Pearson Education, Inc.
Aorta
Left lung
Fat in
epicardium
Rib 5
Pericardium
(cut)
Apex of
heart
Figure 19.2
Structure of the Heart—Coverings
• Pericardium—two primary layers
• Fibrous pericardium
• Strong layer of dense connective tissue
• Serous pericardium
• Formed from two layers
• Parietal layer of the serous pericardium
• Visceral layer of the serous pericardium
© 2014 Pearson Education, Inc.
Layers of the Pericardium and of the Heart
Wall
Pericardium
Myocardium
Pulmonary
trunk
Fibrous pericardium
Parietal layer of serous
pericardium
Pericardial cavity
Epicardium (visceral
layer of serous
Heart
pericardium)
wall
Myocardium
Endocardium
Heart chamber
© 2014 Pearson Education, Inc.
Figure 19.3
Structure of the Heart—Layers of the Heart
Wall
• Epicardium
• Visceral layer of the serous pericardium
• Myocardium
• Consists of cardiac muscle
• Muscle arranged in circular and spiral patterns
• Endocardium
• Endothelium resting on a layer of connective
tissue
• Lines the internal walls of the heart
© 2014 Pearson Education, Inc.
Heart Chambers
• Right and left atria
• Superior chambers
• Right and left ventricles
• Inferior chambers
• Internal divisions
• Interventricular septum
• Interatrial septum
© 2014 Pearson Education, Inc.
Heart Chambers
Aorta
Superior vena cava
Right pulmonary artery
Pulmonary trunk
Right atrium
Left pulmonary artery
Left atrium
Left pulmonary veins
Mitral (bicuspid) valve
Right pulmonary
veins
Fossa ovalis
Pectinate muscles
Tricuspid valve
Right ventricle
Chordae tendineae
Trabeculae carneae
Inferior vena cava
Aortic valve
Pulmonary valve
Left ventricle
Papillary muscle
Interventricular septum
Epicardium
Myocardium
Endocardium
(e) Frontal section
© 2014 Pearson Education, Inc.
Figure 19.5e
© 2014 Pearson Education, Inc.
Right Atrium
• Forms right border of heart
• Receives blood from systemic circuit
• Superior vena cava
• Inferior vena cava
• Coronary sinus
• Right auricle projects anteriorly from
superior corner of atrium
• Opens into right ventricle via tricuspid
valve (right atrioventricular valve)
© 2014 Pearson Education, Inc.
Gross Anatomy of the Heart
Brachiocephalic trunk
Left common carotid
artery
Left subclavian artery
Superior vena cava
Aortic arch
Ligamentum arteriosum
Right pulmonary artery
Left pulmonary artery
Ascending aorta
Pulmonary trunk
Left pulmonary veins
Right pulmonary
veins
Right atrium
Right coronary artery
(in coronary sulcus)
Anterior cardiac vein
Auricle of
left atrium
Circumflex artery
Left coronary artery
(in coronary sulcus)
Left ventricle
Right ventricle
Inferior vena cava
Great cardiac vein
Anterior interventricular
artery (in anterior
interventricular sulcus)
(b) Anterior view
Apex
Right marginal artery
Small cardiac vein
© 2014 Pearson Education, Inc.
Figure 19.5b
Inferior View of the Heart
Aorta
Left pulmonary artery
Superior vena cava
Right pulmonary artery
Right pulmonary veins
Left pulmonary veins
Auricle of left atrium
Left atrium
Right atrium
Inferior vena cava
Great cardiac vein
Posterior vein of
left ventricle
Left ventricle
Coronary sinus
Right coronary artery
(in coronary sulcus)
Posterior interventricular
artery (in posterior
interventricular sulcus)
Middle cardiac vein
Right ventricle
Apex
(d) Inferior view; surface shown rests on the diaphragm.
© 2014 Pearson Education, Inc.
Figure 19.5d
© 2014 Pearson Education, Inc.
Heart Chambers
Aorta
Superior vena cava
Right pulmonary artery
Pulmonary trunk
Right atrium
Left pulmonary artery
Left atrium
Left pulmonary veins
Mitral (bicuspid) valve
Right pulmonary
veins
Fossa ovalis
Pectinate muscles
Tricuspid valve
Right ventricle
Chordae tendineae
Trabeculae carneae
Inferior vena cava
Aortic valve
Pulmonary valve
Left ventricle
Papillary muscle
Interventricular septum
Epicardium
Myocardium
Endocardium
(e) Frontal section
© 2014 Pearson Education, Inc.
Figure 19.5e
Right Ventricle
• Receives blood from right atrium through the
tricuspid valve
• Pumps blood into pulmonary circuit via
• Pulmonary trunk
• Internal walls of right ventricle
• Trabeculae carneae
• Papillary muscles
• Chordae tendineae
• Pulmonary semilunar valve
• Located at opening of right ventricle and
pulmonary trunk
© 2014 Pearson Education, Inc.
Left Atrium
• Makes up heart’s posterior surface
• Receives oxygen-rich blood from lungs through
pulmonary veins
• Opens into the left ventricle through
• Mitral valve (left atrioventricular valve)
© 2014 Pearson Education, Inc.
Inferior View of the Heart
Aorta
Left pulmonary artery
Superior vena cava
Right pulmonary artery
Right pulmonary veins
Left pulmonary veins
Auricle of left atrium
Left atrium
Right atrium
Inferior vena cava
Great cardiac vein
Posterior vein of
left ventricle
Left ventricle
Coronary sinus
Right coronary artery
(in coronary sulcus)
Posterior interventricular
artery (in posterior
interventricular sulcus)
Middle cardiac vein
Right ventricle
Apex
(d) Inferior view; surface shown rests on the diaphragm.
© 2014 Pearson Education, Inc.
Figure 19.5d
Gross Anatomy of the Heart
Brachiocephalic trunk
Left common carotid
artery
Left subclavian artery
Superior vena cava
Aortic arch
Ligamentum arteriosum
Right pulmonary artery
Left pulmonary artery
Ascending aorta
Pulmonary trunk
Left pulmonary veins
Right pulmonary
veins
Right atrium
Right coronary artery
(in coronary sulcus)
Anterior cardiac vein
Auricle of
left atrium
Circumflex artery
Left coronary artery
(in coronary sulcus)
Left ventricle
Right ventricle
Inferior vena cava
Great cardiac vein
Anterior interventricular
artery (in anterior
interventricular sulcus)
(b) Anterior view
Apex
Right marginal artery
Small cardiac vein
© 2014 Pearson Education, Inc.
Figure 19.5b
Heart Chambers
Aorta
Superior vena cava
Right pulmonary artery
Pulmonary trunk
Right atrium
Left pulmonary artery
Left atrium
Left pulmonary veins
Mitral (bicuspid) valve
Right pulmonary
veins
Fossa ovalis
Pectinate muscles
Tricuspid valve
Right ventricle
Chordae tendineae
Trabeculae carneae
Inferior vena cava
Aortic valve
Pulmonary valve
Left ventricle
Papillary muscle
Interventricular septum
Epicardium
Myocardium
Endocardium
(e) Frontal section
© 2014 Pearson Education, Inc.
Figure 19.5e
Left Ventricle
• Forms apex of the heart
• Internal walls of left ventricle
• Trabeculae carneae
• Papillary muscles
• Chordae tendineae
• Pumps blood through systemic circuit via
• Aortic semilunar valve (aortic valve)
© 2014 Pearson Education, Inc.
Inferior View of the Heart
Aorta
Left pulmonary artery
Superior vena cava
Right pulmonary artery
Right pulmonary veins
Left pulmonary veins
Auricle of left atrium
Left atrium
Right atrium
Inferior vena cava
Great cardiac vein
Posterior vein of
left ventricle
Left ventricle
Coronary sinus
Right coronary artery
(in coronary sulcus)
Posterior interventricular
artery (in posterior
interventricular sulcus)
Middle cardiac vein
Right ventricle
Apex
(d) Inferior view; surface shown rests on the diaphragm.
© 2014 Pearson Education, Inc.
Figure 19.5d
Heart Chambers
Aorta
Superior vena cava
Right pulmonary artery
Pulmonary trunk
Right atrium
Left pulmonary artery
Left atrium
Left pulmonary veins
Mitral (bicuspid) valve
Right pulmonary
veins
Fossa ovalis
Pectinate muscles
Tricuspid valve
Right ventricle
Chordae tendineae
Trabeculae carneae
Inferior vena cava
Aortic valve
Pulmonary valve
Left ventricle
Papillary muscle
Interventricular septum
Epicardium
Myocardium
Endocardium
(e) Frontal section
© 2014 Pearson Education, Inc.
Figure 19.5e
Heart Valves—Valve Structure
• Each valve composed of
• Endocardium with connective tissue core
• Atrioventricular (AV) valves
• Between atria and ventricles
• Aortic and pulmonary valves
• At junction of ventricles and great arteries
© 2014 Pearson Education, Inc.
Heart Valves—Valve Structure
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Myocardium
Tricuspid valve
Tricuspid
(right atrioventricular)
valve
Mitral
(left atrioventricular)
valve
Aortic
valve
Pulmonary
valve
Fibrous
skeleton
(a)
© 2014 Pearson Education, Inc.
Anterior
Figure 19.6a
Fibrous Skeleton
• Surrounds all four valves
• Composed of dense connective tissue
• Functions
• Anchors valve cusps
• Prevents overdilation of valve openings
• Main point of insertion for cardiac muscle
• Blocks direct spread of electrical impulses
© 2014 Pearson Education, Inc.
Function of the Atrioventricular Valves
1
Blood returning to
the heart fills atria,
putting pressure
against atrioventricular
valves; atrioventricular
valves are forced
open.
2 As ventricles fill,
atrioventricular
valve flaps hang
limply into
ventricles.
3 Atria contract,
forcing additional
blood into ventricles.
Direction of
blood flow
Atrium
Cusp of
atrioventricular
valve (open)
Chordae
tendineae
Ventricle
Papillary
muscle
(a) AV valves open; atrial pressure greater than ventricular pressure
© 2014 Pearson Education, Inc.
Figure 19.7a
Function of the Atrioventricular Valves
1
Ventricles contract,
forcing blood against
atrioventricular valve
cusps.
2 Atrioventricular
valves close.
3
Papillary muscles
contract and
chordae tendineae
tighten, preventing
valve flaps from
everting into atria.
(b) AV valves closed; atrial pressure less than ventricular pressure
© 2014 Pearson Education, Inc.
Atrium
Cusps of
atrioventricular
valve (closed)
Blood in
ventricle
Figure 19.7b
Function of the Semilunar Valves
Aorta
Pulmonary
trunk
As ventricles contract
and intraventricular
pressure rises, blood
is pushed up against
semilunar valves,
forcing them open.
(a) Semilunar valves open
As ventricles relax
and intraventricular
pressure falls, blood
flows back from
arteries, filling the
cusps of semilunar
valves and forcing
them to close.
(b) Semilunar valves closed
© 2014 Pearson Education, Inc.
Figure 19.8
Heart Sounds
• “Lub-dup”—sound of valves closing
• First sound “lub”
• The AV valves closing
• Second sound “dup”
• The semilunar valves closing
© 2014 Pearson Education, Inc.
Heart Sounds
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Myocardium
Tricuspid valve
Tricuspid
(right atrioventricular)
valve
Mitral
(left atrioventricular)
valve
Aortic
valve
Pulmonary
valve
Fibrous
skeleton
(a)
© 2014 Pearson Education, Inc.
Anterior
Figure 19.6a
Pathway of Blood Through the Heart
• Beginning with oxygen-poor blood in the
superior and inferior venae cavae
• Go through pulmonary and systemic circuits
• A blood drop passes through all structures
sequentially
• Atria contract together
• Ventricles contract together
© 2014 Pearson Education, Inc.
Blood Flow Through the Heart
Superior vena cava (SVC)
Inferior vena cava (IVC)
Coronary sinus
SVC
Right
atrium
Tricuspid
valve
Right
ventricle
Pulmonary
semilunar valve
Pulmonary
trunk
Pulmonary
trunk
Coronary
sinus
Tricuspid
valve
Right
atrium
IVC
Pulmonary
semilunar
valve
Right
ventricle
Oxygen-poor blood
To heart returns from the body
tissues back to the heart.
Two pulmonary arteries
To lungs
carry the blood to the
lungs (pulmonary circuit)
Pulmonary
to be oxygenated.
arteries
Oxygen-rich blood
Oxygen-poor blood
To body
Oxygen-rich blood is
delivered to the body
tissues (systemic circuit).
Oxygen-rich blood returns To heart
to the heart via the four
pulmonary veins.
Aorta
Mitral
valve
Left
ventricle
Aortic
semilunar
valve
Aorta
© 2014 Pearson Education, Inc.
Aortic
semilunar
valve
Pulmonary
veins
Left
atrium
Left
ventricle
Mitral
valve
Left
atrium
Four
pulmonary
veins
Figure 19.10
Heartbeat
• 70–80 beats per minute at rest
• Systole—contraction of a heart chamber
• Diastole—expansion of a heart chamber
• Systole and diastole also refer to
• Stage of heartbeat when ventricles contract and
expand
© 2014 Pearson Education, Inc.
Structure of Heart Wall
• Walls differ in thickness
• Atria—thin walls
• Ventricles—thick walls
• Systemic circuit
Left
ventricle
Right
ventricle
Interventricular
septum
• Longer than pulmonary circuit
• Offers greater resistance to blood flow
• Left ventricle—
three times thicker than right
• Exerts more pumping force
© 2014 Pearson Education, Inc.
Cardiac Muscle Tissue
• Forms a thick layer called myocardium
• Striated like skeletal muscle
• Contractions pump blood through the heart and
into blood vessels
• Contracts by sliding filament mechanism
• Cardiac muscle cells
• Short
• Branching
• Have one or two nuclei
© 2014 Pearson Education, Inc.
Microscopic Anatomy of Cardiac Muscle
Nucleus
Intercalated discs
Cardiac muscle cell
Gap junctions
Fasciae adherens
(a)
Cardiac
muscle cell
Mitochondrion
Nucleus
Intercalated
disc
Mitochondrion
T tubule
Sarcoplasmic
reticulum
(b)
Z disc
Nucleus
Sarcolemma
© 2014 Pearson Education, Inc.
I band
A band
I band
Figure 19.12
Cardiac Muscle Tissue
• Cells join at intercalated discs
• Complex junctions
• Form cellular networks
• Cells are separated by delicate
endomysium
• Binds adjacent cardiac fibers
• Contains blood vessels and nerves
© 2014 Pearson Education, Inc.
Cardiac Muscle Tissue
• Intercalated discs—complex junctions
• Adjacent sarcolemmas interlock
• Possess two distinct regions
• Fasciae adherens-bind adjacent cells together &
transmit contractile force to them
• Gap junctions-allow ions to pass between cells &
transmission of signals to adjacent cells
© 2014 Pearson Education, Inc.
Cardiac Muscle Tissue
• Triggered to contract by Ca2+ entering the
sarcoplasm
• Signals sarcoplasmic reticulum to release Ca2+
ions
• Ions diffuse into sarcomeres
• Trigger sliding filament mechanism
© 2014 Pearson Education, Inc.
Conducting System
• Cardiac muscle tissue has intrinsic ability to
• Generate and conduct impulses
• Signal these cells to contract rhythmically
• Conducting system
• A series of specialized cardiac muscle cells
• Sinoatrial (SA) node sets the inherent rate of
contraction
© 2014 Pearson Education, Inc.
Conducting System
Superior vena cava
Right atrium
1 The sinoatrial (SA)
node (pacemaker)
generates impulses.
Internodal pathway
2 The impulses
Left atrium
pause (0.1 sec) at the
atrioventricular
(AV) node.
3 The atrioventricular
Purkinje
fibers
4 The bundle branches
Interventricular
septum
(AV) bundle connects
the atria to the ventricles.
conduct the impulses
through the interventricular
septum.
5 The Purkinje fibers
stimulate the contractile
cells of both ventricles.
© 2014 Pearson Education, Inc.
Figure 19.14
Innervation
• Heart rate is altered
by external controls
• Nerves to the heart
include
The vagus nerve
(parasympathetic)
decreases heart rate.
Cardioacceleratory
center
Sympathetic
trunk
ganglion
• Visceral sensory
fibers
© 2014 Pearson Education, Inc.
Cardioinhibitory
center
Medulla oblongata
Thoracic spinal cord
Sympathetic trunk
Sympathetic cardiac
nerves increase heart rate
and force of contraction.
• Parasympathetic
branches of the
vagus nerve
• Sympathetic
fibers—from
cervical and
upper thoracic
chain ganglia
Dorsal motor nucleus
of vagus
AV node
SA node
Parasympathetic fibers
Sympathetic fibers
Interneurons
Figure 19.15
Blood Supply to the Heart
• Functional blood supply
• Coronary arteries
• Arise from the aorta
• Main branches
• Left and right coronary arteries
© 2014 Pearson Education, Inc.
Blood Supply to the Heart
Aorta
Pulmonary
trunk
Left atrium
Superior
vena cava
Anastomosis
(junction of
vessels)
Left
coronary
artery
Right
atrium
Right
coronary
artery
Right
ventricle
Circumflex
artery
Left
ventricle
Right
marginal
artery
Posterior
interventricular
artery
(a) The major coronary arteries
© 2014 Pearson Education, Inc.
Anterior
interventricular
artery
Superior
vena cava
Great
cardiac
vein
Anterior
cardiac
veins
Coronary
sinus
Small
cardiac vein
Middle cardiac vein
(b) The major cardiac veins
Figure 19.16