Download Left Ventricle

NURS1004
Physical dimensions of being human
Week 10
Prepared by Didy Button
The Heart Part 1
Figure 20-1 An Overview of the Cardiovascular System
PULMONARY CIRCUIT
SYSTEMIC CIRCUIT
Pulmonary arteries
Systemic arteries
Pulmonary veins
Systemic veins
Capillaries
in lungs
Right
atrium
Right
ventricle
Capillaries
in trunk
and lower
limbs
Capillaries
in head,
neck, upper
limbs
Left
atrium
Left
ventricle
Anatomy - location
• Sits within the thoracic cavity.
• Between the Lungs.
• Behind (posterior) the
Sternum.
• Mediastinum (Midline)
• Rests superior (top) to the
diaphragm.
• Apex – 5th intercostal space ≈
5cm left midline
Anatomy – Internal Structure
• Four Heart Chambers:
• Right Atrium
– Receives blood from Systemic Circuit.
• Right Ventricle
– Pumps blood to the Pulmonary Circuit.
• Left Atrium
– Receives blood from Pulmonary Circuit.
• Left Ventricle
– Pumps blood to the Systemic Circuit.
Figure 20-6a The Sectional Anatomy of the Heart
Superior
vena cava
Pulmonary trunk
Aortic arch
Pulmonary valve
Right
pulmonary
arteries
Left pulmonary
arteries
Ascending aorta
LEFT
ATRIUM
Left pulmonary
veins
Aortic valve
RIGHT ATRIUM
Cusp of left AV
(mitral) valve
LEFT VENTRICLE
Cusp of right AV
(tricuspid) valve
Interventricular
septum
RIGHT VENTRICLE
Inferior vena cava
Descending aorta
© 2012 Pearson Education, Inc.
Anatomy – Internal Structure
• Pulmonary Circuit:
– Begins in the Pulmonary Truck – blood leaves the RV
and enters the Pulmonary Artery.
• Past the Pulmonary Semi-lunar valve.
– Deoxygenated blood present in the Artery – the only
example, as usually oxygenated blood.
– The left and right Pulmonary Arteries enter the lungs
→ branch numerous times → Pulmonary Capillaries
where gas exchange occurs.
– Oxygenated blood enters the Pulmonary Veins (4) →
Left Atrium.
– Only example of ↑O2 in a Vein.
Figure 20-1 An Overview of the Cardiovascular System
PULMONARY CIRCUIT
SYSTEMIC CIRCUIT
Pulmonary arteries
Systemic arteries
Pulmonary veins
Systemic veins
Capillaries
in lungs
Right
atrium
Right
ventricle
Capillaries
in trunk
and lower
limbs
© 2012 Pearson Education, Inc.
Capillaries
in head,
neck, upper
limbs
Left
atrium
Left
ventricle
Figure 20-2c The Location of the Heart in the Thoracic Cavity
Base of heart
Cut edge of
parietal pericardium
Fibrous tissue of
pericardial sac
Parietal pericardium
Areolar tissue
Mesothelium
Wrist (corresponds
to base of heart)
Inner wall (corresponds
to epicardium)
Air space (corresponds
to pericardial cavity)
Outer wall (corresponds
to parietal pericardium)
Cut edge of epicardium
Balloon
Fibrous
attachment
to diaphragm
Apex of heart
The relationship between the heart and the pericardial cavity; compare with the fist-and-balloon example.
© 2012 Pearson Education, Inc.
Anatomy – Internal Structure
• Systemic Circuit:
– Begins in the Left Ventricle where freshly oxygenated
blood is ejected into the Aorta.
• Past the Aortic Semi-lunar Valve.
– Supplies blood to the vascular system not serviced by
the Pulmonary Circuit.
– The Aorta is the biggest artery in the body.
– Predominantly elastic fibres to absorb the pressure
changes with each heart beat
• i.e. Systolic and Diastolic e.g. 120/80
– This propels blood through the arterial circuit.
Know this !
Blood flow through the Heart:
• Right atrium  right ventricle  pulmonary
arteries  lungs
• Lungs  pulmonary veins  left atrium 
left ventricle  Aorta  Systemic Circulation.
Figure 20-6a The Sectional Anatomy of the Heart
Superior
vena cava
Pulmonary trunk
Aortic arch
Pulmonary valve
Right
pulmonary
arteries
Left pulmonary
arteries
Ascending aorta
LEFT
ATRIUM
Left pulmonary
veins
Aortic valve
RIGHT ATRIUM
Cusp of left AV
(mitral) valve
LEFT VENTRICLE
Cusp of right AV
(tricuspid) valve
Interventricular
septum
RIGHT VENTRICLE
Inferior vena cava
Descending aorta
Figure 20-4a The Heart Wall
Parietal pericardium
Dense fibrous layer
Areolar tissue
Mesothelium
• Endo – inside or within.
• Myo – muscle.
• Epi – on top.
• Peri – to go around.
•These are common medical prefixes.
Pericardial cavity
Myocardium
(cardiac muscle tissue)
Epicardium
(visceral pericardium)
Cardiac muscle cells
Mesothelium
Connective tissues
Areolar tissue
Endocardium
Areolar tissue
Endothelium
© 2012 Pearson Education, Inc.
Anatomy – Internal Structure
• Epicardium – outer cardiac layer
– A layer of serous membrane contiguous with the
visceral pericardial layer i.e. very closely aligned.
– Attached to the myocardium.
• Myocardium –muscular middle layer
– Specialised layers of concentric cardiac muscle
• Intercalated discs.
– Atria and Ventricles have muscle bundles requiring
high blood supply.
– Bundles allow for repetitive contraction and
relaxation i.e. each heart beat.
Anatomy – Internal Structure
• Endocardium – Inner cardiac layer
– Inner surface of the heart of simple squamous cells.
– Contiguous with the endothelial layer of the attached
great blood vessels –direct contact with blood.
• Pericardium – Pericardial Sac
– Surrounds the heart with two layers.
– Pericardial fluid provides lubrication for reducing
friction between opposing surfaces during each heart
beat – abnormality = Pericarditis.
20-1 Anatomy of the Heart
• Cardiac Muscle Tissue
– Intercalated discs
• Interconnect cardiac muscle cells
• Secured by desmosomes
• Linked by gap junctions
• Convey force of contraction
• Propagate action potentials
Figure 20-5a Cardiac Muscle Cells
Cardiac muscle cell
Mitochondria
Intercalated
disc (sectioned)
Nucleus
Cardiac muscle
cell (sectioned)
Bundles of
myofibrils
Intercalated discs
Cardiac muscle cells
Figure 20-5b Cardiac Muscle Cells
Intercalated disc
Gap junction
Opposing plasma
membranes
Desmosomes
Structure of an intercalated disc
Figure 20-5c Cardiac Muscle Cells
Intercalated discs
Cardiac muscle tissue
Cardiac muscle tissue
LM  575
20-1 Anatomy of the Heart
• Characteristics of Cardiac Muscle Cells
1. Small size
2. Single, central nucleus
3. Branching interconnections between cells
4. Intercalated discs
Anatomy – Internal Structure
• Myocardium - differences:
• The difference in workload is revealed in the comparative anatomy of the
myocardium.
• The walls of the left ventricle (LV) are three times as thick as those of the
right ventricle (RV).
• LV generates high pressure to eject blood against:
–
–
–
–
Gravity
Systemic Blood Pressure (SBP)
Viscosity of the blood, and
Length of the systemic circuit.
• RV - only pulmonary circulation, therefore less force required.
• Atria have much smaller muscle.
Figure 20-7a Structural Differences between the Left and Right Ventricles
Posterior
interventricular sulcus
Right
ventricle
Left
ventricle
Fat in anterior
interventricular sulcus
A diagrammatic sectional view through the heart,
showing the relative thicknesses of the two ventricles.
Notice the pouchlike shape of the right ventricle and
the greater thickness of the left ventricle.
Anatomy – Internal Structure
Ventricular Diastole
Ventricular Systole
Anatomy – Internal Structure
• Four valves
• control blood flow → in one
direction
2 x Semilunar – half moon
2 X Atrio-ventricular (AV):
• Bicuspid = Mitral
• Tricuspid
• Pressure in each chamber controls
opening/closing of each valve.
Anatomy – Internal Structure
Anatomy – Internal Structure
• AV Valves – speciality:
– Prevent blood from reentering the atria when
ventricles contract.
• When ventricles are relaxed – the CT
are also relaxed → no resistance to
flow of blood from the Atria to the
Ventricles – both AV’s are open.
– CT and PM play vital roles.
• Provide an anchorage and
strength.
– When ventricles contract:
• Blood forced upwards
• Cusps of AV close
• Papillary muscles tense the
Chordae Tendinae to prevent
AV inverting into the atria
(Murmur = abnormal
retrograde flow).
Anatomy – Internal Structure
Chordae Tendinae
Papillary muscles
Anatomy – Internal Structure
• Semi-lunar Valves:
Pulmonary
Valve
Aortic Valve
Prosthetic
Valve
• Various pathogens or diseases can
cause valvular dysfunction which →
regurgitation of blood – Murmurs.
E.g. RHD or MI.
– Prevent blood from reentering the ventricles
when ventricles relax.
– i.e. preventing blood
returning from the
Pulmonary trunk and
Aorta.
– No muscular support.
– Both close when ventricles
relax.
– Blood then has gravity to
close valves.
Figure 20-8a Valves of the Heart
Transverse Sections, Superior View,
Atria and Vessels Removed
POSTERIOR
Cardiac Left AV (bicuspid)
skeleton
valve (open)
Relaxed ventricles
RIGHT
VENTRICLE
LEFT
VENTRICLE
Right AV
(tricuspid)
valve (open)
Aortic valve
(closed)
ANTERIOR
Aortic valve closed
© 2012 Pearson Education, Inc.
Pulmonary
valve (closed)
When the ventricles are relaxed, the AV valves
are open and the semilunar valves are closed.
The chordae tendineae are loose, and the
papillary muscles are relaxed.
Figure 20-8a Valves of the Heart
Frontal Sections through Left Atrium and Ventricle
Pulmonary
veins
Relaxed ventricles
LEFT
ATRIUM
Left AV (bicuspid)
valve (open)
Aortic valve
(closed)
Chordae
tendineae (loose)
Papillary muscles
(relaxed)
LEFT VENTRICLE
(relaxed and filling
with blood)
© 2012 Pearson Education, Inc.
Figure 20-8b Valves of the Heart
Contracting ventricles
Cardiac
Right AV
skeleton
(tricuspid) valve
(closed)
RIGHT
VENTRICLE
Left AV
(bicuspid) valve
(closed)
LEFT
VENTRICLE
Aortic valve
(open)
Pulmonary
valve (open)
Aortic valve open
© 2012 Pearson Education, Inc.
When the ventricles are contracting, the
AV valves are closed and the semilunar
valves are open. In the frontal section
notice the attachment of the left AV valve
to the chordae tendineae and papillary
muscles.
Anatomy – Internal Structure
• The closing of the Heart Valves can be heard
(Auscultate):
– S1 – closure of both AV valves – soft ‘Lub’ sound.
• Represents the beginning of Systole – blood leaving Ventricles.
– S2 – closure of both semilunar valves – sharp ‘Dub’.
• Represents the beginning of Diastole – blood leaving Atria.
– S3 – abnormal low-intensity sound which may indicate LV
failure or mitral valve regurgitation.
– S4 – abnormal low-intensity sound indicative of CAD, LV
hypertrophy, or aortic stenosis.
– Murmurs are indicative of abnormal turbulence through the
heart e.g. valve insufficiency.
– Cardiac Auscultation requires training and skill acquired from
practice.
Figure 20-18b Heart Sounds
Semilunar
valves close
Pressure
(mm Hg)
Semilunar
valves open
Left
ventricle
Left
atrium
AV valves
open
AV valves
close
S1
S4
S2
S3
Heart sounds
“Lubb”
“Dubb”
The relationship between heart sounds and key events in the
cardiac cycle
© 2012 Pearson Education, Inc.
S4
Figure 20-18a Heart Sounds
Sounds heard
Valve location
Aortic
valve
Valve location
Sounds heard
Pulmonary
valve
Sounds heard
Valve location
Left
AV
valve
Valve location
Sounds heard
Right
AV
valve
Placements of a stethoscope for
listening to the different sounds
produced by individual valves
© 2012 Pearson Education, Inc.
Anatomy – Internal Functionality
• Blood flow through the Heart:
– Right atrium  right ventricle 
pulmonary arteries  lungs
– Lungs  pulmonary veins  left
atrium  left ventricle  Aorta 
Systemic Circulation.
•
•
•
This one-way flow of blood is controlled
by the four heart valves.
Requires adequate functioning of the
Heart:
– Coordination of each chamber.
– Usual functioning of all valves.
– Adequate pressure generated
within each chamber.
– Adequate muscle contraction.
Only example where an artery has
reduced O2, and a vein has raised O2
(and opposite for CO2).
Blood Flow
• Factors promoting blood flow TO the Heart:
– Leg muscles – walking contracts the large deep veins
in the legs to assist propel the blood.
– Valves in deep leg veins prevent back flow.
– Breathing – inspiration and exhalation alters the intrathoracic pressure and propels the blood.
– Functioning of the RHS & LHS of the Heart.
– Viscosity of the blood.
Figure 20-9a Coronary Circulation
Aortic
arch
Ascending
aorta
Right coronary
artery
Atrial arteries
Anterior
cardiac veins
Small
cardiac vein
Marginal
artery
Left coronary
artery
Pulmonary
trunk
Circumflex
artery
Anterior
interventricular
artery
Great
cardiac
vein
Coronary vessels supplying
and draining the anterior
surface of the heart.
Anatomy – Blood Flow
• Blood flow of the Heart:
• Coronary Arteries (CA) only supply the heart:
– Any problems can cause: Angina/Myocardial Infarction (MI).
• Coronary Veins only drain the heart.
• LV has highest blood supply –why?
• CAs begin at base of ascending aorta, and Aortic semilunar valve.
– CAs therefore fill when ventricles relax (Diastole) – as the aortic valve closes.
• Cardiac Veins drain into the coronary sinus which drains into the right
atrium → usual flow of blood through the heart.
Anatomy – Blood Flow
• Right Coronary Artery supplies blood to:
– Right Atrium, Segments of both Ventricles, Marginal arteries,
posterior ventricular artery, and SA Node cells.
• Left Coronary Artery – has two main branches:
– Circumflex Artery, and Anterior Interventricular Artery.
– Blood supplies to: Left Ventricle, Left Atrium, and
interventricular septum.
• Coronary Veins:
– Returns blood to the Coronary Sinus → drains in to Right
Atrium.
• As the Heart pumps continuously, it requires a reliable
blood flow for O2 and nutrients.
Figure 20-9b Coronary Circulation
Circumflex artery
Coronary sinus
Great cardiac vein
Marginal artery
Posterior
interventricular
artery
Posterior
cardiac
vein
Left
ventricle
Small cardiac
vein
Right coronary
artery
Middle cardiac vein
Marginal artery
Coronary vessels supplying and draining
the posterior surface of the heart.
Figure 20-9c Coronary Circulation
Auricle of
left atrium
Left pulmonary
veins
Circumflex artery
Great cardiac vein
Marginal artery
Posterior
cardiac vein
Left pulmonary
artery
Right pulmonary
artery
Superior
vena cava
Right pulmonary
veins
Left atrium
Right atrium
Inferior vena cava
Coronary sinus
Middle cardiac vein
Posterior interventricular artery
Right ventricle
A posterior view of the heart; the vessels have been
injected with colored latex (liquid rubber).
Figure 20-10 Heart Disease and Heart Attacks
Narrowing of Artery
Normal Artery
Tunica
externa
Lipid deposit
of plaque
Tunica
media
Cross-section
Cross-section
20-1 Anatomy of the Heart
• Heart Disease - Coronary Artery Disease
– Coronary artery disease (CAD)
• Areas of partial or complete blockage of coronary
circulation
– Cardiac muscle cells need a constant supply of
oxygen and nutrients
• Reduction in blood flow to heart muscle produces a
corresponding reduction in cardiac performance
• Reduced circulatory supply, coronary ischemia, results
from partial or complete blockage of coronary arteries
20-1 Anatomy of the Heart
• Heart Disease - Coronary Artery Disease
– Usual cause is formation of a fatty deposit, or
atherosclerotic plaque, in the wall of a coronary
vessel
– The plaque, or an associated thrombus (clot), then
narrows the passageway and reduces blood flow
– Spasms in smooth muscles of vessel wall can
further decrease or stop blood flow
– One of the first symptoms of CAD is commonly
angina pectoris
20-1 Anatomy of the Heart
• Heart Disease - Coronary Artery Disease
– Angina Pectoris
• In its most common form, a temporary ischemia
develops when the workload of the heart increases
• Although the individual may feel comfortable at rest,
exertion or emotional stress can produce a sensation of
pressure, chest constriction, and pain that may radiate
from the sternal area to the arms, back, and neck
Figure 20-10 Heart Disease and Heart Attacks
Normal Heart
A color-enhanced digital subtraction
angiography (DSA) scan of a normal
heart.
Figure 20-10 Heart Disease and Heart Attacks
Occluded
Coronary
Artery
Damaged
Heart
Muscle
Abnormal cardiovascular conditions
• Atherosclerosis – Gk = athere means gruel, and skleros means
hard.
• Starts as soft fat deposits (atheromas) and hardens with age
(Thrombus) – long time to detect.
• Major cause of coronary artery disease (CAD).
– Complex interaction within the endothelium of Coronary Arteries and
fatty deposits.
– These harden to reduce the lumen of the artery and so the blood flow
below (distal) to it ↓.
– The endothelium can become damaged (denuded) from BP, smoking
chemicals and/or diabetes.
– This begins the construction of Thrombus clot.
– Diet also linked with thrombus formation.
Abnormal cardiovascular conditions
• Coronary Artery Disease (CAD)
• Leading cause of death in westernised countries.
• Results in partial or total blockage (occlusion) of the
coronary circulation.
– Coronary Ischaemia
• Cardiac muscle cells required constant supply of
blood carrying O2 and nutrients to function.
• Chest pain is reported by patients experiencing
Angina or MI.
Abnormal cardiovascular conditions
• Angina
– Reversible myocardial ischaemia (↓
blood flow).
– Blood flow can be restored with rest
and/or medication.
– Can be stable or unstable.
– Predisposes to MI risk.
• Myocardial Infarction
– Non reversible ischaemia.
– Permanent cell death (necrosis) of
myocardial tissue →permanent scar
tissue.
– Permanent changes to heart
functioning.
– Usually blockage of one of the three
main coronary arteries.
• RCA, LCA, and LCxA.
Abnormal cardiovascular conditions
• Non-Modifiable:
– Ageing
– Gender - Males higher
than females.
– Hereditary
– Ethnicity
Modifiable:
- Healthy weight/Diet
- ↓Na intake
-  physical exercise
- Moderate Alcohol (ETOH)
- Monitor BP
- CEASE SMOKING
• We therefore have significant
control
References
1. Martini, F. H., & Nath, J. L., 2012. Fundamentals of
Anatomy and Physiology, 9th ed. Pearson, Benjamin
Cummings, San Francisco.