Transcript Cardiovascular Anatomy and Physiology

心血管解剖和生理学概述
Cardiovascular Anatomy and Physiology
葛 雷
复旦大学附属中山医院 上海市心血管病研究所
Cardiovascular Anatomy
and Physiology
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Heart – the pump
Vasculature
Pulmonary circuit
Systemic circuit
Cardiovascular Anatomy
and Physiology
Heart Anatomy
Four chambered, four valves, muscular
organ.
Adult
12 cm long
9 cm wide at the widest point
6 cm thick
Weight is 250 to 350 grams
Cardiovascular Anatomy
and Physiology
Pericardial Sac
1. Holds the heart in place in the
medisternum
2. Prevents extreme over dilation of heart
during sudden rises of volume
3. Barrier to protect heart from infection
(like the blood brain barrier)
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Cardiovascular Anatomy
and Physiology
Pericardial Effusion
• Normal pericardium holds
15-50 cc fluid
• More than 50 causes
trouble especially if the
sac is ‘restrictive’
• Acute vs. Chronic buildup
– Rupture the RA and there is
a quick effusion –
tamponade
– Slower chronic diseases
can stretch the sac and it
can hold 1000cc or more
5
Cardiovascular Anatomy
and Physiology
Right Atrium (RA)
• Receives blood from
the body or systemic
venous circulation
• Forms the right
cardiac border
• Receives blood from
vena cava (SVC &
IVC) and coronary
sinus
Cardiovascular Anatomy
and Physiology
Left Atria (LA)
• Receives blood from
the lungs (oxygenated)
• Smooth walled except
appendage
• Most posterior cardiac
chamber
• Receive blood through
right and left
pulmonary veins
Cardiovascular Anatomy
and Physiology
Right Ventricle (RV)
• Provides blood flow
to the pulmonary
circuit
• Low pressure pump
– <35 mmHg
• Crescent-shaped
wraps around the LV
• Most anterior heart
structure
Cardiovascular Anatomy
and Physiology
Left Ventricle (LV)
• Provides blood flow to
the systemic circuit
• High pressure pump
– >100 mmHg
• Egg shaped (ellipse)
• Forms the left cardiac
border
Cardiovascular Anatomy
and Physiology
Valves of the Heart
Figure 20.8a
Cardiovascular Anatomy
and Physiology
Coronary Vessel Anatomy
Cardiovascular Anatomy
and Physiology
Coronary arteries and Distribution
Left coronary artery
LAD
Left Circumflex
SA node 45%
AV node 10%
Right coronary artery
SA node 55%
AV node 90%
Collaterals- factors that foster the
development include: exercise,
anemia, hypoxemia, arteriosclerosis
Cardiovascular Anatomy
and Physiology
Myocardial O2 Supply and Demand
• Coronary blood flow
–Approximately 250 ml/min at rest
–Myocardium will regulate its own blood flow between
perfusion pressures of 50 mm Hg and 120 mm Hg
–The myocardium receives 5% of cardiac output and
extracts 65% to 80% of oxygen in the blood, even at
basal rate.
Cardiovascular Anatomy
and Physiology
Conduction System
• Specialized cells for conduction of
electrical & chemical impulses
rapidly from point to point
–
–
–
–
–
–
SA node
Internodal pathway
AV node
Bundle of HIS
Bundle Branches
Perkinje Fibers
• Automaticity, Excitability,
Conductivity & Contractility
Cardiovascular Anatomy
and Physiology
Action Potentials- Ventricular
1 = Brief repolarization
Cl diffuses into cell
2= plateau phase
K diffuses out of cell
1
Ca diffuses into the cell
2
0= rapid
depolarization
Na diffuses into
the cell
3
0
4
- 90 mV
The resting potential of cardiac
ventricular cell is -90 mV
4
Cardiovascular Anatomy
and Physiology
Action Potentials- Ventricular
3= repolarization
K diffuses out of cell
4 = diastole
1
2
Na-K pump
functions to
restore Na & K
to normal levels
3
0
4
- 90 mV
The resting potential of cardiac
ventricular cell is -90 mV
4
Cardiovascular Anatomy
and Physiology
Refractoriness
Absolute refractory period
The correlation with AP is phase 0 to mid-phase 3
1
2
3
0
-55mv
-60mv Local Response Period
4
4
Effective Refractory Period
Cardiovascular Anatomy
and Physiology
Refractoriness
Relative refractory period
The correlation with AP is from mid to late-phase 3
1
2
0
4
3
-60mv
Relative Refractory Period
-80mv 4
Cardiovascular Anatomy
and Physiology
Supranormal Period
The correlation with AP is phase late-phase 3 (-80mv to 90mv)
1
2
0
4
3
-80mv
Supranormal Period
-90mv
Cardiovascular Anatomy
and Physiology
Sinoatrial node action potential
(pacemaker cell action potential)
Phase 0- Calcium in; some sodium in
Phase 1- N/A
Phase 2- N/A
Phase 3- Potassium out
Phase 4- Potassium out is progressively
slowing; Sodium in is progressively
increasing; Calcium in during last 1/3
of phase
**Changing the slope of phase 4 leads to
a change in HR
Cardiovascular Anatomy
and Physiology
Cardiac muscle
Cardiac muscle
Striated
Intercalated discs
Cardiovascular Anatomy
and Physiology
Striations /Sarcomeres
• Z discs (lines): the
boundary between
sarcomeres; proteins anchor
the thin filaments
• A band: overlap of thick
(myosin) filaments & thin
filaments
• I band: thin (actin) filaments
only
• H zone: thick filaments only
• M line: proteins anchor the
adjacent thick filaments
Cardiovascular Anatomy
and Physiology
Myofilaments
• Thin filaments: actin
(plus some tropomyosin
& troponin)
• Thick filaments: myosin
• Elastic filaments: titin
(connectin) attaches
myosin to the Z discs
(very high mol. wt.)
Cardiovascular Anatomy
and Physiology
CARDIAC OUTPUT
The cardiac output is the volume of blood that is ejected from the
left ventricle into the aorta over a given time period (L/min).
At rest cardiac output is 4-8 L/min in an healthy adult. This can
rise up to 25 litres/min during severe exercise.
Cardiac Output = Heart Rate X Stroke Volume
Stroke Volume - volume of blood ejected per beat
Cardiac Index – the cardiac output divided by the body surface area (2.54.0L/min/m2)
Cardiovascular Anatomy
and Physiology
Stroke Volume
Volume of blood ejected from the ventricle with
each beat
– Preload
• The amount of blood in the ventricles at the end of
diastole (LVEDP, RVEDP)
– Afterload
• The amount of pressure that the ventricle has to pump
against (left SVR, right PVR)
– Contractility
• Intrinsic ability of the ventricular mussles to shorten
(Dp/Dt)
Cardiovascular Anatomy
and Physiology
Frank-Starling’s Law of the Heart
Maximum Capacity
To Produce SV
Stroke
Volume
Normal Range:
SV increases with EDV
End-Diastolic Volume
Cardiovascular Anatomy
and Physiology
F-S Curves: Contractility and Afterload
At a given EDV, SV increases
With cardiac contractility
High
Increased
contractility or
decreased afterload
Stroke
Volume
Low
Decreased
contractility or
increased afterload
Preload (End-Diastolic Volume)
Cardiovascular Anatomy
and Physiology
Frank-Starling Ventricular Function Curves:
Increased Contractility and Decreased Afterload
High
Stroke
Volume
Normal curve
Preload (End-Diastolic Volume)
Function curve of
positive inotrope
administration
(increased
contractility) or
decreased
afterload.
Cardiovascular Anatomy
and Physiology
Frank-Starling Ventricular Function Curves:
Altered Preload
Increased Preload
Stroke
A
Volume
C
Decreased preload
Preload (End-Diastolic Volume)
B
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2010-3