Download Cardiovascular Physiology Cardiovascular Physiology

Cardiovascular
Cardiovascular Physiology
Physiology
Cardiovascular
Cardiovascular System
System
¾
Purpose
• Transport O2 to tissues and removal of waste
• Transport of nutrients to tissues
• Regulation of body temperature
¾
Two Systems:
• Pulmonary Circulation
9Blood flow to, within, and from the lungs
• Systemic Circulation
9Blood flow to, within & from the remainder of the
body
Heart Anatomy
6
Aorta
7
Pulmonary trunk
Superior vena cava 1
Right coronary artery 2
Right atrium
3
Right ventricle
4
Inferior vena cava
5
8
9
Left atrium
Great cardiac vein
10 Left ventricle
1
Heart Anatomy cont.
semilunar valve
5 Aortic
not pictured
6 Left pulmonary artery
Right pulmonary artery 1
Tricuspid valve
7 Pulmonary semilunar
2
valve
8 Bicuspid (Mitral) valve
Chordae tendineae 3
Papillary muscle 4
9 Myocardium
Aorta artery
Pulmonary artery
The Heart
Pulmonary
veins
Superior vena cava
Aortic valve
Mitral valve
Left ventricle
Inferior vena cava
Tricuspid valve
Pulmonary
Semilunar valve
Right ventricle
Pulmonary
semilunar
valve
Bicuspid
(Mitral)
valve
Aortic
semilunar
valve
Tricuspid valve
Figure 9.5 (1)
Figure 9.5 (1)
Page 307
Page 307
2
Valve opened
Valve closed; does not open in opposite direction
Figure 9.4 Page 307
Figure 9.4 Page 307
The
The Circulatory
Circulatory System
System
¾
Heart
• Pumps blood
¾
Arteries and arterioles
• Carry blood away from the heart
¾
Capillaries
• Exchange of nutrients with tissues
¾
Veins and venules
• Carry blood toward the heart
Systemic
Systemic &
& Pulmonary
Pulmonary Circuits
Circuits
¾
Systemic circuit
¾
Pulmonary circuit
• Left side of the heart
• Right side of the heart
• Pumps oxygenated
blood to the whole
body via arteries
• Pumps deoxygenated
blood to the lungs via
pulmonary arteries
• Returns deoxygenated
blood to the right heart
via veins
• Returns oxygenated
blood to the left heart
via pulmonary veins
3
Driving Pressures
Pulmonary
capillaries
Arterioles Venules
Pulmonary
circulation
Pulmonary
artery
Pulmonary
veins
Aorta
(major
systemic
artery)
Systemic
veins
Systemic circulation
Systemic
capillaries
Venules
Figure 10.4
Figure 10.4
Page 346
Page 346
Arterioles
Smaller arteries
branching off
to supply
various tissues
Tissues
Figure 9.3 (2)
Figure 9.3 (2)
Page 306
Page 306
Venae cavae
Other
systemic
organs
Brain
Digestive
tract
Kidneys
Aorta
Right
atrium
Muscles
Right
ventricle
Systemic
circulation
Left
ventricle
Left
atrium
Pulmonary artery
Pulmonary
circulation
Lungs
Pulmonary veins
Electrical
Electrical Conduction
Conduction
System
System
4
The
The Myocardium
Myocardium
Electrical
Electrical Activity
Activity of
of the
the Heart
Heart
¾
Cardiac muscle cells
• Contractile (99%)
• Autorhythmic
9Pacemaker potential
¾
Impulse is initiated in the
right atrium and spreads
throughout entire heart
¾
May be recorded on an
electrocardiogram (ECG)
= Action potential
= After hyperpolarization
Na+ equilibrium
potential
Figure 4.6
Figure 4.6
Page 103
Page 103
Threshold
potential
Resting
potential
Triggering event
K+ equilibrium
potential
5
Pacemaker
Pacemaker Potential
Potential (Autorhythmic
(Autorhythmic Cells)
Cells)
Slow initial depolarization caused by:
1.
•
Decrease in K+ leaving cell
9 Cardiac cells – membrane decreases in permeability to K+
between AP
•
Slow, inward leak of Na+
9 No voltage gated Na+ channels, only leak
Membrane gradually becomes less negative
2.
•
More Na+ coming in than K+ leaving
Pacemaker
Pacemaker Potential
Potential (Autorhythmic
(Autorhythmic Cells)
Cells)
One of 2 Ca2+ channels open (T) (prior to
threshold)
3.
•
Short acting channel
Once threshold is reached, 2nd Ca2+ channels
open (L) & membrane depolarized
4.
Return is similar to nerve cell
5.
•
•
Calcium begin to close
K+ leaves cell
Self-induced
action potential
Slow
depolarization
(pacemaker
potential)
Figure 9.10 Page 310
Figure 9.10 Page 310
6
Conduction
Conduction System
System of
of the
the Heart
Heart
Interatrial
pathway
Figure 9.11
Page 311
Atrioventricular
(AV) node
Sinoatrial
(SA) node
Internodal
pathway
Left
branch
of bundle
of His
Right
branch
of bundle
of His
Purkinje
fibers
Action
Action Potential
Potential Discharge
Discharge
Tissue
AP’s per minute
SA node
70 – 80
AV node
40 – 60
Bundle of His &
Purkinje fibers
20 – 40
Cardiac
Cardiac Contractile
Contractile Cells
Cells
1.
Explosive increase in Na+ (similar to skeletal)
2.
Membrane potential remains positive (despite
decrease in Na+ permeability)
•
Plateau phase:
Activation of slow L-type Ca2+ channels
Decrease in K+ permeability
3.
Falling phase due to inactivation of Ca2+
channels & increase in K+ permeability
7
Figure 9.16
Figure 9.16
Page 316
Page 316
Action potential
in cardiac
contractile cell
Travels down
T tubules
Entry of small
amount of
Ca2+
from ECF
Induces
larger influx
of Ca2+
Release of large
amount of Ca2+
from sarcoplasmic
reticulum
Cytosolic
Ca2+
Troponin-tropomyosin complex
in thin filaments pulled aside
Cross-bridge cycling between
thick and thin filaments
Thin filaments slide inward
between thick filaments
Contraction
AP
AP of
of Contractile
Contractile Cardiac
Cardiac Cells
Cells
Plateau
phase of
action
potential
Threshold
potential
Path
Path of
of Conduction
Conduction
Autorhythmic to Contractile
8
Interatrial pathway
Right atrium
Left atrium
SA node
AV node
Internodal
pathway
Purkinje
fibers
Figure 9.14
Figure 9.14
Page 314
Page 314
Bundle
of His
Right ventricle
Left ventricle
Electrocardiogram
Electrocardiogram (ECG)
(ECG) (EKG)
(EKG)
¾
Records the electrical activity of the heart
•
•
•
•
Size
Position
Rate
Condition (healthy/sick)
Electrocardiogram
Electrocardiogram
•P-wave
–Atrial
depolarization
•QRS complex
–Ventricular
depolarization
•T-wave
–Ventricular
repolarization
9
Relationship
Relationship
Between
Between the
the
ECG
ECG and
and
Cardiac
Cardiac
Contraction
Contraction
Figure 9.17
Figure 9.17
Page 317
Page 317
Action
potential
Contractile
response
Refractory
period
Diagnostic
Diagnostic Use
Use of
of the
the ECG
ECG
¾
ECG abnormalities may indicate coronary heart disease
• ST-segment depression can indicate myocardial ischemia
10