Transcript Cardiovascular System: Heart & Blood Vessels

Cardiovascular
System:
Heart & Blood Vessels
Kirby - BHCC
An Overview of the Cardiovascular
System
• Pulmonary circuit
– blood to and from the
lungs
• System circuit
– blood to and from the
rest of the body
– Vessels carry the blood
through the circuits
• Arteries carry blood
away from the heart
• Veins carry blood to the
heart
• Capillaries permit
exchange
The Heart
Structure of Heart
• Pericardium – surrounds heart
– protection & reduces friction
• Layers:
– Epicardium- thin, transparent covering
– Myocardium-cardiac muscle tissue
– Endocardium- connective tissue surrounding chambers &
valves
• Chambers: two atrium (top), two ventricles (bottom)
• Valves:
– Two atrioventricular valves: tricuspid and bicuspid (mitral)
– Two semilunar valves: pulmonary and aortic
Pulmonary Circuit
• Pathway:
– Deoxygenated blood through the vena cava to
the right atrium
– Deoxygenated blood through the right
atrioventricular valve to the right ventricle
– Deoxygenated blood through the pulmonary
semilunar valve to the pulmonary trunk and
the lungs
– Oxygenated blood through the pulmonary
veins to the left atrium
– Oxygenated blood through the left
atrioventricular valve to the left ventricle
Systemic System
• Pathway:
– Oxygenated blood through the aortic semilunar
valve to the aorta
– Oxygenated blood through branching arteries and
arterioles to the tissues
– Oxygenated blood through the arterioles to
capillaries
– Deoxygenated blood from capillaries into venules
and veins
– Ultimately to the vena cava and into the right
atrium
Phases of the Cardiac Cycle
Conduction System
•
•
•
•
1. Sinoatrial (SA)node - pacemaker,
located at the surface of the right atrium,
impulse causes both atria to contract (rate
60-100 BPM); a conduction pathway
called Bachman's bundle runs from right
to left atrium allowing for simultaneous
atrial contractions. SA node sends
impulse to the AV node via the anterior,
medial and posterior internodal
pathways.
2. Atrioventricular (AV) node - (rate 4060 BPM)last part of atria to be
depolarized, sends impulse down the:
3. Bundle of His- distributes action
potential over medial surfaces of the
ventricles (rate 20-40 BPM) runs to the
top of the interventricular septum to the:
4. Right and left bundle branches - Actual
contraction stimulated by conductive
myofibers called Purkinje fibers that pass
into the fibers of the myocardium of the
ventricles.
EKG - Electrocardiogram
• A recording of the
electrical events
occurring during the
cardiac cycle
– The P wave accompanies
the depolarization of the
ventricles
– The QRS complex
appears as the ventricles
depolarize
– The T wave indicates
ventricular
repolarization
Heart Sounds
• Auscultation – listening to heart sound via
stethoscope
• Four heart sounds
– S1 – “lubb” caused by the closing of the AV valves
– S2 – “dupp” caused by the closing of the
semilunar valves
– S3 – a faint sound associated with blood flowing
into the ventricles
– S4 – another faint sound associated with atrial
contraction
Blood Vessels of the Heart
Blood Vessels
– Arteries: carry
oxygenated blood
away from heart
– Veins: carry
deoxygenated blood
back to the heart.
– Capillaries: exchange
of nutrients, waste,
and defensive cells
between vessel and
tissue
Structure of Blood Vessels
• Composed of three layers (tunics)
– Tunica intima – composed of simple
squamous epithelium
– Tunica media – sheets of smooth muscle
• Contraction – vasoconstriction
• Relaxation – vasodilation
– Tunica externa – composed of connective
tissue
• Lumen
– Central blood-filled space of a vessel
Structure of Arteries, Veins &
Capillaries
Arteries vs. Veins
•
•
•
•
•
•
Arteries
Transports blood away
from heart
Carry oxygenated blood
(except pulmonary
artery)
Relatively narrow lumens
More elastic/muscle
tissue
Transports blood under
high pressure
Do not have valves
Veins
• Transports blood toward
heart
• Carry deoxygenated
blood (except pulmonary
vein)
• Relatively wide lumens
• Less elastic/muscle tissue
• Transports blood under
low pressure
• Has valves
Blood Pressure
• the force of the blood pushing against the
walls of the arteries
• systolic pressure
– blood pressure is at its highest when the heart
beats, pumping the blood
• diastolic pressure
– When the heart is at rest, between beats, your
blood pressure falls
Top number (systolic)
in mm Hg
Bottom
number
(diastolic) in
mm Hg
Your category*
What to do**
Below 120
and
Below 80
Normal blood
pressure
Maintain or adopt a
healthy lifestyle.
120-139
or
80-89
Prehypertension
Maintain or adopt a
healthy lifestyle.
Stage 1
hypertension
Maintain or adopt a
healthy lifestyle. If
blood pressure goal
isn't reached in
about six months,
talk to your doctor
about taking one or
more medications.
Stage 2
hypertension
Maintain or adopt a
healthy lifestyle.
Talk to your doctor
about taking more
than one
medication.
140-159
160 or more
or
or
90-99
100 or more