Transcript Cardiovascular System

Cardiovascular System
Systemic Circulation
Delivers blood to all body cells and
carries away waste
Pulmonary Circulation
Eliminates carbon dioxide and
oxygenates blood (lung pathwy)
Arteries and Veins
Arteries
• Carry blood AWAY from the
heart
Veins
• Carry blood TO the heart
Structure of the Heart
• Heart Size: about 14 cm x 9 cm (the size of a
fist)
Structure of the Heart
• Coverings:
– Pericardium: encloses the heart like a bag
– Pericardial cavity: contains fluid for the heart to
float in reducing friction
Structure of the Heart
Wall of the Heart:
– Epicardium: outer layer,
reduces friction
– Myocardium: middle layer,
mostly cardiac muscle
– Endocardium: inner layer,
blood vessels
Structure of the Heart
Pathway of blood through the heart
• Label the major chambers, valves and blood
vessels and draw the pathway of blood
through the heart…
Heart Chambers and Valves
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Atria: top chambers
Ventricles: bottom chambers
Septum: divides left and right sides
Atrioventricular Valve (AV) valves located
between the atrium and the ventricle
• Tricuspid: right side AV
• Bicuspid: left side AV (Mitral valve)
Heart Chambers and Valves
• Superior vena cava: vessel that returns blood
from the heart from the upper body
• Inferior vena cava: vessel that returns blood to
the heart from the lower body
Heart Chambers and Valves
• Coronary sinus: a collection of veins joined
together to form a large vessel that collects
blood from the heart muscle (myocardium). It
delivers deoxygenated blood to the right
atrium
Heart Chambers and Valves
• Chordae tendinae/papillary muscles: muscles
and tendons that hold the heart valves in
place
Heart Chambers and Valves
• Pulmonary Trunk/Arteries: large vessel that splits
into the left and right pulmonary arteries (the
only arteries that carry deoxygenated blood)
• Pulmonary Valve: controls flow of blood into the
pulmonary trunk
• Pulmonary Veins: returns oxygenated blood from
the lungs
• Aorta: large vessel that delivers blood to the body
• Aortic Valve: controls the flow of blood into the
aorta
Branches of the aorta
• Ascending and Descending Aorta
• Aortic arch
• Right and Left Coronary Arteries: supply blood to
the heart itself
• Brachiocephalic Artery: branches into the right
subclavian and right common carotid
• Right subclavian: supplies blood to the right arm
• Left subclavian: supplies blood to the left arm
• Common carotid: branches into left and right
carotid, which supply blood to the head
Note that blood
vessels are not
symmetrical**
Blood vessels: arteries, veins,
capillaries
• Arteries: strong elastic vessels which carry blood
moving away from the heart
– Smallest ones are arterioles which connect to capillaries
• Veins: Thinner, less muscular vessels carrying blood
toward the heart
– Smallest ones are called venules which connect to
capillaries
– Contain valves
• Capillaries: penetrate nearly all tissues
– Walls composed of a single layer of squamous cells
– Allows exchange of materials between blood and tissues
Arteries, veins and capillaries
Control of Blood Flow
• Precapillary sphincters:
circular, valve-like
muscle at arteriolecapillary junction
Control of Blood Flow
• Vasoconstriction: narrowing blood vessel’s
lumen (passageway)
• Vasodilation: expanding blood vessel’s lumen
Control of Blood Flow
• Blood flow through the veins is not very
efficient
– Important factors:
1. Sympathetic Nervous Pump
2. Skeletal Muscle Pump
3. Respiratory pump
Don’t be Nervous!
• Sympathetic Nervous Pump: Sympathetic input
causes vasoconstriction, which increases pressure,
which drives blood back to the heart. When the body
needs to mobilize more blood for physical activity,
the sympathetic nervous system induces
vasoconstriction of veins.
Move your muscles!
• Skeletal Muscle Pump: Veins pass between
skeletal muscles. The contraction of skeletal
muscle squeezes the vein, thus increasing
blood pressure in that section of the vein.
Pressure causes the upstream valve (furthest
from the heart) to close and the downstream
valve (the one closest to the heart) to open.
Repeated cycles of contraction and relaxation,
as occurs in the leg muscles while walking,
effectively pumps blood back to the heart.
Veins Pass Between Skeletal Muscles
Breathe In!
• Respiratory pump: the act of breathing helps
to drive venous blood out of the abdominal
cavity. As air is inspired, the diaphragm
descends and abdominal pressure increases.
The increasing pressure squeezes veins and
moves blood back toward the heart. The
rhythmic movement of venous blood causes
by the act of breathing is called
the respiratory pump.
Atherosclerosis
• Atherosclerosis is the major cause of coronary
artery disease and stroke.
• Blood flow is diminished and could become
blocked
• Due to development of fatty plaque
Risk Factors for Atherosclerosis
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genetic predisposition
obesity
age
smoking
hypertension
diabetes
high cholesterol
Disorders of the Circulatory System
• MVP: mitral valve prolapse
– The mitral valve does not close all the way
– Creates a clicking sound at the end of a contraction
– https://www.youtube.com/watch?v=HP7nIeQAEGM
• Heart Murmurs: valves do not close completely
– Causes an (often) harmless murmur sound
– Sometimes holes can occur in the septum of the heart
which can also cause a murmur
– Normal:
https://www.youtube.com/watch?v=dDg7GDpR1RE
– Murmurs:
https://www.youtube.com/watch?v=6YY3OOPmUDA
Disorders of the Circulatory System
• Myocardial Infarction (MI): a blood clot obstructs
a coronary artery
– Commonly called a heart attack
• Atherosclerosis: deposits of fatty materials form a
“plaque” in arteries which reduces blood flow
– Treatment: angioplasty, where a catheter is inserted
into the artery and a balloon is used to stretch the
walls
– Stent and Angioplasty:
https://www.youtube.com/watch?v=S9AqBd4RExk
– Heart Bypass:
https://www.youtube.com/watch?v=DpyqtPjuPIw
Disorders of the Circulatory System
• Hypertension: high blood pressure
– The force within the arteries is too high
– A sphygmomanometer can diagnose hypertension
Blood Pressure
• Systolic occurs when blood is forced out of the
left ventricle, and the aortic valve OPENS
– This is the high number
• Diastolic occurs when the aortic valve closes
and the ventricle relaxes
– This is the lower number
• Average blood pressure: 120/80
• Average heart rate 72
Blood Pressure
• The cusps (flaps) of the bicuspid and tricuspid
valves are anchored to the ventricle wall by
chordae tendinae
– This prevents valves from being pushed up into
the atria during ventricular systole
• SPHYGMOMANOMETER: device used to
measure blood pressure
Blood Pressure
• Factors affecting blood pressure:
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4.
Cardiac output
Blood volume (5Liters for avg adult)
Blood Viscosity
Peripheral Resistance