Download Cardiovascular System

Heart
• Double Pump: Rt side is pulmonary circulation, left side is systemic
circulation.
• Pulmonary circulation – blood in the right side of heart, pulmonary
vessels, and lungs.
• Systemic circulation – blood in the left side of heart and the rest of
the body.
• Heart is the size of your fist.
• Located between lungs within the mediastinum, apex found in the 5th
intercostal space, approx. 9 cm of midline.
• Round point is called apex, this is what you see beating.
• Flat portion is called base, it lies on diaphragm.
• Pericardial sac: closed sac that surrounds heart and anchors to the
mediastinum.
Cardiovascular System
External Features of Heart
• Left and right coronary artery, feeds the heart
with blood.
• Left and Right pulmonary artery, feeds the lungs
with deoxygenated blood from RV.
• Left and Right pulmonary vein, feeds the LA with
oxygenated blood from lungs.
• Aorta: ascending, transverse, and descending.
• Superior and Inferior Vena Cava
• Apex
• Base
Internal Features of Heart
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Right Atrium
Tricuspid Valve
Right Ventricle
Left Atrium
Mitral Valve (Bicuspid)
Left Ventricle
Papillary Muscles
Chordae Tendinae
Aortic and Pulmonary Semi-lunar valve.
Heart
• Composed of myocardial muscle.
• Heart is autorhythmic, it beats automatically and
rhythmically. If taken out of body, it can continue to beat
under proper circumstances.
• SA node is the pacemaker of the heart. It signals the
contraction of the atria, which in turn signal the AV node
to send impulse to cause ventricles to contract.
• Heart sounds: first sound- Lubb, closing of tricuspid and
bicuspid valves.
• Second sound- Dupp, closing of semilunar valves
Arteries and Veins
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• Veins lead to heart.
Arteries lead away from
• Always carry
the heart.
deoxygenated blood.
Always carry oxygenated
• Exception is
blood.
Pulmonary vein,
Exception is Pulmonary
which flows toward
artery, which flows away
heart from lungs with
from heart to lungs with
oxygenated blood.
deoxygenated blood.
• Veins are non-elastic,
Arteries are very elastic in
don’t need to expand
order to expand to hold
for pressure.
up to high pressure.
• Contain valves to
prevent backflow,
moves passively by
• Adventicia: (Tunica
Extera), glues blood
vessels to
surrounding areas.
• Media: mostly smooth
muscle, some
connective tissue.
• Intima: endothelium
Vessels and blood flow
• Artery, arteriole, capillary, venule, vein.
• Connective tissue in the arteries is elastic
connective tissue.
• Smooth muscle provides a smooth steady flow
at end of arterioles, even though at beginning its
pulsatory.
• Velocity of flow is inversely related to the cross
sectional area, smaller vessel = faster flow,
wider vessel = slower flow.
• Total cross section is what counts, smallest in
aorta, largest in capillaries.
Vessels and blood
• Total blood volume is about 5 liters.
• Broken into pulmonary and systemic
systems.
• Pulmonary: blood flow from Rt. Ventricle to
lungs and back to Lt. Atrium
• Systemic: blood flow from Lt. Ventricle to
tissues of body and back to heart.
• 15% is in systemic arteries.
Arterioles
• Terminal arteries, last of the arteries on the
branching tree.
• Very little elastic tissue, with more smooth
muscle to adjust size of vessel, adjustable
vessel allows us to have adjustable flow. Like
faucets on a sink.
• Vasoconstriction: decreasing diameter of vessel
• Vasodilation: increasing diameter of vessel.
• Must be about 20 thick before you can see
• Pre-capillary sphincter are faucets that control
flow into capillary bed.
Capillaries
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Site of gas and waste exchange.
Very small, cells go through one at a time.
No connective tissue or smooth muscle.
Consists of a single layer of endothelium.
Very permeable
Dissolved materials in blood that is smaller
than proteins can leak out from cracks of
capillary into ISF because of pressure
difference.
Blood flow back into venuoles
• Arteriole end has high pressure inside of
vessel, ISF is low pressure, results in
blood flow out.
• Venuole end of capillary, there is higher
pressure in ISF and wants to flow back
into low pressure venuole.
Veins
• Have thinner walls with more smooth muscle
which allows for alteration of diameter of veins.
• Valves run all along length of veins
• Vein wall thickened at place of valve.
• Valves are needed for unidirectional flow.
• Veins have low pressure, high volume.
• 50% of blood in veins at all times.
• Venous side is a reservoir for blood.
Veins
• Contraction of smooth muscle leads to
high venous return and an increased
cardiac output.
• “Venous Pumps” concept, not real pumps
1. Passive constriction of veins by skeletal
muscle.
2. Arterial pulses
3. Valves
EKG- electrocardiograph
• A normal EKG
consists of a P wave,
a QRS complex, and
a T wave.
• P wave is the result of
A.P. that cause
depolarization of atria,
it signals the onset of
atrial contraction.
EKG (QRS Complex)
• The QRS complex is
composed of three
individual waves, the
Q, R, and S waves.
• The QRS complex
results from
ventricular
depolarization and
signal the onset of
ventricular
contraction.
EKG (T wave)
• T wave represents
the repolarization and
precedes ventricular
relaxation.
• A wave of
repolarization of atria
cannot be seen
because it happens
during QRS complex.
Major cardiac disorders
• Tachycardia- heart rate in excess of 100 beats per
minute.
• Ventricular Tachycardia (Asystole)- frequently causes
fibrillation. Heart vibrates uncontrollably.
• Brachycardia- Heart rate less than 60 beats per minute.
• SA Node Block- Cessation of P wave, low heart rate due
to AV node acting as pacemaker.
• Myocardial Infarction (Heart Attack)- section of heart
does not receive blood, usually coronary artery is
blocked. Usually caused by a thrombus.
• Stroke – lack of blood to the brain, either caused by an
embolus, clot in vessel, or a hemorrhage, a burst vessel,
in brain.