Transcript A View of Life

Cardiovascular System
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Outline
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The Blood Vessels
The Arteries
The Capillaries
The Veins
The Heart
Cardiac Cycle
Cardiovascular Pathways
Lymphatic System
Cardiovascular Disorders
– Treatment
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The Blood Vessels
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In humans, the right side of the heart pumps
blood to the lungs, and the left side pumps
blood to the tissues.
– Three types of blood vessels.
 Arteries.
 Capillaries.
 Veins.
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Blood Vessels
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The Arteries
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Arteries carry blood away from the heart to
the capillaries.
– Arterioles are small arteries visible to the
naked eye.
 The greater the number of dilated
vessels, the lower the blood pressure.
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The Capillaries
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Capillaries permit exchange of material with
tissues.
– Arterioles branch into capillaries.
– Capillary beds are present in all regions of
the body.
 Relative constancy of tissue fluid is
dependent upon capillary exchange.
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Capillary Bed Anatomy
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The Veins
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Veins return blood from the capillaries to the
heart.
– Venules are small veins that drain blood
from the capillaries and then join to form a
vein.
 Veins often have valves to prevent
backward blood flow.
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The Heart
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Major portion of the heart, myocardium,
consists largely of cardiac muscle.
Humans have a four chambered heart.
– Two artria and two ventricles.
 Septum separates heart into halves.
Heart has four valves.
– Atrioventricular valves between atria and
ventricles.
– Semilunar valves between ventricles and
attached vessels.
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External Heart Anatomy
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Passage of Blood through the Heart
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Oxygen-poor blood never mixes with
oxygen-rich blood.
– Blood must go through the lungs to pass
from right side to left side of the heart.
 Right ventricle sends blood through
lungs.
 Left ventricle sends blood throughout
the body.
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Internal Heart Anatomy
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The Heartbeat
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Each heartbeat is referred to as a cardiac
cycle.
– Systole - Contraction of heart muscle.
– Diastole - Relaxation of heart muscle.
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Cardiac Cycle Stages
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Intrinsic Control of Heartbeat
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Intrinsic conduction system is composed of
four major regions.
– Sinoatrial (SA) node.
– Atrioventricular (AV) node.
– Atrioventricular (AV) bundle.
– Purkinje fibers.
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Extrinsic Control of Heartbeat
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Cardiac control center in the medulla
oblongata can alter the beat of the heart by
way of the autonomic system.
– Parasympathetic system.
– Sympathetic system.
Hormones epinephrine and norepinephrine
are released by the adrenal medulla and
also stimulate the heart.
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The Electrocardiogram
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An electrocardiogram (ECG) is a recording
of electrical changes that occur in the
myocardium during a cardiac cycle.
– SA node triggers an impulse, and atrial
fibers produce electrical charge (P wave).
 QRS complex signals ventricles are
about to contract, and electrical
changes produce T wave.
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Conduction System of the Heart
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Features of the Cardiovascular System
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Rhythmic expansion and recoil of an arterial
wall can be felt as a pulse in an artery close
to the body’s surface.
Blood pressure is the pressure of blood
against the wall of a blood vessel.
– Highest pressure, systolic pressure, is
reached when blood ejects from the heart.
– Lowest pressure, diastolic pressure is
reached when the ventricles are relaxing.
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Blood Flow in Capillaries and Veins
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Slow movement of blood through capillaries
allows time for exchange of substances
between the blood and surrounding tissues.
Venous return is dependent on three factors.
– Skeletal muscle contraction.
– Presence of valves in veins.
– Respiratory movements.
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The Cardiovascular Pathways
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Cardiovascular system includes two circuits.
– Pulmonary circuit circulates blood through
the lungs.
 Pulmonary arteries take oxygen-poor
blood to the lungs, and pulmonary veins
return oxygen-rich blood to the heart.
– Systemic circuit takes blood from the left
ventricle and then back to the right atrium.
 Coronary arteries serve heart muscle.
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Cardiovascular System
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Lymphatic System
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Lymphatic system consists of lymphatic
vessels and lymphatic organs.
– Three functions contribute to homeostasis.
 Lymphatic capillaries take up excess
tissue fluid, and return it to bloodstream.
 Lacteals receive lipoproteins and
transport them to bloodstream.
 Lymphatic system helps defend body
against disease.
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Lymphatic System
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Lymphatic Organs
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Lymph nodes filter lymph because
macrophages phagocytize debris or
pathogens and activate lymphocytes.
Spleen cleanses blood with macrophages.
– Filters debris, pathogens, and worn-out
red blood cells.
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Lymph Node
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Cardiovascular Disorders
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Hypertension - High blood pressure.
Atherosclerosis - Accumulation of plaque in
arterial linings.
– Stroke - Portion of brain dies due to lack
of oxygen.
– Heart Attack - Portion of heart muscle dies
due to lack of oxygen.
– Aneurysm - Ballooning of a blood vessel.
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Medical Treatment for Blood Clots
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Dissolve clot using t-PA biotechnology drug.
Coronary Bypass.
– Attach other blood vessels to heart and
bypass clogged areas.
Angioplasty.
– Thread tube into artery to the region of
plaque, where a balloon attached to the
tube is inflated, forcing the vessel open.
 Stents or chemicals may be needed.
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Coronary Bypass
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Angioplasty
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Medical Treatment for Congestive Heart Failure
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Wrap back muscle around heart and
stimulate with a pacemaker.
Heart Transplants.
Artificial Hearts.
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Homeostasis
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Homeostasis is possible only if the
cardiovascular system delivers oxygen and
nutrients to, and takes metabolic wastes
away from, the tissue fluid surrounding cells.
– Cardiovascular system must work with
other systems to maintain homeostasis.
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Review
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The Blood Vessels
The Arteries
The Capillaries
The Veins
The Heart
Cardiac Cycle
Cardiovascular Pathways
Lymphatic System
Cardiovascular Disorders
– Treatment
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