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Cardiovascular System

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Outline

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• Wrap back muscle around heart and stimulate with a pacemaker.

• Heart Transplants.• Artificial Hearts.

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Homeostasis

• 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

• The Blood Vessels• The Arteries• The Capillaries• The Veins• The Heart• Cardiac Cycle• Cardiovascular Pathways• Lymphatic System• Cardiovascular Disorders

– Treatment

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