Circulation

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Circulation

• Movement of fluid through an organism

• Circulatory system– Transport system– Uses fluid to move substances

No Circulatory Systems

• In simple organisms in moist environments

Open Circulatory Systems

Closed Circulatory Systems

Human Circulatory System

• Heart – muscular pump

• Blood vessels– Network of tubes– Closed system

• Blood

Cardiovascular System

• Heart & blood vessels

• Transport functions – Nutrients– Wastes– Oxygen– Carbon dioxide

• Temperature maintenance

• Hormone circulation

Nutrient & Waste Transport

• Absorbed nutrients to liver for processing

• Liver releases glucose into bloodstream

• Transports amino acid building blocks

• Transfers nitrogenous waste to kidney

Oxygen & Carbon Dioxide Transport

• Cells require oxygen

• Cells produce carbon dioxide

• Blood carries gasses to & from lungs

Temperature Maintenance

• Heat is constantly produced by cells

• Blood distributes heat

• Brain regulatory center (hypothalamus) maintains homeostasis– Surface vessels constrict to conserve heat– Surface vessels dilate to dissipate heat

Hormone Circulation

• Hormones are chemical messengers

• The circulatory system is the highway

within which hormones travel through

out the body, from their site of production

to the target tissues that are capable of

responding to them.

Blood Circulatory Vessels

• Arteries

• Arterioles

• Capillaries

• Venules

• Veins

Arteries & Arterioles

• Carry blood away from heart

• Aorta leaves heart (largest artery)

• Aorta branches into other arteries

• Arteries branch into arterioles

• Arterioles are smaller in diameter

Walls of Arteries

Capillaries

• Connect arterioles & venules

• One cell thick walls

• Blood cells move through single file

• Site of diffusion of gasses, nutrients, & wastes

Capillary Beds• Sphincters regulate blood flow

• Capillaries found throughout tissue

Veins & Venules

• Capillaries empty into venules

• Venules merge into larger veins

• Return blood toward the heart

Valves

• Found in veins

• Prevent backflow of blood

• Varicose veins result from incompetent valves

Heart

• Pump of the circulatory system

• Human heart has two pumps

• Each side has two chambers– Atrium above– Ventricle below

Circulatory Pathways

Heart Valves• Prevent backflow of blood

• Semilunar valves– Pulmonary & aortic– Between ventricle & artery

• Atrioventricular valves– Between atrium and ventricle

• Right-tricuspid• Left-bicuspid

Heart Contractions

• Depends on autorhythmic cells in heart– Sinoatrial node – starts heartbeat (pacemaker)

located in upper wall of right atria– Atrioventricular node-located at base of rt. atria– Atrioventricular bundle – in septum, 2 branches– Purkinje fibers-in ventricular walls

• Cells fire in order

Monitoring Heartbeat• Heartbeat

– Cycle of contraction & relaxation

• Ways to monitor– Stethoscope-lubb and dupp sounds– Monitor blood pressure

• Ventricular diastole – relaxation• Ventricular systole – contraction

– Electrocardiogram• P wave-atria contract, ventricles relax• QRS wave-ventricles contract, atria relax• T wave-electrical changes that precede ventricular contraction

Blood Pressure

• Measured in millimeters of mercury

• Normal blood pressure– Less than 120 over 80

• Hypertension – High blood pressure– Over 140 over 90– Risk of heart attack, stroke, heart failure

• Prehypertension– 120 to 139 over 80 to 89

Electrocardiogram

Blood

• Plasma

• Cells

• Platelets

Plasma

• Mostly water• Dissolved substances

– Nutrients, hormones, gases, wastes– Salts & ions electrolytes (Ca, Mg, Zn, K) serve 3 functions:– Proteins-helps balance osmotic pressure

between cells and blood. Examples include serum albumin, antibodies, fibrinogen, &

prothrombin

Blood Cells & Platelets

• Suspended in plasma

• Types of formed elements– Red blood cells = erythrocytes– White blood cells = leukocytes– Platelets

Platelets

• Cell fragments

• Important for clotting or coagulation

Lymphatic System

• One way circulatory system toward heart

• Returns lost fluid to blood

• Picks up material from tissue

• Cleans material

Lymph Nodes

• Activates immune response

• Cleans lymph

Other Lymphatic Organs

• Spleen– Destroys old blood cells– Has emergency blood supply– Filters blood

• Thymus – Matures T-cells for immune system

Atherosclerosis• Thickening & hardening of artery walls

• Accumulation of plaque

• Can block blood, increase pressure

Heart Attack

• Most common cause of death in U.S.

• Insufficient blood supply to heart muscle

• May be result of blood clot

• Warning signs of heart attack– Tightness in center of chest– Pain in neck, shoulder or arms– Lightheadedness, nausea, sweating,

shortness of breath

Angina Pectoris

• Chest pain

• Caused by similar reasons as heart attack

• Reduced blood flow

• Does not kill heart muscle

Stroke

• Interference with blood supply to brain

• Can cause weakness, numbness, paralysis or Death

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