THE CIRCULATORY SYSTEM I.THE CIRCULATORY SYSTEM IS AN INTERNAL TRANSPORT SYSTEM WITH 3 COMPONENTS: BLOOD IS A FLUID TISSUE COMPOSED OF WATER, SOLUTES AND CELLS.

B. THE HEART IS A MUSCULAR PUMP THAT GENERATES PRESSURE TO KEEP THE BLOOD FLOWING. C. BLOOD VESSELS ARE TUBES THROUGH WHICH BLOOD IS TRANSPORTED.

II. BLOOD: A. FUNCTIONS OF THE BLOOD: CARRIES OXYGEN AND NUTRIENTS TO CELLS. 2. CARRIES WASTES AND SECRETIONS AWAY FROM CELLS.

3. CONTAINS PHAGOCYTIC CELLS THAT FIGHT INFECTION. 4. HELPS STABILIZE INTERNAL PH. 5. EQUALIZES BODY TEMPERATURE.

B. BLOOD COMPONENTS: PLASMA- MOSTLY WATER, SOME PROTEINS, TRANSPORT LIPIDS, VITAMINS, IONS, GLUCOSE, HORMONES AND DISSOLVED GASES.

2. ERYTHROCYTES (RED BLOOD CELLS = RBC’S) – BICONCAVE CELLS THAT CON- TAIN HEMOGLOBIN THAT BINDS WITH OXYGEN. NO NUCLEI, DEVELOP IN BONE MARROW, LAST ~120 DAYS.

3. LEUKOCYTES – (WHITE BLOOD CELLS) a. LEUKOCYTES REMOVE DEAD OR WORN- OUT CELLS AND PROTECT AGAINST INVADING MICROBES. b. THEY ARE DERIVED FROM STEM CELLS IN THE BONE MARROW. -THERE ARE 5 TYPES OF LEUKOCYTES:

1.MONOCYTES AND NEUTROPHILS ARE PHAGOCYTES – THEY DIGEST PATHOGENS. 2. BASOPHILS AND EOSINOPHILS ARE IN- VOLVED IN INFLAMMATORY RESPONSE. 3. LYMPHOCTYES –FIGHT OFF INFECTION, MAJOR COMPONENT OF IMMUNITY.

4. PLATELETS- FRAGMENTS OF CELLS PRODUCED IN THE BONE MARROW, NO NUCLEUS, NEEDED FOR BLOOD CLOTTING. Plasma 55% Constituent Major functions Cellular elements 45% Water Solvent for carrying other substances Cell type Number Functions per µL (mm3) of blood Erythrocytes (red blood cells) Ions (blood electrolytes) 5–6 million Transport oxygen and help transport carbon dioxide Sodium Potassium Calcium Magnesium Chloride Bicarbonate Osmotic balance, pH buffering, and regulation of membrane permeability Separated blood elements Leukocytes (white blood cells) Defense and immunity 5,000–10,000 Plasma proteins Albumin Osmotic balance, pH buffering Lymphocyte Fibrinogen Clotting Basophil Immunoglobulins (antibodies) Defense Eosinophil Substances transported by blood Neutrophil Monocyte Nutrients (such as glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O2 and CO2) Hormones Platelets 250,000– 400,000 Blood clotting

III. CIRCULATION: BLOOD IS TRANSPORTED FROM THE RIGHT SIDE OF THE HEART TO THE LUNGS IN THE PULMONARY CIRCUIT; THE BLOOD IS RETURNED TO THE LEFT SIDE OF THE HEART, FROM WHICH IT IS PUMPED TO THE REST OF THE BODY. B. BLOOD TRAVEL FOLLOWS THIS ROUTE: HEART  ARTERIES ARTERIOLES  CAPILLARIES  VENULES  VEINS  HEART.

C. THE HUMAN HEART: THE HEART IS A DURABLE PUMP MADE OF MOSTLY CARDIAC MUSCLE. IT IS ENCLOSED IN A TOUGH, FIBROUS SAC CALLED THE PERICARDIUM. THE HEART’S CHAMBERS ARE LINED WITH CONNECTIVE TISSUE AND ENDOTHELIUM. 2. EACH HALF OF THE HEART HAS AN ATRIUM (RECEIVING) AND VENTRICLE (PUMPING) CHAMBER.

3. THE CARDIAC CYCLE: -CONSISTS OF A SEQUENCE OF CON- TRACTIONS (SYSTOLE) AND RELAXATIONS (DIASTOLE). -AS THE ATRIA FILL, THE VENTRICLES ARE RELAXED. THE ATRIA FILL SIMULTANEOUSLY.

-PRESSURE OF THE BLOOD FORCES THE ATRIOVENTRICULAR VALVES TO OPEN AND THE VENTRICLES TO FILL. THE VENTRICLES CONTRACT, THE ATRIOVENTRICULAR VALVES CLOSE AND BLOOD FLOWS THROUGH THE SEMILUNAR VALVES.

IN THE “LUB, DUB” HEART SOUND, THE “LUB” COMES FROM THE CLOSING OF THE ATRIOVENTRICULAR VALVES AND THE “DUB” FROM THE CLOSING OF THE SEMILUNAR VALVES.

Pulmonary artery Aorta Anterior vena cava Pulmonary artery Right atrium Left atrium Pulmonary veins Pulmonary veins Semilunar valve Semilunar valve Atrioventricular valve Atrioventricular valve Posterior vena cava Right ventricle Left ventricle

4. EXCITATION FOR A HEARTBEAT IS INITIATED BY THE SINOATRIAL (SA) NODE, (ALSO CALLED THE PACEMAKER). THE ATRIA CONTRACT FORCING THE BLOOD INTO THE VENTRICLES. NEXT, THE ELECTRICAL SIGNAL PASSES TO THE ATRIOVENTRICULAR (AV) NODE.

-THE BUNDLES OF HIS AND PURKINJE FIBERS CONDUCT SIGNALS TO THE APEX (BOTTOM OR POINT) OF THE HEART. THE VENTRICLES CONTRACT.

SA NODE AV NODE

IV. THE CIRCULATION: A. BOTH ARTERIES AND VEINS HAVE THREE LAYERS OF TISSUE: ENDOTHELIUM, SMOOTH MUSCLE AND AREOLAR TISSUE B. ARTERIES CONDUCT BLOOD AWAY FROM THE HEART. THEY HAVE ELASTIC AND MUSCULAR WALLS.

Endothelium Smooth muscle Connective tissue Capillary 100 µm Basement membrane Valve Artery Arteriole Venule Vein

C. ARTERIES ARE TESTED WHEN TESTING BLOOD PRESSURE. NORMAL SYSTOLIC PRESSURE IS 120 MM HG AND NORMAL DIASTOLIC IS 80 M HG. MEASURED WITH A SPHYGMOMANOMETER  Blood pressure reading: 120/70 Pressure in cuff above 120 Pressure in cuff below 120 Pressure in cuff below 70 Rubber cuff inflated with air 120 120 70 Sounds audible in stethoscope Sounds stop Artery Artery closed

D. ARTERIES BRANCH INTO ARTERIOLES. THEIR WIDTH IS MANAGED BY HORMONES & NERVES. E. CAPILLARIES – THE MOST NARROW BLOOD VESSELS - THESE ARE DIFFUSION ZONES FOR EXCHANGES BETWEEN THE BLOOD AND THE INTERSTITIAL FLUID.

-ERYTHROCYTES TRAVEL SINGLE-FILE THROUGH CAPILLARIES. F. CAPILLARIES MERGE INTO VENULES AND THEN VEINS. G. VEINS HAVE VALVES TO PREVENT BACKFLOW.

CONTRACTING SKELETAL MUSCLES SQUEEZE THE VEINS. THIS SQUEEZING HELPS THE BLOOD TO MOVE UPWARDS AGAINST GRAVITY.

H. BLOOD PRESSURE IS MONITORED BY THE MEDULLA OBLONGATA. IF BLOOD PRESSURE INCREASES, THE ARTERIOLES RELAX = VASODIALATION. IF BLOOD PRESSURE DECREASES, THEN VASOCON- STRICTION OCCURS.

-Blood pressure is also affected by hormones such as aldosterone. -Blood pressure is greatly influenced by the sympathetic nervous system – activated in flight or fight situations. Conversely, the parasympathetic nervous system tends to decrease blood pressure.

I. BLOOD CLOTTING- SPASMS OF SMOOTH MUSCLE STOPS BLOOD FLOW TEMPORARILY. 2. PLATELETS STIMULATED BY THROMBIN CLUMP TO MAKE A PLUG. 3. A FIBRIN MESH FORMS WITH THE PLATELETS. THE BLOOD COAGULATES TO MAKE A CLOT.

A BLOOD CLOT

TYPE A HAS A MARKERS, TYPE B HAS B MARKERS, AB HAS BOTH A AND B J. BLOOD TYPES TYPE A HAS A MARKERS, TYPE B HAS B MARKERS, AB HAS BOTH A AND B MARKERS AND O HAS NO MARKERS. 2. TYPE O IS THE UNIVERSAL DONOR AND AB IS THE UNIVERSAL RECEIVER. Blood Type A B AB O Antigens A B A and B None Antibodies in Plasma Anti-B Anti-A None Both Anti-A and Anti-B

3. RH IS ANOTHER MARKER ON THE BLOOD CELLS. RH+ MEANS YOU HAVE THE MARKER AND RH- MEANS YOU DO NOT.