IBHS 527 lecture 1

• 1. pump - heart
• 2. conducting system - blood vessels
• 3. fluid medium - blood (specialized fluid of connective tissue which contains cells suspended in a fluid matrix known as plasma)

• 1. transport: dissolved gases, nutrients, hormones, and waste
• -via RBCs and plasma
• 2. defend: against toxins and pathogens
• -via circulating WBCs and antibodies
• 3. contain: minimizes fluid loss at injury site
• -via platelets (clot) and vasoconstriction
• 4. regulate:
• a) body temperature by absorbing and redistributing heat
• -via vasoconstriction and vasodilation
• b) pH and ion composition
• -blood absorbs acids generated by active tissues
• -diffusion between ECF and blood eliminates ion gradients

• 1. volume:
• -average male: 5.5 liters
• -average female: 4.5 liters
• depends on body size differences, ~7% of body weight
• 2. viscosity (viscosity is resistance of fluid to flow resulting from cohesion of its particles. Due to interactions of dissolved proteins formed elements and water molecules in plasma):
• -5X more viscous than water: 5X more sticky
• -5X more cohesive, resistant to flow
• 3. temperature: 37-38 degrees celcius = slightly above normal body temp
• 4. pH:
• -avg - 7.40 (slightly alkaline)
• -physiological range - 7.35-7.45

• 1. plasma
• 2. formed elements

fluid consisting of water, dissolved plasma proteins and other solutes

bloods cells and cell fragments suspended in plasma

• 1. red blood cells
• 2. white blood cells
• 3. platelets

• erythrocyte/red corpuscle
• more numerous, transport oxygen

• leukocyte
• less numerous, five classes, defense/immune

small membrane bound cell fragments contain enzymes and substances important for clotting

• 1. plasma (top): proteins-water-other solutes
• 2. buffy coat: platelets-white blood cells
• 3. erythrocytes (bottom) -significantly more (4.2-6.2 million)

• 1. neutrophils (60-70%) most
• 2. lymphocytes (20-25%)
• 3. monocytes (3-8%)
• 4. eosinophils (2-4%)
• 5. basophils (0.5-1%) least
• "Never Let Monkeys Eat Bananas"

FALSE. nucleated --> Anucleated (without nucleus); nitrogen --> oxygen (duh)

• 1. granulocytes: cytoplasm contains large granules; have multi-lobed nuclei
• 2. agranulocytes: cytoplasm contains small granules and nuclei that are not lobed

agranulocytes

granulocytes

granulocytes

agranulocytes

granulocytes

thrombocytes (nucleated cells)

• pale, yellow color
• colloid: a liquid substance containing suspended substances that do not settle out of solution

• 1. water: 92%
• 2. proteins: 7%
• 3. other solutes: 1%

• FALSE.
• large size and globular shape of most plasma proteins prevents them from crossing capillary wall and therefore they remain trapped in circulatory systems

• 1. albumin (most)
• 2. globulin
• 3. fibrinogen
• 4. regulatory proteins (least)

• 60% (of 7% that is proteins of plasma)
• 2 functions:
• 1. viscosity and osmotic pressure of blood (total molarity of that that pass across the wall):
• -indirectly regulates ECF volume
• 2. transport:
• (a) fatty acids, (b) thyroid hormones, (c) steroid hormones, (d) drugs

• 35% (of 7% that is proteins in plasma)
• 2 functions:
• 1. immunoglobulins: aka antibodies; defense
• 2. transport globulins: bind small ions, hormones or compounds that might be lost in kidney or have low solubility

• 1. ions: ex. is metalloproteins (Fe²⁺ via transferrin)
• 2. lipids: apolipoproteins carry triglycerides and lipids
• 3. hormones: thyroxine via thyroid binding globulin

• 4% (of 7% that is proteins in plasma)
• clotting protein
• coagulation: soluble fibrinogen --> insoluble fibrin = clot formation

• 1% (of 7% that is proteins in plasma)
• ex: peptide hormones, luteinizing hormone (LH), thyroid stimulating hormone (TSH), prolactin (PRL), follicle stimulating hormone (FSH), insulin
• info:
• -levels may vary day to day or hour to hour
• -without plasma proteins, substances would have low solubility or be excreted by kidneys

• 1. liver: synthesize great than 90%
• -all albumins
• -all fibrinogens
• -most globulin
• 2. plasma cells (derived from lymphocytes):
• -antibodies (of globulins)
• *liver dysfunction can alter blood function

• 1. electrolytes/ions
• 2. organic nutrients
• 3. organic wastes

• ex: Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^-, HCO₃^-, HPO₄^-, SO₄^-
• 3 functions:
• 1. Contribute to osmotic pressure
• 2. Reservoir for cells' needs
• 3. some buffer pH of blood (keep at narrow window)

• ex: lipids, carbohydrates, amino acids
• 3 functions:
• 1. energy
• 2. maintenance
• 3. growth

• ex: Nitrogenous wastes (from proteins) like urea, uric acid, ammonium ion,
• -Bilirubin (from hemoglobin of RBCs)

cell fragments pinched or derived from megakaryocytes in red bone marrow

• 1. have surface glycoproteins and receptors and proteins that allow adhesion to other molecules ex- collagen
• 2. important in preventing blood loss (platelet plugs, promoting formation and contraction of clots)
• 3. circulate for 9-12 days
• 4. removed by phagocytes in the spleen
• 5. 1/3 are reserved (in spleen) and mobilized for circulatory emergency like in cases of severe bleeding or hemorrhaging crisis
• 6. ~150,000 - 500,000/µl of blood ~ avg. 350,000/µl

membrane-bound pieces of cytoplasm 'shed' from megakaryocytes, have receptors, granules, actin, myosin

• enormous cells (up to 160µm in diameter)
• process: shed cytoplasm in membrane packets during development and maturation in bone marrow --> membrane packets enter bloodstream as platelets (~4000 platelets made before nucleus of megakaryote gets phagocytosed)

~10 days before removal via phagocytosis in spleen

stimulation of platelet production

• 1. thrombopoietin (TPO)/ thrombocyte stimulating factor (produced in the kidneys):
• - INC. megakaryocyte production
• - INC. platelet formation by breaking down more of the megakaryocyte
• 2. interleukin (IL-6):
• -hormone INC. platelet formation
• 3. multi-CSF (IL-13):
• -stimulate platelets via promotion of megakaryocyte growth and formation

• 1. thrombocytopenia
• 2. thrombocytosis

• -penia = deficient
• abnormally low platelet count
• - DEC. platelet production
• - INC. platelet destruction
• - less than 80,000/µl
• - signs include bleeding digestive tract, skin, CNS

• accelerated platelet formation
• in response to:
• -cancer, inflammation, infection
• greater than 1,000,000/µl

• 1. primary player in the clotting system
• -including plasma proteins and vessels
• 2. transport of chemicals important to clotting process
• -release chemicals like enzymes and other factors at appropriate time and platelets help initiate and control clotting process
• 3. formation of temporary patch in walls of damaged b.v.
• 4. clump together at injury site, forming platelet plug - DEC. blood loss while clotting occurs
• 5. active contraction after clot formation since it contains actin and myosin
• -contract after clot is formed

• coagulation
• -can occur anywhere like in blood vessels, test tube, floor, etc.

• hemostasis (healthy process)
• -initiated inside a leaking/damaged blood vessel
• -formation of a clot at site of injury
• -establishes the framework for tissue repair

• thrombosis
• -obstruction of blood flow (vessel occlusion)
• -clot (thrombus) formation inside a minimally damaged or non-leaking (but perhaps diseased) vessel

• 1. vessel wall
• 2. coagulation
• 3. platelets

a thrombus may grow large enough to obstruct a small vessel or piece may break loose and travel as an embolus

blockage of blood vessel by an embolus

a thrombus that has moved from its site for formation (thromboembolus) and is now occluding a vessel (occurs mostly in veins which have lower pressure/force)

• 1. vascular: begins immediately
• 2. platelet phase: occurs within 15 seconds
• 3. coagulation: occurs after 30 seconds

• 1. direct mechanical stimulation of perivascular nerves
• 2. damage to endothelial cells of blood vessels (b.v.)

• damage to b.v. triggers contraction of vascular smooth muscle cells (SMC) in vessel wall
• -reflex neurogenic mechanism --> vasoconstriction for ~30 mins --> local, transient vascular spasm --> decreases blood flow

damaged endothelial cells contract: expose basal lamina and collagen (INC. thrombogenic) and allows platelets to become "activated" --> damaged endothelial cells become sticky: promotes 'sealing' the edges of damaged blood vessels together and favors attachment of platelets to site of injury

• 1. endothelins
• 2. ADP
• 3. tissue factor

quickly stimulate SMC contraction --> spasm --> augments neurogenic vasoconstriction --> eventually stimulate division of endothelial cells, SMC and fibroblasts --> repair

initiates platelet phase

• aka factor III or thromboplastin
• initiate coagulation phase

platelets at site of injury encounter collagen (or test tube, or kicked around by eddy flow, etc.) and sticky endothelium and become "activated"

platelets undergo shape change, change in membrane receptors and release secretory granules (2 types)

• 1. adhesion and shape change
• 2. secretion
• 3. aggregation

• platelets attach to sticky endothelial cells, the exposed basal lamina and/or the exposed collagen --> develop cytoplasmic processes that "reach" toward other platelets --> express receptors favoring adhesion and aggregation
• Players:
• 1. glycoprotein Ib (GpIb):
• binds vWF (von willebrand factor - "paste") in ECM
• 2. GpIIb-IIIa:
• binds fibrinogen (aggregation)
• 3. ADP (aggregation)

• release granules
• 5 chemicals secreted (positive feedback loop):
• 1. more ADP --> more aggregation and more ADP release
• 2. thromboxane A₂ (cox enzyme used) --> aggregation and vasoconstriction
• 3. 5-HT --> vasoconstriction
• 4. Ca²⁺ --> aggregation, coagulation
• 5. coagulation factors (V and VIII) --> coagulation
• *looks like a SAC (serotonin, ADP, calcium)

• more platelets arrive at site and adhere to each other
• -platelet aggregation results in plugging the leak (platelet plug) --> may seal slightly damaged blood vessel

• blood clotting
• process: involves a complex sequence of steps leading to conversion of circulating fibrinogen into insoluble protein fibrin

proteins found in plasma that circulate in inactive state until tissues are injured and damaged tissues and platelets produce chemicals that begin activation of the factors

• 1. extrinsic
• 2. intrinsic
• 3. common pathway
• *results in blood clot. A network of threadlike fibrinfibers, trapped blood cells, platelets and fluid, effectively seals off the damaged portion of the blood vessel

• initiated via release of tissue factor III/thromboplastin from damaged endothelium. shorter, faster
• -begins in the vessel wall, outside bloodstream
• -damaged cells release tissue factor (TF)
• TF + other compounds = enzyme complex that activates factor X

• initiated by exposure of blood to negatively charged surface (collagen, glass tube) --> activation of pro-enzymes (ex - factor XII) aided by platelet factors (PF-3)
• -begins with circulating proenzymes within bloodstream
• activation of enzymes by collagen --> platelets release factors (ex- PF-3) --> series of reactions activates factor X

• activation of factor X by the extrinsic and/or intrinsic pathways
• -intrinsic and extrinsic pathways converge
• forms enzyme prothrombinase (factor Xa with calcium and potassium + other compounds) --> converts prothrombin to thrombin --> thrombin converts soluble fibrinogen to insoluble fibrin (KEY step in clotting)

• both extrinsic and intrinsic pathways:
• 1. are activated during vessel damage
• 2. results in activation of factor X
• 3. require Ca²⁺ (brings together the negative factors due to gamma carboxylation)
• 4. contain factors that are synthesized in the liver and platelets and require vitamin K (important in post-translational modification with glutamic acid and negative charge)

• activated coagulation factors (enzyme) + proenzyme of coagulation factor (substrate) + cofactors (speed)
• *13 clotting factors total, not activated in numerical order

• fibrinogen --> fibrin -- (activated factor XIII) --> x-linked fibrin net
• -fibrin net: traps RBCs and plasma (controls snowball effect) --> platelets contract (actin and myosin) via thrombin --> pull fibrin net and ultimately edges of blood vessels closer together --> clot retraction (30-60 mins to DEC. bleeding and INC. healing) --> bleeding stops in 1-4 mins.

• removal of fibrin clots after vessel has healed and is tightly regulated
• once damaged vessel has een repaired, fibrin clot must be dissolved to restore normal flow

endothelial cells during reduced blood flow release tissue plasminogen activator (tPA) --> plasminogen --> plasmin (enzyme) --> hydrolyze fibrin --> clot dissolved

• use: for patients with: heart attack or stroke
• 1. tPA
• 2. recombinant forms- ex: alteplase, reteplase, tenecteplase)
• 3. stretokinase (bacterial enzyme)
• 4. urokinase
• *"cool" treatment: vampire bat venom saliva

blood clotting restricted by substances that deactivate or remove clotting factors

function to prevent coagulation factors from initiating clot formation and coagulation occurs when coagulation factor concentration exceeds a given threshold. at site of injury, threshold is exceeded

• 1. antithrombin III
• 2. Heparin
• 3. prostacyclins
• 4. thrombomodulin
• 5. protein C

• produced by the liver
• inactivates thrombin and other factors

• produced by basophils (wbc) and endothelial cells
• a cofactor that accelerates activity of antithrombin III

• prostaglandin derived from endothelial cells
• causes vasodilation and inhibits release of coagulating factors from platelets

• released by damaged endothelial cells
• converts thrombin to an enzyme that activate protein C

a plasma protein that inactivates several clotting factors and stimulates plasmin (breaks fibrin strands)

(1) thrombomodulin activates protein C --> (2) tissue-plasminogen activator [T-PA] converts plasminogen to plasmin [released by damaged tissue] --> plasma proteins: (a) plasmin breaks down fibrin strands through process of fibrinolysis which is normal healing process, (b) protein C activates plasmin --> Heparin activates antithrombin --> (c) antithrombin inhibits thrombin

• un-damaged (healthy) endothelial cells release prostacyclin which is an anti-aggregation factor
• WBC entering damaged area release platelet inhibitory factors
• plasma enzyme and high levels of 5-HT inhibit ADP
• clot development isolates pro-aggregation factors from circulation

• 1. anti-clotting drugs
• 2. anti-platelet drugs

• 1. Warfarin: inhibits coagulation factors VII, IX, X (inhibits vitamin-K dependent Gamma- carboxylation reactions)
• 2. Heparin: binds to and activates anti-thrombin III (enhances anti-thrombin III which inhibits thrombin and inhibits fibrin net formation)

• 1. Aspirin (acetylsalicyclic acid or ASA): inhibits cyclooxygenase reduces production of or DEC. thromboxane A₂ and ultimately DEC. platelet activation
• 2. Plavix (Clopidogrel): DEC. platelet aggregation via block ADP receptor on platelets
• 3. Aggrastat (Tirofiban): block glycoprotein IIb/IIIa ex- blocks fibrinogen induced platelet aggregation to DEC. aggregation
• 4. Integrilin: "cool" drug that is a synthetic hexapeptide from venom in rattlesnake