BLOOD & CIRCULATORY SYSTEMSA & P

BLOOD3-4 times thicker than H2O (hence the saying)

Heavier than waterpH 7.35-7.455-6 L M/4-5 L F

FUNCTIONSTransportRegulation

pHbody tempH2O

ProtectionBlood lossForeign microbes

COMPONENTS

Formed elements Plasma

Formed elementscells & cell like structures(rbcs, wbcs, platelets)

45% of volume

RBC % is HematocritFormed elements are:

erythrocytes- RBCsleucocytes- WBCsthrombocytes- platelets

ErythrocytesBiconcave, no nuclei

???red due to hemoglobin

33% of cell weight1 globin + 4 hemeEach Hgb carries 4 O2 & each RBC has 280,000,000

Heme molecules contain iron that can exist in 2 states (ferrous & ferric)Ferrous combines w/O2 forms Oxyhemoglobin

When in periphery changes to ferric & O2 released

O2 released combines w/CO2 forms carbaminohemoglobin

HEMOGLOBIN

23% CO2 transported RBCs live 120 days M 5.4 /F 4.8 Million per Cubic millimeter of bloodAnemia- insufficiencyPolycethemia- abundance

ErythropoiesisHomeostasisRenal erythropoietic factorconverts plasma protein to erythropoietin

Leucocytes (WBCs)Have nuclei, no hemoglobin5-10,000 per cubic millimeterLeucocytosis- high WBC

infection Leucopenia- low WBC

Cancers & viruses

Thrombocytes (platelets)no nucleus250-400 thousand repair/initiates clottingproduced in Red marrow

Plasmastraw colored55% of whole blood

H2O= 91.5%proteins= 7.5%,electrolytes= 1%

Plasmatransport medium

cellular wastefoodenzymesrespiratory gases

Human Red Blood Cells, Platelets and T-lymphocyte (erythocytes = red; platelets = yellow; T-lymphocyte = light green)

HEMOSTASISstoppage of bleeding (in order that it occurs)vascular spasmplatelet plug formationcoagulation

Vascular Spasmcontraction of tunica media

reduces blood losscaused by pain receptor reflex

Platelet Plugplatelets adhere to rough edges of injurythis forms a plug

this stops the bleeding

Coagulation- clotprothrombin activators

thrombinfibrinogen

fibrin (spider’s web)clot

Clot replaced by healthy tissueThrombus- abnormal vessel clot

Embolus- floating clot

HEMOSTASIS REVIEW

BLOOD TYPING

Agglutination- transfusion reaction

Agglutinogens (antigens)- glycoproteins stuck to cell wall

Agglutinins- antibodies in plasma

ABO blood groupingspresence or absence of

Agglutinogen A and/or BAntibodies found in the plasmaAnti-A or B agglutinin

Blood transfusionmust be done correctly (dah)

Universal recipient- AB Blood

Universal donor- type O

Rh blood Groupif Rh factor (Antigen D) is presentRh positive

if Rh factor is not presentRh negative

VESSEL TYPES

ArteryCapillaryVeins

STRUCTURETunica Intima-

SmoothTunica Media

Smooth Muscle & connective tissue (elastic)

Tunica Externa-–Thin layer of connective tissue

–Elastic and Collagenous fibers running parallel to long axis of vessel

ARTERIESWall composition differs according to size

Transports blood under high pressure

Walls are generally thicker than that of veins

TYPES–Elastic (Large)–Muscular (Medium)–Arterioles

ELASTICVery thick T-mediaElastic fibersVery little Smooth MuscleTunica Externa thin but strong to limit stretching

Suited as shock absorber

Maintaining constant flow of blood

Examples–Aorta–Pulmonary TrunkPulmonary Trunk

MUSCULAR

More Smooth MuscleVery Few Elastic FibersInfluences:

Blood flowPressureDistribution

ARTERIOLES

Under 0.5mm in diameter

Thick Tunica Media Major role in regulating blood into capillaries

END ARTERIES

Have no or inadequate anastomosis

Found within organsOcclusion causes death of supplied areabed sores

CAPILLARIESMicro CirculationPenetrate almost every tissue in body1.5 acresend-to-end 60,000 miles

Single layer endothelial cells

Allows relatively free exchange of H20 electrolytes, O2 and CO2

Surface area and slow rate of flow allows for efficient exchange

CAPILLARY BEDSThoroughfare ChannelsTrue CapillariesPre-capillary sphincter

Channels- –scattered smooth muscle cells

–between arteries & venules

True Capillaries–branch from and join with channels

Pre Cap. Sphincter–Usually surrounds true capillary where it arises from thoroughfare channel

–Contraction helps regulate blood flow

VEINSSame 3 layers as ArteriesMuch thinner Greater in diameter and #Types

Small (Venules)Large

Small- closest to capillariesLarge- Tunica Media is quite

thinTunica Externa composes greatest part of wall

BLOOD PROPULSION

Slight positive pressureActivity of MusclesValves found in larger veins usually of lower extremities

CIRCULATORY SYSTEM

Composed of 2 distinct circuitsPulmonarySystemic

Coronary Circulation- takes blood to heart (nutritional)

Portal Circulation- blood from digestive tract

PULMONARY CIRCUIT

Pulmonary TrunkPulmonary Arteries- 2 (deoxygenated)

Pulmonary Veins- 4 (oxygenated)

SYSTEMIC CIRCUIT

VEINS

VASCULARIZATION

Small Vessels - blood withinLarger Vessels-

Diffusion not enoughSmall adjacent Arts. (Vasa Vasorum)

Arteries penetrate through Tunica Externa

Veins penetrate to Tunica Intima

PHYSIOLOGY OF CIRCULATION

Blood FlowBlood Pressure

Systolic DiastolicPulse

Blood Pressure- force exerted on inner walls

Systolic Pressure (SP)- maximum pressure

Diastolic Pressure (DP)- Minimum or lowest pressure

Pulse- Rhythmic expansion and recoil of arterial wall

Pulse Pressure Pulse Pressure (PP)(PP) - - difference between difference between Systolic and Diastolic Systolic and Diastolic pressure usually 40mm pressure usually 40mm HgHg

PP= SP - DPPP= SP - DP

Mean Arterial Pressure (MAP)

Pressure in system for driving blood to tissues

MAP = DP + 1/3 PP

INFLUENCES ON BP

Cardiac Output Peripheral Resistance

Cardiac Output (CO)Heart Rate (HR)Stroke Volume (SV)

– CO= HR x SV

PERIPHERAL

RESISTANCE (TPR)Resistance through vessels

DiameterViscosityLength of VesselBlood Volume

BP = CO x TPR

BP CONTROLVasomotor Center

In MedullaControls DiameterSymp. incr. Vasoconstriction

Symp dec. Vasodialation

Pressoreceptors–in carotid Sinus and Aorta–Impulses go to Cardiac Center resulting in inc. or dec. cardiac output

–Also sends impulses to Vasomotor Ctr.

Chemoreceptors–In Carotid and Aortic bodies

–Sensitive to Art. content of O2, CO2 and H+ ions

–When stim. send impulses to vasomotor Center

CONTROL BY HIGHER BRAIN FUNCTION

Strong emotions (anger, stress)Increases Sympathetic Impulses to VM Centers–vasoconstriction

Decrease in Sympathetic Impulses to VM Centersvasodilation

CHEMICALS

Epinephrine & Norepinephrine produced by adrenal medullaCauses vasoconstriction of abd and cutaneous arterioles

Dilation of cardiac & skeletal arterioles

Antidiuretic Hormone (ADH) produced by hypothalamus–Vasoconstriction in the case of severe blood loss

AUTOREGULATION (LOCAL CONTROL)

Automatic adjustments are made to regulate blood flow

In most cases O2 is the principal stimulus

QUESTIONS????