2011 foms pl11 - blood & blood vessels - cop

8/3/2019 2011 FOMS PL11 - Blood & Blood Vessels - Cop

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Blood & Blood Vessels


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Aims & Objectives

To describe different blood cell types.

To explain plasma (serum & its difference withplasma) & its composition.

To outline the structures & properties o

fthethree main types ofblood vessels, namely,

arteries, veins & capillaries.

Clinical relevance: supply ofO2, nutrients &removal ofwaste products,functioning immune

system..


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Functions ofBlood

Maintenance ofhomeostasis:

1. Transport ofgases, nutrients & waste products.

2. Transport ofprocessed molecules.

3. Transport of regulatory molecules.4. Regulation ofpH & osmosis.

5. Maintenance ofbody temperature.

6. Protection against foreign substances.

7. Clotform

ation.Transport/ distribution, regulation (body temperature,

pH, fluid volume), protection (blood loss, infection).


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Composition ofBlood

Connective tissue cells & cell fragments (formedelements) surrounded by liquid matrix (plasma) Totalblood volume (whole blood), ~ 4 to 5 L (females), 5 to 6L (males)

Plasma pale yellow fluid, ~91% water, 7% proteins, 2%

other substances: ions (ECF), nutrients, gases, wasteproducts, regulatory substances.

Plasma proteins albumin (58%)- Oncotic pressure

globulins (38%)-transport protein

fibrinogen (4%), clotting factors

Serum = plasma minus clotting factors (used up to formclots).


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Composition ofBlood

O2 enters blood in lungs, CO2 fromtissues

Formed elements :

erythrocytes/ red blood cells/ RBCs;

leukocytes/ white blood cells/ WBCs

thrombocytes /platelets

% packed RBCs (after spinning/ centrifugation) =

hematocrit,ind

icat

ion o

fanemia.


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Formed Elements ofBlood

RBC biconcave, no nucleus, contains hemoglobin (Hb) red colour,

7.5 microm diam transports O2 & CO2, pH regulation duration ofdevelopment (DD) 5-7 days, life span (LS) 100-120 days.

WBCwith nucleus, (no Hb) 5 types, each with specific functions:

Granulocytes:

(1) neutrophil nucleus 2 to 4 lobes, cytoplasmic granules light pink/reddish purple, 10-12 microm diam phagocytizesmicroorganisms & other substances

(2) basophil nucleus with 2 distinct lobes, granules blue-purple, 10-12 microm diam releases histamine & othermediators ofinflammation, & heparin which prevents clot formation/

anticoagulant(3) eosinophil nucleus o ften bilobed, granules orange-red/ bright

red, 11-14 microm diam, kills parasitic worms, destroys Ag-Abcomplexes, inactivates some inflammatory chemicals ofallergy


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Agranulocytes:(4) lymphocyte round nucleus, thin ring ofcytoplasm

(pale blue) around nucleus, 6-14 microm diam , mountimmune response by direct cell attack orviaantibodies, allergic reactions, graft rejection, tumorcontrol, regulation ofimmune system

(5) monocyte nucleus round/ kidney/ horseshoe/ U-shaped, pale blue cytoplasm, 12-20 microm diam,phagocytic cell in blood, leaves blood to become tissuemacrophage (bacteria, dead cells, cell fragments/ debris

Platelets/ thrombocytes discoid cytoplasmic fragmentswith granules, deep purple, 2-4 microm diam, seal smalltears in blood vessels/ platelet plugs, blood clottingDD 4-5 days, LS 5-10 days.


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WBC Count

Differential WBC count - % different types of leukocytes inblood sample :

N (50-70%),

E (2-4%),

B (0.5-1%),L (25-45%),

M (3-8%).

Descending order: NeverLet Monkey Eat Bananas.


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Formed Elements ofBlood & Their Origins


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Blood Vessels

Peripheral circulation, heart as central pump.

Functions ofcirculation to carry blood to all tissues & backto heart; exchange nutrients & gases (between blood &all tissues); transport (eg hormones, clotting factors,

enzym

es); regulate blood pressure (+ heart action BP within normal range); direct blood flow as required

by tissue need.

Systemic vessels all parts ofbody from left ventricleback to right atrium (+ coronary vessels supplying heartitself).

Pulmonary vessels to lungs from right ventricle to leftatrium.

Systemic + pulmonary = peripheral circulation, closedcircuit. Central=heart.


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Circulatory System


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Overview ofBlood Vessel

Structures &F

uncti

ons3 major types arteries (As), capillaries (Cs),veins (Vs).

From heart into large artery, then into

successively smaller arteries to smallestbranches (arterioles), then into capillaries (inorgans & tissues, close to cells), then intosmallest veins (venules), into larger & largerveins that merge into large veins emptying intoheart - ~ 100,000 km (60,000 miles).

Systemic circulation Arteries high O2, Veins lowO2, opposite in pulmonary circulation.


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Blood Vessels


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Blood Vessels

Microcirculation arterioles, capillaries, venules.


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Arterial vessels

Arteries -Thick, strong wall, 3 layers: endothelium,middle layer ofsmooth M & elastic tissue, outer layer ofconnective tissue high pressure elastic/ conductingArteries,

Arterioles thinner wall, still 3 layers, smooth M in middlelayer, control blood flow into cap by vasoconstricting/vasodilating major effect on BP has SympatheticNS innervation. Highest RESISTANCE

Endothelium smooth surface, inhibition ofplateletaggregation/ clot, regulation local Blood Flow bysecreting vasodilators/ vasoconstrictors.


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Capillaries

Thin wall nutrients, gases & wastes exchanged between blood &

tissue fluid/ ISF, close intimate contact with cells of tissues/ organs connect arterioles to venules 1 mm length, 8-10 microm diam(diam ofRBCs?).

Types

continuous C (skin, skeletal M), tight junctions between cells,intercellular clefts allow fluid & small solutes through,especially tightin bra

in (BBB);fenestrated C - endothelial cells with pores/ fenestrations (small

intestine for absorption, kidney for glomerularfiltration);

sinusoidal C/ sinusoids (liver, bone marrow, lymphoid tissues,some endocrine glands) large intercellular clefts to allow largemolecules, blood cells - liver: discontinuous endothelium withmacrophages (Kuppfer cells).

Metarterioles

--thoroughfare channels/ shunts arterioles directly to venules

true capillaries/ exchange vessels, precapillary sphincters atm

etarterioles.


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Capillary


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Capillary Endothelium


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Capillary Endothelium


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Exchanges at Capillary


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Exchanges at Capillary


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Veins

enules thinner walls, less smooth M & elastic tissuesthan arterioles, connect Cappilaries to veins.

Veins thinner walls than arteries, but similar layers,

valves (unidirectional Blood Flow), larger lumens,contain large amount ofblood (65%) capacitancevessels, blood reservoirs ( venoconstriction pushesblood to heart), low pressure.

2011 foms pl11 - blood & blood vessels - cop

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