Blood. Connective tissue with a fluid matrix Three main functions: –Transportation –Regulation...
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Transcript of Blood. Connective tissue with a fluid matrix Three main functions: –Transportation –Regulation...
Blood
Blood
• Connective tissue with a fluid matrix
• Three main functions:– Transportation– Regulation– Protection
Physical Characteristics of Blood• Heavier, thicker, and 3-4 X more viscous
than water
• 38o C (100.4oF)
• pH : 7.35 – 7.45
• 8% of body weight
• 4-6 liters in an adult
• Varies with electrolyte concentration and amount of adipose tissue
Components of Blood
• Plasma – 55 %• Formed elements – cells and cell
fragments – 45%• Hematocrit (HCT) or Packed Cell Volume
(PCV)• See:
– Plasma– Buffy coat (< 1%)– Red cells - erythrocytes
Formation of blood cells
Before birth blood is formed by the yolk sac, liver, spleen, thymus gland, lymph nodes and red bone marrow.
After birth only by red bone marrow
Stem cells are hemocytoblasts
Process is hematopoiesis
Colony stimulating factors
ErthrocytesBiconcave discs without nuclei
1/3 hemoglobin by volume
Hemoglobin – 4 peptide chains and an iron containing pigment called heme
The iron binds reversibly with oxygen
oxyhemoglobin deoxyhemoglobin
Cyanotic – skin and mucous membranes
appear blue
Also transports 23 % of CO2
bound to globin as carbaminohemoglobin
CO – carbon monoxide binds more tightly to hemoglobin than oxygen
Males = 5.4 million RBCs per cubic mm
Females and children = 4.8 million/ cubic mm
People at high altitudes = 8 million/cubic mm
LeukocytesGranular leukocytes (granulocytes)
neutrophils
eosinophils
basophils
Agranular leukocytes (agranulocytes)
Lymphocytes
Monocytes
Eosinophils
• Granules stain red with acidic dyes
• Nuclei us. have 2 lobes
• Combat effect of histamine in allergic reactions
• Combat parasitic worms
• 1-3% of leukocytes
Basophils
•Have granules that stain blue with basic dyes
•Release heparin, and histamine
•Increase in allergic reactions that intensify the inflammatory response
•Less than 1% of leukocytes
Neutrophils
•Granules stain pale purple in a combination of acidic and basic dye
•Older cells have many lobed nuclei – gives the name polymorphonuclear leukocytes (PMNs)
•Younger neutrophils are called bands
•Phagocytes
•54 -62 % of the leukocytes
Lymphocytes•May be small or large
•Nuclei stain darkly, very little cytoplasm
•Only 2% of lymphocytes are in blood
•B lymphocytes make antibodies
•T lymphocytes attack invaders directly
•Long lived
•25-33% of leukocytes
Monocytes•Largest leukocyte
•Nuclei horseshoe-shaped
•Cytoplasm blue-gray and foamy
•When leave blood and enter tissues become transformed into macrophages
•3 - 9 % of leukocytes
Normal blood contains 5,000 -10,000/mm3
An increase in the number of wbcs is leukocytosis
A deficiency in wbcs is leukopenia
Differential white blood cell count is useful in diagnosis of disease
Major histocompatibility (MHC) antigens used in tissue typing
Function of leukocytes
Protect against infection
phagocytosis, antibodies, direct attack
Platelets, or thrombocytes, are cell fragments
•Formed from megakaryocytes
•130,000 – 360,000/mm3
•Involved in blood clotting
•Release serotonin which contracts smooth muscle in walls of blood vessels – reducing blood flow – and blood loss
Plasma
• 92 % water
• 8% solutes – ions, nutrients, enzymes, gases, wastes, hormones, but mostly proteins
•These proteins are mostly made by the liver
Serum
Plasma without the clotting factors
Still contains :
ions, nutrients, enzymes, gases, wastes, hormones, and some proteins – including antibodies
Blood Groups and Blood Types• Erythrocytes have surface antigens, called
isoantigens or agglutinogens• Most common are the ABO and Rh groups• A and B are isoantigens, O is absence of
antigen• Antibodies activate complement which
causes hemolysis• Typing outside the body uses
agglutination, NOT clotting !
Persons with type A blood make antibodies against B
Persons with type B blood make antibodies against A
Persons with type O blood make antibodies against A and B
Persons with type AB do not make antibodies.
Rh factor
• First discovered in the rhesus monkey
• Either have the antigen = positive
• Or don’t have the antigen = negative
• Do not automatically make antibodies – must first encounter the antigen
• Hemolytic disease of the newborn – or- erythroblastosis fetalis
• Give RhoGAM – anti Rh antibodies
Remember:
Rh factor is only a problem if the mother is negative and the father is positive.
Blood Pressure and pulse
• Systolic pressure occurs during ventricular systole (contraction)
• When you can first hear the sound of blood flowing through the brachial artery
• Diastolic pressure occurs during ventricular diastole (relaxation)
• Point when you no longer hear the flow of blood
First heart sound due to closing of A-V valvesSecond heart sound due to closing of semilunar valves.
Heart Murmurs – abnormal sounds caused by the flow of blood.Mitral stenosisMitral valve prolapse
Blood pressure by pulse points• Popliteal or dosalis pedis – 100 -110
(normal)
• Femoral 80-95
• Radial – 80
• Carotid – 60 (exsanguination)
Anatomy of blood vessels
• Arteries carry blood away from the heart
• Hole is called the lumen
• Three layers or tunics:– Tunica interna (intima)– Tunica media– Tunica externa (adventitia)
Tunica interna
• Simple squamous epithelium called endothelium
• Secretes biochemicals that inhibit platelet aggregation
• Also substances that dilate or constrict vessels
Tunica media
• Bulk of vessel wall
• Smooth muscle fibers
• Innervated by the sympathetic N.S. – vasoconstriction; decreased impulses = vasodilation
• Thick layer of elastic connective tissue
Tunica externa
• Thin layer
• Connective tissue
• Attaches artery to surrounding tissue
• Contains tiny vessels – vasa vasorum that form capillaries and provide blood to external cells of the vessel
Arteries
• Large arteries are elastic (conducting) arteries – pressure reservoirs
• Medium arteries are muscular (distributing) arteries – more smooth muscle
Capillaries
• Only a single layer of endothelium and a basement membrane
• Connect arterioles and venules
• Microcirculation
• Functional part of system for exchange of gases, wastes and nutrients
• True capillaries begin at a precapillary sphincter
Types of capillaries
• Continuous - intercellular clefts, but otherwise uninterrupted
• Fenestrated capillaries – have “windows” or pores – act in filtration
• Sinusoids or discontinuous capillaries have spaces between cells, and basement membrane is incomplete or absent
• Tight junctions – form a barrier
Veins
• Have same three tunics as arteries, but have a thinner tunica media
• Contain valves
• Act as blood reservoirs