ANS 331: Blood

I.	Functions

	1.	Transport
		A.	Nutrients
		B.	Oxygen
		C.	Carbon Dioxide
		D.	Waste Products
		E.	Hormones
		F.	Heat
		G.	Immune Bodies
	2.	Fluid Balance
	3.	pH

II.	Composition and Characteristics of Blood

	1.	Components
		A.	Cells
			a.	Erythrocytes (Red Blood Cells; RBCs)
			b.	Leukocytes (White Blood Cells, WBCs)
			c.	Platelets (Thrombocytes)
		B.	Plasma
			a.	Liquid Component of Blood
	2.	Hematocrit
		A.	Centrifugation of column of blood
			a.	Separates components by specific gravity
		B.	Three layers of cells
			a.	Packed Cell Volume
				--Bottom Layer
				--Erythrocytes
			b.	Buffy Coat
				--Middle Layer
				--Leukocytes and Platelets
			c.	Plasma
				--Top Layer
		C.	Used to determine abnormalities in the blood (Body)
	3.	Blood color
		A.	Red color imparted by Hemoglobin
			a.	Range bright red to bluish-purple
			b.	Degree of Oxygen saturation
		B.	Plasma is Yellow to Colorless
			a.	Due to Bilirubin
				--Degradation Product of Hemoglobin
			b.	Plasma is particularly dark in cow and horse
	4.	Blood Volume
		A.	Horse = 8-10% of body weight
		B.	Sheep & Cow = 5-6% of body weight
		C.	Pig  = 8-10% of body weight
	5.	Blood pH
		A.	Arterial Blood=7.4
		B.	Venous Blood=7.36
			a.	Due to Carbon Dioxide in the Blood

III.	Erythrocytes

	1.	Numbers
		A.	Cow and Pig = 7 billion per ml
		B.	Horse = 10 billion per ml
		C.	Sheep = 11 billion per ml
		D.	Goat = 13 billion per ml
	2.	Shape
		A.	Discoid with concavity
			a.	Larger surface area:volume ratio
			b.	Minimal diffusion distance
			c.	Greater osmotic swelling
		B.	Have some Plasticity
	3.	Size
		A.	4-7 µm
	4.	Erythropoiesis
		--The production of erythrocytes
		A.	Organs of Production
			a.	Before Birth--Liver, Spleen, Bone Marrow
			b.	Postnatal to Adult--Bone Marrow
				I.	Axial Bones = 35%
				ii.	Appendicular Bones = 65%
		B.	Continually formed and destroyed
			a.	1000 lb Horse produces 35 million RBCs/sec
		C.	Progenitor Cells
			a.	Rubriblast
			b.	Rubricyte
			c.	Reticulocyte
				--Nucleus expelled
			d.	Chickens have nucleated RBCs
		D.	Lifespan of RBCs
			a.	110 days in Domestic Animals
			b.	30 days in Chickens
		E.	Rate of Erythropoiesis
			a.	Controlled by Tissue Oxygen Need
			b.	Low Oxygen stimulates Erythropoietin 
				from Kidney
			c.	Erythropoietin stimulates bone marrow 
				to produce new RBCs
			d.	Takes 5 days to enter circulation
	5.	Hemoglobin
		A.	Principle component of RBCs
			a.	33% of RBC content
		B.	Composition of Hemoglobin
			a.	Heme
				--Iron containing
				--4 hemes/globin
			b.	Globin
				--Protein component
		C.	Iron binds Oxygen
			a.	Four oxygens per hemoglobin molecule
			b.	Blood can carry 60X more Oxygen 
				than a simple solution
		D.	CO combines with 200X higher affinity
			a.	Disallows oxygen binding
			b.	Carbon Monoxide Poisoning
	6.	Destruction
		A.	10% of old RBCs undergo hemolysis
		B.	90% by Mononuclear Phagocytic System (MPS)
			a.	Also called Reticuloendothelial System
			b.	Found mostly in spleen, liver, and marrow
			c.	Monocytes
				--Phagocytotic cells
		C.	Components are recycled or excreted
	7.	Anemia
		A.	Reduction in RBCs and/or Hemoglobin
		B.	Causes
			a.	Blood Loss
			b.	Iron Deficiency
			c.	Nutritional Factors Missing
			d.	Bone Marrow Poisoning
				--Aplastic Anemia	
	8.	Polycythemia
		A.	RBCs greatly increased
		B.	Rarely recognized in animals
		

		

IV.	Leukocytes

	1.	Classifications and Appearance

		A. 	Granulocytes

			a.	Contain Granules in Cytoplasm
			b.	Three Types
				i.	Neutrophils
				ii.	Basophils
				iii.	Eosinophils
			c.	All granulocytes are made in Bone Marrow
			d.	Have odd shaped nuclei

		B.	Agranulocytes

			a.	Few or no granules in cytoplasm
			b.	Two Types
				i.	Monocytes
				ii.	Lymphocytes
					--B cells
					--T cells
			c.	Monocytes made in Bone Marrow
			d.	Lymphocytes made in Lymph glands

	2.	Life Span and Numbers

		A.	Granulocytes and Monocytes spend 6-10 hours in 
			circulation 

		B.	Granulocytes go to tissues (2-3 days) and leave 
			body by: 

			a.	Inflammatory sites
			b.	Intestinal, Urinary, Respiratory, 
				or Reproductive Tracts

		C.	Monocytes remain in body for months

			a.	Become fixed Macrophages in liver, spleen, 
				bone marrow, and lymph nodes

		D.	Lymphocytes recirculate between blood to lymph

			a.	T-cells live 100 to 200 days
			b.	B-cells live 2-4 days
			c.	Memory T and B live for years

		E.	Numbers of WBCs in body

			a.	10 million/ml
			b.	Percentages of types vary among species
			c.	Neutrophils and Lymphocytes make up 
				majority (>90%)
				i.	Cloven-Hoofed
					--More lymphocytes than neutrophils
				ii.	Other animals
					--More neutrophils than lymphocytes
	3.	Functions of WBCs

		A.	Neutrophils

			a.	Line Organ system tracts
			b.	Highly Phagocytic
				--Engulf bacteria, cells, and degenerating 
				tissues
			c.	Dead neutrophils and fluid 
				is called Pus
			d.	Pus accumulated in a C.T. capsule is an 
				abscess

		B.	Monocytes

			a.	Circulating
				i.	Phagocytize bacteria, viruses, 
					and antigen-antibody complexes
			b.	Tissues
				i.	Become Macrophages
					--Phagocytize same entities
				ii.	Clean-up extra debris left over 
					from neutrophils

		C.	Eosinophils

			a.	Dampen allergic inflammatory reactions
			b.	Recognize certain parasites that are 
				opsonized (attacked by Abs)
				--discharge contents on parasite kills
			c.	Decrease during stress

		D.	Basophils
			a.	Enhance allergic reaction	

		E.	Lymphocytes

			a.	Involved in immune responses
			b.	T-lymphocytes
				i.	Cell Mediated Immunity
				ii.	Mature in Thymus
				iii.	Sensitized by Antigen
					--Memory T-Cells
				iv.	Cytotoxic (Killer or Effector) 
					T-Cells are produced when antigenic 
					entity is encountered again.
				v.	Search and Destroy

			c.	B-cells
				i.	Humoral Immunity
				ii.	Produce antibodies that inactivate 
					foreign substances
					--Plasma Cells
				iii.	Cause:
					--Agglutination
					--Precipitation
					--Neutralization
					--Lysis
					--Opsinization and Phagocytosis

	4.	Megakaryocytes and Platelets
	
		A.	Megakaryocytes
			a.	Found in bone marrow
			b.	Fragment into Platelets
		B.	Platelets
			a.	Assist in Hemorrhage control
			b.	3 µm in diameter
			c.	400 million/ml of blood

	5.	Diagnostics
		A.	Leukocytosis--Increased WBCs
			a.	Bacterial Infections
		B.	Leukopenia--Decrease WBCs
			a.	Viral Infectiooons
		C.	Leukemia
			a.	Cancer of WBCs
			b.	Leukocytosis

			

V.	Prevention of Blood Loss

	1.	Hemostatic Summary

		A.	Hemostasis
			a.	The stoppage of bleeding or hemorrhage.
			b.	The stoppage of blood flow through 
				a blood vessel or body part.
		B.	Summary of Hemostasis
			a.	Endothelial cells separated
				i.	Collagen exposed
				ii.	Loss of smoothness and nonwetability
			b.	Platelet reactions
				i.	Adhesion begins
				ii.	Platelets develop projections 
					(pseudopods) and become sticky
				iii.	Adhered platelet undergo a reaction 
					which cause more platelets 
					to accumulate
				iv.	Loose platelet plug forms
			c.	Blood Coagulation (clotting)
				i.	Plug is strengthened by fibrin 
					meshwork 
			d.	Damaged area is repaired by connective tissue 
				and endothelial cell growth
			e.	Platelet-fibrin complex and other debris 
				is removed
				i.	Return to normal

	2.	Hemostatic components

		A.	Vascular endothelium
			a.	Intact endothelium will not activate 
				hemostasis
				i.	Negative charge repels platelets
				ii.	Synthesizes inhibitors of platelet 
					function and fibrin formation
				iii.	Generation of activators of fibrin 
					degradation
			b.	Damage exposes subendothelial tissues
				i.	Collagen activates platelets
				ii.	vonWillebrand factor (vWF) 
					and fibronectin enhance platelet 
					aggregation
		B.	Platelets
			a.	Also known as thrombocytes
			b.	Cytoplasmic body, no nucleus
			c.	Involved with initial stages of hemostasis
		C.	Clotting Factors
			a.	Elements essential for blood coagulation
			b.	Most need to be activated to be used
			c.	Most are identified by Roman numerals
			d.	Vitamin K is needed for the production 
				of II, VII, IX, and X

	3.	Platelet Reaction

		A.	Initiation
			a.	Collagen is usual activator
			b.	Other activators
				i.	ADP
				ii.	Serotonin
				iii.	Thromboxane A2 (TXA2)
		B.	Platelet adhesion
			a.	Platelets attach to disrupted area
			b.	vWF and fibronectin are required
		C.	Platelet activation
			a.	TXA2 is produced in response to collagen 
				or ADP
			b.	Causes intracellular Calcium release
		D.	Platelet release reaction
			a.	Intracellular Calcium causes release 
				of Platelet granules containing coagulation 
				factors
		E.	Platelet aggregation
			a.	Granule contents fibrinogen, fibronectin, 
				vWF, and factor V lead to formation 
				of platelet plug
				i.	Platelets pile on top of each other 
					and fuse
			b.	Exterior surface highly reactive to the 
				formation of thrombin and fibrin

	4.	Blood Coagulation

		A.	General
			a.	Stabilizes platelet plug
			b.	Proenzymes are activated
			c.	Cascade phenomena
				i.	Each step is amplified
				ii.	Small start gets large response
		B.	Two mechanisms for blood coagulation
			a.	Intrinsic
				i.	Contact of blood with a foreign 
					surface
				ii.	More steps (slower)
				iii.	Activation sequence
					--XII, XI, IX, VIII
			b.	Extrinsic
				i.	Contact of blood with 
					a extravascular tissue
				ii.	More direct (faster)
				iii.	Activation sequence
					--Tissue Factor (III) and VII
			c.	Convergence of pathways
				i.	Activation of Factor X
				ii.	Followed by Prothrombin to Thrombin
				iii.	Followed by Fibrinogen to Fibrin
			d.	Both require Calcium (Factor IV)

	5.	Prevention of Coagulation in Normal Circulation

		A.	Antithrombin III
			a.	Inactivates Thrombin 
				(Homeostasis under normal conditions)
		B.	Endothelium characteristics
			a.	Platelets don't adhere
		C.	Endogenous Heparin
			a.	Produced by Mast cells
			b.	High in lung
			c.	Also works with Antithrombin III
	
VI.	Plasma and its Composition

	1.	Liquid Part of Blood
	2.	Medium of Exchange
	3.	92% Water
	4.	Other Components
		A.	Proteins
			a.	Albumin
			b.	Globulins
			c.	Fibrinogen
		B.	Gases
		C.	Lipids
		D.	Non-Protein Nitrogen
		E.	Inorganic compounds
		D.	Hormones