Blood

Avian Physiology

Function of Blood -

Transport

•

Oxygen,•

CO2

•

Nutrients -

glucose, amino-acids, lipids, lactate

•

Water•

Waste -

uric acid/urates

•

Heat –

body temperature•

Hormones

•

Immune protection•

Osmotic balance/ minerals

Components of blood

•

Plasma–

60-70% of blood

•

Cells/corpuscles–

30-40% of blood

–

Hematocrit

= 30-50

Hematocrit•

Hematocrit

= Packed Cell Volume (PCV)

after

centrifugation of whole blood

Components of Plasma•

90% water

•

10% solutes–

Minerals -

Na, K, Ca, Mg, HCO3, Cl, Phosphate

–

Nitrogenous Compounds:•

Proteins –

3-6 g/dl

•

non-protein nitrogen (uric acid, urate)–

Nutrients -

glucose 150-250 mg/dl (fasting)

–

Lipids -

free fatty acids, neutral fats, phospholipids, cholesterol esters

–

Yolk precursors + Hormones

Centrifuge blood with an anticoagulant (prevents clotting) to separate plasma from cells.Prior to

CentrifugationAfter

Centrifugation

Plasma

Red Blood CellsBuffy coat = WBC

Corpuscles

Plasma proteins•

Albumins

–greatest, 40% of total plasma protein

–

Transport other substances (hormones)–

Osmolality

of blood and Egg formation

•

Clotting proteins= fibrinogen, pro-thrombin•

Globulins –

α

and β

globulins are transporters

–

γ

globulins

are antibodies•

Hormones

•

Lipoproteins, i.e. yolk proteins•

Glycoproteins

•

Hemoglobin•

Enzymes

Clotting Proteins and Clotting

•

Clotting should not occur unless injury

•

Initiated by Prothrombin

activating factors, ie Thromboplastin

•

Factors that cause release of thromboplastin:–

Extrinsic Factors

= external trauma that damages

vessels–

Intrinsic Factors

= damage of blood cells

•

Fast uncontrolled once started

Clotting Proteins and Clotting

•

Cascade:

Prothrombin

activating factors

Prothrombin

Thrombin(an α

globulin)

Fibrinogen Fibrin threads

+ Ca++

+ fibrin stabilizing factor

=Polymerization and clotting

Clotting Time

•

Whole chicken blood clots in 2 –

120 min.

•

Prothrombin

time

is more sensitive:–

Add Ca chelator

–

sodium citrate or Ca

precipitator –

sodium oxalate (anticoagulants) to prevent blood from clotting prior to test.

–

Separate cells from plasma by centrifugation–

Add excess of Ca and known amount of prothrombin

to plasma

–

Record time required for clot formation.

Prothrombin

Time

•

Chicken prothrombin

time is 10-20 sec with 12 sec average.

•

Vit. K is needed for synthesis of many procoagulation

factors

–

↓Vit. K in diet and blood = ↑Prothrombin

time–

Prothrombin

time is an accepted bioassay for Vit.

K levels in chickens.

What prevents blood from clotting in the circulatory system, since

everything is in there that is needed for clotting?

•

Natural anticoagulants = heparin•

Roughed surface is needed for clot formation

•

No injured vessel then intravascular clotting is rare.