What is blood?? Blood is a fluid which is often regarded as a connective tissue because of the two main reasons.
1) Embrologically it has the same origin (mesodermal) as do the other connective tissue types
2) Blood connects the body systems together bringing the needed oxygen, nutrients, hormones and other signaling molecules, and removing the wastes.
2) Blood connects the body systems together bringing the needed oxygen, nutrients, hormones and other signaling molecules, and removing the wastes.
Composition of Blood
1) Plasma - water liquid extracellular matrix 55% of total blood volume
2) Formed elements (cells & cells fragments) 45% of tottal blood volume.
a. Red blood cells (erythrocytes).
b. White blood cells (leukocytes).
c. Platelets (thrombocytes).
Plasma is 91.5% water and 8.5 solutes (primarily proteins and mineral ions).
Functions of blood
1. Transportation (gases, minerals, wastes, hormones etc)
2.Regulation (pH, osmotic balance etc)
3. Protection (through clotting and other mechanisms)
Characteristics
> Temperature 38°C (100.4°F)
n
n> Total blood volume is 5-6 L
Hematocrit
The volume percentage of erythrocyes in whole blood is known as hematocrit
qNormal female hematocrit – 38-46%
qNormal male Hematocrit – 40-54%
Formation of Blood cells (Haemopoiesis)
Pluripotent stem cells produce qMyeloid stem cells which give rise to red blood cells, platelets, monocytes, neutrophils, eosinophils and basophils while qLymphoid stem cells give rise to nLymphocytes.
Formation of RBCs is called Erythropoisis.
RBCs (Red Blood cells)
> Biconcave Discs
> mean dia of about 7.8 micrometers
> thickness of about 2.5 micrometers at the thickest point and
> 1 micrometer or less in the center
> avg volume: 90 to 95 cubic micrometer
> contains hemoglobin (Hb) upto 34 grams in each ml of cells.
> lack nucleus- can't reproduce
> lack mitochondria
> Life- just 120 days
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