Blood is a connective tissue consisting of plasma and blood cells. It contains three main cell types: red blood cells, which carry oxygen; white blood cells, which help fight infection; and platelets, which help control bleeding. Red blood cells are non-nucleated and contain hemoglobin. White blood cells include granulocytes like neutrophils and lymphocytes that provide immunity. Platelets play a vital role in hemostasis by activating the blood clotting cascade. Together, these blood components perform essential functions in transport, defense, and hemostasis.

1. CONNECTIVE TISSUE:BLOOD
DR. KINGSLEY OKON

2. • Blood is a specialized fluid connective tissue
consisting of some cells suspended in a liquid
intercellular substance known as plasma
• Blood is composed of mainly two parts
• i. plasma
• ii. Blood cells

3. Blood cells type
3 major functional classes
i. Red blood cells
(RBC)-
erythrocytes
ii. White blood cells
(WBC)-leukocytes
iii. Platelets -
thrombocytes

4. • Erythrocytes contain large amounts of oxygen-
carrying haemoglobin
• Involved in transport of oxygen and carbon
dioxide
• Leukocytes constitutes an important part of the
defense and immune system
• Platelets plays a vital role in the controlling of
bleeding (haemostasis)-i.e activation of blood-
clothing cascade

5. Erythrocytes
Life span-120
days
Non-nucleated
Consist of
plasma
membrane
enclosing
haemoglobin and
some organelles

6. White blood cells (leukocytes)
• The leukocytes are the mobile units of the
body’s protective system
• They are form partially in the bone marrow
(granulocytes & monocytes) and a few
lymphocytes
• Partially in the lymph tissue (lymphocytes &
plasma)
• After formation, they are transported in the
blood to diff. parts of the body

7. • All WBCs have nucleus and no haemoglobin
• Protects body against microorganism and
remove dead cells & debris
• Their average total number is 6000-8000 per
mm3
• Granular or agranular classification based on
presence of cytoplasmic granules made visible
by staining

8. Types and Functions
• Granulocytes
Neutrophils: small phagocytic cells
Eosinophils: reduce inflammation
Basophils: release histamine & ↑se inflammatory
response
• Agranulocytes
Lymphocytes: immunity
Monocytes: becomes magrophages

9. Neutrophils(polymorpho-
nuclear leukocytes)
• Life span- 1 week
• About 9-12µm in
diameter
• Nucleus long &
multilobed (2-4)
• Cytoplasm has
small, neutrally
stained specific
granules

10. Functions
• Primarily antibacterial
• Gives fastest response of all WBCs to
bacterials and paracytes
• Leave the blood & folloe chemotaxic signals
to sites of wounding or other inflammations
• Phagocytise foreign agents such as bacteria
• Pus is composed largely of dead neutrophils

11. Eosinophils
• Life span- 2 weeks
• Bilobed nucleus
• Cytoplasm stains
pink/red
• Granule are effective
against parasites
• Functions
• Release histamine &
heparin
• Allergies & anaphylaxis

12. Lymphocytes
• Life san- varies (few
days to several years)
• Less than 8µm (small
lymphocytes)/(15µm
large)
• Round dense nucleus
• Cytoplasm is a narrow
rim round the nucleus
• Functions
• T-lymphocytes
• B-lymphocytes

13. Monocytes
• Life span- few days in
blood, several months in
CT
• About 16 µm in
diameter-largest
• Large eccentric nucleus-
oval, kidney-shaped or
horse-shoe shape
• Cytoplasm contains
mitochondria &
lysosomes

14. Functions
• Mononuclear phagocytic system
i. tissue macrophages
– Kupffer cells (liver)
– Osteoclast cells (bone)
– Dust cells (lungs)
– Microglia (brain)
ii. Mediate inflammatory response
iii. Antigen presenting cells

15. Platelets
• Small, non-nucleated cells form in bone
marrow by megakaryoctes
• Round/oval biconvex disc
• 1.5-3.5µm in diameter

16. Functions
• i. Form plug to occludes sites of vascular damage
by adhering to collagenous tissue at the margin of
wound--- later the plug is reinforced by fibrin
• ii. Promote clot formation by producing a surface
for assembly of coagulation protein complex
• iii. Secretes factors that modulate coagulation &
vascular repair

17. Major functions of WBCs
• Defense action
• Phagocytosis: the neutrophils & monophils
engulf foreign particles & microorganisms
• Antibody formation: lymphocytes produce
antibodies (gamma globulin) and play an
important role in defensive mechanism of the
body

18. • Secretion of heparin: The basophils secretes
heparin which helps in the prevention of
intravascular clot.
• Manufacture of trephones: Leukocytes
produces some special protein like substance
known as ‘trephones’ which have great
influence on nutrition, growth & tissue repair