ANAT #3 Blood

Functions of blood

1. Transport

2. Regulates body temperature

3. Protects against blood loss by mediating clotting

4. Blood is a connective tissue

Where does blood transport

1. oxygen from the lungs to the body, and CO2 from the body to the lungs

2. Nutrients from intestines to body organs; waste from body to kidneys

3. Hormones and enzymes

4. Cells of the immune system

Blood cells are produces in

bone marrow

Composition of blood

55% plasma, 45% erythrocytes, 1% leukocytes and platelets

Composition of Plasma

-92% water

-contains ions, nutrients, wastes, and hormones

3 main plasma proteins

albumin, globulin, fibrinogen

Albumin

-produced by the liver

-used to maintain osmotic pressure

-carrier protein (binds and transports proteins)

Globulin

-produced by leukocytes

-immunoglobins or antibodies

Fibrinogen

-produced by platelets

-forms clotting fibers called Fibrin

Serum

fluid left after clot is formed

Purpose of erythrocytes

transport oxygen and carbon dioxide

What are surface antigens on cell membrane of all cells

Glycoproteins and glycolipids

3 most important surface antigens

A, B, and Rh (D)

-produces 4×2 blood types, each blood type has to have a compatible donor to receive transfusion

What happens if a blood transfusion is given with incompatible blood

agglutination (clumping) can occur and the cells may hemolyze (rupture)

Type O

neither A or B antigens present on the RBC

-universal donor

-46% of population

-has both A and B antibodies present in plasma therefore can receive only type O RBC’s

Type A

-A antigens present on the RBC

-40% of population

-has type B antibodies present in plasma

-can receive type A or type O RBC’s

Type B

-B antigens present on the RBC

-10% of population

-has type A antibodies present in plasma

-can receive type B or type O RBC’s

Type AB

-both antigens present on the RBC

-4% of population

-no antibodies present in plasma, can receive any type of RBC’s; universal recipient

Characteristics of Erythrocytes

1. Biconcave disc

2. Most numerous of all blood cells

3. 97% hemoglobin; oxygen carrying protein

4. Dead RBC’s are recycled by macrophages in the spleen

Characteristics of Leukocytes

1. Complete cells with the usual organelles

2. function outside of the blood vessels in the connective tissue surrounding them (in lymphatic system)

3. Move towards a site by following chemical attractants (chemotaxis) and move (diapedesis) into the tissues through small openings between the endothelial cells of capillaries and post capillary venules

4. Produces in bone marrow and released continuously; some stored in bone marrow and released in a surge during infection

5. Classifies as granular or agranular

granular leukocytes

neutrophils, eosinophils, basophils

Neutrophils

• nucleus contains 2-6 connected lobes

• most abundant, 60-70% of all WBCs

• defends against bacterial infections

• active phagocytosis, quick to site of infection as first line of defense

• granules are digestive enzymes to digest bacteria

• can also release enzymes extra-cellularly

Eosinophils

• nucleus has 2 lobes connected

• granules stain red

• 2-4% of WBC’s

• fight parasite infections, mediate allergic reactions, and phagocytosis of antigen/antibody complexes

• granules contain digestive enzymes

Basophils

• nucleus has 2 lobes connected in a U or S shape

• granules stain dark purple

• 1% of WBCs

• release histamine during allergic reaction

• function is similar to mast cells in tissues

Agranular Leukocytes

monocytes, lympcytes

monocytes

• nucleus is dark and kidney, horse show, or U shaped

• 3-8% of WBCs

• precursor to the macrophage, found in circulatory system

lymphocytes

• dark round nucleus that fills up cell

• 20-25% of WBCs

• major component of the immune system

• immune attack cells (T-lymphocytes and B lymphocytes)

• Produced in the bone marrow

B-lymphocytes

• educated in bone marrow

• stimulated against an antigen, become plasma cells, make antibodies (immunoglobulins) against the antigen (opsonization)

• Antigen-antibody complexes are then phagocytes by macrophages

T-lymphocytes

• T-Helper cells + T cytotoxic cells

• T helpers help stimulate B-lymphocytes and T-cytotoxic lymphocytes

• T cytotoxic lymphocytes are cell killers

Platelets (Thrombocytes)

• not cells, but disc shaped fragments enclosed by a plasma membrane

• derived from megakaryocytes

Blood clots

firing forms network with platelets to trap RBCs into a clot, actin and myosin contract fibers to tighten clot and close laceration