Functions of Blood

• Transportation of O2 and nutrients to the body cells, and removal of CO2 and metabolic wastes.
• Transports hormones from endocrine glands to target cells and organs.
• Regulation of body temperature
• Protection from disease and infection because contains the immune defence cells.

Physical Charactertistics of Blood

• More viscous than water
• Slightly adhesive
• Temperature of 38 Celsius/100.4 F
• pH between 7.35 and 7.45
• constitutes 8% of total body weight
• Volume breakdown: males 5-6 liters

                   females 4-5 liters

Components of Blood

• over 90% water
• 7% plasma proteins which are created in the liver and confined to the bloodstream: such as:

- albumin: to maintain osmotic pressure

- globulins (immunoglobulins): antibodies that bind to foreign substances called antigens.

- fibrinogen: for clotting

• 2% other substances like: Electrolytes (Na and Cl), nutrients, hormones, vitamins, gases, waste products (urea, ammonia).

Formed Elements of Blood

Erythrocytes

Leukocytes

Platelets

What are the two types of leukocytes?

• Granular
• Agranular

Red Blood or Erythrocytes

• Contain O2 carrying protein: hemoglobin
• Biconcave disk that increase surface area/volume ratio
• Flexible shape
• No nucleus or other organelles but a few may contain polyribosomes called reticulocytes.
• Life span 120 days bc lack of the imp organelles to repair cells after damage that can occur when squeezing thru capillaries.
• greater than 99% of formed elements are erythrocytes
• Produced in the red bone marrow

Hemoglobin

• Consists of 4 chains of AAs bonded to 4 iron atoms: iron is the binding site for O2.
• Reversibly binds to O2
• Reversibly binds to CO2

Reticulocytes

Form 1% of circulating RBCs

Contain residual ribosomal RNA visible as cell inclusions

An increase in these means an increased need for O2: often the result of hemorrhage

Can also happen in people moving to high altitudes

[image][image]All WBCs (leucocytes) have a nucleus and no hemoglobin

Granular or Agranular classifcation based on presence of cytoplasmic granules made visible by staining.

Granular

Granular Leukocytes or Granulocytes

All Phagocytic

Have lobed Nuclei

Classified into three groups:

1. Neutrophils

2. Eosinophils

3. Basophils

Agranular

Lack granules

Classified into two groups:

1. Lymphocytes which include B cells and T

   cells

2. Monocytes

Monocytes

Agranular

Nucleus is kidney or horse-shoe shaped

Largest WBC in circulation

Doesnt wonder too long in blood before making it to the tissues

Monocytes exit blood vessels and differentiate into macrophages:

1. Fixed macrophages found in specific tissues

      - alveolar macrophages in lungs

      - kupffer cells in liver

      - osteoclasts in bone

2. Wandering (free) macrophages gather at sites of infection. 

Neutrophils

Granulocytes

Polymorphonuclear Leukocytes

Nuclei = 2 to 5 lobes connected by thin strands

Granules filled with digestive enzymes

Monocytes leave the blood stream --> Become macrophages to carry out their phagocytic Function

Fastest response of all to bacteria

Direct actions against bacteria

Eosinophils

Granulocyte

Nucleus with 2 or 3 lobes connected by a thin strand

Large, uniform-sized granules stain orange-red with acidic dyes

Granules contain enzymes that end allergic reactions and attack parasites

Cells phagocytize antigen-antibody complexes formed in allergic responses.

Synthesize substances that inactivate/degrade histamine and leukotrienes in order to reduce inflammatory reactions

Basophils

Granulocyte

Large, dark purple, variable-sized granules

Irregular, multi-lobed nuclei

Granules contain substances that intensify inflammatory reaction

These and mast cells contain granules containing heparin (anticoagulant), and histamine (vasodilator).

Lymphocyte

Agranulocyte

Dark, oval to round nucleus

NO Granules

Plays role in immunity

Lymphocyte Functions

B Cells

- Destroy bacteria and their toxins

- Turn into plasma cells tht produces antibodies

T Cells

- Attack viruses, fungi, transplanted organs, cancer cells, and some bacteria.

- NK cells (large T-lymphocytes).

WBC Physiology

1 WBC for every 700 RBC

Condition: Leukocytosis is a high WBC count

- Results from microbes, strenuous exercise, anesthesia, or surgery.

Condition: Leukopenia is low WBC count

- Results from radiation, shock or chemotherapy.

WBCs are produced in the red bone marrow.

Emigration & Phagocytosis in WBCs

Near the site of injury: adhesion molecules (selectins) help WBCs stick to endothelium.

Integrins, which are found on neutrophils, assist in movement through wall.

Neutrophils and macrophages phagocytize bacteria & debris:

- Chemotaxis of both

- Kinins from injurt site and toxins.

Platelet (Thrombocyte) Anatomy

-Disc-shaped, 2-4 micron cell fragment with no nucleus.

- Fragments of large cells called megakaryocytes

Promote blood clotting by sticking together in response to certain release factors that are released from the wall of damaged blood vessels.