Chapter 11Blood

Composition

• Plasma: Yellowish liquid that contains various organic and inorganic molecules dissolved in water.

• Formed elements: Cells including white and red blood cells as well as platelets.

Functions of Blood

• Transport: To move materials like oxygen, carbon dioxide, and hormones to the organs.

• Defense: Protects the body from pathogens (infectious agents) and forms clots to prevent blood loss.

• Regulation: Helps regulate body heat, pH, and water levels.

Plasma

• Contains many proteins that help maintain homeostasis.

• Two important plasma proteins are antibodies (help fight infections) and fibrinogen (required for blood clotting).

Blood Cell Formation

• Process is called hematopoiesis.

• Stem cells have the ability to differentiate into different types of cells.

• This is a hot topic in politics and research because it holds the potential of being able to regenerate body tissue in the lab. For more information on stem cells visit: http://stemcells.nih.gov/info/basics/

Red Blood Cells (RBCs or (Erythrocytes)

• No nucleus when mature.

• Contain hemoglobin, the molecule which carries oxygen.

• Formed by the red bone marrow stem cells.

• Live only about 120 days and are then destroyed by the liver and spleen.

White Blood Cells (WBCs or Leukocytes)

• Less numerous than RBCs.

• Derived from stem cells in the red bone marrow.

• Fight infections.

• Able to squeeze through capillary walls and enter the lymph where they continue to fight infection.

Platelets

• Formed elements responsible for hemostasis (the cessation of bleeding).

• Live only about 10 days.

Hemostasis

• Vascular spasm: 1st response to bleeding. Constriction of a broken blood vessel.

• Platelet plug formation: Platelets adhere to exposed collagen fibers.

• Coagulation: Many reactions occur during this process. The result is that firbrin threads wrap around the platelet plug and RBCs are trapped within the threads.

Gas Exchange within Capillaries

• Influenced by:Blood pressure: the

pressure against blood vessels caused by the pumping of the heart.

Diffusion: movement of substances from an area of higher concentration to an area of lower concentration.

Osmotic pressure: the force caused by a difference in solute concentration on either side of a membrane.

Arterial End of Capillary

• Water and other small molecules leak out of capillaries creating tissue fluid. Molecules leaving include water, oxygen, amino acids, & glucose.

Midsection of Capillary

• Carbon dioxide and other waste products diffuse into the capillaries.

Venous End of Capillary

• Blood is a dark maroon color because it lacks oxygen.

• Water that previously left the capillary reenters it.

Blood Typing• Based on the presence or absence of two

possible antigens on the surface of blood cells: A type and B type antigen.

• Having A type antigen results in type A blood.• Having B type antigen results in type B blood.• Having both A & B type antigens results type

AB blood.• Having neither A type nor B type antigen

results in type O blood.

Blood Transfusions

• It is very important that bloods involved in transfusions are compatible.

• Blood types that are incompatible will result in clumping of the blood.

• Anyone can receive type O blood because it does not contain any antigens. Called a universal donor.

• People with type AB blood can receive any type blood because their blood contains both antigens. Called the universal recipient.

Rh Blood Groups

• Rh is another factor present in red blood cells.

• People without the RH factor do not have antibodies to the factor but make them when exposed to the Rh factor.

Diseases of the Blood

• Anemia is a condition that results from a reduction in the amount of hemoglobin or RBCs or the bursting of RBCs.

• Sickle-cell disease is inherited. Cells tend to wear out or rupture easily as they pass through the capillaries.

• Leukemia is a cancer of the blood characterized by abnormally high numbers of white blood cells.

Sickle cell shaped red blood cells

Diseases of the Blood Continued

• Hemophilia: An inherited clotting disorder caused by a deficiency in a clotting factor.

• Hemolytic disease of the newborn. A disease where a Rh+ child is born to a Rh- mother. Excessive RBC destruction can lead to brain damage, mental retardation, or death of the child.