Docstoc

Unit The Blood The Cardiovascular System

Document Sample
Unit The Blood The Cardiovascular System Powered By Docstoc
					The Blood


Chapter 12
             The Blood
• 7-8% of human body weight
• Volume of blood is 4-6 liters
• 22% solids, 78% water
• Blood is 5x more viscous (in other words, 5x
  stickier, and more resistant to flow) than water
• Temp. of blood in body is 38 degrees Celsius
  (100.4 degrees Fahrenheit)
• Alkaline (pH 7.35-7.45)
• Blood’s color depends on oxygen content. It can
  range from scarlet (oxygen-rich) to dark red
  (oxygen-poor).
          Functions of Blood
• The main functions of blood can be
  described as
  – distribution
  – regulation
  – protection
        Blood transports and
            distributes…
• Nutrients from the digestive tract and body
  reserves to all cells;
• oxygen from lungs to all cells;
• wastes from cells to elimination sites;
• hormones from endocrine glands to target
  tissues
           Blood regulates…
• Body temperature

• Blood is responsible for maintaining:
  – normal pH of body fluids;
  – adequate fluid volume in the body;
  – electrolyte balance in the body.
  Blood’s protective functions…
• preventing blood loss by initiating clotting
  mechanisms when blood vessel damage
  occurs;

• preventing infection by transporting
  immune cells (leukocytes) and immune
  proteins
 4 Main Components of Blood
• 1. Red blood cells (RBCs)
• 2. White blood cells
  (WBCs)
• 3. Platelets
• 4. Plasma
• Produced in red
  bone marrow

• Adult red marrow is
  primarily found in
   –   ribs
   –   vertebrae
   –   sternum
   –   pelvis
   –   proximal humeri and
       femurs
          Red Blood Cells (RBCs)
               (Erythrocytes)

• Red blood cells are small (7.5m
  diameter), biconcave discs
   – Flexible and increased surface area


• 4-6 million RBCs per L of blood

• 120 day lifespan (viability)

• 40-50% of blood volume
                    RBCs
• No nucleus or
  organelles



• Their primary function
  is O2 transport.
       White Blood Cells (WBCs)
             (Leukocytes)
• 1% of blood volume

• 5000-10,000 WBCs per L of blood

• Only a small fraction of the body’s total WBCs are
  found in the blood at any one time.

• Most are in lymphatic organs and other tissues
  (e.g., lymph nodes, spleen, tonsils, and appendix)
                  WBCs
• They help protect the body from
  pathogens, toxins, and cancerous cells.


• Individual WBCs typically viable for only
  18-36 hours
             Types of WBCs
•   Neutrophils
•   Lymphocytes
•   Monocytes
•   Eosinophils
•   Basophils



• Never let
  monkeys eat
  bananas
  (abundance)
            What do they do?
• Neutrophils: fight bacterial infections

• Eosinophils: fight allergens and parasites

• Basophils: release histamine (vasodilator) and
  heparin (anticoagulant); both are released
  during inflammation
         What do they do?
• Lymphocytes: defend against viruses and
  tumor cells; produce antibodies

• Monocytes: the largest leukocyte – they
  can be more than 3x the size of an RBC;
  Monocytes leave the bloodstream to
  become macrophages – eat cell debris
  (phagocytosis)
                        Platelets
                     (Thrombocytes)
• Cells that clot the blood at the
  site of wounds

• 1/3 the size of RBCs

•   300,000 platelets per L blood
• Lifespan of 7-10 days
                  Plasma
• Relatively clear liquid medium carries
  RBCs, WBCs, and platelets
• 50% of blood volume
• 95% of plasma is water
Blood Components
                        Blood Types
    • Different types because of different
      antigens (proteins) on surface of RBCs
                            ABO Blood Groups

                                                Blood that can be received
Blood Group   RBC Antigen    Plasma Antibody
                                                     during transfusion

AB            A and B       None                A, B, AB, and O

B             B             Anti-A              B and O

A             A             Anti-B              A and O

O             None          Anti-A and Anti-B   O
         Frequency of Blood Groups, % of U. S. Population



     Blood Group         White          Black           Asian

AB                  4              4               5

B                   11             20              27

A                   40             27              28

O                   45             49              40
                Rh factor
• Rh is another antigen (protein) found on
  RBCs
• Originally identified in Rhesus monkeys
• Rh+ means that the RBCs of this person
  carries the Rh antigen
• Most Americans are Rh+
     Rh Factor in Pregnancy?
• If Rh- woman gets pregnant with Rh+
  child…

                                   Fetus could
                                   develop a blood
                                   disease (severe
                                   anemia)



                                   Rh- mother gets
                                   shots during
                                   pregnancy to
                                   prevent problems
             Donating Blood
• Transfusions – must be of the same blood group

• Blood banks usually mix donated blood with an
  anticoagulant (prevent clotting)

• Can be stored for about 35 days

• This is why blood banks are constantly in need of
  donors

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:3
posted:8/12/2011
language:English
pages:23