Blood

http://www.dorlingkindersley-uk.co.uk/static/cs/uk/11/clipart/humanbody/img/image_body005.jpg

• Blood transports substances between body cells and external environment.

• Blood volume determined by body size, amount of adipose tissue, and changes in fluid concentrations.

• Blood is usually about 45% cells.

• Hematocrit – measure of amount of cells in blood (most are red blood cells).

• Other 55% of blood is mostly plasma (clear liquid made of water, amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, and cellular wastes).

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• Red blood cells (erythrocytes) are concave disks.

• Responsible for carrying hemoglobin (carries oxygen for the body)

• When hemoglobin has oxygen, bright red; if not, it is a dark red color.

• Have nuclei that are lost as they mature.

http://www.sciencemuseum.org.uk/exhibitions/lifecycle/images/1-2-6-4-0-0-0-0-0-0-0.jpg

• Red blood cell count - number of red blood cells in a cubic millimeter.

• Ranges from 4 million to 6 million depending on gender.

• Determines how much oxygen can be carried (used to diagnose diseases)

• Red blood cells become fragile as they age.

• Macrophages destroy damaged red blood cells; found in the liver and spleen.

• RBCs contain iron (stored liver as bilirubin) and eventually excreted in bile.

• Babies that don’t excrete it become jaundice (bilirubin is building up)

• Red blood cells produced through hematopoiesis (adults occurs in the red bone marrow)

• Red blood cell lives for about 120 days.

• If oxygen deficit, erythropoietin released from kidneys - increase red blood cell production in the red bone marrow.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/Hematopoiesis2.gif

• At high altitudes - less oxygen in the air, less oxygen delivered to tissues.

• Drop triggers production of erythropoietin which stimulates red blood cell production.

http://www.tarleton.edu/~anatomy/erythro.jpg

*

• Iron required to make RBCs• Iron absorbed in small intestine from

food.• Body recycles iron released during

decomposition of RBCs that die, so iron needed in small amounts in the body.

• Not enough RBCs - anemia develops.

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White blood cells

• Also called leukocytes - protect against disease.

• 5 types of WBCs depending on size and shape.

• Neutrophils - over half of the WBCs

• Help ward off infection in initial stages.

WHITE BLOOD CELL

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• Eosinophils - 3% of WBCs.• Present in large numbers during

allergic reactions and parasitic infections.

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• Basophils - less than 1% of white blood cells.

• They release histamines (allergic reactions) and heparin (used in bleeding).

• Monocytes - 2-3 times larger than red blood cells; make up 3-9% of white blood cells.

• They are responsible for eating large particles.

http://www.anatomy.dal.ca/Human_Histology/Lab7/61_LO6.JPG

• Lymphocytes - 25-33% of white blood cells.

• They help in providing immunity to the body.

http://www.anatomy.dal.ca/Human_Histology/Lab7/61_LO4.JPG

• WBC counts can indicate a serious problem with the individual.

• Number > 10000 - leukocytosis, a serious acute (short-term) infection like appendicitis.

• Number < 5000 – leukopenia, a longer term disease like AIDS, cancer, or measles.

Platelets

• Platelets - thrombocytes - not real cells.

• Come from megakaryocytes, large cells found in red bone marrow.

• Platelets help to form clots in broken vessels.

http://www.uiowa.edu/~cemrf/archive/sem/large/Platelets.gif

http://www.teachersfirst.com/getsource.cfm?id=9260

Plasma

• Liquid part of blood - used to transport materials through body.

• Helps to regulate fluid levels, pH levels, and electrolyte levels.

• Carries fats (which do not mix with water) - can become stuck in the blood vessels.

http://www.ndsu.nodak.edu/instruct/tcolvill/435/plasma.gif

Hemostasis

• Hemostasis - stoppage of bleeding.

• Damage in vessel - vessel spasms, blood flow decreases to area.

• Coagulation forms blood clot.• Prothrombin found in plasma.• In presence of calcium, turns into

thrombin.

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• Thrombin starts reaction that joins fibrinogen fragments.

• Fragments join, forming chains of fibrin.

• Netting traps RBCs, forming clot.• Blood clots form in blood vessel (not

in the break), it is a thrombus.• If blood clot breaks free - embolus.

http://www.medicalprogress.org/uploads/images/blood-clot200px.jpg

Fibers trapping RBCs to form clot.

http://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/m1/s7/trm1s7_3.htm

Blood type

• Type A - anti-B antibodies, A antigen.

• Type B - anti-A antibodies, B antigen.

• If a person with type A blood receives type B blood, the blood will clump together.

• Type O - no antigens, anti-A and anti-B antibodies.

• Type AB - A and B antigens, neither anti-A nor anti-B antibodies.

• AB can receive from anybody and O can donate to anybody.

• Clumping happens with wrong blood type.

http://gslc.genetics.utah.edu/units/basics/blood/images/bloodtrans.gif

Rh factor

• Person has Rh antigen (positive) or not (-).

• Antibodies only form in Rh -.• If Rh- woman pregnant with an

Rh+ baby, she develops antibodies (attack future Rh+).

• Known as erythroblastosis fetalis.

http://www.healthofchildren.com/images/gech_0001_0002_0_img0106.jpg

Diseases

• 1Anemia – person either has low RBC or the RBC don’t have enough hemoglobin.

• Result is person feeling tired all the time (not enough oxygen)

• 2Hemophilia – person has little or none of clotting factor.

• Result is easy bleeding, excessive bleeding, and sometimes internal bleeding.