Chapter 6

Biology 25: Human Biology 25: Human BiologyBiology

Prof. GonsalvesProf. Gonsalves

Los Angeles City CollegeLos Angeles City College

Loosely Based on Mader’s Loosely Based on Mader’s Human Human BiologyBiology,7,7thth edition edition

1. Blood1. Blood

Average Blood Volume:Average Blood Volume: 4 to 6 liters. 4 to 6 liters.

Blood composition:Blood composition:

55% Plasma (fluid matrix of water, salts, proteins, etc.)55% Plasma (fluid matrix of water, salts, proteins, etc.)

45% Cellular elements:45% Cellular elements:

Red Blood Cells (RBCs):Red Blood Cells (RBCs): 5-6 million RBCs/ml of blood. Contain 5-6 million RBCs/ml of blood. Contain

hemoglobin which transport oxygen and COhemoglobin which transport oxygen and CO22..

White Blood Cells (WBCs):White Blood Cells (WBCs): 5,000-10,000 WBCs/ml of blood. Play an 5,000-10,000 WBCs/ml of blood. Play an

essential role in immunity and defense. Include:essential role in immunity and defense. Include:

Lymphocytes:Lymphocytes: T cells and B cells T cells and B cells

MacrophagesMacrophages (phagocytes) (phagocytes)

Granulocytes:Granulocytes: Neutrophils, basophils, and eosinophils. Neutrophils, basophils, and eosinophils.

Platelets:Platelets: Cellular fragments. 250,000- 400,000/ml of blood. Cellular fragments. 250,000- 400,000/ml of blood.

Important in blood clotting.Important in blood clotting.

Composition of Blood

Formed Elements.Formed Elements. Erythrocytes.Erythrocytes. Leukocytes.Leukocytes. Platelets.Platelets. Plasma.Plasma.

Composition of Human Blood

Plasma

Straw-colored liquid.Straw-colored liquid. Consists of HConsists of H220 and dissolved solutes.0 and dissolved solutes.

Ions, metabolites, hormones, antibodies.Ions, metabolites, hormones, antibodies. NaNa++ is the major solute of the plasma. is the major solute of the plasma.

Plasma Proteins

Constitute 7-9% of plasma.Constitute 7-9% of plasma. Provide the colloid osmotic pressure Provide the colloid osmotic pressure

needed to draw Hneeded to draw H220 from interstitial fluid 0 from interstitial fluid

to capillaries.to capillaries. Maintain blood pressure.Maintain blood pressure.

Albumin: Albumin: Accounts for 60-80% of plasma Accounts for 60-80% of plasma

proteins.proteins.

Plasma Proteins

Globulins:Globulins: globulin:globulin:

Transport lipids and fat soluble vitamins.Transport lipids and fat soluble vitamins. globulin: globulin:

Transport lipids and fat soluble vitamins.Transport lipids and fat soluble vitamins. globulin: globulin:

Antibodies that function in immunity.Antibodies that function in immunity.

Plasma Proteins

Fibrinogen:Fibrinogen: Constitutes 4% of plasma proteins.Constitutes 4% of plasma proteins. Important clotting factor.Important clotting factor. Converted into fibrin during the clotting Converted into fibrin during the clotting

process.process.

Formed Elements of Blood

Include 2 types of blood cells:Include 2 types of blood cells: RBCs (red blood cells):RBCs (red blood cells):

Most numerous of the two.Most numerous of the two. WBCs (white blood cells).WBCs (white blood cells).

Erythrocytes

Flattened biconcave discs.Flattened biconcave discs. Provides increased surface area through Provides increased surface area through

which gas can diffuse.which gas can diffuse. Lack nuclei and mitochondria.Lack nuclei and mitochondria. Half-life ~ 120 days.Half-life ~ 120 days. Contain 280 million hemoglobin with 4 Contain 280 million hemoglobin with 4

heme chains (contain iron).heme chains (contain iron).

Leukocytes

Contain nuclei and mitochondria.Contain nuclei and mitochondria. Move in amoeboid fashion.Move in amoeboid fashion.

Can squeeze through capillary walls Can squeeze through capillary walls (diapedesis).(diapedesis).

Almost invisible, so named after stains.Almost invisible, so named after stains. Neutrophils are the most abundant WBC.Neutrophils are the most abundant WBC.

Accounts for 50 – 70% of WBCs.Accounts for 50 – 70% of WBCs. Involved in immune function.Involved in immune function.

Platelets

Also called thrombocytes.Also called thrombocytes. Smallest of formed elements.Smallest of formed elements.

Are fragments of megakaryocytes.Are fragments of megakaryocytes. Lack nuclei.Lack nuclei.

Have amoeboid movement.Have amoeboid movement. Important in blood clotting:Important in blood clotting: Constitute most of the mass of the clot.Constitute most of the mass of the clot.

Release serotonin to reduce blood flow to area.Release serotonin to reduce blood flow to area. Secrete growth factorsSecrete growth factors

Maintain the integrity of blood vessel wall.Maintain the integrity of blood vessel wall.

Hematopoiesis

Formation of blood cells.Formation of blood cells. 2 types of hematopoiesis:2 types of hematopoiesis: Erythropoiesis:Erythropoiesis:

Formation of RBCs.Formation of RBCs. Leukopoiesis:Leukopoiesis:

Formation of WBCs.Formation of WBCs. Occurs in myeloid tissue (bone marrow of long Occurs in myeloid tissue (bone marrow of long

bones) and lymphoid tissue.bones) and lymphoid tissue. Stem cells differentiate into blood cells.Stem cells differentiate into blood cells.

Erythropoiesis

Active process.Active process. 2.5 million RBCs are produced every second.2.5 million RBCs are produced every second. Regulated by erythropoietin.Regulated by erythropoietin.

Erythropoietin binds to membrane receptors, Erythropoietin binds to membrane receptors, stimulating cell division. stimulating cell division.

Old cells are destroyed in spleen and liver.Old cells are destroyed in spleen and liver. Iron recycled back to myeloid tissue to be Iron recycled back to myeloid tissue to be

reused in RBC synthesis.reused in RBC synthesis. Need iron, vitamin BNeed iron, vitamin B1212 and folic acid for synthesis. and folic acid for synthesis.

Leukopoiesis

Cytokines stimulate different types and stages of WBCs Cytokines stimulate different types and stages of WBCs production.production.

Multipotent growth factor-1, interleukin-1, and interleukin-Multipotent growth factor-1, interleukin-1, and interleukin-3:3: Stimulate development of different types of Stimulate development of different types of

WBC cells.WBC cells. Granulocyte-colony stimulating factor:Granulocyte-colony stimulating factor:

Stimulates development of neutrophils.Stimulates development of neutrophils. Granulocyte-monocyte colony stimulating factor:Granulocyte-monocyte colony stimulating factor:

Simulates development of monocytes and Simulates development of monocytes and eosinophils.eosinophils.

Blood Clotting

Hemostatic mechanisms:Hemostatic mechanisms: Cessation of bleeding.Cessation of bleeding.

Breakage of endothelial lining exposes collagen Breakage of endothelial lining exposes collagen proteins causing:proteins causing: Vasoconstriction.Vasoconstriction. Platelet plug.Platelet plug. Web of fibrin.Web of fibrin.

Function of Platelets

Platelets normally repelled away from Platelets normally repelled away from endothelial lining by prostacyclin endothelial lining by prostacyclin (prostaglandin).(prostaglandin).

Do not want to clot normal vessels.Do not want to clot normal vessels.

Damage to Endothelian Wall

Exposes subendothelial tissue to blood.Exposes subendothelial tissue to blood. Platelet release reaction:Platelet release reaction:

Endothelial cells secrete von Willebrand Endothelial cells secrete von Willebrand factor to cause platelets to adhere to factor to cause platelets to adhere to collagen.collagen.

Platelet secretory granules release ADP, Platelet secretory granules release ADP, serotonin and thromboxane Aserotonin and thromboxane A22..

Platelet Release Reaction

Serotonin and thromboxane ASerotonin and thromboxane A22 stimulate stimulate vasoconstriction.vasoconstriction.

ADP and thromboxane AADP and thromboxane A22 make other make other platelets “sticky”.platelets “sticky”.

Platelets adhere to collagen. Platelets adhere to collagen. Produce platelet plug.Produce platelet plug. Strengthened by activation of plasma Strengthened by activation of plasma

clotting factors. clotting factors.

Platelet plug strengthened by fibrin.Platelet plug strengthened by fibrin. Clot reaction:Clot reaction:

Contraction of the platelet mass forms a Contraction of the platelet mass forms a more compact plug.more compact plug.

Conversion of fibrinogen to fibrin Conversion of fibrinogen to fibrin occurs.occurs.

Fluid squeezed from the clot is called serum Fluid squeezed from the clot is called serum (plasma without fibrin).(plasma without fibrin).

Clotting Factors

Intrinsic Pathway:Intrinsic Pathway: Initiated by exposure of blood to a negatively Initiated by exposure of blood to a negatively

charged surface (collagen).charged surface (collagen). This activates Factor XII (protease), which This activates Factor XII (protease), which

activates other clotting factors.activates other clotting factors. CaCa++++ and phospholipids convert prothrombin to and phospholipids convert prothrombin to

thrombin.thrombin. Thrombin converts fibrinogen to fibrin.Thrombin converts fibrinogen to fibrin. Produces meshwork of insoluble fibrin Produces meshwork of insoluble fibrin

polymers.polymers.

Conversion of Fibrinogen to Fibrin

Extrinsic Pathway

Thromboplastin is not a part of the blood, Thromboplastin is not a part of the blood, so called extrinsic pathway.so called extrinsic pathway.

Damaged tissue release a thromboplastin.Damaged tissue release a thromboplastin. Thromboplastin initiates a short cut to Thromboplastin initiates a short cut to

formation of fibrin.formation of fibrin.

Dissolution of Clots

Activated factor XII converts an inactive Activated factor XII converts an inactive molecule into the active form (kallikrein). molecule into the active form (kallikrein).

Kallikrein converts plasminogen to Kallikrein converts plasminogen to plasmin.plasmin.

Plasmin is an enzyme that digests the Plasmin is an enzyme that digests the fibrin.fibrin.

Clot dissolution occurs.Clot dissolution occurs.

Types of Blood VesselsTypes of Blood Vessels

A. Arteries and Arterioles: A. Arteries and Arterioles: Carry blood Carry blood awayaway fromfrom heartheart to body. to body. Have high pressure.Have high pressure. Have thick muscular walls, which make them elastic and contractile.Have thick muscular walls, which make them elastic and contractile.

Vasoconstriction:Vasoconstriction: Arteries contract: Arteries contract: Reducing flow of blood into capillaries.Reducing flow of blood into capillaries. Increasing blood pressure.Increasing blood pressure.

Vasodilation:Vasodilation: Arteries relax: Arteries relax: Increasing blood flow into capillaries.Increasing blood flow into capillaries. Decreasing blood pressure.Decreasing blood pressure.

Types of Blood VesselsTypes of Blood Vessels

Capillaries: Capillaries: Only blood vessels whose walls are thin enough to Only blood vessels whose walls are thin enough to permit gas exchange.permit gas exchange.

Blood flows through capillaries relatively slowly, allowing Blood flows through capillaries relatively slowly, allowing sufficient time for diffusion or active transport of substances sufficient time for diffusion or active transport of substances across walls.across walls.

Only about 5 to 10% of capillaries have blood flowing through Only about 5 to 10% of capillaries have blood flowing through them. Only a few organs (brain and heart) always carry full them. Only a few organs (brain and heart) always carry full load of blood. load of blood.

Blood flow to different organs is controlled by Blood flow to different organs is controlled by precapillary precapillary sphincterssphincters of smooth muscle. of smooth muscle.

Types of Blood VesselsTypes of Blood Vessels

Veins and Venules:Veins and Venules:

Collect blood from all tissues and organs and Collect blood from all tissues and organs and carrycarry it back it back

towardstowards heart. heart.

Have low pressure and thin walls.Have low pressure and thin walls.

Veins have small Veins have small valvesvalves that prevent backflow of blood that prevent backflow of blood

towards capillaries, especially when standing. If the towards capillaries, especially when standing. If the

valves cease to work properly, may result in:valves cease to work properly, may result in:

Varicose veinsVaricose veins: Distended veins in thighs and legs.: Distended veins in thighs and legs.

HemorroidsHemorroids:: Distended veins and inflammation of the Distended veins and inflammation of the

rectal and anal areas.rectal and anal areas.

Lymphatic and Immune SystemLymphatic and Immune SystemComponents: Components: Lymph, lymphatic vessels, bone marrow, thymus, spleen, and lymph Lymph, lymphatic vessels, bone marrow, thymus, spleen, and lymph

nodes.nodes.Functions:Functions:

Defends against infection: bacteria, fungi, viruses, etc.Defends against infection: bacteria, fungi, viruses, etc. Destruction of cancer and foreign cells.Destruction of cancer and foreign cells. Synthesis of antibodies and other immune molecules.Synthesis of antibodies and other immune molecules. Synthesis of white blood cells.Synthesis of white blood cells.

Homeostatic Role:Homeostatic Role: Returns fluid and proteins that have leaked from blood capillaries Returns fluid and proteins that have leaked from blood capillaries

into tissues. into tissues. Up to 4 liters of fluid every day.Up to 4 liters of fluid every day. Fluid returned near heart/venae cavae.Fluid returned near heart/venae cavae.

Red Blood Cell Antigens ABO system:ABO system: Major group of antigens of RBCs.Major group of antigens of RBCs.

Type A:Type A:Only A antigens present.Only A antigens present.

Type B:Type B:Only B antigens present.Only B antigens present.

Type AB:Type AB:Both A and B antigens present.Both A and B antigens present.

Type O:Type O:Neither A or B antigens present.Neither A or B antigens present.

RBC Antigens

Each person inherits 2 genes that control Each person inherits 2 genes that control the production of ABO groups.the production of ABO groups.

Type A:Type A: May have inherited A gene from each May have inherited A gene from each

parent.parent. May have inherited A gene from 1 May have inherited A gene from 1

parent and O gene from the other.parent and O gene from the other.

RBC Antigens

Type B:Type B: May have inherited B gene from each parent.May have inherited B gene from each parent. May have inherited B gene from 1 parent and O May have inherited B gene from 1 parent and O

gene from the other parent.gene from the other parent. Type AB:Type AB:

Inherited the A gene from one parent and the B Inherited the A gene from one parent and the B gene from the other parent.gene from the other parent.

Type O:Type O: Inherited O gene from each parent.Inherited O gene from each parent.

Transfusion Reactions If blood types do not match, the recipient’s If blood types do not match, the recipient’s

antibodies attach to donor’s RBCs and antibodies attach to donor’s RBCs and agglutinate.agglutinate.

Type O:Type O: Universal donor.Universal donor. Recipient’s antibodies cannot agglutinate the Recipient’s antibodies cannot agglutinate the

donor’s RBCs.donor’s RBCs. Type AB universal recipient:Type AB universal recipient:

Lack the anti-A and anti-B antibodies.Lack the anti-A and anti-B antibodies. Cannot agglutinate donor’s RBCs.Cannot agglutinate donor’s RBCs.

Rh Factor

Another group of antigens found on RBCs.Another group of antigens found on RBCs. Rh positive:Rh positive:

Have these antigens.Have these antigens. Rh negative:Rh negative:

Do not have these antigens.Do not have these antigens. Significant when Rh negative mother give birth to Significant when Rh negative mother give birth to

Rh positive baby.Rh positive baby. At birth, mother may become exposed to Rh At birth, mother may become exposed to Rh

positive blood of fetus.positive blood of fetus. Mother at subsequent pregnancies may produce Mother at subsequent pregnancies may produce

antibodies against the Rh factor.antibodies against the Rh factor.