Biomedical Innovations Unit 3

Tissues of LifeA Focus on Blood

Blood Introduction• Blood is a special Connective Tissue, and is the major component of

the Circulatory System

• Connective tissue is a group of cells that collectively function to support, connect, and/or separate other tissues and organs.

• The Circulatory System is comprised of two sub-systems:

1. Cardiovascular System

• Includes network of blood vessels, blood, and heart

• Major function is to transport nutrients, gases and hormones to cells and wastes from cells for excretion outside the body

2. Lymphatic System

• Includes network of lymph vessels, the lymphocyte white blood cell, and lymphoid organs (tonsils, spleen, thymus, bone marrow, and lymph nodes)

• Major functions are to return fluid that escapes from blood vessels back to the bloodstream AND fight infections and give immunity to disease

Functions Of Blood1. Transportation

• Blood transports dissolved gases, nutrients, hormones and metabolic wastes

2. Protection & Clotting

• White Blood Cells (WBC) protect the body against foreign molecules

• Platelets (cell) and clotting proteins in blood minimize blood loss when a blood vessel is damaged (clot)

3. Regulation

• Blood regulates the pH and electrolyte composition of the interstitial fluids (fluid between cells)

• Blood regulates body temperature: transfers heat via counter-current exchange

COUNTER-CURRENT EXCHANGE

Composition of Blood• Contains cellular and liquid components

• Liquid Portion: ~ 55% plasma

• Cellular Portion: ~ 45% formed elements

• Normal blood pH is ~7.35-7.45 (neutral)

• Blood volume

• Varies inversely with body fat

• Blood volume as body fat

• Males typically have 5 to 6 liters (~10.5 to 12.5 pints)

• Females typically have 4 to 5 liters (~8.5 to 10.5 pints)

• How can blood volume be determined?

• How much is a “unit” of donated blood?

Volume:•Assess: Blood pressure•Calculate: Radioactive dye

Units:•1 unit donated = ~ 1 pint (0.5L)•1 unit accepted = ~0.75 pint Packed RBC (prBC)

Composition of Blood• 55% Plasma

• 92% - Water

• 7% - Proteins (fibrinogen, hormones, albumins & globulins)

• 1% - other solutes (ions, gases, nutrients, wastes, etc.)

• 45% Formed Elements

• 99.9% - erythrocytes (Red Blood Cells - RBCs)

• 0.1% - leukocytes (White Blood Cells - WBCs) & thrombocytes (Platelets)

Figure 19.1b

Composition of Blood - Plasma

Figure 19.1c

Composition of Blood – Formed Elements

ID the Formed Elements

• Be able to identify any of the formed elements to RBC, WBC, or Platelet.

Lecture 1a - Review Break

• Visualize the Composition of Blood

• Microscopy & Blood Cell Identification Lab

Lecture 1b – Overview: Composition of Blood

• Hematocrit or Packed Cell Volume (PCV)

• measure of % RBC

• Males: 47% ± 5% Females: 42% ± 5%

Figure 17.1

Erythrocytes – Red Blood Cells (RBCs)

• Oxygen-transporting cells

• 7.5 µm in diameter (diameter of capillary 8 – 10µm)

• Most numerous of the formed elements

• Females: 4.3 – 5.2 million cells/mm3

• Males: 5.2 – 5.8 million cells/mm3

• Made in the red bone marrow in long bones, cranial bones, ribs, sternum, and vertebrae

• Average lifespan is 100 – 120 days

RBC Structure And Function• Have no organelles or nuclei

• Significance?

• True for all species?

• Hemoglobin – oxygen carrying protein

• Each RBC has 200-300 million hemoglobin molecules

• Biconcave shape

• Significance?

Hemoglobin• Comprised of four protein chains, each called a globin.

• Each globin is bound to a red pigment, called a heme molecule.

• Contains a single Fe atom

• Each Fe atom can bind to a single O2 molecule

• How many O2 molecules can each hemoglobin combine with?

• What is the term for when hemoglobin binds with O2?

• CO2?

• Are either a reversible reaction?

Leukocytes – White Blood Cells (WBCs)• Protect the body from:

• infectious microorganisms

• Cancerous cells

• Foreign particles

• Typically, function outside the bloodstream in loose connective tissue

• Diapedesis - circulating leukocytes leave the capillaries and enter the interstitial fluid

• Exception?

• WBCs have a nucleus and are larger than RBCs

• Most produced in bone marrow

• Exception?

• Lifespan of 12 hours to several years

Leukocytes – White Blood Cells (WBCs)

• Two types of leukocytes

• Granulocytes

• Agranulocytes

• Relative WBC Count

• Never

• Let

• Monkeys

• Eat

• Bananas

Figure 17.5

White Blood Cells

Type Of White Blood Cells

% By Volume Of WBC Description Function

Neutrophils 60 – 70 % Nucleus has many interconnected lobes; blue granules

Phagocytize and destroy bacteria; most numerous WBC

Eosinophils 2 – 4 % Nucleus has bilobed nuclei; red or yellow granules containing digestive enzymes

Play a role in ending allergic reactions

Basophils < 1 % Bilobed nuclei hidden by large purple granules full of chemical mediators of inflammation

Function in inflammation medication; similar in function to mast cells

Lymphocytes (B Cells and T Cells)

20 – 25 % Dense, purple staining, round nucleus; little cytoplasm

the most important cells of the immune system; effective in fighting infectious organisms; act against a specific foreign molecule (antigen)

Monocytes 4 – 8 % Largest leukocyte; kidney shaped nucleus

Transform into macrophages; phagocytic cells

Lymphocyte• Compose 20 – 45% of WBCs

• The most important cells of the immune system

• Nucleus – stains dark purple

• Effective in fighting infectious organisms

• Act against a specific foreign molecule (antigen)

• Two main classes of lymphocyte

• T cells – attack foreign cells directly

• Active in cell mediated immune response

• B cells – multiply to become plasma cells that secrete antibodies

• Active in the humoral immune response

Figure 17.4d

Platelets• Structure

• Small, nearly colorless bodies appearing as irregular spindles or oval disks (~2-4 μm)

• originate in bone marrow from giant cell megakaryocyte

• Functions

• Hemostasis

• Regulation of blood flow

• Coagulation, or blood clotting

Summary of Formed Elements

Table 17.1

Review Activity Break

• Blood Disorders

Blood Cell Formation

• Hematopoiesis – process by which blood cells are formed

• 100 billion new blood cells formed each day

• Takes place in the red bone marrow of the humerus, femur, sternum, ribs, vertebra and pelvis• Red marrow – actively generates new blood cells

• Contains immature erythrocytes

• Remains in epiphyses, girdles, and axial skeleton

• Yellow marrow – dormant (can become active if needed)

• Contains many fat cells

• Located in the long bones of adults

Cell Lines in Blood Cell Formation

• All blood cells originate in bone marrow

• All originate from one cell type

• Blood stem cell (pluripotential hematopoeitic stem cell)

• Lymphoid stem cells - give rise to lymphocytes

• Myeloid stem cells - give rise to all other blood cells

Cell Lines in Blood Cell Formation• Genesis of erythrocytes

(erythropoiesis)

• Committed cells are proerythroblasts

• Remain in the reticulocyte stage for 1–2 days in circulation

• Loss of nucleus

• Formation of leukocytes (leukopoiesis)

• Granulocytes form from myeloblasts

• Monoblasts enlarge and form monocytes

• Platelet formation (thrombopoiesis)

• Form from megakaryoblasts

• break apart into platelets

The Blood Throughout Life

• First blood cells develop with the earliest blood vessels

• Late in the second month the liver and spleen take over blood formation

• Bone marrow becomes major hematopoietic organ at month 7

RBC life span and circulation

• Replaced at a rate of approximately 3 million new blood cells entering the circulation per second

• Damaged or dead RBCs are recycled by phagocytes

• Components of hemoglobin individually recycled

• Heme stripped of iron and converted to biliverdin, then bilirubin

• Iron is recycled by being stored in phagocytes, or transported throughout the blood stream bound to transferrin

Figure 19.5

Red Blood Cell Turnover

Clotting Mechanisms• Know the general stages of blood clotting

• Stage 1: Source of damage

• Stage 2: prothrombin thrombin

• Calcium, prothrombin activator

• Stage 3: fibrinogen fibrin

• Calcium, thrombin

• Be able to identify the key difference between intrinsic and extrinsic pathways

• Stage 1

Clotting Cont.

• What two conditions increase clotting?

• What two conditions decrease clotting?

• How are clots removed?

• Fibrinolysis

Review Activity Break

You should be able to…

Identify and describe the following blood disorders/conditions:

• Leukemia

• Leukopenia

• Leukocytosis

• Anemia

• Polycythemia

• Blood doping

• Sickle-cell anemia

• Embolus

• Thrombus

• Erythroblastosis fetalis

Identify and describe:

• The different types of tissues

• Functions of the blood

• Blood composition

• Plasma & Formed Elements

• % Hematocrit

• Blood Cell Formation

• The process of clotting

• Blood type based on tests and genetic inheritance

• Antigen vs. antibody

• Coagulation vs. agglutination