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Blood
 Type of connective tissue
 The only fluid tissue in the human body
 38 degrees celsius or 100.4 degrees farenheit
 Slightly alkaline, pH 7.35-7.45
 About 5x’s thicker than water
5.3 Q average adult
 More blood in males than females
Account for approximately 8% of body weight
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Functions: Transport, Regulation and Protection
The transport functions include:
 carrying oxygen and nutrients to the cells.
 transporting carbon dioxide to the lungs (for removal)
 transporting nitrogenous wastes to the kidneys (for removal)
 carrying hormones from the endocrine glands to the target tissues.
The regulation functions include:
 removing heat from active areas, such as skeletal muscles, and
transporting it to other regions or to the skin where it can be
dissipated (maintaining body temp)
 pH regulation through the action of buffers in the blood.
The protection functions include:
 preventing fluid loss by forming clots
 protect the body against microorganisms that cause disease
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
2 Parts of Whole Blood
1. Cells (formed elements)

living component

45% of total blood

3 main types

formed in red bone marrow of long bones, some in
other organs as needed
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
2. Plasma (matrix)

non-living component

55% of total blood

mainly water (90%)

over 100 dissolved substances
ex. nutrients, salts (electrolytes), gases, hormones, proteins,
carbs, amino acids, vitamins, carbon dioxide, urea,
ammonia
 Plasma proteins
 Most abundant solutes in plasma
 Most are made by the liver
Ex. Albumin—regulates osmotic pressure and thickens blood
Clotting proteins—help when a blood vessel is injured
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Separating Blood Components
Layers are based on density
 Plasma rises to the top
 Thin white middle layer: Buffy coat: contains
white blood cells (leukocytes) and platelets)
 Red Blood Cells: Erythrocytes: sink to the
bottom (% is known as the hematocrit)
Red Blood Cells
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
3 Main Formed Elements (Blood Cells)
 Erythrocytes
 Red blood cells (RBCs)
 Leukocytes
 White blood cells (WBCs)
 Platelets
 Cell fragments and not
whole cells, necessary for
blood clotting
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
All formed elements stem from a specific type of cell
 Lost cells are replaced by division of
hemocytoblasts (blood stem cells) in the red bone
marrow
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
1. Erythrocytes
 Commonly known as red blood cells or RBCs
 Main function is to carry oxygen
 Anatomy of circulating erythrocytes
 Biconcave disks
 Essentially bags of hemoglobin
 Anucleate (no nucleus)
 Contain very few organelles
*4-6 million RBCs per cubic millimeter of blood
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Formation of Erythrocytes
 Unable to divide, grow, or synthesize proteins
 Wear out in 100 to 120 days
 RBCs are eliminated by phagocytes in the spleen
or liver
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hemoglobin
 Iron-containing protein
 Binds strongly, but reversibly, to oxygen
 Each hemoglobin molecule has four oxygen
binding sites
 Each erythrocyte has 250 million hemoglobin
molecules
 Hemoglobin is recycled in the body
*Normal blood contains 12–18 g of hemoglobin per
100 mL blood
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
2. Leukocytes
 commonly known as white blood cells or WBCs
 Crucial in the body’s defense against disease
 These are complete cells, with a nucleus and
organelles
 Able to move into and out of blood vessels
 Respond to chemicals released by damaged tissues
 Many types of WBC’s some are macrophages and
some produce antibodies or histamine
*4,000 to 11,000 WBC per cubic millimeter of blood
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Formed Elements
 Types of leukocytes
 Granulocytes
 Granules in their cytoplasm can be stained
 Possess lobed nuclei
 Include neutrophils, eosinophils, and
basophils
 Agranulocytes
 Lack visible cytoplasmic granules
 Nuclei are spherical, oval, or kidneyshaped
 Include lymphocytes and monocytes
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Formed Elements
 List of the WBCs from most  Easy way to remember
to least abundant
this list
 Neutrophils
 Never
 Lymphocytes
 Let
 Monocytes
 Monkeys
 Eosinophils
 Eat
 Basophils
 Bananas
Types will vary depending
on a persons health at the
time
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Types of granulocytes
 Neutrophils
 Multilobed nucleus with fine granules
 Act as phagocytes at active sites of
infection
 Eosinophils
 Large brick-red cytoplasmic granules
 Found in response to allergies and/or
parasitic worms
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
 Basophils
 Have histamine-containing granules
 Initiate inflammation
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Types of agranulocytes
 Lymphocytes
 Nucleus fills most of the cell
 B-lymphocytes produce antibodies —collect and
clump bacteria together, easier for phagocytes to
“eat” them
 T-lymphocytes directly attack cells that do not
belong (cell tag receptor incorrect)
 Monocytes
 Largest of the white blood cells
 Function as macrophages
 Important in fighting chronic infection
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
3. Platelets
 Derived from ruptured multinucleate cells
(megakaryocytes)
 Needed for the clotting process
 Normal platelet count = 300,000/mm3
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings