Blood

1
Blood

• Chapter 12
• Bio160

2
Blood Composition

• Red blood cells

• White blood cells

• Platelets

• Plasma

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Red Blood Cells

• Red blood cells (Erythrocytes)

Biconcave disks that contain oxygen-carrying
hemoglobin
When oxygen combines with hemoglobin bright red
oxyhemoglobin results whereas deoxygenated blood
(deoxyhemoglobin) is darker.
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Red Blood Cells
Red blood cells discard their nuclei during
development and so cannot reproduce or produce
proteins.
The number of red blood cells is a measure of the
blood's oxygen-carrying capacity.
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Red Blood Cells

• Red blood cell production

In the embryo and fetus, red blood cell
production occurs in the yolk sac, liver, and
spleen after birth, it occurs in the red bone
marrow.
The average life span of a red blood cell is 120
days.
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Red Blood Cells
The total number of red blood cells remains
relatively constant due to a negative feedback
mechanism utilizing the hormone erythropoietin,
which is released from the kidneys and liver in
response to the detection of low oxygen levels.
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Red Blood Cells
Vitamins B12, folic acid and iron are needed for
red blood cell production
A deficiency in red blood cells or quantity of
hemoglobin results in anemia.
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Red Blood Cells

• Red blood cell destruction

With age, red blood cells become increasingly
fragile and are damaged by passing through narrow
capillaries.
Macrophages in the liver and spleen phagocytize
damaged red blood cells.
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Red Blood Cells
Hemoglobin from the decomposed red blood cells is
converted into heme and globin.
Heme is decomposed into iron, which is stored or
recycled, and biliverdin and bilirubin, which are
excreted in bile.
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White Blood Cells

• White blood cells (Leukocytes)

Defend the body from disease.
They are formed from hemocytoblasts.
Leukocytes can squeeze between cells lining walls
of blood vessels by diapedesis and attack
bacteria and debris.
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White Blood Cells

• Neutrophils

Have red-staining fine cytoplasmic granules and a
multilobed nucleus they comprise 54-62 of
leukocytes.
They are phagocytic.
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White Blood Cells

• Eosinophils

Have coarse granules that stain deep red, a
bilobed nucleus, and make up only 1-3 of
circulating leukocytes.
Eosinophils moderate allergic reactions as well
as defend against parasitic infections.
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White Blood Cells

• Basophils

Have fewer granules that stain blue they account
for fewer than 1 of leukocytes.
Basophils migrate to damaged tissues and release
histamine to promote inflammation and heparin to
inhibit blood clotting.
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White Blood Cells

• Monocytes

The largest blood cells, have variably shaped
nuclei, and make up 3-9 of circulating
leukocytes.
They are phagocytic, engulfing large particles.
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White Blood Cells

• Lymphocytes

Long-lived, have a large, round nucleus, and
account for 25-33 of circulating leukocytes.
The major players in specific immune reactions
and some produce antibodies.
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Platelets

• Blood platelets

Blood platelets are fragments of megakaryocytes.
Platelets help repair damaged blood vessels by
adhering to their broken edges.
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Blood Plasma

• Blood Plasma

Plasma is the clear, straw-colored fluid portion
of the blood.

• Plasma is mostly water but contains a variety of
  substances.

• Plasma functions to transport nutrients and
  gases, regulate fluid and electrolyte balance,
  and maintain a favorable pH.

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Blood Plasma
Plasma proteins

• The albumins help maintain the osmotic pressure
  of the blood and account for 60 of the plasma
  proteins.

• The globulins, comprising 36 of the plasma
  proteins, are designated as alpha, beta, and
  gamma globulins.

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Action Potentials
Alpha and beta globulins function in transporting
lipids and fat-soluble vitamins.
Gamma globulins are a type of antibody.

• Fibrinogen (4) plays a primary role in blood
  coagulation.

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Blood Plasma
Gases and nutrients

• The most important blood gases are oxygen and
  carbon dioxide.

• The plasma nutrients include amino acids,
  monosaccharides, nucleotides, and lipids.

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Blood Plasma
Nonprotein Nitrogenous Substances

• Nonprotein nitrogenous substances generally
  include amino acids, urea, and uric acid.

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Blood Plasma
Plasma Electrolytes

• They include sodium, potassium, calcium,
  magnesium, chloride, bicarbonate, phosphate, and
  sulfate ions.

• Some of these ions are important in maintaining
  osmotic pressure and pH of the plasma.

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Hemostasis

• Hemostasis

Hemostasis refers to the stoppage of bleeding.

• Blood vessel spasm - muscles in vessel wall
  contract

• Platelet plug formation - platelets stick to the
  exposed edges of damaged blood vessels, forming
  a net with spiny processes protruding from their
  membranes.

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Hemostasis

• Blood coagulation complex series of steps that
  leads to blood clot formation by conversion of
  fibrinogen into net-like fibrin, which catches
  blood cells before they can leave the body.