I. Functions of blood
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I. Functions of blood
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A. Distribution or transport:
1) Deliver oxygen and nutrients to all body cells. (To make ATP.)
2) Transport metabolic wastes from body cells to sites ofelimination.
a) CO2 to the lungs.
b) Nitrogenous wastes to the kidneys.
3) Hormones (chemical messengers)
one hormone, Erythropoieten, promotes the production of red blood cells, thereby
counteracting anemia. Anemia is a condition in which oxygen is not properly
transported.
B. Regulation:
1) Body temperature
2) Maintaining normal pH.
3) Maintaining adequate fluid volume.
C. Protection:
1) Clotting prevents blood loss.
2) Prevents infection – wbc’s, antibodies, complement proteins.
II. Blood Components:
Plasma is 55% of blood volume.
Leukocytes are ~1% (buffy coat).
Erythrocytes are 45% (= the hematocrit).
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A. Plasma:
1. Water
90% of plasma and is responsible for most of distribution function. Most abundant
substance in blood.
2. Others
Proteins – albumin, clotting, complement, antibodies, hormones.
Gases – oxygen (O2) and carbon dioxide (CO2)
Ions – sodium (Na+), potassium (K+), calcium (Ca+2), chlorine (Cl-)
Nutrients – glucose, amino acids, fatty acids, cholesterol, vitamins
Wastes – urea, lactic acid, creatinine
B. Formed Elements: the cells
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1) Erythrocytes:
They are produced in red bone marrow (found within spongy bone diaphyses of
long bones.)
- 7.5 microns in diameter
- biconcave discs
- anucleate
Contain hemoglobin, our iron based respiratory pigment carries:
Almost all oxygen.
Only 20% of carbon dioxide
2) Leukocytes:
- larger than erythrocytes
- have large well-developed nuclei
Abundance in blood:
neutrophils (most)
lymphocytes
monocytes
eosinophils
basophils (least)
a) Neutrophils: phagocytize (eat and digest) bacteria and fungi
b) Eosinophils: phagocytizes parasitic worms, lessens severity inflammation
by releasing anti-histamines
c) Basophils: release histamine thereby promoting inflammation.
d) Lymphocyte: in lymphoid tissue, provides immunity. in two ways
1) T cells directly touch and cut apart invader/abnormal cell membranes.
2)B cells make antibodies that attach to invader/abnormal cell membranes to
promote phagocytosis.
e) Monocytes= macrophages: also phagocytize bacteria
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3) Platelets: fragments of larger cells, clotting and preventing blood loss
in torn vessels.
Helpful web link
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Professor Thomas M. Lancraft
Human Anatomy Courses
at St. Petersburg College
St. Petersburg/Gibbs Campus
11/2008