Blood and Circulation
- Considered a tissue.
o Fluid portion: plasma
consists of water, gases,
proteins, sugars, vitamins,
minerals, hormones, and
waste products.
 55% of blood volume.
o Solid portion: formed portion
consists of red/white blood
cells and platelets.
 Created in the bone
marrow (inside of
bones).
 45% of blood volume.
Red Blood Cells (Erythrocytes)
-
44% of the total volume of blood.
Disk-shaped.
No nucleus.
Transports oxygen.
Life span of 120 days.
Each blood cell is packed with iron-containing molecules of the
respiratory pigment hemoglobin.
o Hemoglobin chemically binds to oxygen in the blood and
transports it to the cells. Hemoglobin then releases the
oxygen, by diffusion, in the presence of cells that need it.
o A small amount of carbon dioxide is diffused into the
hemoglobin.
- Anemia:
o Too few red blood cells or too little hemoglobin inside the red
blood cells.
o Reduces the amount of oxygen that flows through the body.
o Caused by a deficiency of iron.
o An anemic appears to be pale and is tired a lot.
White Blood Cells (Leucocytes)
- Body’s response to infection.
- 1% of total blood volume. When your body if fighting infection, the
amount of white blood cells doubles.
- Have nuclei and are colorless.
- Three groups:
o Granulocytes: consist of neutrophils, basophils, eosinophils.
o Monocytes: leave the bloodstream and become more
specialized to destroy bacteria.
 Both are found in circulating blood and attack bacteria.
 Both have a life span of a few hours to a few days.
o Lymphocytes: produce antibodies (proteins) that identify
bacteria and allow them to be easily detected and destroyed.
(Page 283, Figure 8.17)
Platelets
- Fragments of the cells that form when larger cells in the bone
marrow break.
- No nucleus and quickly break down in the blood.
- Main function is to clot blood.
- Life span of 2-8 days.
o Substances are released by the broken blood vessels at the
injured site which attract platelets.
o Platelets rupture and chemicals are released which combine
with blood components and the enzyme thromboplastin is
produced.
 Thromboplastin reacts with prothrombin (protein) and
produces thrombin (enzyme).
 Thrombin reacts with fibrinogen (protein) and produces
fibrin.
o Fibrin creates a mesh of strands around the injured, forming a
clot.
Plasma
- All blood cells are suspended in the plasma.
- Carbon dioxide is transported in the blood as bicarbonate ions and
carried from tissues to the lungs for gas exchange.
Point of
comparison
Origin
Cells present per
mm3 of blood
(approximate)
Relative size
Function
Life span
Appearance
Red blood cells
red bone marrow
5 500 000 (male)
4 500 000
(female)
small
(8 μm diameter)
to carry oxygen
and carbon
dioxide to and
from cells
120 days
White blood cells
Granulocytes and
monocytes
Lymphocytes
red bone marrow
thymus, red bone
marrow
6000
2000
largest
(up to 25 μm)
to engulf foreign particles
a few hours to a few days
large
(10 μm)
to play a role in
the formation of
antibodies
(defence function)
unknown
Platelets
red bone
marrow, lungs
250 000
smallest
(2 μm)
to play a role in
the clotting of
blood (defence
function)
2–8 days
Read Blood Disorders (page 288 – 291).
Describe hemophilia and leukemia and list the treatments for each.