Blood

2. Blood-the “River of Life”
Blood is the only fluid tissue in the human body. Blood
is classified as a connective tissue. Blood carries
nutrients, waste, and body heat through blood
vessels.
• Components of blood
– Living cells
• Formed elements
– Non-living matrix
• Plasma

3. Blood Composition
If blood is centrifuged
– Erythrocytes sink to the bottom (45%
of blood, a percentage known as the
hematocrit)
– Buffy coat contains leukocytes and
platelets (less than 1% of blood)
• Buffy coat is a thin, whitish layer
between the erythrocytes and
plasma
– Plasma rises to the top (55% of blood)
The formed elements (blood cells) make blood
heavier and 5 times thicker (more viscous)
than water.

4. Figure 10.1 (2 of 2)
Blood

5. Physical Characteristics of Blood
• Color range
– Oxygen-rich blood is scarlet
red
– Oxygen-poor blood is dull
red
• pH must remain between 7.35–
7.45
Acidosis (pH7. 2) Death (pH 7)

6. Physical Characteristics of Blood
• Blood temperature is slightly higher than body
temperature at 100.4°F
• In a healthy man, blood volume is about 5–6
liters or about 6 quarts
• Blood makes up 8% of body weight

7. Functions of Blood
• Functions include (More details on next 3
slides)
– Distributing substances
– Regulating blood levels of substances
– Protection

8. Distribution Functions
• Delivering O2 and nutrients to body cells
• Transporting metabolic wastes to lungs
and kidneys for elimination
• Transporting hormones from endocrine
organs to target organs

9. Regulation Functions
• Maintaining body temperature by
absorbing and distributing heat
• Maintaining normal pH using buffers;
alkaline reserve of bicarbonate ions
• Maintaining adequate fluid volume in
circulatory system

10. Protection Functions
• Preventing blood loss
– Plasma proteins and platelets initiate clot
formation
• Preventing infection
– Antibodies
– Complement proteins
– WBCs

11. Blood Plasma
Composition
• Composed of
approximately 90%
water
• Includes many
dissolved substances
– Nutrients
– Salts (electrolytes)
– Respiratory gases
– Hormones
– Plasma proteins
– Waste products

12. Blood Plasma
• Plasma proteins
– Most abundant solutes in
plasma
– Most plasma proteins are
made by liver
– Various plasma proteins
include
• Albumin—regulates
osmotic pressure
• Fibrinogen: Clotting
proteins—help to stem
blood loss when a blood
vessel is injured
• Globulins: Antibodies—
help protect the body
from pathogens

13. Blood Plasma:
Homeostatic imbalances
• Acidosis
– Blood becomes too
acidic
• Alkalosis
– Blood becomes too
basic
• In each scenario,
the respiratory
system and kidneys
help restore blood
pH to normal

14. Formed Elements
• Erythrocytes
– Red blood cells (RBCs)
• Leukocytes
– White blood cells (WBCs)
• Platelets
• Cell fragments