1. Chapter 11 The Cardiovascular System: Blood
Anatomy & Physiology

2. Chapter 11 The Cardiovascular System: Blood
“The living body is in constant communication with it’s external environment. Nutrients are absorbed through the lining of the digestive tract, gases move across the epithelium of the lungs, and wastes are excreted in the feces and urine. Even though these chemical exchanges occur at specialized sties, they affect every cell, tissue, and organ in a matter of moments because all parts of the body are linked by the cardiovascular system, an internal transport network.” (p. 365)
Chapter 11 The Cardiovascular System: Blood

3. Objective 3 & 4
Describe the origins and production of the formed elements in blood.
Discuss the characteristics and functions of red blood cells.

4. Production of Formed Elements
Hemopoiesis – process by which formed elements are produced
In adults the main site of hemopoiesis is in red bone marrow
erythopoiesis – RBC formation
leukopoiesis – WBC formation
thrombopoiesis – platelet formation

5. Red Blood Cells RBC’s contain the pigment hemoglobin
Oxygen and carbon dioxide bind to hemoglobin
RBC’s account for 99% of the formed elements
How many RBC’s are in…
One drop of blood
One cc or mL
Whole Human Body
Male
Female
2.6 million
5.4 million
4.8 million
75 trillion

6. Hematocrit
Hematocrit - the percentage of whole blood volume occupied by cellular elements
so this is MAINLY referring to the amount of RBC’s present
Hematocrit values increase when:
You are dehydrated
Less plasma (water) relative to # of RBC’s
You make more RBC’s due to low oxygen levels
More RBC’s are made in response to the hormone erythropoietin, stimulates production

7. RBC Structure Unusual shape Biconcave
Increases surface area to volume ratio
Increases diffusion of gases
Makes them flexible
Easier to pass through tiny capillaries

8. RBC Structure continued…
During formation, RBC’s lose their organelles
Mitochondria
Ribosomes
Nuclei
This prevents them from dividing (mitosis)
Short life span

9. Hemoglobin Structure & Function
Hemoglobin – a gas transporting protein
makes up 95% of a mature RBC
Hemoglobin contains a pigment called heme
Each heme molecule holds a iron ion
Oxygen binds to the iron on each heme
When CO2 levels rise around the RBC,
It releases O2
And gains CO2
This process reverses when O2 levels rise around the RBC

10. RBC Life Span & Circulation
RBC’s have a life span up to 120 days
They get beat up traveling around
Macrophages in the liver, spleen, and bone marrow eat the really old & beat up looking RBC’s
10% of RBC’s sneak by macrophages and hemolyze (explode!)
A round trip of the circulatory system takes only one minute
Approximately 3 million new RBC’s enter the blood stream every second

11. The Role of EPO in the Control of Erythropoiesis
Tissues deprived of oxygen release EPO (the hormone erythropoietin)
This accelerates
division of stem cells in bone marrow
maturation of RBC’s
Effect is more RBC’s entering circulation
This improves oxygen delivery to tissues