Chapter 14: The Cardiovascular System-Blood

Functions of the Blood

1) Transportation- Gases (O2 and CO2)- Nutrients- Heat and waste- Hormones

2) Regulation- pH- Temperature- Osmotic pressure of cells

3) Protection- Blood loss- Sickness/Disease

Components of Blood

- A type of connective tissue

- Two main components:1) Blood Plasma (55%)

- Water, Protein, Amino Acids

2) Formed Elements (45%)- RBCs, WBCs, Platelets

- Hematocrit: % of total blood volume occupied by RBCs

Blood Plasma

- 91% Water

- 7% Proteins (plasma proteins)- Albumins: maintain osmotic pressure- Globulins: immune responses- Fibrinogen: forms blood clots

- 2% Other Solutes- Electrolytes, nutrients, enzymes,

hormones, vitamins, etc

Formed Elements

- Red Blood Cells, White Blood Cells, Platelets

- Developed through hemopoiesis- Early Development: Occurs in

embryonic yolk sac, liver, and lymphatic organs

- Late Development/After Birth: red bone marrow

- Pluripotent stem cells become specialized blood cells

Red Blood Cells-Erythrocytes

- Transports oxygen and carbon dioxide

- Contain hemoglobin- Oxygen carrying protein- Gives blood its red color

- Bioconcave disc

- No nucleus or organelles

RBC Life Cycle

- Approximately 5 million RBC/µL blood

- RBC Life span = 120 days

- 2 million new cells produced every second

+

+

Circulation for about120 days

Reused forprotein synthesis

Aminoacids

Red blood celldeath andphagocytosis

Macrophage inspleen, liver, orred bone marrow

Urine

Kidney

Feces

Bacteria

Largeintestine

Smallintestine

Liver

Erythropoiesis inred bone marrow

Erythopoietin

Vitamin B12

Key:in blood

in bile

1

2

2

3

4

5

6

10

7

Globin

Transferrin

Iron

IronHeme

Biliverdin Bilirubin

Bilirubin

Bilirubin

Urobilinogen

Stercobilin

Globin+

Urobilin

RBC Life Cycle

RBC Production

- Hemopoiesis: formation of blood cells

- Erythropoiesis: formation of only RBCs- RBC precursor ejects nucleus -> bioconcave shape forms- Iron + Globlin + B12 form hemoglobin -> Stimulated by Erythropoietin

- RBCs become fully mature while in circulation

- Hypoxia (oxygen deficiency) stimulates increased release of erythropoietin- Prolonged hypoxia, often caused by anemia, can lead to cyanosis

Erythopoietin

Vitamin B12

Iron

Globin

Some stimulus disrupts homeostasis by

Oxygen delivery to kid-neys (and other tissues)

Receptors

Kidney cellsdetect lowoxygen level

Control center

Stem cells inred bone marrowmature more quicklyinto RBC precursors

Effectors

Larger numberof RBCs incirculation

Increased oxygendelivery to tissues

Return to homeostasiswhen oxygen deliveryto kidneys increases tonormal

Increased erythropoietinsecreted into blood

Input

More RBCs entercirculating blood

Output

Decreasing

Medical Tests Involving Blood

- Reticulocyte (RBC precursor cells) count: rate of erythropoiesis

- High reticulocyte count may indicate internal bleeding or iron deficiency

- Low reticulocyte count + anemia may indicate malfunctioning red bone marrow

- Hematocrit count: percent of RBCs - Used to diagnose anemia, polycythemia, and

dehydration or over hydration- Athletes and people at high altitudes have

higher-than avg hematocrit

EPO Doping