Function and Formation of the Blood

Question 1

Be familiar with the items transported in blood.

Answer 1

Transport O2 from the lungs and nutrients from the digestive tract to body cells

Transport waste to elimination sites

The lungs eliminate CO2

The kidneys eliminate nitrogenous wastes via urine

Transport hormones from endocrine organs to target organs

Example: growth hormone is secreted from the anterior pituitary gland to the bones

Question 2

Describe the composition and physical characteristics of whole blood. Why is it classified as connective tissue?

Answer 2

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Question 3

Know the general pathway of blood circulating in the human body.

Answer 3

Circulation of blood is initiated by the pumping action of the heart

Oxygen-rich blood is pumped out of the heart via arteries

Arteries repeatedly branch until they become capillaries

At capillaries, Oxygen and nutrients exit the blood to enter the body’s tissues; Carbon Dioxide and waste enter the blood

Oxygen-poor blood flows into veins which repeatedly converge

Oxygen-poor blood enters the heart, moves to the lungs, returns to the heart

Oxygen-rich blood exits the heart via arteries

Question 4

What type of blood vessel is the site of gas and nutrient exchange?

Answer 4

At capillaries, Oxygen and nutrients exit the blood to enter the body’s tissues; Carbon Dioxide and waste enter the blood

Question 5

Be familiar with the transport, regulatory, and protective functions of whole blood.

Answer 5

Maintenance/Regulatory Functions

Maintain appropriate body temperature by absorbing and distributing heat

Maintain normal pH in body tissues (~7.35 to 7.45)

Maintain necessary fluid volume to adequately perfuse body tissues

Protective Functions

Prevent blood loss through clotting

Prevent infection by defending against foreign invaders

Question 6

List the 3 formed elements of blood and know the relative percentages of each in whole blood.

Answer 6

Cellular (Solid) Components = Formed Elements

Erythrocytes: Red Blood Cells (45% BV)

Leukocytes: White Blood Cells (< 1% BV)

Platelets: Cell Fragments (< 1% BV)

Question 7

Define the terms Hematocrit and Buffy Coat.

Answer 7

Hematocrit = the % of blood made up by erythrocytes

Buffy Coat = the % of blood made up by leukocytes and platelets

Question 8

Know the average blood volume in adult males and females.

Answer 8

Average blood volume in adult males 5-6L (1.5 gallons)

Question 9

What type of formed elements are true cells? What is a typical lifespan for an erythrocyte? How do erythrocytes get replaced?

Answer 9

Erythrocytes have a useful lifespan of 100-120 days

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Question 10

What is hematopoiesis? Where does it take place? What stem cell gives rise to blood cells?

Answer 10

Hematopoiesis: the creation of ALL blood cells

Location: within the red bone marrow of the bones and girdles of the axial skeleton

All blood cells arise from a hematopoietic stem call – a hemocytoblast

Question 11

State some reasons why erythrocytes are able and efficient at carrying Oxygen.

Question 12

How does Oxygen bind to erythrocytes? How many Oxygen molecules can 1 erythrocyte carry?

Answer 12

Each hemoglobin molecule can bind to 4 O2 molecules

Each erythrocyte contains 250 million Hgb molecules

Question 13

Know the normative values for hemoglobin in adult males and females.

Answer 13

Male: 13-18g/100mL

Female: 12-16g/100mL

Question 14

Be familiar with the process of erythropoiesis – especially in relation to what makes erythrocyte function and shape unique from other formed elements.

Answer 14

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Question 15

What are the dangers of having too few erythrocytes in circulation? Too many?

Answer 15

of erythrocytes in circulation is highly regulated, remains fairly constant

Too few erythrocytes leads to tissue hypoxia – O2 deprivation

Too many erythrocytes leads to excessive blood viscosity

Question 16

What hormone triggers the creation of erythrocytes? What events can trigger the secretion of this hormone?

Answer 16

Rates of erythrocyte production/destruction is controlled hormonally and is dependent on the availability of amino acids, B vitamins and iron

Erythropoietin (EPO) –hormone that stimulates erythrocyte formation

EPO is produced in the kidneys and liver

Events that may trigger release of EPO:

Reduced numbers of erythrocytes as might occur after hemorrhage (bleeding)

Insufficient hemoglobin as might occur in iron deficiency

Reduced availability of O2 as might occur at high altitude or during respiratory illness

EPO stimulates more rapid production of erythrocytes

Question 17

State 2 erythrocyte disorders. Be able to generally describe their cause, symptoms, and management.

Answer 17

Anemia: a decrease in the O2 carrying capacity of blood

Symptoms: fatigue, pallor, shortness of breath, and feeling chilled

Causes: acute or chronic blood loss, low RBC production, excess RBC destruction

Causes of Low RBC Production: deficiency of iron, B12, EPO, or red bone marrow

Polycythemia: an excessive or abnormal increase in the number of RBCs

Causes: bone marrow cancer, living at high altitude, “blood doping”

Excessive amounts of RBCs increase blood viscosity – blood flows sluggishly; clots become more likely

Question 18

What is blood doping? How would it benefit competitors in aerobic sports?

Answer 18

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