Function and Formation of Blood Study Guide Flashcards
items transported in the blood
Nutrients
Gasses
Hormones
waste
describe the composition and physical characteristics of whole blood. Why is it classified as connective tissue?
red blood cells, white blood cells, and platelets suspended in a protective yellow liquid known as plasma.
- Sticky, opaque liquid
- Color varies from scarlet red to maroon
- Metallic taste
- Slightly alkaline (pH 7.35 to 7.45)
- Slightly warmer than body temperature
- 5x more viscous than water – viscosity determined by hematocrit
general pathway of blood circulating in the human body
- 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
type of blood vessel that is the site of gas and nutrient exchange
Capillaries
transport functions of whole blood
- 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
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
buffy coat
% of blood made up by leukocytes and platelets
Hematocrit
% of blood made up by erythrocytes
protective functions
- Prevent blood loss through clotting
- Prevent infection by defending against foreign invaders
3 formed elements of blood + their relative percentages
Erythrocytes: Red Blood Cells (45% BV)
Leukocytes: White Blood Cells (< 1% BV)
Platelets: Cell Fragments (< 1% BV)
average blood volume in adult males and females
adult males 5-6L (1.5 gallons), adult females about 4.5-5.5 liters (1.2 gallons)
formed element that is a true cell
leukocytes
typical lifespan of erythrocyte
100-120 days
where does hematopoiesis take place?
within red bone marrow of the bones and girdles of the axial skeleton
how do erythrocytes get replaced?
stem cells dividing in red bone marrow (not cellular mitosis)
hematopoiesis
creation of all blood cells
stem cell that gives rise to blood cells
hemocytoblast
reasons why erythrocytes are able and efficient at carrying Oxygen
small + flexible so they fit through narrow vessels, have bi-concave shape which maximizes surface area to absorb oxygen, have thin membrane so gasses easily diffuse through, + contain hemoglobin which binds to oxygen.
How does Oxygen bind to erythrocytes?
Hemoglobin – iron containing protein that binds oxygen to the RBC
dangers of too few erythrocytes
leads to tissue hypoxia - O2 deprivation
How many Oxygen molecules can 1 erythrocyte carry?
Around 1 billion oxygen molecules
normative values for hemoglobin in adult males and females
Male: 13-18g/100mL
Female: 12-16g/100mL
hormone that triggers creation of erythrocytes
Erythropoietin (EPO)
dangers of too many erythrocytes
leads to excessive blood viscosity (thickening)
events that triggers secretion 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
- Testosterone also enhances the kidneys’ production of EPO
3 erythrocyte disorders
anemia
sickle cell anemia
polycythemia
sickle cell anemia
excessive RBC destruction caused by abnormal, misshapen Hgb molecules
- RBCs are crescent shaped; tend to clog small blood vessels and/or rupture
- Symptoms: shortness of breath and extreme pain
- Most prominent in the malaria belt of Africa – the gene that causes mishappen Hgb can offer some protection against malaria
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
What is blood doping? How would it benefit competitors in aerobic sports?
Increased amount of RBCs → increased amount of hemoglobin → boosts the amount of oxygen able to be supplied to the muscles, which enhanced endurance
