blood

What are the 3 major functions of blood?

Transport, protection, and regulation.

What does blood transport?

Oxygen, carbon dioxide, nutrients, wastes, hormones, and stem cells.

How does blood protect the body?

It helps with inflammation, limits infection, destroys microorganisms and cancer cells, neutralizes toxins, and initiates clotting.

What does blood regulate?

Fluid balance, pH of extracellular fluid, and body temperature.

What are the two major components of blood?

Plasma and formed elements.

What is plasma?

The liquid extracellular matrix of blood.

What are the formed elements of blood?

Red blood cells, white blood cells, and platelets.

What are the 7 formed elements?

Erythrocytes, platelets, neutrophils, eosinophils, basophils, lymphocytes, and monocytes.

What are erythrocytes?

Red blood cells (RBCs).

What are leukocytes?

White blood cells (WBCs).

What are platelets?

Cell fragments produced from megakaryocytes.

What are the two groups of WBCs?

Granulocytes and agranulocytes.

Which WBCs are granulocytes?

Neutrophils, eosinophils, and basophils.

Which WBCs are agranulocytes?

Lymphocytes and monocytes.

What is the memory trick for granulocytes?

NEB = neutrophils, eosinophils, basophils.

What is the memory trick for agranulocytes?

LM = lymphocytes, monocytes.

What is hematocrit?

The percentage of whole blood volume composed of RBCs.

What is the typical male hematocrit?

42–52%.

What is the typical female hematocrit?

36–48%.

What is the buffy coat?

The thin layer containing WBCs and platelets.

What are the 3 major plasma proteins?

Albumin, globulins, and fibrinogen.

What does albumin do?

It contributes to viscosity and osmolarity and helps regulate blood pressure, flow, and fluid balance.

What do globulins do?

They are involved in immune function.

What does fibrinogen do?

It is converted into fibrin threads during blood clotting.

What is serum?

The fluid remaining after blood clots and the solids are removed; it lacks fibrinogen.

What is hypoproteinemia?

A deficiency of plasma proteins.

What is hemopoiesis?

The production of blood and formed elements.

Where are all 7 formed elements produced?

Red bone marrow.

What is a PPSC?

A pluripotent stem cell that can develop into different types of blood cells.

What is a CFU?

A specialized stem cell committed to producing one formed-element class.

What is the main function of RBCs?

Carry oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs.

What shape are RBCs?

Disc-shaped.

What organelles do mature RBCs lack?

A nucleus, DNA, and mitochondria.

Why do mature RBCs use anaerobic fermentation?

They lack mitochondria and therefore cannot use mitochondrial respiration to produce ATP.

Why is losing the nucleus useful for an RBC?

It makes more room for hemoglobin.

What protein is responsible for oxygen transport in RBCs?

Hemoglobin.

Approximately how much of an RBC's cytoplasm is hemoglobin?

About 33%.

How many hemoglobin molecules are in one RBC?

About 280 million.

How many globin chains does adult hemoglobin have?

Four.

What are the globin chains in adult hemoglobin?

Two alpha and two beta chains.

How many heme groups does one hemoglobin molecule have?

Four.

What does the iron in heme do?

It binds oxygen.

Why must RBCs be flexible?

They need to bend and squeeze through tiny capillaries.

What is erythropoiesis?

The production of RBCs.

How long does a normal RBC live?

About 120 days.

What hormone stimulates RBC production?

Erythropoietin (EPO).

Which organ produces EPO?

The kidneys.

What stimulates EPO release?

Low oxygen levels.

What does EPO do?

It stimulates red bone marrow to increase RBC production.

What is the RBC negative feedback pathway?

Low O2 → kidneys release EPO → bone marrow increases RBC production → RBC count rises → oxygen delivery improves.

What is a reticulocyte?

An immature RBC that has lost its nucleus but still contains a fine network of endoplasmic reticulum.

Where does most RBC destruction occur?

In the spleen.

What happens to globin when an RBC is destroyed?

It is broken down into amino acids.

What happens to iron from heme?

It is removed and reused.

What happens to heme after iron is removed?

It is converted to biliverdin and then bilirubin.

What color is biliverdin?

Green.

What color is bilirubin?

Yellow.

What organ processes bilirubin?

The liver.

What is polycythemia?

An abnormally high number of RBCs.

What is primary polycythemia/polycythemia vera?

Excessive RBC production caused by a bone marrow cancer.

What can cause secondary polycythemia?

Dehydration, emphysema, high altitude, and conditioning/training.

Why is polycythemia dangerous?

It increases blood volume, blood pressure, and blood viscosity, increasing the risk of embolism, stroke, and heart failure.

What is anemia?

A condition involving inadequate oxygen-carrying capacity of blood.

What are 3 major causes of anemia?

Inadequate RBC production/hemoglobin synthesis, blood loss, and excessive RBC destruction.

What is hemorrhagic anemia?

Anemia caused by excessive bleeding.

What is hemolytic anemia?

Anemia caused by RBCs being destroyed too quickly.

What is pernicious anemia?

Anemia caused by an autoimmune problem that interferes with vitamin B12 absorption.

What is aplastic anemia?

Anemia in which RBC production stops.

What is hypoplastic anemia?

Anemia caused by slowed RBC production.

What is the major consequence of anemia?

Tissue hypoxia due to inadequate oxygen delivery.

What is sickle-cell disease?

A hereditary disorder involving abnormal hemoglobin (HbS) that causes RBCs to become rigid, sticky, and sickle-shaped.

What causes HbS?

A recessive allele that changes the sixth amino acid of the beta-globin chain.

What happens to sickle cells under low-oxygen conditions?

They become rigid, sticky, and pointed and can clump together.

Why are sickle cells dangerous?

They can block small blood vessels and reduce blood flow and oxygen delivery to tissues.

What can sickle-cell disease cause?

Joint pain, kidney and heart failure, stroke, and paralysis.

What is an advantage of being heterozygous for the sickle-cell allele?

Resistance to malaria.

What is the normal WBC count?

5,000–10,000 WBCs/µL.

What is the primary function of WBCs?

Protect the body against pathogens and other threats.

What are the 5 types of WBCs?

Neutrophils, eosinophils, basophils, lymphocytes, and monocytes.

What percentage of WBCs are neutrophils?

60–70%.

What percentage of WBCs are lymphocytes?

25–33%.

What percentage of WBCs are eosinophils?

2–4%.

What percentage of WBCs are monocytes?

3–8%.

What percentage of WBCs are basophils?

Less than 1%.

Which WBC is the most abundant?

Neutrophils.

Which WBC is the least abundant?

Basophils.

What are neutrophils mainly associated with?

Bacterial infections.

What is neutrophilia?

An increase in neutrophils.

What are eosinophils mainly associated with?

Parasitic infections and allergies.

What do eosinophils do during parasitic infections?

They help destroy large parasites.

What do eosinophils do during allergic reactions?

They help limit histamine and participate in the inflammatory response.

What are basophils mainly associated with?

Histamine and heparin release.

What does histamine do?

It causes vasodilation.

What does heparin do?

It acts as an anticoagulant and helps prevent clotting.

What do leukotrienes do?

They attract and activate neutrophils and eosinophils.

What are lymphocytes mainly associated with?

Specific immune responses and immune memory.

What can lymphocytes destroy?

Cancerous cells, foreign cells, and virus-infected cells.

What else do lymphocytes do?

Present antigens, coordinate immune cells, participate in antibody responses, and provide immune memory.

What are monocytes?

Large WBCs that leave the blood and become macrophages in tissues.

What do macrophages do?

They phagocytize pathogens and cellular debris and can present antigens.