BME350 - L19

What is the collective term for White Blood Cells?

Leukocytes.

What two components make up the 'buffy coat' in centrifuged blood?

White Blood Cells (WBCs) and platelets.

What is the approximate concentration of platelets in blood?

Around 2.5 X 10^8 per milliliter.

What is the approximate concentration of White Blood Cells (WBCs) in blood?

Around 7 X 10^6 per milliliter.

What is the normal range for White Blood Cell (WBC) concentration in the blood?

The range is (4-11) X 10^6 per milliliter.

How many main types of leukocytes exhibit varied morphology?

There are five main types.

What is the primary function of leukocytes in the immune system?

They fight foreign microbial infections.

How do leukocytes utilize the blood system?

They use blood as a route of transport from production/storage sites to sites of function.

Most innate immune leukocytes cannot _____ or _____ on their own.

divide; reproduce

From which type of cells do leukocytes arise?

They arise from the same hematopoietic stem cells as Red Blood Cells (RBCs).

The process of leukocyte development is called _____.

Leukopoiesis.

Which subgroup of leukocytes originates from a different stem cell line in bone marrow or the lymph system?

Lymphocytes.

Where do lymphocytes migrate to differentiate and mature?

They migrate into lymph organs, such as lymph nodes or the thymus.

Which type of WBCs are classified as polymorphonuclear granulocytes and primarily kill bacteria and fungi?

Neutrophils.

What is the primary function of eosinophils?

They attack parasites.

Which WBCs release histamine and heparin during allergic reactions?

Basophils.

What is the primary function of lymphocytes?

They attack viruses and cancer cells.

What is the function of monocytes after they enter tissues?

They differentiate into macrophages and consume bacteria or dead/damaged cells.

What is the typical lifespan of a neutrophil in tissue?

They live for 3-4 days in tissue.

What is the typical lifespan of a monocyte in tissues?

They can live for 100-300 days in tissues.

What is the typical lifespan of a lymphocyte in lymphoid tissues?

They can live for days or years in lymphoid tissues.

What is the definition of immunity?

It is the ability of the body to resist or eliminate potentially harmful foreign materials or abnormal cells.

What constitutes the body's first line of defense in its multi-tiered system?

The skin and mucosal linings.

What constitutes the body's second line of defense?

Phagocytes, such as neutrophils and eosinophils.

What constitutes the body's third line of defense?

Adaptive responses involving lymphocytes.

What are the two main functional classifications of defense responses?

Innate immune responses and adaptive immune responses.

Which type of immunity is described as inborn and non-specific?

Innate immunity.

Which type of immunity is described as acquired and specific?

Adaptive immunity.

Innate immunity defends the host in a _____ manner and does not require prior exposure to an antigen.

non-specific

Which WBCs are involved in innate immunity?

All WBCs except lymphocytes (i.e., granulocytes and phagocytic agranulocytes).

What specialized chemical mediators are involved in recruiting immune cells to sites of infection and inflammation?

Cytokines.

What is the role of the complement cascade in innate immunity?

It identifies bacteria, activates cells, and promotes clearance of dead cells or antibody complexes.

What substance released during innate inflammation causes vasodilation?

Histamine.

Adaptive immunity requires prior _____ to an antigen.

sensitization/exposure

How does the efficacy of the adaptive immune response change with exposure?

It increases its efficacy of defense upon subsequent exposures.

Which two types of lymphocytes are primarily involved in adaptive immunity?

B- and T-lymphocytes.

What defines active immunity?

The immune system produces its own antibodies against a specific agent.

What are the two ways active immunity can be acquired?

By contracting an infectious disease or by receiving a vaccination.

What defines passive immunity?

It is immunity produced by the transfer of antibodies from one person to another.

How long does the protection from passive immunity typically last?

It diminishes within a few weeks or months.

Antibodies passed from a mother to a baby before birth confer passive immunity for how long?

For the first 4-6 months of the baby's life.

Where are B-cells derived from?

They are derived from bone marrow.

Where do B-cells mature and produce antibodies?

They move to secondary lymphoid organs to mature.

Where are T-cells derived from and where do they multiply?

They are derived from/multiply at the thymus.

The adaptive immune system is described as having a _____ because it can remember previous pathogens.

memory

What are the specific proteins on the surface of bacteria that are recognized by the immune system?

Antigens.

In antibody-mediated immunity, B-cells 'activate' by enlarging and becoming what type of cells?

Plasma cells, which produce antibodies.

In antibody-mediated immunity, what is the function of antibodies produced by plasma cells?

They 'tag' bacteria, viruses, and other pathogens for destruction by phagocytes.

How do T-cells directly attack and destroy foreign cells in cell-mediated immunity?

By lysing (rupturing) them or by summoning macrophages to destroy them.

T-cell responses are particularly involved in defense against what type of bacteria?

Slow-acting bacteria, such as those that cause Tuberculosis.

What is the function of 'helper' T-cells?

They bind to other immune cells and release chemicals (cytokines) that augment their activity.

A virus consists of nucleic acid wrapped in a _____.

protein sheath

How do viruses cause disease in a host?

They enter a host cell and take over its replication machinery, thereby destroying the host cell.

What instructions do mRNA vaccines provide to a person's cells?

They provide instructions to generate a specific protein normally found on the surface of a virus.

How does the protein produced via an mRNA vaccine lead to immunity?

It stimulates the immune system to synthesize antibodies against that specific protein.

What are platelets?

They are anuclear cell fragments called thrombocytes.

From which large bone marrow cells are platelets shed?

Megakaryocytes.

What is the primary function of platelets?

To initiate the blood-clotting process (hemostasis).

The overall response to vascular injury is known as _____.

Hemostasis.

What is the first step in hemostasis after a blood vessel is damaged?

Platelets adhere to exposed collagen fibers and release serotonin.

What is the effect of serotonin release during hemostasis?

It causes a vascular spasm, leading to vasoconstriction to reduce blood flow.

What is the role of ADP (adenosine diphosphate) in hemostasis?

It attracts neighboring platelets and makes them 'sticky' to form a plug.

What substance, released by injured tissue and platelets, initiates the clotting cascade?

Thromboplastin.

Thromboplastin causes the conversion of _____ to Thrombin.

Prothrombin

Thrombin acts as an enzyme to convert the soluble protein _____ into the insoluble protein Fibrin.

Fibrinogen

What is the function of fibrin in a blood clot?

It forms a mesh that catches blood cells to form the clot.

What is hemophilia?

A genetic disorder characterized by a deficiency of a clotting factor, known as 'bleeding sickness'.

What is thrombocytopenia?

A condition of reduced platelet production or increased platelet destruction.

Why is Vitamin K important for blood clotting?

It is required for the synthesis of prothrombin at the liver.

The ability of hematopoietic stem cells to differentiate into different blood cells is known as _____.

pluripotency

What enables differentiated blood cells to pass through the blood vessel endothelium from the bone marrow?

They contain specific membrane proteins required to attach to and pass through the endothelium.

What is the general goal of leukocyte engineering?

To enhance immunity, including wound healing and inflammatory responses.

What is immunoengineering?

A relatively new field focused on defining how to manipulate the immune system, for example, to fight cancer.