Microbiology exam 4

What are the three lines of defense?

1st: Physical/chemical barriers.

2nd: Innate internal defenses.

3rd: Specific/adaptive immunity.

Which lines of defense are innate?

The first and second lines

Name the three granulocytes

Neutrophils, eosinophils, basophils

Name the two agranulocyte categories

Monocytes and lymphocytes

What is the primary function of neutrophils?

Phagocytosis, especially of bacteria

Which leukocyte fights parasites and is involved in allergies?

Eosinophils

Which leukocyte releases histamine during inflammation?

Basophils

Which leukocyte develops into a macrophage in tissues?

Monocyte

Which leukocyte category includes B cells, T cells, and NK cells?

Lymphocytes

What is the difference between chemotaxis and diapedesis?

Chemotaxis: Movement toward chemical signals. Diapedesis: Movement out of blood vessels into tissues.

What is a phagolysosome?

A phagosome fused with a lysosome, allowing microbial digestion.

What does PAMP stand for?

Pathogen-associated molecular pattern.

What recognizes PAMPs?

Pattern-recognition receptors (PRRs), including Toll-like receptors (TLRs).

What causes redness and heat during inflammation?

Vasodilation, which increases blood flow to the area.

What causes swelling during inflammation?

Increased vascular permeability, allowing fluid to enter surrounding tissues.

What are the four cardinal signs of inflammation?

Redness, heat, swelling, and pain.

What is a PAMP?

A pathogen-associated molecular pattern: a common microbial structure recognized by innate immune receptors.

What is an antigen?

A molecule or molecular structure recognized by specific immune receptors, such as antibodies or B-cell/T-cell receptors.

What type of immunity recognizes PAMPs through Toll-like receptors?

Innate immunity

What type of immunity uses B cells and T cells to recognize specific antigens?

Acquired (adaptive) immunity

What is chemotaxis?

Movement of an immune cell toward chemical signals at an infection site.

What is diapedesis?

Movement of a white blood cell through a blood vessel wall into tissues.

What is phagocytosis?

The engulfment of a microorganism or particle by an immune cell.

A neutrophil reaches bacteria but cannot engulf them. Which process is defective?

Phagocytosis

What are pyrogens?

Fever-producing substances that contribute to raising the hypothalamic temperature set point

What part of the brain regulates fever?

The hypothalamus

What is the main function of interferons?

To signal cells to activate antiviral defenses that inhibit viral replication.

What are the three major functions of complement?

Opsonization, inflammation, and cell lysis through the membrane attack complex.

What is opsonization?

Coating a pathogen to make it easier for phagocytes to engulf.

What does the membrane attack complex (MAC) do?

Forms pores in susceptible microbial membranes, potentially causing cell lysis.

What is the difference between MAC and lysis?

MAC forms pores; lysis is cell rupture.

What is an antigen?

A molecule or structure recognized by adaptive immune receptors.

What is an epitope?

The specific region of an antigen recognized by an antibody or immune receptor.

What produces antibodies?

Plasma cells, which develop from activated B cells.

What is neutralization?

Antibodies block pathogens or toxins from interacting with host cells.

What is agglutination?

Antibodies cross-link particles, causing them to clump together.

Which cells produce and secrete antibodies?

Plasma cells, derived from activated B cells.

What is the difference between an antigen and an antibody?

An antigen is recognized by immune receptors; an antibody is a protein that binds a specific antigen.

Where do B cells mature?

Bone marrow

Where do T cells mature?

Thymus

Which MHC

molecule interacts with CD8+ T cells?

MHC I

Which MHC

molecule interacts with CD4+ T cells?

MHC II

Where is MHC I found?

On nearly all nucleated cells.

Where is MHC Il found?

Primarily on professional antigen-presenting cells

What is the main function of CD8+ cytotoxic T cells?

Kill infected or abnormal cells displaying appropriate antigen on MHC I.

What is the main function of CD4+ helper T cells?

Coordinate and activate other immune cells

What happens if a patient lacks functional plasma cells?

reduced antibody production, impairing humoral immunity

What is humoral immunity?

Adaptive immunity mediated by antibodies produced by plasma cells.

What is cell-

mediated immunity?

Adaptive immunity involving Tcells that coordinate responses or kill target cells.

Which type of immunity neutralizes bacterial toxins using antibodies?

Humoral immunity

Which T cells directly kill virus-infected cells?

CD8+ cytotoxic T cells

MHC I presents antigens to which T cells?

CD8+ cytotoxic T cells

MHC Il presents antigens to which T cells?

CD4+ helper T cells.

Why does MHC I

deficiency impair viral defense?

CD8+ T cells have difficulty recognizing and killing infected cells.

IgG

Most abundant in blood; crosses the placenta

IgM

First antibody produced in a primary immune response

IgA

Protects mucosal surfaces; found in saliva, tears, and breast milk

IgE

Involved in allergies and parasite defense

IgD

Functions mainly as a receptor on naive B cells

What is active immunity?

Protection produced by your own adaptive immune response.

What is passive immunity?

Protection from antibodies received from another source.

What is natural active immunity?

Immunity developed after natural infection.

What is artificial active immunity?

Immunity developed in response to vaccination.

What is natural passive immunity?

Maternal antibodies

transferred through placenta or breast milk.

What is artificial passive immunity?

Receiving prepared antibodies, such as immune globulin.

Which produces immune memory: active or passive immunity?

Active immunity can produce immune memory.

Does passive immunity create immune memory?

No. It provides immediate, temporary protection through transferred antibodies.

What is a live attenuated vaccine?

A vaccine containing a living, weakened pathogen.

What is an inactivated vaccine?

A vaccine containing a killed or inactivated whole pathogen.

What is a toxoid vaccine?

A vaccine containing an inactivated bacterial toxin.

What is a subunit vaccine?

A vaccine containing selected antigens or components of a pathogen.

Which vaccine type may be unsafe for some severely immunocompromised patients?

Live attenuated vaccines

What does complement protein C3b do?

C3b acts as an opsonin, coating pathogens to promote phagocytosis.

What do antibodies produced after a toxoid vaccine do?

Neutralize the active toxin if the person encounters it later.

Why is the secondary immune response faster and stronger?

Memory B and T cells formed during earlier exposure respond more rapidly.