Immunity Lecture Notes

Flashcards based on lecture notes about immunity, lymphatic system, antigens, antibodies, immunoglobulin classes, and immune cells.

T cells

Produced in the bone marrow, mature in the thymus.

Types of lymphocytes

B lymphocytes and T lymphocytes.

Role of monocytes in immunity

They become macrophages in tissues and perform phagocytosis and antigen presentation.

Cell type that is the first to respond to infection

Neutrophils.

Role of the lymphatic system in immunity

Drains excess tissue fluid, filters lymph through lymph nodes, houses immune cells.

Cause of lymph node swelling

Active immune response with accumulation of immune cells and trapped pathogens.

Tissue fluid

Fluid formed from plasma that bathes body cells, formed by pressure at capillary beds.

Hydrostatic pressure

Pressure exerted by blood on capillary walls; it drives plasma out at the arteriole end.

What happens at the venule end of a capillary?

Osmotic pressure draws tissue fluid back into the blood.

What happens if the lymphatic system is blocked?

Fluid accumulates in tissues, causing oedema.

Antigen

A foreign substance that triggers an immune response.

Antibodies (also known as)

Immunoglobulins.

Part of the antibody that binds to antigens

Variable region (Fab region).

Part of the antibody that determines its class and function

Constant region (Fc region).

What triggers conformational change in an antibody?

Antigen binding.

Neutralisation

Antibodies block pathogen binding to cells.

Agglutination

Clumping of pathogens by antibodies.

Opsonisation

Marking pathogens for phagocytosis by binding Fc receptors on phagocytes.

Complement activation

Activation of the complement system by antibody-antigen complexes (IgG/IgM).

Complement fixation

Binding of C1q to antibody’s Fc region, starting the complement cascade.

Antibody class that crosses the placenta

IgG.

Antibody class found in mucosal secretions

IgA.

Antibody class produced first in infection

IgM.

Antibody class involved in allergic reactions

IgE.

Function of IgD

Acts as B cell receptor on immature B cells.

IgG subclass that activates complement most strongly

IgG3.

IgG subclass that is anti-inflammatory

IgG4.

Type of immunity IgG provides to the fetus

Passive immunity.

Do IgG antibodies stimulate fetal B cell differentiation?

No, passive immunity doesn’t activate fetal immune system.

Membrane-bound antibodies

Antibodies on B cell surface that detect antigens.

Secreted antibodies

Free antibodies produced by plasma cells to neutralise antigens.

Cells that release histamine in allergies

Basophils and mast cells.

Cells that fight parasitic worms and reduce inflammation

Eosinophils (release anti-histamine substances).

Cells that include both B cells and T cells

Lymphocytes.