Lymphatic System and Immunity

pe test 2

Name 5 lymphatic organs.

Spleen, thymus, lymph nodes, vessels, tonsils.

What does the lymphatic system do?

Fights infection, returns fluid, moves fats.

What is lymph?

Fluid like blood plasma.

What do lymph vessels do?

Collect fluid and return it to blood.

How does lymph move?

Tissues → capillaries → vessels → veins.

1 difference between lymph and blood vessels?

Lymph: open start, thin walls.

Main lymph cells?

Lymphocytes + phagocytes.

3 types of lymphocytes?

T cells, B cells, NK cells.

What do phagocytes do?

Eat germs and dead cells.

2 types of immunity?

Innate (born with), Adaptive (learned).

First defence?

Skin and barriers.

Second defence?

Cells like phagocytes, NK cells, fever.

3 phagocytes?

Neutrophils, macrophages, eosinophils.

What do NK cells do?

Kill sick or abnormal cells.

What do interferons do?

Slow viruses, alert cells.

What does the complement system do?

Helps destroy germs.

Why is inflammation good?

Stops infection, helps healing.

What is an antigen?

A molecule that triggers an immune response (e.g. virus, bacteria).

What is an antibody?

A Y-shaped protein that protects the body by binding to antigens.

What happens first when a pathogen enters?

Physical barriers are crossed; phagocytes are activated.

What is antigen presentation?

Phagocytes show part of the pathogen to activate T & B cells.

What makes specific immunity different?

Targets specific pathogens and needs exposure first.

Which cells are involved?

T cells and B cells (lymphocytes).

What do T cells do?

Use cell-mediated immunity to kill infected cells.

What do B cells do?

Use antibody-mediated immunity to produce antibodies.

What are 4 traits of specific immunity?

Specific, versatile, memory, tolerance.

3 types of T cells?

Cytotoxic, Helper, Suppressor.

What do cytotoxic T cells do?

Kill infected cells using perforin and toxins.

What do helper T cells do?

Signal other immune cells using cytokines.

What do suppressor T cells do?

Stop the response after infection is cleared.

What do memory T cells do?

Remember the antigen for faster future responses.

What do B cells become?

Plasma cells (make antibodies) or memory B cells.

What do antibodies do?

Bind to antigens to inactivate them.

What is an epitope?

Part of an antigen that triggers the response.

Why vaccinate?

It creates memory B cells for faster future response.

What’s the difference between IgM and IgG?

IgM acts fast but is weaker; IgG is stronger and lasts longer.

What’s a primary response?

First time fighting an antigen; slower.

What’s a secondary response?

Faster, stronger response due to memory B cells.

Difference between antigen and antibody?

Antigen triggers; antibody defends.

What links innate and adaptive immunity?

Antigen presentation.

Types of lymphocytes in adaptive immunity?

T cells and B cells.

Is adaptive immunity present at birth?

No – it develops after exposure.