Module 5 part 1

Is the immune system functional or anatomical?

Functional. The lymphatic system is its anatomical part.

Besides pathogens, what else does the immune system destroy?

Cancerous cells

What are the 2 primary lymphoid organs, and why are they primary?

Red bone marrow and thymus. They are where WBCs are produced and develop.

Name 5 secondary lymphoid organs or tissues.

Spleen, lymph nodes, tonsils, appendix, MALT (Peyer's patches), plus lymphatic vessels

What does the thymus do, and where is it?

Matures T cells. It is in the chest behind the sternum.

What does the spleen do, and where is it?

Filters blood, removes old RBCs, activates immune cells. It is on the left side of the abdomen.

What are Peyer's patches?

MALT in the small intestine (and bronchi) that defends mucosal surfaces

What are the 3 tonsils?

Palatine, pharyngeal, lingual

What makes a lymphoid organ different from a lymphoid tissue?

Organs have a connective tissue capsule

What are lacteals?

Lymphatic capillaries in the small intestine that absorb fat

How does lymph form?

Tissue pressure pushes interstitial fluid into lymphatic capillaries

Where do the lymphatic ducts drain?

Into the subclavian veins

Which duct drains most of the body, and into where?

The thoracic (left lymphatic) duct, into the left subclavian vein

How much of the body does the right lymphatic duct drain?

About 1/4 (the upper right part)

What is lymphadenopathy?

Swollen lymph nodes, usually from infection

What do lymph nodes do?

Filter lymph and mediate immune reactions

Which lines of defense make up innate immunity?

The 1st and 2nd

What makes up the 3rd line of defense?

T and B lymphocytes (adaptive, specific, with memory)

Which cell has both innate and specific (memory) functions?

NK cells

What do regulatory T cells do?

Suppress overkill, preventing excessive immune reactions

Which WBC is the most abundant, the first responder, and the shortest-lived?

The neutrophil

Basophils vs. mast cells?

Same job (histamine and heparin). Basophils are short-lived and in the blood. Mast cells are long-lived and in tissues.

What are microphages?

a small, short-lived white blood cell that acts as an early-responding phagocyte (a cell that "eats" or engulfs harmful particles) in the innate immune system

Neutrophils and eosinophils

Fixed vs. wandering macrophages?

Fixed ones settle in tissues. Wandering ones travel through lymphatic vessels.

What is an MHC

a large group of genes that code for surface proteins on cells, which help the immune system recognize "self" versus "foreign" substances (such as viruses and bacteria

What is the main job of dendritic cells?

Present antigens on MHC molecules to activate T cells

What 2 cell types do activated B cells become?

Plasma cells (antibodies) and memory B cells

Which WBCs come from the lymphoid line?

B cells, T cells, NK cells

What does an eosinophil kill?

Parasites (it is a parasitic phagocyte that kills eukaryotes)

What 2 properties make skin harmful to pathogens?

It is hydrophobic and acidic

What do mucus, cilia, and lysozyme each do?

Mucus traps, cilia sweep out, lysozyme kills

Name a chemical barrier enzyme and 2 other chemical barriers.

Lysozyme, plus stomach acid and defensins

What are defensins?

Antimicrobial peptides (a chemical barrier)

Besides skin and mucous membranes, what else counts as a barrier?

The microbiome

Name the 4 phagocytic cells of innate immunity.

Macrophages, dendritic cells, neutrophils, eosinophils

What causes fever?

Pyrogens (cytokines)

Which complement proteins are there?

C1 through C9

Which interferons do virus-infected cells release?

IFN-alpha and IFN-beta

What are the 2 jobs of IFN-alpha and IFN-beta?

Warn neighboring cells (antiviral proteins block viral replication) and activate NK cells

Which cells release IFN-gamma?

NK cells, macrophages, and CD4 T cells (helper and regulatory)

What does IFN-gamma do?

Activates other immune cells throughout the body

What is a MAC, and how does it kill?

A hollow protein channel in the pathogen's membrane. Water rushes in, contents rush out, and the cell lyses.

Which complement protein starts the cascade?

C3

What does C3b do?

Opsonization: it coats pathogens to tag them for phagocytosis

What do C3a and C5a do?

Trigger inflammation and recruit leukocytes (chemotaxis)

What are opsonins?

Proteins that coat pathogens so macrophages are drawn to them

What does the lectin pathway bind to?

Carbohydrates on pathogens

Name the 4 functions of complement.

Membrane destruction (MAC), inflammation, opsonization, chemotaxis

Do complement proteins need leukocytes to kill pathogens?

No. They can destroy pathogens on their own.

Cytotoxic T

Kills infected cells

Regulatory T

Prevents excessive immune reactions

NK cell

Kills abnormal cells, and has memory