Lymphatic and Innate Immunity

A comprehensive set of practice questions covering the lymphatic system's structure, various pathogens, and the mechanisms of innate and adaptive immunity.

What are the three primary functions of the lymphatic system?

1) Removes excess fluid from tissues, 2) filters fluid (lymph), and 3) acts as an early warning system for the body.

How is net filtration pressure defined in the context of the lymphatic system?

The difference between hydrostatic and osmotic pressure, where hydrostatic pressure is typically higher.

Where does lymph from the top right side of the body drain?

It drains from the right lymphatic duct into the junction of the right jugular and right subclavian veins.

Where does lymph from the top left side and bottom half of the body drain?

It drains from the thoracic duct into the junction of the left jugular and left subclavian veins.

What does MALT stand for, and which structures are included in it?

MALT stands for mucosal associated lymphatic tissue and includes the tonsils, Peyer’s patches, and appendix.

What are the functions of the Thymus and Red bone marrow?

The Thymus trains specific leukocytes, while the red bone marrow is the origin of all leukocytes and trains B-cells.

What is the characteristic structure of bacteria according to the notes?

Simple single-celled organisms that live in colonies with no organelles and are much smaller than human cells.

How are fungi described in comparison to bacteria and human cells?

Complex single-celled organisms that are smaller than human cells but larger than bacteria; they often use hyphae to connect.

How do many protists, such as those causing African Trypanosomiasis, infect humans?

Via insect vectors, such as the Tsetse fly.

Why is a virus particularly difficult for the immune system to find?

It is the size of a molecule (very small) and requires a host cell to replicate, turning the host cell into a factory for producing more virions.

What are the three types of barriers provided by the skin?

1) Mechanical barrier (keratinocytes and waterproof keratin protein), 2) Chemical barrier (salts, pH, and defensins), and 3) Biological barrier (normal flora).

What is the function of mucus membranes in the respiratory and gastrointestinal tracts?

Respiratory mucus membranes trap inhaled pathogens; gastrointestinal mucus protects digestive walls and decreases friction.

What are the three categories of internal innate defenses?

1) Inflammation & Fever, 2) Phagocytes & Natural Killer Cells, and 3) Antimicrobial Proteins.

What are the defining characteristics of adaptive (specific) immunity?

It is specific in what it destroys, systemic (defends the whole body), and has memory (attacks faster upon later encounters).

How do macrophages differ from neutrophils?

Macrophages remain in specific tissues, can eat whole colonies of pathogens, and act as antigen-presenting cells, whereas neutrophils roll through the vascular system and use diapedesis to enter tissue.

What are antigens?

Chemicals on the surface of cells or particles that the immune system recognizes as 'self' or 'non-self'.

What are the steps of phagocytosis?

1) Antigen identification, 2) creation of a phagosome (endocytosis), 3) fusion with a lysosome to make a phagolysosome, 4) destruction by chemicals, and 5) release of digested particles or antigen presentation.

How do Natural Killer (NK) Cells identify targets?

They look for the absence of chemical identification, specifically checking for MHC-1 receptors and a special inhibitory receptor.

What chemicals do activated Natural Killer cells release to destroy pathogens?

Perforins, which create holes in the cell membrane, and granzymes, which enter the pathogen to activate enzymes for apoptosis.

Define diapedesis and chemotaxis.

Diapedesis is the ability of neutrophils and monocytes to squeeze through capillary walls to enter tissue; chemotaxis is the ability of phagocytes to move within a tissue.

What are pyrogens?

Any chemicals the hypothalamus can detect as an indication of immune activity, such as interleukin or inflammatory mediators.

What core temperature range does the hypothalamus typically establish for the body?

Between $97-99$ degrees.

What are the three benefits of fever?

1) Pathogens do not grow as well at higher temperatures, 2) immune chemical reactions occur faster, and 3) the liver sequesters nutrients that pathogens need.

What is the function of the antimicrobial protein known as 'Complement'?

Free-floating proteins that bind to foreign cells to create holes (cell lysis), enhance inflammation, and make pathogens more visible to phagocytes.

What is the specific role of Interferon in the immune response?

It alerts cells in a tissue that a virus is present so they can interfere with the virus's ability to replicate.