Innate Host Resistance Vet micro exam 3 Part 1

What must most pathogens overcome to infect a host?

•Overcome surface barriers and reach underlying tissues

•Overcome resistance by host: makes up immunity

•Nonspecific resistance

•Specific resistance

What is the challenge of the immune system?

Recognizes foreign substances or microbes and acts to neutralize or destroy them

Host defenses are?

A multilevel network of innate, nonspecific protections AND adaptive, specific protections

What are the three levels of host defense mechanisms?

•Three levels of defense:

•First line of defense

Any barrier that blocks invasion at the portal of entry

•Second line of defense

Innate, internalized system of protective cells and fluids

•Third line of defense

Acquired on an individual basis as each foreign substance is encountered by lymphocytes

What is the development of immunity?

Ability of host to resist a particular disease or infection

Most host defenses?

Overlap and are redundant in some of their effects. This assault force makes the survival of invading microbes unlikely

What is immunology?

•The study of all features of the body’s second and third lines of defense

•Study of the body’s response to infectious agents

Immune system as a network (3)

The immune system does not exist in a single, well-defined site it is a large, complex, diffuse network of cells and fluids that permeate every organ and tissue

•Promotes surveillance and recognition process that help screen the body for harmful substances

•Activities of one compartment must be communicated to other compartments

What is the lymphatic system?

A compartmentalized network of vessels, cells, and specialized accessory organs

What does the lymphatic system provide?

Provides a route for the return of extracellular fluid to the circulatory system

What does the lymphatic system contain?

Contains lymphatic fluid, which transport WBCs and other materials

What happens with waste in an immune response?

When the body starts an immune response any waste will go into the lymphatic system and get excreted through the lymphatic system

Primary lymphatic organs (location and function)

Red bone marrow - internal matrix of long bones, b cell maturation (red blood cells)

Thymus - originates in the lower neck two lobes that fuse together, produces T cells

What are primary lymphatic organs sites of?

Sites of immune cell birth and maturation

What are secondary lymphatic organs sites of?

Sites of immune cell activation, residence, and functioning

What are the secondary lymphatic organs?

•Lymph nodes

•Spleen

•Various lymphoid tissues

Whole blood consists of:

Blood cells, plasma, serum

What are blood cells?

Formed elements suspended in plasma

What is plasma?

Clear, yellowish fluid

What is serum?

•Essentially the same of plasma, except that it is the clear fluid from clotted blood

•Lacks clotting factors

What is hematopoiesis?

Production of blood cells

What are the cells of the immune system?

•Granulocytes

•Mast cells

•Monocytes and macrophages

•Dendritic cells

•Lymphocytes

Each has a specialized role in defending host

•Leukocytes

White blood cells

Both innate and adaptive immunity

What is the shape of granulocytes?

Irregularly-shaped nuclei with two to five lobes

What is in the cytoplasm of granulocytes?

Granules with reactive substances that kill microbes, and enhance inflammation

What are the three types of granulocytes?

•Basophils

•Eosinophils

•Neutrophils (most concerned in this class)

Polymorphonuclear neutrophil PMN

Neutrophils (2)

first to arrive 

highly pathogenic

What do neutrophils do?

•Circulate in blood then migrate to sites of tissue damage

•Kill ingested microbes with lytic enzymes and reactive oxygen metabolites contained in primary and secondary granules

Mast cells (2)

•Bone marrow-derived cells

•Differentiate in blood and connective tissue

What do mast cells contain?

Contain granules containing histamine and other pharmacologically active chemicals

What role do mast cells play?

•Play important role in development of allergies and hypersensitivities

Monocytes and Macrophages (1)

Highly phagocytic

Monocytes (2)

•Are mononuclear phagocytic leukocytes

•After circulating for ~8 hours, mature into macrophages

Macrophages (3)

•Larger than monocytes, reside in specific tissues, highly phagocytic

•Have a variety of surface receptors

•Bind pathogen associated molecular patterns

Monocytes can become?

Osteoclast, macrophage, dendric cell

What are dendritic cells?

Heterogenous group of cells with neuron-like appendages

Dendritic cells (4)

•Present in small numbers in blood, skin, and mucous membranes of nose, lungs, and intestines

•Also express pattern recognition receptors

•Contact, phagocytose, and process antigens

•Display foreign antigens on their surface

What are lymphocytes?

•Major cells of the adaptive immune system

•Mahor populations include T cells, B cells, and natural killer (NK) cells

B and T lymphocytes (2)

•Differentiate in bone marrow from stem cells

•Are only activated by binding of specific antigens onto lymphocyte surface receptors

Where do B lymphocytes mature?

In bone marrow

Where do B lymphocytes circulate?

In blood

Where can B lymphocytes settle?

In lymphoid organs

B lymphocytes are called plasma cells and produce antibodies after?

Maturation and activation

Where do T lymphocytes mature?

In thymus

T lymphocytes can?

Remain in thymus, circulate in blood, or reside in lymphoid tissue

Like B cells, T lymphocytes require?

Antigen binding to surface receptors for activation and continuation of replication

Activated T cells?

Cytokines, chemicals that have effects on other cells

T lymphocytes secrete?

Cytokines, chemicals that have effects on other cells