Intro duction to immune system animal phys

Plasma Proteins: Albumin

Source: Liver

Function: Major Contributors to colloid osmotic pressure of plasma; carriers for various substances

Plasma Proteins: Globulins

Source: Liver and lymphoid tissue

Function: Clotting factors, enzymes, antibodies, carriers for various substances

Plasma Proteins: Fibrinogen

Source: Liver

Function: Forms fibrin threads essential to blood clotting

Plasma Proteins: Transferrin

Source: Liver & Other Tissues

Function: Iron transport

Key Cells of the immune system: Basophils and Mast cells

% of WBC’s in blood: Rare

Subtypes and nicknames: None

Primary functions: Release chemicals that mediate inflammation and allergic responses

Basophils specific:

-release histamine

-Inflammation

Classifications: Granulocytes

Key Cells of the immune system: Neutrophils

% of WBC’s in blood: 50-70%

Subtypes and nicknames: Called “polys” or “segs”. Immature forms called “bands” or “stabs.”

-ingest bacteria

-release cytokines

Primary functions: Ingest and destroy invaders

Classifications: Granulocytes, phagocytes

Key Cells of the immune system: Eosinophils

% of WBC’s in blood: 1-3%

Subtypes and nicknames: None

Primary functions: Destroy invaders particularly antibody coated parasites

-Allergic Reactions

-Parasitic diseases

Classifications: Cytotoxic cells, granulocytes(morphological), phagocytes

Key Cells of the immune system: Monocytes and Macrophages

% of WBC’s in blood: 1-6%

Subtypes and nicknames: Called the mononuclear phagocyte system

Primary functions: Ingest and destroy invaders, antigen presentation

Monocytes specific:

-Mature to macrophages

-Phagocytic

-APCs

Classifications: Antigen-presenting cells (APC), phagocytosis

Key Cells of the immune system: Lymphocytes and plasma cells

% of WBC’s in blood: 20-30%

Subtypes and nicknames: B lymphocytes Plasma Cells, T lymphocytes, Cytotoxic T cells, Helper T Cells, Natural killer cells

Primary functions: specific responses to invaders, including antibody production

-acquired immunity (lymphocytes)

Classifications: Antigen presenting cells (APC), Cytotoxic cells

Key Cells of the immune system: Dendritic Cells

% of WBC’s in blood: NA

Subtypes and nicknames: Langerhans cells, veiled cells

Primary functions: Recognize pathogens and activate other immune cells by antigen presentation. These guys don’t move, and need cells to activate it.

-Activate lymphocytes

Classifications: Antigen presenting cells (APC)

Composition of Blood

plasma, platelets, red blood cells, white blood cells

Steps in an immune system response

1. Detect and ID invader/foreign cells

2. Communicate, alarm, and recruit immune cells

3. Coordinate response among all participants

4. Suppress or destroy invader

Steps in an immune system response: cytokine signaling

How it works:

•A helper T cell (essential white blood cells that coordinate the body’s response to infections) releases IL-2 (Interleukine-2: a critical signaling cytokine that acts as a growth factor for T and B lymphocytes, essential for immune system homeostasis, activation, and tolerance) after recognizing an antigen from an APC (Antigen Presenting Cell).

•That same T cell expresses IL-2 receptors.

•Antigen-activated T cells produce IL-2 themselves, creating a positive feedback loop.

•IL-2 binds back to its own receptors, stimulating intracellular pathways (JAK-SAT, MAPK/Erk an Pi3K/Akt) promoting proliferation, differentiation and survival.

Antigen Presentation Cells involved:

APCs such as a macrophage (a large phagocytic cell found stationary in tissues, or as mobile white blood cells. Especially at sites of infection) phagocytizes  a foreign antigen (any substance that is foreign). The antigen is broken down into peptides

Antigen Presentation Key Communication:

APC presents antigen on MHC molecules → recognized by T cell receptor (TCR) → activates T cells.

Type: Contact dependent.

Inflammatory Response: Roles  and Players: General

Attract immune cells and chemical mediators to site of infection

Produce physical barrier to prevent infection from spreading

Promote tissue repair

Inflammatory Response: Roles  and Players: Histamines from mast cells

Swelling, edema, vasodilation (widening of blood vessels caused by the relaxation of smooth muscle in vessel walls, increases blood flow and lowers blood pressure)

Inflammatory Response: Roles  and Players: Interleukins

Fever, blood vessels more permeable to white blood cells

and proteins, acute-phase proteins

Inflammatory Response: Roles  and Players: Bradykinin

Pain and swelling

Inflammatory Response: Roles  and Players: Complement cascade

Membrane attack complex

Histamine Release and Action

•Mast cells release histamine into the local tissue.

•Histamine diffuses a short distance and binds to histamine receptors (H1, H2, H3, H4) on nearby target cells.

•Effects:

•Blood vessels dilate (vasodilation) → increased blood flow → redness and warmth.

•Capillary permeability increases → fluid leaks out → swelling (edema).

•Smooth muscle contraction in airways or gut → constriction.

•Immune cell recruitment → more white blood cells drawn to the site of infection or allergy.

What does the Neuro-Endocrine-Immune Interaction look like?

It looks like this

Granulocytes

Produced by the bone marrow into 3 different types of WBCs. (neutrophils, eosinophils, and basophils). These guys produced granules that they release to destroy pathogens.

High counts of this in the blood indicate the presence of pathogens, infection, or leukemia.