immune and lympathetic system bio exam

Definition: A network of organs, vessels, and structures mediating important physiological functions.
- Functions:
- Remove excess fluids, fats, and wastes from body tissues.
- Circulate hormones.
- Mediate immunity by producing, maturing, and circulating lymphocytes.

Lymphatic Capillaries:
- Function: Pick up larger molecules, cells, and excess fluid from the interstitial space.
Lymph:
- Definition: The solution flowing through lymphatic vessels and nodes.
Lymph Nodes:
- Purpose: Filtration sites that remove pathogens and cellular debris.
Lymphoid Organs:
- Definition: Organs composed of lymphatic tissue that serve specific functions.

Fluid Origins:
- Interstitial fluid derived from osmosis and diffusion across tissues and capillary beds.
- Composition: Contains intracellular fluid (ICF) and plasma.
Flow:
- Lymph flows from lymphatic capillaries to lymphatic ducts, eventually draining into the systemic circulation via the superior right/left subclavian vein.

Structure:
- Lymphatic ducts are large vessels such as the thoracic duct and right lymphatic duct.
Mechanisms Maintaining Flow:
- Autorhythmic peristalsis (smooth muscle contraction).
- Valves (similar to veins).
Lymphatic Capillaries:
- Features: Small, thin vessels with porous junctions facilitating the diffusion of fluid, proteins, fats, and white blood cells.

Pathway Details:
- Lymph from capillaries flows through lymphatic ducts, passing through lymph nodes along the way.
- Ends up at the thoracic duct or right lymphatic duct before entering the systemic circulation.
Lymph Node Functionality:
- Filters 99% of antigens and removes pathogens via phagocytic cells.
Conditions:
- Infection results in enlargement due to increased lymphocyte production at germinal centers.

Definition: Organs, cells, and processes that mediate defense against disease-causing agents (pathogens).
Immunity Types:
- Innate (Non-specific) Immunity:
- Protects against a broad range of pathogens without targeting specific ones.
- Components include structural (skin, epithelial cells) and cellular (phagocytes, NK cells) agents.
- Adaptive (Specific) Immunity:
- Acquired following pathogen exposure, facilitates targeted responses and immunological memory via lymphocyte-mediated recognition and defense.

Mediators:
- Non-cellular agents:
- Skin, gastric acid, antimicrobial peptides, interferons, fever.
- Cellular agents:
- Phagocytes and Natural Killer (NK) Cells.

Lymphocytes:
- B cells and T cells play critical roles in immune responses.
- Antigens:
  - Cell-surface proteins that act as recognition markers for the immune system.
  - Classified into self and non-self antigens.
- Antibodies:
  - Proteins produced by B lymphocytes that tag specific antigens.

Pathogen Behavior:
- Infection triggers both innate and acquired immunity through chemical changes in the intracellular and extracellular environment triggered by pathogen secretions and host responses.

Mechanism:
- Non-specific cells engulf and remove cellular debris/pathogens while triggering inflammation.
- Key phagocytes include neutrophils, monocytes, and specific organ-associated phagocytes (Kupffer cells, microglia, alveolar macrophages).
Extravasation:
- Process of leukocytes exiting circulation into affected areas through temporary gaps between vessel wall cells triggered by cellular damage.

Functionality:
- NK cells provide innate protection against viruses by secreting perforin, which forms pores in pathogen membranes and allows granzymes to enter and induce apoptosis.
- Effective particularly against pathogens with cell membranes.

Description:
- Short polypeptides that inhibit viral replication directly through the induction of intracellular antiviral enzymes and indirectly by activating NK cells and macrophages.

Characteristics:
- Defined by body temperature exceeding 37˚C (98.6 ˚F) induced by pyrogens.
Physiological Effects:
- Increased metabolism, heat production, and cutaneous vasoconstriction.
- Promotes interferon production, enhances neutrophil activity, and reduces plasma iron levels, hindering pathogen metabolism.

Branches:
- Humoral Immunity: Involves antibody production and action.
- Cell-mediated Immunity: Involves T-cells and does not utilize antibodies.
Key Lymphocytes:
- B-Cells: Produce antibodies and retain memory of pathogens.
- T-Cells: Various functions including the direct destruction of infected cells and activation of other immune cells.

Step 1: Recognition
- Mediated by T-lymphocytes recognizing foreign antigens on antigen-presenting cells (APCs) such as macrophages, dendritic cells, and B-cells.
Step 2: Sensitization
- Involves Major Histocompatibility Complex (MHC) proteins presenting non-self antigens to activate T-cells; classified as Class 1 MHC and Class 2 MHC for different T-cell activation.
Step 3: Activation
- Lymphocyte binds to MHC + non-self antigen complex leading to activation and proliferation.
Helper T-cells (Th Cells): Work by stimulating B-cell function and activity of cytotoxic T-cells.
Cytotoxic T-cells (Tc Cells): Attack and induce apoptosis of virus-infected or cancerous cells.
Memory T-cells (Tm cells): Facilitate immune response upon re-exposure.
Suppressor T-cells (Ts Cells): Inhibit immune response to maintain tolerance towards self-antigens.

Mechanism:
- Mediated by antibodies from B-lymphocytes, inactive until activation by antigens and T-cells. Upon activation, differentiate into plasma cells (antibody producers) and memory B-cells (long-term response preparation).

Description:
- Exaggerated immune response to typically harmless allergens.
- Involves helper T-cell activation and sensitization leading to severe responses upon re-exposure to the allergen, primarily through histamine release.

Overview:
- Integration of innate (non-specific) and adaptive (specific) immune mechanisms to produce a comprehensive response against pathogens.
- Activation involves T-cells, B-cells, and various immune effector cells in both humoral and cell-mediated immunity, with mechanisms ensuring both recognition and elimination of pathogens effectively.