UWEC BIOL 314 Lecture Exam 2

Immune System

Cell population that inhabits all organs and defends body from agents of disease

Lymphatic System - Fluid Recovery

15% of water and half of the plasma proteins enter the lymphatic system and are then returned to the blood

Lymphatic System - Immunity

Excess filtered fluid picks up foreign cells and chemicals from tissues

Lymphatic System - Lipid Absorption

Lacteals, in the small intestine, absorb dietary lipids that aren't absorbed by blood capillaries

Lymphatic System - Lymph

The recovered fluid

Lymphatic System - Lymphatic Vessels

Transport the lymph

Lymphatic System - Lymphatic Tissues

Composed of aggregates of lymphocytes and macrophages that populate organs

Lymphatic System - Lymphatic Organs

- Where defense cells are mostly concentrated

-Separated from surrounding organs by CT capsules

Lymphatic Vessels - Right Lymphatic Duct

Receives lymph from right arm, right side of head and thorax; empties into right subclavian vein

Lymphatic Vessels - Thoracic Duct

Larger and longer, begins as a prominent sac in abdomen; receives lymph from below diaphragm, left arm, left side of head, neck, and thorax; empties into left subclavian vein

Lymphatic Vessels - Subclavian Veins

Collect from thoracic duct

Lymphatic Cells - Natural Killer (NK) Cells

Large cells that destroy bacteria, transplanted tissue, host cells infected with viruses or that have turned cancerous

Lymphatic Cells - T Lymphocytes (T cells)

Mature in thymus

Lymphatic Cells - B lymphocytes (B cells)

Activation causes proliferation & differentiation into plasma cells that produce antibodies

Lymphatic Cells - Dendritic cells

Alert immune system to pathogens that have breached body surface

Lymphatic Cells - Reticular cells

Branched stationary cells that contribute to the stroma of a lymphatic organ

Lymphatic Tissues - Lymphatic (lymphoid) tissue

Aggregations of lymphocytes in CT of mucous membranes and various organs

Lymphatic Tissues - Diffuse lymphatic tissue

Simplest form

- Not clustered

Lymphatic Tissues - Lymphatic nodules

Dense masses of lymphocytes and macrophasges that congregate in response to pathogens

Lymphatic Organs - Primary lymphatic organs

Red bone marrow and thymus

- Where T & B cells become immunocompetent

Lymphatic Organs - Secondary lymphatic organs

Lymph nodes, tonsils, and spleen

Lymph Nodes

- Most numerous lymphatic organs

- Cleanse the lymph

Metastasis

Cancerous cells break free from original tumor, travel to other sites of body & establish new tumors

Tonsils

Patches of lymphatic tissue located at the entrance to the pharynx

Spleen

Body's largest lymphatic organ

Spleen - Red pulp

Sinuses filled with erythrocytes

Spleen - White pulp

Lymphocytes, macrophages surrounding small branches of splenic artery

Spleen functions

Removal, storage, initiation

Pathogens

Agents capable of producing disease

First line of defense

Skin and mucous membranes

Second line of defense

Several innate defense mechanisms

- Leukocytes & macrophages, antimicrobial proteins, natural kilelr cells, inflammation, & fever

Third line of defense

Adaptive immunity | "memory"

Innate Immunity - Innate defenses

Guard equally against a broad range of pathogens

Innate Immunity - Adaptive immunity

Body must develop separate immunity to each pathogen

Innate Immunity - R0

For every infected person, how many new infections will they cause

External Barriers - Skin Acid mantle

Thin film of lactic and fatty acids from sweat & sebum that inhibits bacterial growth

External Barriers - Skin

Pathogens cannot infect dead cells

External Barriers - Mucous membranes Lysozyme

Enzyme destroys bacterial cell walls

Eosinophils

Guard against parasites, allergens, and other pathogens

Monocytes & Macrophages - Wandering macrophages

Actively seek pathogens

Monocytes & Macrophages - Fixed macrophages

Phagocytize only pathogens that come to them

Interferons

Secreted by certain cells infected by viruses

- No benefit to the cell that secretes them

Complement System - Inflammation

- C3a stimulates mast cells and basophils to secrete histamine and other inflammatory chemicals

- Activates and attracts neutrophils and macrophages

- Speeds pathogen destruction in inflammation

Complement System - Immune clearance

- C3b binds with antigen-antibody complexes to RBCs

- RBCs circulate through liver and spleen

- Macrophages of those organs strip off and destroy Ag-Ab complexes, RBCs unharmed

Complement System - Phagocytosis

Neutrophils and macrophages cannot phagocytize "naken" bacteria, viruses, or other pathogens

Complement System - Cytolysis

- C3b splits complement protein C5 into C5a & C5b

- C5b binds to enemy cell

-Attracts more complement proteins - membrane attack-complex forms

Inflammation - Cytokines

Small proteins that regulate inflammation and immunity

Inflammation - Heat

Results from hyperemia

Inflammation - Redness

Due to hyperemia, and extravasated RBCs in the tissue

Inflammation - Swelling (edema)

Due to increased fluid filtration from the capillaries

Inflammation - Pain

From direct injury to the nerves, pressure on nerves from edema

Inflammation - Neutrophile Behavior: Margination

Selectins cause leukocytes to adhere to blood vessel walls

Inflammation - Neutrophile Behavior: Diapedesis

Leukocytes squeeze between endothelial cells into tissue space

Inflammation - Neutrophile Behavior: Chemotaxis

Attraction to chemicals such as bradykinin and leukotrienes that guide them to the injury site

Characteristics distinguishing immunity from innate immunity

- Systemic effect: Throughout the body

- Specificity: immunity directed against a particular pathogen

- Memory: when reexposed to same pathogen, body reacts quickly

Forms of Adaptive Immunity - Cellular (cell-mediated) immunity

Lymphocytes directly attack and destroy foreign cells or diseased host cells

Forms of Adaptive Immunity - Humoral (antibody-mediated) immunity

Mediated by antibodies that do not directly destroy a pathogen but tag it for destruction

Forms of Adaptive Immunity - Natural active immunity

Production of one's own antibodies or T cells as result of infection

Forms of Adaptive Immunity - Artificial active immunity

Production of one's own antibodies or T cells as result of vaccination against disease

Artificial active immunity - Vaccine

Consists of dead or weakened pathogens that stimulate immune response without disease

Artificial active immunity - Booster shots

Periodic immunizations to stimulate immune memory to maintain a high level or protection

Forms of Passive Immunity - Natural passive immunity

Temporary immunity that results from antibodies produces by another person

Forms of Passive Immunity - Artificial passive immunity

Temporary immunity that results from the injection of immune serum (antibodies) from another person or animal

Antigen

Any molecule that triggers and immune response

Antigens - Epitopes

Certain regions of an antigen molecule that stimulate immune responses

Antigens - Haptens

Too small to be antigenic in themselves

Antibodies - Immunoglobulin (Ig)

A defensive gamma globulin found in blood plasma, tissue fluids, body secretions, and some leukocyte membranes

Antibody Classes - IgG

Monomer; constitutes 80% of circulating antibodies

Antibody Classes - IgA

Monomer in plasma; dimer in mucus, saliva, tears, breast milk, and intestinal secretions

Antibody Classes - IgE

Monomer; transmembrane protein on basophils and mast cells

Antibody Classes - IgM

Pentamer in plasma and lymph

Antibody Classes - IgD

Monomer; B cell transmembrane antigen receptor

Recognition - Antigen presentation

- APC encounters and processes an antigen

- Migrates to nearest lymph node

- Displays it to the naive T-cells

T Cell Activation

Successful contemplation will trigger clonal selection

Attack - Perforin and granzymes

Kill cells in the same manner as NK cells

Attack - Interferons

Inhibit viral replication

Attack - Tumor necrosis factor (TNF)

Aids in macrophage activation and kills cancer cells

Memory

Following clonal selection, some Tc and Th cells become T memory cells

Humoral Immunity

A more indirect method of defense than cellular immunity

Recognition - Triggers clonal selection

- B cell mitosis gives rise to a battalion of identical B cells programmed against the same antigen

- Plasma cells secrete antibodies at a rate of 2,000 molecules per second during their life span of 4 to 5 days

Humoral Attack - Agglutination

Antibody has 2 to 10 binding sites; binds to multiple enemy cells, immobilizing them from spreading

Humoral Attack - Complement fixation

IgM or IgG bind to antigen, change shape and initiate complement binding which leads to inflammation, phagocytosis, immune clearance, or cytolysis

Humoral Attack - Precipitation

Antibody binds antigen molecules; creates antigen-antibody complex that precipitates

Humoral Attack - neutralization

Antibodies mask pathogenic region of antigen

Humoral Memory - Primary immune response

Immune reaction brought about by the first exposure to an antigen

Senescence of the Immune System - Lymphocytes fail to mature

Decline of Thymus

Nasal Fossae

Right and Left halves of nasal cavity

The Nose - Vestibule

Beginning of nasal cavity; small, dilated chamber just inside nostrils

The Nose - Nasal Conchae

Chamber behind vestibule is occupied by three folds of tissue

- Superior, middle, and inferior nasal conchae

The Nose - Meatus

Narrow air passage beneath each concha

The Nose - Olfactory epithelium

Detects odors

The Nose - Respiratory Epithelium

Line rest of the nasal cavity except vestibule

The Nose - Erectile tissue

- Extensive venous plexus in epithelium of inferior concha

- Swells with blood every 30-60 minutes

- Preponderant flow of air shifts between the right and left nostrils once or twice an hour

Pharynx

Muscular funnel extending about 5 inches from the choanae to the larynx

Pharynx regions

- Nasopharynx: Receives auditory tubes and contains pharyngeal tonsil

- Oropharynx: Space between soft palate and epiglottis, contains palatine tonsils

Laryngopharynx: Epiglottis to cricoid cartilage, esophagus begins here

Larynx

- Cartilaginous chamber about 4 cm long

- Keeps food and drink out of airway

The larynx - Epiglottis

- Flap of tissue that guards the superior opening of the larynx

- Closes airway and directs food to esophagus behind it

The Larynx - Epiglottic cartilage

Spoon-shaped supportive plate in epiglottis; most superior one

The Larynx - Thyroid cartilage

- Largest, laryngeal prominence (Adam's Apple); shield-shaped

- Testosterone stimulates growth; larger in males

The Larynx - Cricoid cartilage

Connects larynx to trachea, ring like