Introduction to the Immune System

Introduction to the Immune System

• Innate and Acquired immunity are the two divisions of the immune system.
• The innate defenses have 3 lines: physical, chemical and bloodborne

Lines of Innate Defense

• The 1st line of defense (physical) includes mucosal tissues, urine, hair, vomiting, and diarrhea
• Skin is the most important physical barrier
• The 2nd line of defense (chemical) includes saliva, gastric juices, sebum, lysozyme, skin acidity, and hyaluronic acid
• The 3rd line of defense (bloodborne) includes inflammation, NK cells/Interferon, complement activation, and phagocytosis/degranulation

Innate vs Acquired Immunity

Innate Immunity

• Fast response
• 3 lines of defense
• Present from birth
• No memory
• Utilizes neutrophils, eosinophils, basophils, and NK cells

Acquired Immunity

• Slow response
• Exposure-based
• Retains memory
• Pathogen and antigen specific
• Utilizes T cells and B cells

Cells and Processes in Innate Response

• Basophils release histamine, playing a role in allergic reactions and inflammation
• Complement System consists of blood proteins forming holes in bacterial cell walls
• Eosinophils are white blood cells killing large foreign cells, immobilizing and killing parasites, involved in allergic reactions, and stimulates macrophages
• Interferon is a cytokine that interferes with viral replication
• Macrophages are large cells ingesting bacteria and foreign material, assisting T cells in identifying antigens and presenting antigens
• Mast Cells release histamine and other inflammatory/allergic substances
• NK (Natural Killer) Cells are white blood cells recognizing and killing abnormal cells
• Neutrophils are white blood cells ingesting and killing bacteria and foreign material

Immune Organs & Innate Immunity

• Be able to label diagrams of palatine tonsils, cervical lymph nodes, axillary lymph nodes, inguinal lymph nodes, right lymphatic duct, thoracic duct, and cisterna chyli
• Physical, chemical, and bloodborne aspects are parts of the innate immune system

Inflammation

• Caused by tissue injuries, stimulates the release of mast cell granules including histamine, leukotrienes, and prostaglandins.
• Histamine and prostaglandins cause vasodilation, resulting in swelling, heat, and redness
• Four steps of inflammation include heat, redness, swelling and pain
• Acute inflammation is a short-term inflammatory response
• Chronic inflammation is an ongoing or long-term inflammatory response
• Histamine and prostaglandins cause vasodilation
• Neutrophils, macrophages, eosinophils and basophils are for phagocytosis or degranulation.
• Mast cells release cytokines like histamine to start inflammation
• NK cells secrete IFN (Interferon), which interferes with viral replication

Acquired Immunity

• Primary response is the initial reaction of the immune system to a foreign substance (antigen)
• Secondary response is a faster, stronger reaction upon subsequent encounter with an antigen
• Primary disease is the original condition causing other health issues
• Immunological memory is the immune system's ability to recognize and respond effectively to encountered pathogens or antigens

MHC System

• The MHC system is how the immune system differentiates between self and nonself cells

MHC Class I

• Found on virtually every cell in the body (except RBCs)
• Presents "endogenous" antigens like viral fragments or tumor proteins
• Activates cytotoxic T cells

MHC Class II

• Found on B-cells, macrophages, and other antigen presenting cells
• Presents "exogenous" antigens like digested fragments of foreign cells
• Activates helper T cells

Endogenous & Exogenous Antigens and APCs

• Endogenous originates within a system or organism, while exogenous originates outside
• Main types of professional antigen-presenting cells (APCs) are dendritic cells, macrophages, and B cells
• CMI immunity utilizes T cells, while humoral immunity utilizes B cells
• APCs capture, process and display antigens, activating antigen-specific T cells
• Activated immune cells activate other immune cells via surface interactions and chemical messengers called cytokines, initiating and coordinating the immune response

T Cell Functions

T Helper (Th) Cells

• Coordinate the adaptive immune system
• Activate and direct other immune cells like B cells and cytotoxic T cells through cytokine release

Cytotoxic T Cells (CTLs)

• Directly kill infected, damaged, or cancerous cells

Regulatory T Cells (Tregs)

• Maintain immune system balance
• Suppress excessive immune responses and prevent autoimmune diseases

Plasma and Memory B Cells

• Plasma cells produce many antibodies
• Memory B cells divide to form plasma cells upon re-encountering the same antigen

Antibody Functions and Features

Functions

• Agglutination (binds pathogens together)
• Opsonization (enhances phagocytosis)
• Neutralization (inactivates pathogens and toxins)

Features

• Specificity (1 antibody = 1 antigen)
• Diversity (antibodies against a variety of antigens)
• Immunological memory (quick response to 2nd exposure)
• Immune Tolerance (self-cells/tissues are not attacked)

Antibody Classes

IgG

• Most abundant in blood
• Used in gamma globulin injections
• Transfers to fetus via placenta

IgM

• Largest antibody
• Produced in the first response to a new pathogen

IgA

• Found in mucosal secretions

IgE

• Involved in allergic reactions and anaphylactic shock

IgD

• Unknown function

Primary and Secondary Immune Responses

• Primary response is delayed/slow, with IgM antibody produced first
• Secondary response is super-fast/rapid, with IgG produced first, then low levels of IgM

Hypersensitivity

• Overreaction by the immune system
• Four types: Type I, Type II, Type III, and Type IV

Type I Hypersensitivity (Immediate)

• Response to a nonpathogenic antigen is immediate and involves IgE, mast cells, and histamine
• Nasal allergies and anaphylactic shock can result

Type II Hypersensitivity

• Involves IgG-mediated lysis of cells by complement proteins
• Involved in mismatched blood transfusions, transplantation rejections, and blood compatibility diseases

Type III Hypersensitivity

• Occurs with autoimmune diseases like systemic lupus erythematosus
• Soluble antigens and antibodies complex, precipitate, lodge in organs like the kidneys/joints, activating complement proteins and causing inflammation

Type IV Hypersensitivity (Delayed)

• First exposure is sensitization
• Subsequent exposure results in a secondary cellular response (tuberculin skin tests, contact sensitivity)

Autoimmune Diseases

• Know the autoimmune diseases, the target tissue, and the self antigens if known: multiple sclerosis, psoriasis, rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes mellitus, ulcerative collitis.

Leukemia

• Four types: Acute Leukemia, Chronic Leukemia, Myelogenous leukemia and Lymphocytic leukemia

Acute Leukemia

• Abnormal immature blood cells increase rapidly
• Requires aggressive, timely treatment

Chronic Leukemia

• Mature blood cells replicate/accumulate more slowly

Myelogenous leukemia

• Affects myeloid cells- give rise to red blood cells, white blood cells, and platelet producing cells

Lymphocytic leukemia

• Affects lymphoid cells (lymphocytes), which form lymphoid or lymphatic tissue

Lymphoma

• Cancer that begins in lymphocytes (T cells or B cells)
• Abnormal lymphocytes build up in lymph nodes and vessels

Hodgkin's Lymphoma

• Abnormal lymphocytes are called Reed Sternberg cells
• Usually from B cells and is often curable

Non-Hodgkin's Lymphoma

• Large group of cancers starting in lymphocytes
• Can grow quickly/slowly and form from B cells or T cells

Multiple Myeloma

• Cancer starting in plasma B cells
• Myeloma cells build up in bone marrow, forming bone tumors
• Nonfunctioning antibodies increase risk of infections, bone thinning/fractures, and kidney problems

The Respiratory System

Conducting Zone

• Organs/structures NOT directly involved with gas exchange (trachea, bronchial tree, primary bronchus, etc.)

Respiratory Zone

• Where gas exchange occurs (alveoli)

Functions of the Conducting Zone

• Provide a route for incoming and outgoing air
• Remove debris/pathogens from incoming air
• Warm and humidify air

Pathway of Air

• Air travels from the nares to alveoli during inhalation/exhalation

Functions of Pharynx

Nasopharynx

• Only an air passageway

Oropharynx

• Passageway for swallowed food and inhaled air

Laryngopharynx

• Passageway for food and air

Epiglottis

• Flexible elastic cartilage covering the trachea opening, allowing food to pass into the esophagus

Pleural Fluid

• Reduces friction between pleural layers to prevent trauma during breathing

Parts of the Larynx

• The three parts include thyroid cartilage, epiglottis, cricoid cartilage
• Thyroid cartilage is the largest cartilage piece (Adam's apple)

Boyle's Law

• Know Boyle's law (equation) of volume and pressure and be able to work a simple problem.

Breahing

• Know characteristics that most influence breathing must be known

Respiratory Cycle

• Respiratory cycle is one sequence of inspiration and expiration

Muscles Controlling Breathing

• Diaphragm and the external intercostal muscles are the two muscle groups involved

Respiratory Volume vs Respiratory Capacity

Respiratory Volume

• Varying volumes of air moved or associated with lungs at a given point in the respiratory cycle

Respiratory Capacity

• Combination of two or more volumes describing air amount in the lungs

Respiratory Volumes & Capacities

Tidal Volume (TV)

• Amount of air normally entering lungs during quiet breathing (~500 mL)

Expiratory Reserve Volume (ERV)

• Amount of air forcefully exhaled past normal tidal expiration (up to 1200 mL for men)

Inspiratory Reserve Volume (IRV)

• Extra volume brought into lungs during forced inspiration after tidal inspiration

Residual Volume (RV)

• Air left in lungs after exhaling as much air as possible (prevents alveoli collapse making breathing easier)

Total Lung Capacity (TLC)

• Sum of all lung volumes (TV, ERV, IRV, RV)
• Total air a person can hold in lungs after a forceful inhalation (~6000 mL for men, ~4200 mL for women)

Vital Capacity (VC)

• Air amount a person can move into/out of lungs
• Sum of TV, ERV, IRV (~4000-5000 mL)

Inspiratory Capacity (IC)

• Maximum air amount inhaled past normal tidal expiration
• (Sum of tidal volume and inspiratory reserve volume)

Functional Residual Capacity (FRC)

• Air amount remaining in the lung post a normal tidal expiration
• (Sum of expiratory reserve volume and residual volume)

The Brain and Breathing

• Know the definition of respiratory rate and what part of the brain controls respiration rate.

Simple Diffusion

• Know what simple diffusion is.

Functions of Hemoglobin

• Know the functions of hemoglobin & the heme group.

CO2 Transport

• Know the 3 mechanisms for transporting CO2 in the blood.

Respiratory Diseases

• Review the respiratory diseases and basic knowledge of what happens in each disease.

Digestive Organs & Processes

• Be able to label the digestive organs of the body

Digestion Steps

• Know the 6 steps of digestion in order and what peristalsis is

Small Intestine

• Know the 3 parts of the small intestine

Liver

• Know the Function of hepatocytes, bile, bilirubin

Pancreatitis

• Know what pancreatitis is & what causes it, function of gallbladder

Chemical Digestion

• Know the enzymes & what they break down should be known
  • Carbohydrates: amylase, sucrase, lactase
  • Proteins: peptidase
  • Lipids: lipase
  • Nucleic acids: nuclease

Transport

• Know how passive diffusion, facilitated diffusion, & active transport work

Digestive Disorders

• Know the digestive disorders & their basic characteristic