Homeostasis and Response to Stress PDF

**Homeostasis** - the maintaining of balance between the body's internal and external environment - requires feedback systems to help regulate functioning of the body - internal environment of cells excretes their waste into external environment **Stress Response** - control sys...

**Homeostasis** - the maintaining of balance between the body's internal and external environment - requires feedback systems to help regulate functioning of the body - internal environment of cells excretes their waste into external environment **Stress Response** - control system mediates the physical, emotional, and behavioral reactions to stressors This involves the negative feedback system, opposes the stressor: 1. **Sensor**: detects change 2. **Integrator**: processes information from the sensor 3. **Effector**: system that sets the change back to normal; response Positive feedback system implements more instability rather than stability. **General adaptation syndrome (GAS)** - 3 step process describing how the body responds to exposure of a stressor **Local adaptation syndrome (LAS)** - Localized version of GAS - Body's attempt to minimize the reaction/ damage from stress to a smaller area of body **Both GAS and LAS** has 3 strep process: 1. **Alarm** - Sympathetic nervous system is stimulated and HPA axis; catecholamines and cortisol is released - \*[Body is preparing to deal with threat that was notified]\* **\*Fight or Flight response\*** - Part of alarm stage; response triggered by a threat or stressor - Surge of hormones are released that prepares the body to confront or escape the danger - Sympathetic system works with endocrine system (hormones); parasympathetic system is suppressed [RESPONSE SYMPTOMS AND SIGNS]: **[Immune system]**: Repressed/inhibited **[Heart:]** -Hypertension (more blood is pumping) -Beats faster -Blood increases to muscles, decreases to organs **[Lungs:]** -Tachypnea (breathing faster) -Consuming more oxygen; more CO2 expelled [**Endocrine system**:] -pumps out: - Adrenaline, - Noradrenaline (neurotransmitter causing vasoconstriction), - Cortisol (glucocorticoid hormone; adrenal cortex) -produces fewer sex hormones and growth hormones **[Skin:]** -sweating **[Pancreas:]** -Hyperglycemia -pumps out glucagon by a-cells -produces less insulin **[Adrenal Medulla ]** [**(center of adrenal gland; on top of kidneys)**:] Releases catecholamines hormones: - epinephrine (adrenaline) - norepinephrine (noradrenaline) 2. **Resistance** - Body selects most effective channel of defense - Body recovers from the threat and cortisol levels drop 3. **Exhaustion** - The stressor becomes prolonged and overwhelms the body causing it to become depleted of recovering and/or defense - Coping was not successful if this occurs **Cortisol** - A glucocorticoid hormone - Source: adrenal cortex in the adrenal gland sitting on kidney - Increases actions of epinephrine (catecholamine) and glucagon - inhibits the release and actions of reproductive hormones and TSH (thyroid stimulating hormone) - produces a decrease in immune cells and inflammatory cells - this contributes to Immunity and Stress **Sympathomimetics** - drugs that mimic the functions of the sympathetic system **Endorphins** - body's natural painkiller - release during times of stress and in exercise - released from hypothalamus and pituitary gland **Immune response** Immunity - defined as the body's ability to defend against specific pathogen or foreign substances responsible for disease **[Lines of defense against pathogens]** Primary, secondary, and tertiary **Innate immunity** (nonspecific/natural) - the body's first line of defense; resistance we are already born with - occurs early and more rapidly in response to pathogens - **Primary** (non-specific physical and chemical defenses) - Barriers: skin, mucous membranes, stomach acid, lysozyme in tears - Expulsion: coughing, sneezing, vomiting, diarrhea - **Secondary** (innate/natural immunity) - Macrophages, neutrophil, eosinophils, basophils, monocytes - Complement system- group of proteins that help fight off infection, viruses, bacteria, and heal injury (cytokines and chemokines) **Adaptive immunity**(specific/acquired) - the delayed (3^rd^ ) line of defense unless the host has been previously exposed; developed after antigen exposure - **Tertiary** (adaptive/acquired immunity) - Cellular/ cell-mediated immunity (cytotoxic) (intracellular) - T lymphocytes - Matures in thymus gland - Kills intracellular pathogens (infected and cancerous cells) directly - Produce cytokines which help activate other immune cells - Develop receptors that recognize viral peptides on surface of infected cells and signal destruction of the cell - Immunocompetence: T cells have acquired ability to recognize and respond specifically to foreign substances/antigens - Immunocomp. Develops during embryonic life but not fully established until after birth - humoral immunity (antibodies)(extracellular) - B Lymphocytes - Matures in bone marrow - Defenses against extracellular microbes and their toxins - transform into plasma cells that secrete antibodies after exposure to antigen - produces antibodies that bind to and destroy pathogens **Both Innate and Adaptive immunity** - have Dendritic cells (DCs) which serves as a communication link between the two immune responses through the release of chemokines and cytokines - innate immune cells communicate to B and T lymphocytes about invading to activate adaptive immunity - other immune cells are then recruited as a defense Passive acquired immunity When a person receives antibodies from another source, rather than producing through their own immune system - ex: breast milk, placental transfer Antigen A foreign substance or molecule to the body - When introduced to a cell, it triggers the production of antibodies from B lymphocytes leading to it being destroyed - Recognized by specific receptors on lymphocytes and by antibodies secreted by the B lymphocyte when antigen is present - ANTIGENS CAN TAKE FORM OF ANY FOREIGN SUBSTANCE (ex: bacteria, virus, fungi, etc.) Blood Group Antigens - Most important antigens in the blood (on surface of erythrocytes) - A, B, AB, O, ABO - MATERNAL FETAL HEMOLYTIC DISEASE - Blood disorder where mother's blood is incompatible with her fetus's - Most common: Rh- mom and Rh+ fetus - 85% Rh positive - 15% Rh negative Other Defenses Inflammatory response Local response, vascular reaction, triggered by mast cells (WBCs that respond to immune and allergic reactions) Clinical manifestations: - Redness, heat, pain, swelling, loss of function Pyrogenic (fever) response Fever producing reaction caused by pyrogens - Substances that can contaminate medicines, vaccines, and other products - PYROGENIC PATHWAY: - A process where activated macrophages releases pyrogenic cytokines (proteins; producing fever) Interferons - are cytokines (anti-inflammatory proteins secreted by cells of innate and adaptive immune systems) that protect the host against viral infections - plays a role in influencing the inflammatory response - proteins released from virus infected cells; bind to nearby uninfected cells; the uninfected cell releases an enzyme that prevents viral replication; when the virus infects the cells, replication of the virus is prevented Major Histocompatibility Complex (MHC) - allows the body to decipher between antigens on the surface of the cells that belong to the host and those that don't - allows for adaptive immunity to function properly - also called human leukocyte antigens Antigen-presenting cells - help bridge with communication innate and adaptive immunity systems - also known as dendrite cells - responsible for activating T lymphocytes Two phases of antibody-mediated response to antigen PRIMARY PHASE - IgM marks primary response - Host cell is exposed to antigen; proliferation of Igs neutralize the invader SECONDARY/ AMNESTIC RESPONSE - IgG marks secondary response - A second exposure to same antigen initiates increases in levels of IgG immunoglobulin as secondary response Immunoglobulins Antibodies/protein molecules - when B cells mature to plasma cells they produce these specific proteins IgG - most abundant of all Igs - possesses antiviral, antibacterial, and antitoxin properties - present in all bodily fluids and readily enters tissues - ONLY ONE capable of crossing placenta for passive immunity to fetus - SECONDARY immune responder IgA - Found in tears, saliva, and breast milk - Primarily found in secretions IgM - First antibody produced by the developing fetus and by immature B cells - Responsible for the primary immune response - Forms antibodies to ABO blood antigens - LARGEST and FIRST responder IgE - Causes symptoms of allergic reactions - Binds to basophils and mast cells in hypersensitivity reactions IgD - Found in skin and digestive and respiratory tracts T cells; CD4 CELLS; CD8 CELLS CD4 CELLS - T helper cells - Cell mediated immunity and antibody-mediated immunity - Influences all other immune cells CD8 CELLS - Cytotoxic T cells - Directly attacks an antigen Immunization Vaccine - A weakened virus - Cannot cause disease - The body builds specific Igs against the vaccine because it thinks it is an antigen Active acquired adaptive immunity - **Long-term immunity** - Patient contracts a disease and develops Igs and recovers - Or Patient is given a vaccine Passive acquired adaptive immunity - **Short term immunity** - Injection of premanufactured immunoglobulins - Body passively accepts them and does not have to manufacture them - Administered when patient needs immunity IMMEDIATELY Hypersensitivity Type 1: immediate hypersensitivity - an allergic reaction - ex: anaphylaxis Type 2: cytotoxic - Antibodies bind to antigens on surface of a person's own cells leading to destruction of those cells - Ex: blood transfusion reaction, hemolytic disease of newborn, myasthenia gravis Type 3: immune complex deposition - Antigen-antibody complexes form and deposit into various tissues leading to inflammation and damage - Ex: systemic lupus, rheumatoid arthritis Type 4: delayed hypersensitivity - Delayed allergic reaction - Ex: contact dermatitis, poison ivy rash HIV: HUMAN IMMUNODEFICIENCY VIRUS - ATTACKS CD4 CELLS AND MACROPHAGES - HIV slowly debilitates T cell and B cell immunity - Routes of transmission: - Sexual activity - Blood - Transplants - Saliva (open mouth wounds) - Transplacenta - Breast milk - High risk individuals - IV Drug abusers - MSM - Unprotected sex practicers - ACUTE HIV INFECTION - Flu-like symptoms after 2 weeks of contracting - HIV RNA LEVEL - Earliest test to detect HIV - Measures viral load in blood - HIV antibody - Formation of antibody take a prolonged time to develop - Between 2 weeks to 6 moths - ELISA/ WESTERN BLOT TESTS: test for HIV antibody - "Seronegative patient" at window period - Time from contraction of virus to antibody development Blood levels of CD4 CELLS and HIV As HIV particles multiply, CD4 cells decrease - 1,200 CD4 cells to 200 CD4 cells - Virus particles increase - Cd4 levels decrease - Increased infection vulnerability HAART for treatment HIV PrEP is antiretroviral medication AIDS diagnosis - 200 CD4 CELLS - HIV ANTIBODY - PRESENCE OF OPPORTUNISTIC INFECTION