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The Immune System, Hormones and the Endocrine System (Chapter 45…

- - - - Acquired immunodeficiency syndrome (AIDS)- is a viral replication and cell death triggered by the virus lead to the loss of helper t cells, impairing the hormonal and cell-mediated immune response
      - Autoimmune disease- the immune system is active against particular molecules of the body
    - - Monoclonal antibodies- antibodies prepared from a single clone of B cells grown in culture
      - Passive immunity- antibodies in the recipient are produced by another individual
      - Active immunity- the defense that arise when a pathogen prompts an immune response
      - Immunization- the use of antigens artificially introduced in the body to generate an adaptive immune system
      - Cytotoxic T cell- the toxic proteins to kill cells infected by viruses or other intracellular pathogens
      - Antigen-presenting cell- can be a dendritic cell, macrophage, or B cell
      - Helper T cell- activates humoral and cell-mediated response
      - Cell-mediated immune response- specialized T cells destroy infected host cells
      - Humoral immune response- antibodies help neutralize or eliminate toxins and pathogens in body fluids
    - - Proliferation of B Cells and T Cells
        
        Secondary immune response- response that is faster that peaks 2-7 days after exposure, the concentration of specific antibodies in the blood is the main difference between the two
        
        Primary immune response- the effector cells formed by clones of lymphocytes after an initial exposure to an antigen, peak after 10-17 days
        
        Clonal selection- an encounter with an antigen selects which lymphocyte will divide to produce a clonal population of thousands of cells specific for a particular epitope
        
        Memory cells- long-lived cells that can give rise to effector cells if the same antigen is encountered later in the animal's life
        
        Effector cells- short-lived cells that take effect immediately against the antigen and any pathogens producing the antigen
      - Antigen Recognition by T Cells
        
        Antigen presentation- each antigen fragment binds to an MHC molecule, which transports the bound peptide to the cell surface
        
        Major histocompatibility complex (MHC) molecule- the host protein that displays the antigen fragment on the cell surface
      - Antibody- a secrete protein also, known as immunoglobulin (Ig), antibodies provide a direct defense against pathogens in body fluids
      - Each B cell antigen receptor is a Y-shaped protein consisting of four polypeptide chains: two identical heavy chains and two identical heavy chains
    - - Epitope- the small, accessible portion of an antigen that bind to an antigen receptor
      - Antigen receptor- B cell or t cell binds to an antigen, such as a bacterial or viral protein, via protein called an antigen receptor
      - Antigen- any substance that elicits a B or T
      - B cells- lymphocytes that remain and mature in the bone marrow
      - T cells- lymphocytes mature into T cells
      - Thymus- an organ in the thoracic cavity above the heart
      - Lymphocytes- originate from stem cells in the bone marrow, T cells and B cells are types of blood cells
  - - - Inflammatory Response
        
        Histamine- triggers nearby blood vessels to dilate and become more permeable
        
        Inflammatory response- a set of events triggered by signaling molecules released upon injury or infection
      - Antimicrobial Peptides and Proteins
        
        Complement system- consist of roughly 30 proteins in blood plasma and they circulate in an inactive state and are activated by substances on the surface of many pathogens
        
        Interferons- are proteins that provide innate defense
      - Natural killer cells- cells that circulate throughout the body and detect the abnormal array of surface proteins characteristic of some virus-infected and cancerous cells
      - Dendritic cells- mainly populate tissues, such as skin, that contact the environment, they stimulate adaptive immunity against pathogens that they encounter
      - Macrophages- large phagocytic cells, migrate throughout the body, whereas others reside permanently in organs and tissues where they are likely to encounter pathogens
      - Neutrophils- circulate in the blood, are attracted by signals from infected tissues and then engulf and destroy the infecting pathogens
      - Toll-like receptor (TLR)- a mammalian recognition protein similar to the Toll protein of insects
    - - Phagocytosis- ingest and break down microorganisms
      - Lysosomes- an enzyme that breaks down bacteria cell walls, further protects the insect digestive system
- - - - Local regulators- molecules that act over short distances, reach their target cells by diffusion, and act on their target cells in seconds or milliseconds
      - Paracrine signaling- target cells lie near the secreting cell
      - Autocrine signaling- the secreting cells themselves are the target cells
      - Prostaglandins- promote inflammation and the sensation of pain in response to injury
      - Neurotransmitters- that diffuse a very short distance and bind to receptors on the target cells
      - Neurohormones- diffuse from nerve cell into the bloodstream, many regulate endocrine signaling
      - Pheromones- chemicals that are released in the external environment
      - Nitric oxide (NO)- a gas, functions in the body as both a local regulator and a neurotransmitter
      - Signal transduction- the chain of events that converts the extracellular chemical signal to a specific intracellular response
      - Epinephrine (adrenaline)- the adrenaline glands that lie atop the kidneys secrete a water-soluble hormone, which provides the body with extra fuel
      - Endocrine glands- testes in males and ovaries in females, help with sex characteristics
  - - - Thyroid hormone- act on nearly every cell in the body. They act to increase the basal metabolic rate, affect protein synthesis, help regulate long bone growth (synergy with growth hormone) and neural maturation, and increase the body's sensitivity to catecholamines (such as adrenaline) by permissiveness.
      - Thyroid gland- produces hormones that regulate the body's metabolic rate as well as heart and digestive function, muscle control, brain development, mood and bone maintenance. Its correct functioning depends on having a good supply of iodine from the diet.
  - - - Testosterone- plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair
      - Estrogen- is development of female secondary sexual characteristics. These includes breasts, endometrium, regulation of the menstrual cycle etc. In males estrogen helps in maturation of the sperm
      - Progesterone- hormone secreted by the female reproductive system that functions mainly to regulate the condition of the inner lining (endometrium) of the uterus.