Presentation on theme: "Disruption of Homeostasis. Disease Pathos (Greek – ΠΑΘΟΣ ): Rare suffering; the quality in something experienced or observed which arouses feelings of."— Presentation transcript:
Disruption of Homeostasis
Disease Pathos (Greek – ΠΑΘΟΣ ): Rare suffering; the quality in something experienced or observed which arouses feelings of pity, sorrow, sympathy, or compassion. Passion (compassion) comes from the same root word. Pathology is the study of disease, and disease = a lack of comfort.
Disease Disease results from a lack of homeostasis. Factors that disrupt homeostasis are called stressors. Fever or chilling – really bad for an endotherm like us. Dehydration – a lack of water Bleeding – loss of blood volume Starvation – lack of food Anoxia – lack of oxygen Septicemia – blood infection Trauma – damage to the body Diabetes – glucose regulation
Disease The pancreas secretes hormones that maintain glucose homeostasis. Glucagon increases blood glucose levels: Insulin reduces blood glucose levels:
Disease Diabetes mellitus is caused by a deficiency of insulin or a decreased response to insulin in target tissues. It is marked by elevated blood glucose levels. Type I diabetes is an autoimmune disorder in which the immune system destroys pancreatic beta cells. Type II diabetes involves insulin deficiency or reduced response of target cells due to change in insulin receptors.
Disease Type 1 diabetes Usually starts in childhood and accounts for % of all diagnosed cases of diabetes. People with type 1 diabetes produce little or no insulin and must use insulin daily to control their condition (maintain homeostasis). Injection sites
Disease Type 2 diabetes Usually starts in adulthood, but it is being diagnosed more often in children because of greater childhood obesity. It accounts for % of cases. People with type 2 diabetes are resistant to the insulin the body makes. It is controlled with diet and exercise, and sometimes oral drugs or insulin.
Disease Dehydration – a lack of water (our skin is not water-tight like that of a reptile; cells lose water AND we perspire). Water serves many purposes within the body.
Disease Dehydration – a lack of water (our skin is not water-tight like that of a reptile; cells lose water AND we perspire). Typically we need 2 ½ liters of water per day; more in hot, dry weather or with heavy exertion.
Disease Dehydration Severe dehydration causes heat stroke, which can be deadly in a short time.
Disease Parasites may try to take over our body and upset our homeostasis. Bacteria like Clostridium tetani make a toxin that kills cells. Fungi cause ringworm and athlete’s foot. Protists cause diseases like malaria. Viruses cause colds, chicken pox, AIDS, etc. HIV Staphylococcus
Disease Medicines try to cure disease or at least relieve the symptoms (and restore homeostasis). Americans spend a huge amount of money on healthcare.
Defense against Infectious Diseases
Pathogens cause disease An animal must defend itself from the many dangerous pathogens it may encounter. Pathogen: any organism or virus that causes a disease. Mycobacterium causes the disease tuberculosis in the lungs.
Pathogens cause disease Antibiotics (against life) kill bacteria by blocking metabolism. Tetracycline blocks bacterial translation by binding to the small subunit of the ribosome and distorting it so the codons and anticodons cannot align properly. Penicillin interferes with formation of bacterial cell walls. Viruses are not alive – have no metabolism – so they can’t be killed; they use the host’s metabolism, which isn’t affected by these drugs. Human ribosomes are different from those of bacteria and aren’t affected by tetracycline. Human ribosomes are different from those of bacteria and aren’t affected by tetracycline.
Primary defense against pathogens Skin and mucous membranes are physical barriers to entry of microorganisms and viruses – the 1 st line of defense. Skin provides a barrier & environment hostile to microbes. Secretions make the skin’s pH 3 – 5: kills most microbes. Secretions include proteins such as lysozyme, which digests bacterial cell walls. First line of defense!
Primary defense against pathogens Skin and mucous membranes are physical barriers to entry of microorganisms and viruses – the 1 st line of defense. Mucous membrane cells (nose & throat) produce mucous, a viscous fluid that traps microbes and other particles. In the trachea, ciliated epithelial cells sweep mucus and any entrapped microbes upward, preventing microbes from enter- ing the lungs. H: cilia (little hairs); J: goblet cells make the mucous. H: cilia (little hairs); J: goblet cells make the mucous.
Phagocytic leucocytes Phagocytes (WBCs) consume foreign invaders – a body’s 2 nd line of defense. Phagocytes attach to prey via surface receptors (1) and engulf them (2), form- ing a vacuole (3) that fuses with a lysosome (4). Second line of defense!
Phagocytic leucocytes Phagocytes (WBCs) consume foreign invaders – a body’s 2 nd line of defense. Inflammation: a non-specific defense reaction to tissue damage caused by injury or infection. Blood vessels expand. Infected tissue becomes swollen & painful. Histamines are re- leased that alert the body to invasion. Fever: higher body temperature slows growth of pathogens
Antigens vs. antibodies An antigen is a foreign molecule that is recognized by lymphocytes (WBCs) and elicits a response from them. Molecules such as surface proteins or lipopolysaccharides (cell surface markers). Blood cell antigens Bacterial cell wall antigens Viral antigens
Antigens vs. antibodies An antibody is an antigen-binding protein (an immuno- globulin like IgG) made by the invaded organism that functions in the immune response. Third line of defense!
Antigens vs. antibodies An antibody is an antigen-binding protein (an immuno- globulin like IgG) made by the invaded organism that functions in the immune response. A lymphocyte then recognizes and binds to the antibody to initiate phagocytosis.
Antibody production (Humoral immunity) 1) Macrophages (phagocytes) consume bacteria (with anti- genic molecules on their cell walls), and they present the antigens (like trophies) on their cell membrane.
Antibody production 2) Macrophages search out and activate lymphocytes (WBCs that live in the lymph glands). One type is the helper-T cell, which picks up and incorporates the antigens into their own protein struct- ures. Helper-T cells then act- ivate B cells which proliferate and make antibodies. This is the body’s 3 rd line of defense.
Antibody production Activated helper-T cells activate B cells by passing the antigen to B cell receptors.
Antibody production Many different types of lymphocytes exist within the body as a precaution against unknown invaders. Each type recognizes one specific antigen. If that specific antigen is recognized, that particular lymphocyte responds by dividing to form a clone.
Antibody production Many different types of lymphocytes exist within the body as a precaution against unknown invaders. Some of the cloned cells live for years to respond if that invader returns (like measles, chicken pox) giving immunity. Other clones are short- lived but produce large amounts of antibodies to fight the invader.
Cell-mediated immunity Cell-mediated immunity: body’s defense against its own cells. Helper-T cells also activate Killer-T cells, which will destroy cancerous cells or those infected with para- sites, esp. protists & fungi.
Autoimmune diseases The body fights itself: an abnormal immune response of the body against substances and tissues normally present in the body.immune response Arthritis: the immune system attacks the joint lining and cartilage (right). Diabetes mellitis
Effects of HIV on the immune system HIV (Human Immunodeficiency Virus) attacks cells that respond to foreign invaders: the T lymphocytes. HIV damages the human immune system. This leads to death from infections the body usually controls. Oral thrush (fungal); Karposi’s sarcoma (a skin cancer)
Effects of HIV on the immune system HIV multiplies in T lymphocytes, destroying them.
Effects of HIV on the immune system As a result of HIV infection There is a reduction in the number of active lymphocytes. There is a loss in the ability to produce antibodies.
HIV: the cause HIV is caused by the human immunodeficiency virus. The virus originated in Africa in monkeys. Present in human blood collected in the 1950s; Major human spread beginning in the 1970s (from increased mobility of people). HIV is a retrovirus: the genetic material is RNA
HIV: transmission HIV is transmitted through body fluids. Also through infected blood on any object that pierces the body. Also through infected blood on any object that pierces the body.
Principle of vaccination A weakened or dead version of a pathogen is injected into the body, causing the immune system to mount a primary response. This results in the production of B memory cells. The B-cells "remember" the antibodies to produce in response to the pathogen. When the real pathogen strikes, a secondary response occurs, aided by the memory cell production of pathogen-specific antibodies. This response is much stronger than the primary response and prevents any ill effects.
Principle of vaccination Compare primary and secondary responses: Secondary response is faster and greater. Memory cells are present.