Life 103- Animals week 6
Life 103- Animals week 6 LIFE 103
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This 7 page Class Notes was uploaded by Alexis Darling on Monday May 2, 2016. The Class Notes belongs to LIFE 103 at Colorado State University taught by Jennifer L Neuwald; Tanya Anne Dewey in Fall 2016. Since its upload, it has received 11 views. For similar materials see Biology of Organisms-Animals and Plants in Biology at Colorado State University.
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Date Created: 05/02/16
Immune System ~Immunization purposely generating an immune response to protect for future exposure By 2 methods: Inoculation slight exposure to live disease agent to prompt a minimal infection and future immunity from that disease Vaccination exposure to modified disease agent (dead or altered) to induce an immune reaction that relates to immunity to the disease ~Herd immunity term that applies when the largest portion of a community is immune, therefore reducing the chance that people who are not immune will receive the disease. Immune system: Purposes 1. Prevent entry of pathogens Barrier defensesfirst line of defense, prevents things from entering Skin Mucous membranes (trap pathogens) Secretions (bathe surfaces and contain lysozymes that destroy the cell walls of bacteria) Acidic body pH (kills many) 2. Detect entry of pathogens 3. Eliminate pathogens Through innate and adaptive immune systems Innate Immune System=first responders, always there, includes barrier defenses and 4 types of white blood cells: Neutrophils in blood Macrophages throughout blood and tissues Dendritic cells in tissues in contact with environment, once activated they migrate into lymph nodes to stimulate adaptive immune system Natural killer cells recognize infected or cancerous cells and trigger lysis or apoptosis (cell suicide) of those cells Antimicrobial proteins recognize pathogens and trigger response ~Inflammatory response systemic response to injury or infection that involves swelling and heat. Process: a. Mast cells release histamine as signaling molecules b. Histamine causes dilation and increased permeability of capillaries (increases fluid in tissuesswelling) c. Cytokines released by specialized cells also increase blood flow redness and heat d. Phagocytic cells and debris pus Adaptive Immune System=one responder specialized to one invader Specific to vertebrates *Antigen toxin or anything foreign that induces an immune response from the adaptive system ~Lymphocytes: B Cells have specific antigen binding sites (receptor proteins) to detect intact antigens on cells or circulating in the body; one B cell to one type of antigen o Receptor proteins include heavy chain and light chain, each with constant and variable regions o Mature in bone marrow o Clonal proliferation= that cell makes more of itself o Proliferation of plasma cells results in antibodies (proteins) that are all specific to the antigen that signaled the replication o Memory B cells= some from the proliferation remain for future defense T Cells *NO direct contact with the antigens o Dendritic cells recognize a specific antigen on MHC molecules of host cell surfaces (specific binding sites) o T cells must be signaled by dendritic cells o Results in proliferation of the T cell with clonal selection o Produce cytotoxic T cells and helper T cells o Memory T cells 4 Characteristics of Adaptive Immunity: 1. Diversity of lymphocytes and receptors There are tons of genes, all have random rearrangement, can be variable, joining, or constant regions in antigen receptor sites, and there can be different combinations of light and heavy chains About 3.5 million different combinations 2. SelfTolerance B and T cells must mature then be tested against self before released into body (cannot be selfreactive or else they are destroyed) 3. Cell Proliferation When cells encounter an antigen they are stimulated to reproduce themselves Some become memory cells, some release antibodies 4. Immunological Memory The result of memory cells Summary: Innate Adaptive All animals Only vertebrates Rapid response Slower Response to broad categories of Specific response to specific pathogens pathogens Same response with each infection Immunological memory (strong response with another future exposure) Improper functioning leads to… a. Allergies= use of inflammatory response to something that is not actually a hazardous invader o It was meant for special B cells to target parasitic worms o Hygiene hypothesis too clean; lack exposure to infections and parasites so the immune system does not develop properly o Developed regions have a high rate of allergies and autoimmune disorders, while regions with common parasitic infections have low incidence of allergies (thought that body needs something to fight off, so it makes up that random things are enemies) b. Autoimmune diseases= not recognizing self c. Immunodeficiency= SCID, AIDS Hormones and Chemical Signaling: ~Hormone chemical secreted into bloodstream to impact target cells, often regulate cells reactions by changing gene expression ~Target cells have hormonespecific receptors AntiDiuretic Hormone (ADH) stimulates absorption of fluids in collecting duct of nephron so that body tissues retain more water (diuresis=production of excessive urine) Hypothalamus detects increased concentration of blood, signals pituitary gland to release ADH, ADH receptors in kidney leads to increased permeability of membranes in kidney which increases water absorption Note: Tag team between central nervous system and endocrine system Feedback mechanisms (specifically negative because working to take away the stimulus of hyperosmotic blood (too concentrated)) Chemical signals effect distant tissues (collecting duct and distal tubule) Result= maintain homeostasis (blood becomes more dilute) 5 Modes of Chemical Signaling: *For first three: ‘crine’= ‘secretion’, these effect by hormones 1. Endocrine ‘endo’= ‘global’ endocrine glans secrete hormones into blood so that it can reach target cells anywhere in the body 2. Paracrine ‘para’= ‘local’ secrete hormones to effect nearby target cells 3. Autocrine ‘auto’= ‘self’ *Last two involve neurons: 4. Synaptic local neurotransmitters (little molecules) sent across synapses to signal 5. Neuroendocrine global neurons secrete hormones into blood so it can target tissues anywhere in body. Basically; neurons hormones in blood ~Endocrine secrete into blood via ductless glands, not connected VS ~Exocrine secrete onto surfaces of body or into body cavities via ducted glands Both function to… Maintain homeostasis Integrate and regulate growth and development Control sexual reproduction Signal Transduction When molecular signals from outside of the cell are transmitted to have their impact inside the cell Molecule either binds to receptors at cell membrane or pass through to bind to receptors inside ~Amplifications can happen at any or all steps, resulting in the synthesis of thousands of times more products, therefore only a small amount of molecules can have a large impact ~Hormone solubility changes whether transducted into cell or outside Water soluble cannot diffuse through plasma membrane but requires receptors on the surface of the cell Lipid soluble can diffuse through plasma membrane so receptor proteins must be inside Impacts of hormones: Bind with target receptors Target receptors are found in many tissues Specific response to hormone binding can vary depending on the tissue type (1 hormone can have multiple effects, but each tissue only experiences one effect) ~Pheromones chemicals which influence the behavior of OTHER individuals (Hormones communicate between the systems within each organism, pheromones communicate between different organisms, typically of the same species) Important in eusocial and social animals Influence societal dynamics (like who’s reproducing, leading, etc.) ~Negative feedback regulation works to remove stimulus ~Positive feedback regulation works to enhance stimulus Producing Offspring ~Reproduction asexual or sexual process which results in offspring *Offspring have the same/similar genes as parents to varying degrees Asexual Reproduction: Offspring arise from one organism Offspring are genetic copies of the parent (because only inherit genes from that single organism) No fusion of gametes Types a. Binary fission parent cell simply divides in half to make 2 organisms b. Fragmentation new organism grows from just a part of the parent (like a starfish) c. Budding new organisms form from outgrowths on parent d. Parthenogenesis new organisms forms from an UNfertilized egg Costs offspring are identical to parents (cannot adjust to changing environments well) Benefit offspring are identical to parents (the genotype works and continues with less chance of mistakes) Sexual Reproduction: Offspring arise from two organisms Genetic variation (main benefit) Gametes formed by meiosis Involves fusion of gametes (sperm and egg) Primary form in plants and animals Costs must create two sexes, so only half of organisms can have offspring (instead of 100% of asexual species having their own offspring) Each parent sacrifices 50% of their genes Must find mates Mating can be dangerous Hypotheses for why sexual reproduction continues: Recombination hypothesis Sexual reproduction combines beneficial mutations while avoiding harmful mutations, results in new genotypes. Red Queen hypothesis allows populations to compete in the “coevolutionary arms race” and develop resistance to parasites, diseases, or predators. Other to remove deleterious mutations from lineage In short, if the environment is new or changing, sexual reproduction is favored, but if the environment is stable, asexual reproduction is favored. Challenges of Sexual Reproduction: 1. Generate gametes Takes energy to produce gametes o Females produce eggs; smaller number= bigger energy investment per gamete o Males produce sperm; large number= small energy requirement to produce This difference between female and male is called anisogamy (‘an’=not, ‘iso’=same, ‘gamy’=gametes) 2. Find a mate Sessile animals must have really long intermittent organ For solitary animals with low population concentration, males physically and permanently attach to a female once encountered Some must overcome the danger in interacting with a potential mate (ex big female spider tries to eat male) 3. Fertilization External fertilization requires water (release eggs and sperm into environment) Internal fertilization (all of terrestrial organisms) requires cooperation and coordination o Females get to be choosy increases competitiveness of sperm so males must evolve strategies 4. Support during development Prehatching protection Posthatching teaching, nourishment, etc. ~Simultaneous hermaphrodism one organism possesses both male and female parts at the same time ~Sequential hermaphrodism one organism possesses male and female parts but at different stages of life Protandrous male first, female last o Benefit: larger female can produce more eggs Protogynous female first, male last o Benefit: larger male can better protect territory, gain more females in that territory ~Reproductive success depends on how many genes an individual can get into the next generation through however many offspring
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