Week 14 Notes
Popular in Life 103- Biology of Organisms
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This 8 page Class Notes was uploaded by email@example.com Notetaker on Friday April 29, 2016. The Class Notes belongs to 103 at Colorado State University taught by Tanya Dewey in Winter 2016. Since its upload, it has received 11 views. For similar materials see Life 103- Biology of Organisms in Biology at Colorado State University.
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Date Created: 04/29/16
Week 14 Notes Immune system functions 1. Prevent pathogens from getting in 2. When pathogen get in, being able to detect them and tell the difference between a pathogen and your-self 3. Eliminate pathogens Innate Immune system 1. Barrier defenses: skin, mucus, body pH 2. Cellular innate defenses: phagocytosis 3. Antimicrobial peptides 4. Inflammatory response Adaptive immune system→ requires activation 1. Variety of antigen receptors 2. Self tolerance 3. Cell proliferation 4. Immunological memory All animals have innate immune system, but only vertebrates have adaptive immune system Cellular innate defenses 1. Detect invader and send an alert via TLR receptors a. TLR receptors i. Bind to foreign molecules ii. Not specific iii. Double stranded RNA and DNA with unmethylated CG sequences iv. Lipopolysaccharides v. Flaggellins vi. Starts phagocytosis 2. Neutrophils . In blood a. Attack invaders 3. Macrophages . Throughout body a. Attacks invaders 4. Dendritic cells . In tissues a. When activated, go to lymph nodes b. Trigger the adaptive immune system 5. Natural killer cells . Kill self cells a. Detect infected and cancerous cells b. Kill cell through lysis Antimicrobial proteins -recognizes a pathogen -increases the production of proteins to disrupt the pathogen and viral reproduction Inflammatory response -and infection causes a systemic response that involves signaling molecules (histamine) -Mast cells release histamine -Histamine causes swelling because it increases fluid in tissues by causing dilation and increasing the permeability of blood vessels -Specialized cells release cytokines -Cytokines increases blood flow, which causes redness and heat -pus is caused by phagocytic cells and their waste Adaptive immune system -Requires activation -Recognizes certain and specific pathogens -Lymphocytes *B cells→ mature in bone marrow *T cells→ mature in chest Antigen: a foreign molecule that causes an immune response that produces B and T cells B and T cells: are able to detect antigens that are on cell or floating in the body by their antigen binding sites B cell recognition -B cells are activated by specific receptors for antigen -there is a clonal proliferation of that type of B cell -Then there is an increase in plasma cells that secrete an antigen -Memory B cells are made T cell antigen recognition -Dendritic cells bind to antigen -T cells then bind to the dendritic cell -The T cell recognizes MltC molecules on the host cell’s surface -T cell is activated and activation causes… 1. Increase of T cells 2. Increase of helper and cytotoxic T cells 3. Memory T cells Adaptive immunity 1. Diversity of lymphocytes and receptors 2. Self-tolerance 3. Clonal selection 4. Immunological memory Random rearrangements of genes that code for different things and have different combinations of light and heavy chains leads to lots of variety and diversity. There is about 3.5 million B and T cells are first tested for reacting to itself, and the self-reactive B and T cells are destroyed An interaction with an antigen causes cells to increase and promotes reproduction of Memory B cells and plasma B cells Memory cells -first time the cells come into contact with antigen, it takes a while to respond and kill it -the second time they come into contact with the antigen, they quickly recognize it and destroy it B cells -interact directly with the antigen and produce antibodies (antibodies interfere with antigens) and memory cells T cells -detect antigen displayed on host cells and produce cytotoxic cell, helper T cells, and memory cells of each -cytotoxic T cells kill the foreign cells Innate -in all animals -fast response -respond to a wide range of pathogens -same response time with each infection Adaptive -only in vertebrates -slow response time -specific response to a specific pathogen -immunological memory Improper responses of immune system 1. Allergies→ B cells that target parasitic worms are the same B cells that target allergies 2. Autoimmune disorder→ immune system does not recognize self 3. Immunodeficiency→ SCID, AIDS Hygiene Hypothesis -lack of exposure to infection decreases the development and adaptive progress of the immune system Hormones and chemical signaling Anti-diuretic hormone -keeps water in the tissues by increasing the absorption of fluids in the collecting duct of the nephron Hypothalamus: detects an increase of osmolality in the blood Pituitary gland: secretes ADH (anti-diuretic hormone) when triggered by nerve impulses ADH receptor are located in the kidney The collecting duct and distal tube have a membrane permeable to water, which results in an increase in water absorption and a decrease of osmolality in blood Chemical signals act on distant tissues (the collecting duct and distal tubule) which maintains homeostasis 5 modes of chemical signaling 1. Endocrine a. The endocrine glands secrete hormones into the blood stream. This means that it’s affect can occur at a distance because the hormones in the blood can reach any target cell anywhere in the body 2. Paracrine a. The diffusing cell is nearby the target cells b. Local 3. Autocrine a. Local b. The target cells are also the secreting cell 4. Synaptic a. Involves a neuron b. Neurotransmitters diffuse across synapsis c. Local 5. Neuroendocrine a. Involves a neuron b. Neurons secrete hormones into the bloodstream, therefore, they can reach target cells anywhere c. Can occur at distance Endocrine system: set of glands that secrete hormones into the body Endocrine: ductless glands that secrete hormones into the bloodstream Exocrine: ducted glands that carry secretions directly onto surfaces or into body cavities Functions of the endocrine system 1. Maintain homeostasis 2. Growth and development 3. Control sexual reproduction Hormones: chemicals that impact certain target cells and are secreted into the bloodstream Target cells have hormone specific receptors -regulate cell reactions by changing gene expression through transcription factors Signal transduction -transmission of molecular signals from cell’s exterior to interior -molecule can bind to receptors at the cell membrane or pass through the membrane and bind to receptors in the cell Amplification -molecular signals can be amplified at any step Both signal transduction and amplification have large impacts on low concentrations of molecules Hormone solubility influences transduction Water soluble: can’t diffuse through plasma membrane and requires receptor proteins on cell surface Lipid soluble: can diffuse through plasma membrane, and so receptor proteins can be on the inside of the cell Water soluble hormone: epinephrine -epinephrine hormone binds with receptor coupled with a G protein -catalyzes a cAMP synthesis -activates protein kinase A -catalyzes glycogen breakdown -glycogen energy storage polysaccharide Lipid soluble hormone: estradiol -estradiol diffuses across the plasma membrane -Binds to a receptor protein -A change in gene expression occurs when the receptor protein and hormone bind Pheromones: alters the behavior of individuals of the same species through chemical secretions in body fluids -essential in eusocial and social animals -influences social dynamics -involves communication between individuals and species Impacts of hormones Specific response to hormone binding can vary with tissue type because there can be different receptors or same receptors that have different responses Negative feed-back (reduce stimulus) Stimulus is a low pH that triggers endocrine secretions of hormones -hormone reaches the target cell -bicarbonate is releases, which cause an increase in pH -the stimulus is removed by an increase in pH Positive feed-back (amplifies the stimulus) Stimulus suckling causes a release of necrohormones -the hormones react with target cells in the mammary glands -result more milk is produced Hypothalamus responsible for the coordination of both the endocrine and nervous system Produce offspring Reproduction: producing offspring asexually or sexually A population outlives its members only by reproduction, the generation of new individuals from old ones Asexual -offspring come from a single parent -offspring’s genes are from that parent only -offspring are a genetic copy of the parent -occurs without the fusion of gametes -Bacteria, protists, and archaea mostly use asexual reproduction. It’s common in plants and fungi and rare in animals Forms of asexual reproduction Binary fission -parent cell divides in 2 -does not occur in animals Budding -individuals form from outgrowths of mature organisms -occurs in sponges,cnidarians,acoel flatworms,echinoderms Fragmentation -a new organism grows from a part of the parent -occurs in sponges, flatworms, annelids, echinoderms Parthenogenesis -an organism develops from an unfertilized egg -occurs in arthropods,rotifers,flatworms, snails, reptiles, amphibians, sharks Sexualreproduction -gametesfusetoformazygote -gametesareformedviameiosis,whichcausesareductioninploidy -Majorityofanimalsandplantsreproducesexually Asexualreproduction Benefits -offspringareidentical(knowthatthisgeneissuitedfortheparticularenvironmentsoitwillsurvive) -Everyindividualisabletoreproduce Cons -offspringareidentical(iftheenvironmentchanges,theoffspringmaynotbeabletosurvive Sexualreproduction Benefits -offspringarediverse Cons -youhavetwosexes,sonthenumberoforganismsthatcanhaveoffspringishalved -findingmatescanbedifficult -only50%ofoneoftheparent’sgeneispasseddowntotheoffspring -matingcanbedangerous Whyhavesex? 1. Recombination a. Cancombinegoodmutations b. Avoidbadmutations c. Developnewandusefulgenotypes 2. RedQueenhypothesis a. Co-evolutionaryarmsrace b. Decreasesusceptibilitytoparasites,disease,andpredators 3. Removebadmutationsfromalineage Sexualreproductionworkswellinneworchangingenvironments Asexualreproductionworkswellinconstantorunchangingenvironments Hormonesandreproduction -hormonesregulatesexualbehaviorsuchasaggression,parentalinstincts,andcourtshipdisplays Pheromonesandreproduction -letindividualsknowaboutyoursexualreceptivity -suppresssexualactivityofthoseinyourgroup Challengestomakingoffspringsexually 1. Creatinggametes a. Femalesmakeeggs,thataresmallandrequirelotsofinvestment b. Malesmakesperm,thatarelargeinnumber,butdoesn’trequireasmuchinvestment 2. Findingamate a. Difficultforsessileandsolitaryanimalstomate b. Yourmatemayeatyouspiders c. Hermaphrodismcombatsthisissuebyhavingbothmaleandfemaleorgans i. Simultaneous:havebothMandFpartsatthesametime ii. Sequential:genderisdifferentatdifferentpointsoflives iii. Earthworms,snails,andslugsarehermaphroditic 3. Fertilization-Internalvsexternal a. Synchronousexternalfertilizationspawning b. Asynchronousfertilizationcoordinationisneededbetweenindividuals i. Bothrequirewater c. Internalfertilization i. Doesn’tneedwater ii. Typicallyoccursinthefemale iii. Coordinationofreproductiveorgans iv. Femalescan“cheat”somaleshavetoevolvetoincreasethechancesthattheirspermwill beused 4. Supportduringdevelopment a. Nutritionsuppliedtoembryo b. Protection i. Nests,gestation,guradingetc ii. Malescanbeapartofsupportiftheywereapartoffertilization(seahorses) Reproductivesuccess:passingofgenesfromonegenerationtothenext Sequentialhermaphodisminfish Protandrous:malefirst,femalesecond -biggerbodymass=moreeggs=biggerfemaleshavemorereproductivesuccess Potogynous:femalefirst,malesecond -biggerbodymass=protectalargerterritoryandhavemorefemalemates=biggermaleshavehigherreproductive success