BSC 215: Wk 2 Notes
BSC 215: Wk 2 Notes BSC 215
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This 20 page Class Notes was uploaded by Jordana Baraad on Thursday August 25, 2016. The Class Notes belongs to BSC 215 at University of Alabama - Tuscaloosa taught by Dr. Jason Pienaar in Fall 2016. Since its upload, it has received 39 views. For similar materials see Human Anatomy & Physiology I in Biological Sciences at University of Alabama - Tuscaloosa.
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Date Created: 08/25/16
8/23 Learning outcomes 1. What are the seven characteristics of life? 2. Describe the major structural levels of organization of the human body 3. Describe the principle of homeostasis 4. Explain how negative and positive feedback loops maintain homeostasis 1. Imp for premeds; series of chem rxns in the cell 5. How are structure and function related? 1. Structure indicates function 6. Define gradient using examples of gradients that drive physiological processes imp to physio processes big 3: temp, pressure, concentration 7. Explain how cells communicate with each other and why its essential for multicellular organisms 1. In order to maintain homeostasis 2. LO1: What are the seven characteristics of life? (NOTE: Txt is very outdated on this topic, use the definitions given below) Homeostasis: Truism: if something is alive, has cells Organization Truism: if something is alive, has organization ex. biomolecules cells tissues organs Metabolism anabolism + catabolism = metabolism Breakdown + synthesis Essential property of cells Reason why viruses not considered alive Generally do not have metabolisms Parasitic, use host metabolism; can’t exist isolation Growth maturation; increased size Adaptation Response to stimuli Reproduction Adapation: DNA evolves Structure always evolving toward desired function Responds to stimuli: Humans complex—language Single cells—bacteria move toward sugar Rock wouldn’t do that Reproduction For something to be determined alive, must rep ALL 7 CHAR Ex. viruses reproduce but don’t metabolize—not alive! LO2: Describe the major structural levels of organization of the human body st Chemical level: 1 level Ex. phospholipid: phosphate (hydrophilic) + fatty acid (hydrophobic) organized Imp to structure and function of biomolecules cell membranes Cellular level Biomolecules organize and aggregate inside membrane to form cel Tissue level Cells come together to form tissue Set of cells secrete substance: extracellular matrix Tissue = cells + extracellular matrix secreted Organ system Tissues acting together comprise organs Organ system level Organs working together (e.x. nervous system) Organismal level Only get to organ/ organ system level in A&P I CQ 1: Groups of cells working together to form common function: D) tissue CQ 2: T/F All living orgs composed of 1 or more cells? True (one of simplest defs of life) LO3: Describe the principle of homeostasis Def: The creation and maintenance of a relatively stable internal environment to facilitate the numerous physiological processes that cells undergo Short version: keep selves happy in neutral Enzymatic rxns work best at given pH, temp, etc Body stabilizes at best average temp/pH to make all enzymatic rxns work Body tries to keep internal enviro relatively stable Ex. extreme heat or cold death Body working hard to maintain optimal temp; ultimately fails Internal environment is determined by physiological variables: Variables: can change Physiological: has to do w/ cellular chemistry Temperature pH concentration: denoted as “[ ]” Ex. [Blood glucose] Osmotic balance Diffusion of water across cell membrane [Blood O2/CO2] Vitamin D levels Regulated variables: can be affected by physio mechanism(s) Ex. can control temp, pH, blood concentration glucose or O2/CO2 v. unregulated variables: environmentally determined solely ex. Vit D synth—dep on how much time spent in sun Receptors Used to measure regulated variables All cellbased (diff cells to measure temp, pH, etc) Control center: decisionmaking entity Often is brain; can be other mech Integrates info from receptors; determines response to info Communicates desired response to effector Effector Carries out response to phenomena indicated by receptors, communicated by control center LO3: Describe the principle of homeostasis Stimulus: beginning of cycle Involves regulated variable Ex. Room temp decreases below set point—colder than desired Measured w/ receptor (receptor = thermometer) Info sent to control center (control center = thermostat) Thermostat decides to add heat temp at desirable range (Effector = heater) This describes a negative feedback loop LO3: Describe the principle of homeostasis Stimulus: Core body temp decreases below normal range Note: range, not 1 set point Set point reps average range Norm range: 9799 deg F Narrower range for pH than body temp Body fluctuates around 98 deg F over course of day; not always there May be at tolerable lower/higher range to expend less energy in Inclement environment Receptor: Measuring blood flowing thru body brain Control Center: Certain brain cells detect temperature change Effector: Nerve cells stimulate skeletal (skinetal) muscle cells to start shivering Regulated variable: blood LO4: Explain how negative and positive feedback loops maintain homeostasis Def feedback: Change in regulated variable results in effects that feed back to the same variable Negative feedback loops : Return regulated variables to within “normal” range of values Ex. If body temp goes below norm range, feedback is to raise tempshivering Neg feedback reverses direction of trend Positive feedback loops: Increase / reinforce initial stimulus on regulated variable ex. blood clotting: Activated platelets release chemicals that attract and activate more platelets must work w/n negative feedback loop so rest of blood can flow ex. oxytocin in childbirth: one contraction more continuation of labor works w/n neg feedback loop: stops labor after birth BOTH types maintain homeostasis CQ 3: Which false? C. Pos feedback loops triggered by deviation from norm range; work to decrease val of variable as it increases to maintain var w/n norm range TRUE: A. Structure and funct related at ALL levels of org B. homeostasis: creation and maintenance of dynamic equilib D. ?? LO4: Explain how negative and positive feedback loops maintain homeostasis Negative feedback: decrease in variable results in feedback that increases variable and vice versa Effector: Nerve cells stimulate skeletal muscle cells to start shivering Stimulus: Core body temp decreases below normal range Normal range : 9799 deg F Receptor: Certain brain cells detect temperature change In homeostatic range As body temperature returns to normal, feedback stops shivering Control Center : Brain interprets and acts on body temperature signals LO4: Explain how negative and positive feedback loops maintain homeostasis Postive feedback: increase in variable results in feedback that further increases variable Effector: Platelets seal blood vessel Detect collagen fibers Stimulus : Injury to blood vessel Control Center: Activated platelets release chemicals that attract and activate more platelets Receptor: Receptors on platelets detect Injury to blood vessel Confusing but important: platelets are both control center and effector Brain not involved Go from detector (control cent) activated (effector) from Positive feedback: platelets recruiting more platelets Increase in direction that process started in End point reached: Platelet activity decreases when blood vessel sealed Embedded w/n negative feedback loop NOTHING can be in pos feedback loop forever to maintain homeostasis 2 ways to maintain homeostasis pure neg feedback loops pos feedback loop embedded w/n neg feedback loop LO5: How are structure and function related? Form follows function at all levels of organization organization Chemical level Ex. phospholipid (prev discussed) Cellular level: diff shaped cells det diff functions Same w/ enzymes Tissue level ex. lung tissue need to get O2 from atmosphere to alveoli via diffusion need to get CO2 out to atmosphere via diffusion alveoli very thick, flat (squamous shape) thickness protects from pathogens prob: difficult for gases to diffuse minimal 1 layer of cells in vessel and alveoli 2 close cell layers (both flat cells) reduces dist that gases need to diffuse done via flat shapes; small # layers Organ level Organ system level: not covered Organismal level: not covered LO6: Define gradient using examples of gradients that drive physiological processes Temperature gradients Heat dissipates from source Ex. heat goes from heater outer areas of room Goes fr high low conc. Concentration gradients High low conc Ex. solutes poured into beaker Pressure gradients ex. gas & liquid molecules diffuse to lower concentration areas not a decision; det by Brownian motion if happen randomly to go in direction where fewer molecules, no collision so keep going in that direction CQ 4: Gradient exists when… D)all of the above a. heat conc in one area body b. given subst more conc in 1 region than other c. higher P in one place than other LO7: Explain how cells communicate with each other and why its essential for multicellular organisms Cell to cell communication is required to coordinate physiology & maintain homeostasis What happens in 1 part of body affects other parts of body Must communicate to live Chemical signaling OR Electrical signaling Much of course focuses on electrical signaling Common in nervous system Chemical signaling via 4 ways Endocrine: long distance Chem messenger enters bloodstream (highway system) Paracrine: semilong distance Chem messenger travels across extracellular matrix until finds cell w/ receptor Both messenger and receptor necessary Does not enter bloodstream Autocrine: closerange; signals to self Juxtacrine: closerange 1 cell produces messenger; other cell produces messenger touching one another know how to differentiate btwn juxtacrine and paracrine electrical signaling: shape determines function for vast majority of nerves, signaling from 1 side to another NOT signaling between; IS signaling w/n Way to remember: Electrical signaling is early evolved mech Used in unicellular bacteria Communicates fr 1 side of membrane to the other CQ 5: what kind of chemical signaling occurs at the neuromuscular junction? Chemical signaling 8/25/16 Matter, Energy & Enzymes Learning outcomes 1. Describe electrons, protons & neutrons and distinguish atomic number from mass number 2. Compare and contrast atoms with elements & identify the four major elements found in the body 3. What are isotopes and radioisotopes? 4. Distinguish among solutions, solvents, colloids & suspensions various mixtures—what’s the difference? 5. Describe how the valence shell determines chemical reactivity octet rules and duet rules form bonds? React? 6. What are ions & electrolytes? Atoms • Atoms (usually) consist of: • Protons, neutrons, electrons ALWAYS proton, neutrons/ electrons variable • Atomic number = Proton number determines identity of element / atom need to know several ex. H (basis of pH, essential in biomolecules) also… O, N, C • Atoms have mass: • Protons & neutrons each weigh 1 AMU, electrons are negligible mass is whole # decimal # = avg • Atomic mass = n(Protons) +n(Neutrons) • Atoms are (usually) electrically neutral n(protons) (+) = n (Electrons) () C always has 6 protons; varies in # neutrons (changes mass); # electrons (det charge) If diff # p’s, then NOT carbon Diff neutron # = diff isotopes Basis of carbondating (C14) Atomic # = 6; atomic mass (dep on neutrons) Question: which radioactive element cancer when incorporated into skinetal syst Hm electrons fit into diff orbitals? st nd rd 1 : 2, 2 : 8, 3 : 18 octet rule: need 8 valence electrons in valence (outer) shell to be stable ex. oxygen has 6 valence e; needs to form to bonds to fill shell modification in smaller atoms (H and He): duet rule trying to achieve 2 electons in valence shell LO1: Describe electrons, protons & neutrons and distinguish atomic # from mass # • Element: Simplest form of matter to have unique chemical properties e.g. Water molecule has unique chemical properties • But it consists of H & O atoms, that each have unique properties water not yet at simplest form atoms of O & H consist of protons, neutrons & electrons all protons/ neutrons/ electrons behave same in all elements only differ in quantity # of protons (and valence struct) define everything about that atom • Oxygen & hydrogen are therefore elements LO2: Compare/ contrast atoms with elements & identify 4 major elements found in body Element: is any substance made up of only one kind of atom 4 most abundant elements in human body: C, H, N, O abundant in forming covalent bonds C most abundant in all org material (2 reasons) 1. Has 4 valence electrons; needs 4 more to fill valence shell Can form 4 different bonds; MAX # versatile 2. Forms covalent bonds—strongest type v. ionic—dissolve “Siliconbased life” (alt to Cbased life) other atom that’s relatively small that can form 4 bonds backbones of 4 major biomolecules are built fr carbon skeletons aa’s, lipids, carbohydrates LO3: What are isotopes and radioisotopes? Isotopes: • Atoms that differ only in the number of Neutrons (& therefore mass) • Atomic weight: weighted average mass over all known isotopes of an element decimal number not dealt with much in this course DON’T CONFUSE IT WITH ATOMIC MASS • Isotopes chemically behave the same way • BUT physically unstable isotopes (radioisotopes) DECAY over time (radiation) • Physical halflife V biological halflife? Physical half life more familiar How long before half remains? Basis of carbondating; Uranium series Biological halflife: How long does it take to get rid of radioactive ion? Sometimes we incorporate radioactive molecs into anabolism Eventually we eliminate it Det by which structure it’s incorporated into Ex. incorporated via diet has shorter half life than in bones • Radioactive isotopes emit high energy radiation as their nuclei decay 2 types radiation—differ by distance radiation can travel 1. Low penetrance a. Problem when incorporated into body b. • α & β particles i. α particles = 2 protons+ 2 neutrons 2. high penetrance a. change molecule structure of biomolecules i. including genes cancer, genetic mutation b. reason for lead apron for Xrays i. need high penetrance to see inside body ii. take precautions; avoid freq exposure c. γ rays = high energy photons • All can produces dangerous ions & free radicals free radicals destructive—combat effects w/ antioxidants LO4: Distinguish among solutions, solvents, colloids & suspensions Two ways to combine matter: Mixtures: Different atoms combined retain their chemical properties and can be physically separated Suspensions: can easily separate out larger particles (solid) Ex. blood= erythrocytes (RBC’s) dissolved in plasma Erythrocytes heavy bc contain Fe Colloids: solid particles in liquid but can’t really see separation w/ naked eye Ex. Milk = milk proteins + H20 molecule Solutions Ex. glucose + water… stays dissolved in Will never settle out Chemical bonds: Different atoms combined havenew chemical properties and the resulting molecules can only be separated chemically Ionic bonds Covalent bonds Most permanent type Hydrogen bonds Indep wk, strong when lots joined together Van der Waals forces Exhibited by all molecs to some extent weakest Solute: dissolved in Solvent: substance in which materials are dissolved Ex. water = “universal solvent” Anything with charge will dissolve in it Most biomolecules are charged Uncharged particles stick to selves, not water Ex. fat LO5: Describe how the valence shell determines chemical reactivity • Some atoms are chemically reactive, other are not inert: chemically inactive • Why? Full valence shell—fulfilled octet (or duet) rule ex. He (duet), H’s form H_2 to fulfill octet rules by self Ne, Ar, Xe (octet) Na (basis of neurochem) C has 4 electrons in valence shell; needs 4 more O has 6 electrons in valence shell Can get rid of 6 electrons to fulfill duet rule (LOTS energy) Better strategy: gain 2 electrons Bond w/ 2 H atoms Bonds w/ self like H Na: Easiest way to fulfill octet rule is to lose valence electron unequal # protons and electrons forms cations (pos charged ions) if can give electrons to another molec reason for assoc w/ Cl (needs to gain 1 electron to fulfill octet) Na becomes pos; Cl becomes neg; form ionic bonds OCTET RULE PREDICTS WHICH ATOMS FORM COVALENT V. IONIC BONDS Ex’s O (6) w/ O (6): Share 2 electron pairs double covalent bond Strong bond—almost as strong as triple bonds LO6: What are ions and electrolytes? • Ions = Charged particles via unequal number of protons & electrons cations: pos charge anions: neg charge • Elements or molecules • Ionization • Octet rule (rule of 8) • Atoms with < 4 valence electrons… give them up Cations (+) • Atoms > 3 & < 8 valence electrons… tend to gain more Anions () • Electrolytes: Substances that ionize in water (can conduct electricity) • Anions & cations are separable basis of heartbeat, neural activity, other body processes Na is archetypical ion—use as focal pt
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