BIO 203 Notes Exam 1 PDF

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BIO 203 Lecture 1: Basic Principles  Physiology is “how things work” (anatomy and physiology go together) - Function of organism and their parts - Study of how cells interact with their environment to obtain the things required for life*  “Environment”: internal environment is everything inside the organism, everything outside is external environment - Important to have context for what we are talking about!  cells are part of the organisms internal environment, but individual cells also have their own internal and external environments relative to the organism - Role of organism is to maintain an internal environment that is friendly for all cells  Exchange systems are the mechanisms by which organism exchange vital things with their environment - Bi directional  Exchange Systems: - Any system that allows for the exchange of material “vital substances” - Can go internal to external and vice versa - Need ways to get nutrients to cells, and remove waste - If the cells are within a mm of the organism, they don’t need specialized exchange systems - Circulatory system links the vital substances to all the necessary cells (enables them all to get the material because they are within a mm) - Skin is also a specialized exchange system (sometimes used for respiration, heat exchange etc)  Organization of Complex Biological Organisms:

- Cellular Level (four general cell types)  epithelial, connective tissue, nerve, muscle - Tissue Level (groups of cells with common structure and function)  pay attention to the context, tissue means different things - Organ Level (organization of different tissues to perform specific functions) - System Level (several organs organized to carry out major body functions)  heart is the organ, but cardiovascular system is the whole system of valves and vessels etc  Basic Principles: - All life is aquatic - Is compartmentalized - Deals with same fundamental problems - Is constrained by laws of Physics & Chemistry - Can tolerate only a range of conditions  living systems are subject to the same rules  All Life is Aquatic - Body fluids of all animals have the same general composition (H2O and salt) - All organisms have an aquatic internal environment, mainly composed of water - Almost all vertebrates will have an internal environment that is ~300 milliosmoles (osmolarity is at the index of water)  why?? All living things evolved from the same living organisms that were marine organism  as they evolved, they developed the ability to maintain an internal environment that is similar to the environment they first evolved in - 75% of body weight & 99% of all molecules in humans are water - 0.75% of molecules in humans are salts (simple inorganic substances) - 0.25% of the molecules are biochemical substances (RNA etc)

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 All Life is Compartmentalized - Separation of substances in different compartments - The basic unit of life is the cell (single compartment) - The major fluid compartments inside organisms 1. Intracellular Fluid (ICF): inside of cells 2. Extracellular Fluid (ECF): outside of cells  interstitial fluid – ECF that is not in the circulatory system  plasma – liquid portion of blood - Absolutely essential for living things to maintain these different compartments  allows for various tasks like storage of things like calcium - MAIN REASON for having compartments is to maintain the contents of the compartments (having different components and concentrations) - Asymmetric Distribution of Ions Between Different Compartments Sodium Potassium Calcium ECF High (100 – Low (1 – 10 Low (1 – 3 140 mM) mM) mM) ICF Low (1 – 10 High (100 – 140 Very Low (nM) mM) mM)  relationship is very important!  How do they keep these concentrations? - Need some kind of mechanism to pump ions across the membranes - Need energy to operate, therefore energy is needed to maintain asymmetries  Asymmetries Between Compartments are Essential for Physiological Processes - A fundamental challenge for all organisms is how to maintain asymmetry  hard to transport substances selectively between compartments - Life is energetically unfavorable - Trade-offs (lose H2O during respiration, thermoregulation etc)  All Life Deals with the Same Fundamental Problems

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- Example of problem is all living things need energy - Many animals have solved these problems in interesting ways  can gain unique and distinctive insights by looking at different animals  Comparative Physiology - All life requires the input of energy - Thermoregulation is a fundamental problem, but solutions depend on the organism’s environment (polar bear deals differently than desert mouse)  Adenosine Triphosphate (ATP) - Principal form of energy used by cell - Most common storage form of energy, taken out by breaking it up  Cellular respiration - How do organisms get ATP?  energy coming from the carbohydrate – carbohydrate bonds in foods (glucose is the preferred molecule for most cells) - Two different pathways: 1. Aerobic Metabolism: requires oxygen; 38 ATP per glucose (huge increase in efficiency); need machinery (mitochondria, oxygen binding molecules); slow 2. Anaerobic Metabolism: very fast; 2 ATP per glucose; possible buildup of lactic acid which isn’t good; no extra things needed; done in the absence of oxygen - Aerobic Metabolism is More Efficient  Metabolic Rate (MR) - The amount of energy an animal uses in a unit of time - Measured as O2 consumption in units of calories or kilocalories (1000 calories) - High metabolic rate = consuming lots of oxygen (vice versa) - Sum of all energy – requiring biochemical reactions (basal metabolic rate, movement, heat production, anabolic pathways) - How low can the rates go?

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 can get very low (stop moving, sleeping etc), but it cannot go to zero because there are some basic life functions that always need energy to keep the organism alive  basal metabolic rate is the lowest the rate can go  All Life is Constrained by the Laws of Physics and Chemistry - Ohm’s Law, Boyle’s Law, inertia, momentum, velocity, drag, etc - Physical environment governs what cells can and cannot accomplish - Cells can utilize these laws to their advantage (comparative physiology; signaling)  Question! - Relative to body size, a large animal has greater surface area for heat exchange with the external environment than a small animal  TRUE or FALSE - As an animal gets larger, its surface area grows more rapidly than its volume  TRUE or FALSE - BOTH ARE FALSE  Size Principle – Relationship between Surface Area (SA) and Volume (V)/ relationship between animal size and heat exchange with environment - The SA/V ratio is an index of relative surface area for exchange Large Animal Low

Small Animal High

Heat Exchange/Unit Volume Heat Retention/Unit Good Poor Volume - Important when animal is trying to retain or gain heat from the environment - Large animals are good at retaining heat (small surface area to volume ratio)  that’s why artic animals are generally large - Small animals are good at loosing/gaining heat Lecture 2: Body Temperature

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 All Life can Tolerate only a Limited Range of Conditions - Conditions include:  salts, H2O, O2, CO2, nutrients, waste elimination, temperature, pH…  the process of maintaining these conditions within tolerable ranges is called homeostasis - Homeostasis: maintenance of a relatively constant internal environment  requires a lot of things to happen (cell to cell communication, negative feedback, signaling)  Feedback Systems: - All feedback systems have the following components: 1. Sensor: measures some aspect of the internal environment (e.g. temp) 2. Integrator: compares the sensor measurement to a reference value (set point) (e.g. Normal temp) 3. Effector: the output of the system that changes the internal environment (e.g. increases temp)  example of negative feedback: thermostat -

Set point is the desired temperature Sensor detects the temperature Integrator compares the temperature to the set point Stimulus to turn on the effector is the room being too warm, the effect is the room cooling (negative feedback)  effect is opposite the initial stimulus - Competing negative feedback systems in animals allows the system to remain at homeostasis  Regulatory System: Types of Feedback - Negative Feedback: o The effector counteracts the initial sensor stimulus  an increase in temperature measured by the sensor results in the effector causing a decrease in temperature  critical for maintaining homeostasis

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- Positive Feedback o The effector increases the initial sensor stimulus  an increase in temperature measured by the sensor results in the effector causing a further increase in temperature  child birth, lactation, good examples of positive feedback (little feedback gets amplified by a cascade)  leads to rapid changes  Physiological Ecology - The organism’s relationship to its physiochemical environment - Goal: want to understand how organisms use the basic laws of physics and chemistry to solve basic physiological problems - Two contexts (comparative) 1. Body Temperature and Temperature regulation 2. Water and Ion Balance  Energy Production/Utilization - Every time we use energy we generate heat  biochemical reactions are not 100% efficient (some very inefficient) - Endogenous heat production: heat made inside of our bodies, contributing to our body temperature - Metabolism produces heat and also nitrogenous waste  trade-offs needed to deal with this waste  Nitrogenous Wastes - Ingested foods include proteins, carbs, and fats - The end product of ingested foods are typically CO2 and metabolic H2O - Metabolic breakdown of protein also produces ammonia (NH3) (nitrogenous waste) - All animals produce ammonia! - These wastes are: o Salvaged for amino acid synthesis o Excreted (high levels of ammonia are lethal)

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o In some animals, converted to less toxic forms of nitrogen (urea & uric acid)  much less toxic (hardly toxic) - Major trade-off is between energy and water conservation  Excretion of Nitrogenous Wastes - Trade Offs: energy expenditure vs. water conservation Advantages Disadvantages Nitrogen compound excreted Ammonia No energy Requires lots required of water to eliminate

Urea Uric Acid

Less toxic

Requires ATP to synthesize Requires ATP to synthesize

Animal Water Classification Loss/g Nitrogen 0.5 L Ammonotelic (aquatic/marine animals  lots of water available) Ureotelic 0.05 L (mammals) 0.001 L Uricotelic (birds)

Requires little water to eliminate  Heat/Energy/Body Temperature - What is heat? o A measure of molecular motion (kinetic energy) - What is temperature? o An index of molecular motion (average kinetic energy) o HOT = high heat content, high energy content, high molecular motion, high temperature o COLD = low heat content, low energy content, low molecular motion, low temperature  Thermal Budget - What factors determine how much heat is in an organism/how much heat can be obtained/lost? - Heat only lost one way (to the environment) - Can be obtained from external environment, or from Endogenous heat production

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- IN (Heat Gained) = OUT (Heat Lost)  THEY MUST EQUAL - Higher metabolic rate = higher endogenous heat production - Need to examine the principles of heat transfer 1. Conduction 2. Convection 3. Evaporation 4. Radiation  Conduction - Heat transfer by physical contact - Energy being directly transferred between the objects T1 = T2, no net transfer T2 > T1, net flow from T2 to T1 T1 > T2, net flow from T1 to T2 - Factors that influence heat conduction o Temperature gradient (T2 – T1) is driving force o Surface Area (A) of contact influences ease of movement o Length between objects (L)  how thin or thick the interface is o Composition of interface influence (thermal conductivity) - Physiologists are interested in rates of movement (flow) - Differential Equations – transport equations dQ/dt = K * A / l *(T2 – T1) A is surface area of contact L is length between objects K is the thermal conductivity flow (of heat) = ease of movement x driving force  Thermal Conductivity - Metals have very high conductivity (220 – 430) - Tissue (0.47) - Water (0.6) - Air (0.025)  water and tissue very similar (tissue is mostly water)

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 air is a good insulator (having a layer of air will impede heat loss) - Vasodilation leads to a decrease in L, making it easier for heat to escape (surface area also decreases)  Convection - Occurs when environmental medium (air or water) moves over the body surface o Modified form of conduction (slower) o Transfer equation essentially the same as for conduction - Two types of convection 1. Free Convection: environmental medium not mechanically moved (passive movement – hot air rises, convective currents) 2. Forced Convection: environmental medium physically moved (external energy force making the medium move – fan making the air move etc.) - Boundary layers form when there is little or no forced movement of environmental medium (decreased driving force for heat exchange)  because of boundary layers, body senses environmental temperature at 35° not 20°  if it’s really cold outside, boundary layers are very important to mitigate heat loss (can be artificially made by wearing a sweater/jacket etc.) - Forced convection is beneficial on a hot day, disrupting boundary layers and making air right next to skin the ambient temperature (large temperature difference = large driving force for heat loss) - Wind chill factor  Evaporation - Transformation of water from liquid to vapor (gas) o Requires energy; cools down environment o 1 g/H2O  580 cal (heat of evaporation) - Evaporative Cooling: when water moves from liquid phase to vapor phase, it absorbs energy from the body surface  cooling (sweating in humans; panting in dogs)  Radiation

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- Doesn’t involve contact at all - The absorption of energy through electromagnetic radiation - Specific wavelengths of energy o Infrared Electromagnetic Radiation: longer wavelengths, less energy - Everything that has heat releases infrared radiation - Ability to absorb or reflect depends on the material  Thermal Budget IN Heat Gained from Ext. Env. Conduction Convection Radiation

OUT Heat Loss to Ext. Env. Conduction Convection Radiation Evaporation

Endogenous Heat Production  Metabolic Rate (MR) - All elements have PASSIVE & REGULATED components…  Example: Sea Gulls – feet on ice - High potential for heat loss - Blood coming up from feet lower than 39° because ice is at 0° - Countercurrent heat exchange! o most efficient o “countercurrent” because the two blood flows are in opposite direction - With no heat exchange, huge energetic drain on animal as blood returning from feet are vastly colder than the rest of the blood, so energy needs to be expended to warm up - With heat exchange, arterial blood going down the leg gives up heat to returning venous blood instead of the environment - This way, returning blood is only very slightly cooler than the rest of the blood, so not as much energy is needed to reheat  trade – off is that feet are almost frozen (very very cold!)

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- small driving force for heat exchange from foot to ice – minimal heat loss to environment - works because animal is willing to sacrifice temperature of its foot to maintain its core temperature Lecture 3: Body Temperature Regulations  Why is it important to regulate body temperature? - Almost all reactions that occur in the body are a function of temperature - If body temperature changes, rate of the reactions change - The reaction rate of virtually every process in the body increases exponentially with temperature (but eventually at high enough temperatures, the systems begin to fail because proteins denature) - Birds have a high metabolic rate because they have a higher body temperature  General Stategies to Regulate TB - Ectothermy: use of external heat to thermoregulate o Poikilotherms (older terminology = variable TB)  “cold blooded” – poor term  all non-vertebrate species (insects/crustaceans)  amphibians/reptiles/fishes/sharks - Endothermy: use of internal heat (MR) to thermoregulate o Homeotherms (older terminology = constant TB)  “warm blooded”  birds/mammals  tunas/dinosaurs??? (there are dinosaurs that have feathers)  energetically very costly - Heterothermy: use of both internal and external heat to thermoregulate o Temporal heterothermy o Regional heterothermy (some areas of the body are allows to be colder)  Regulating Body Temperature

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- Ectotherms (proportional): TB varies with Tamb - Endotherms (independent): TB remains fairly constant over a wide range of Tamb Ectotherms Regulate TB Yes Change Physiology (e.g. In a few cases vasoconstrict) Yes Behaviorally Thermoregulate Insulation No

Endotherms Yes Yes Yes

Yes Fat/fur/feathers Metabolic Rate Low High Low Heat Production High Heat Production  Relation Between Metabolic Rate (MR) and Ambient Temperature (Tamb) in Ectotherms - At low Tamb MR is lower: uses less energy; slower (easier prey) - At high Tamb MR is higher: uses more energy; faster (better predator) - Goal is to be in the middle  MR high enough to be competitive, but not high enough it has crazy energy demands  the organism thermoregulates to this optimal temperature  Relation Between TB and Tamb for Endotherms - Major challenge for endotherms is that environment is always either taking heat from them, or forcing heat into them - Thermoneutral Zone: the range of ambient temperatures over which the animal can thermoregulate without increase its metabolic rate  not zero in this zone, just the minimal MR the animal will have  if the animal is too hot, the MR will increase because there will be energy exerted for active mechanisms for heat dispersion (sweating etc) *BE ABLE TO DRAW THE CURVES  Advantages of being an Ectotherms: - Requires less energy

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o Endotherms require ~17 times more energy than an ectotherm of the same size/mass o More suited to variations in food supply o Can tolerate a less predictable environment - Can exploit a broader range of body sizes/shape o Since Tbody = Tamb freedom from heat – conserving constraints o Ectotherms can function with much smaller body masses than endotherms o Greater lengths/diameter variability in ectotherms - More efficient in producing biomass o Ingested food / energy available for producing biomass rather than maintaining high Tbody  Behavioral Thermoregulation - If too cold, lizard can sit on a rock to raise their body temperatures from the sun - Heliotherm = organisms able to get their energy from the sun (sun is heat source) - Thigmotherm = heat source is the substrate (earth) - How gained (IN) – conduction/convection/radiation! - Ectotherms will normally not tolerate rapid temperature changes o Lots live in seasonal climates (catfish) o Maximum Critical Temperature = CTmax (temperature at which the animal begins to fail) o For bullhead catfish, this CTmax changes depending on what time of year (acclimated to warm temperature can better tolerate high temperature than bullhead catfish acclimated to cold temperatures and vice versa)  Thermal Acclimation - Selective synthesis of multiple forms of the same enzyme (as well as other proteins/lipids/etc.) - Isoenzymes (isoforms)  isoform A & isoform B (only one will be produced at a time)

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- Isoenzymes have different optimal temperatures  function at different rates at different temperatures (allows the animal to function at the optimal rate at various temperatures) - Fish is acclimated to 20°C (optimal MR) o What happens when the fish is rapidly moved to a 10°C environment?  acute response – rapid drop in MR (fish becomes very slow!)  chronic response – (acclimation) slow increase in MR (left shift)  Endotherms in the Cold - MR increased  Heat production increased  energetically costly - Thermogenesis: convert chemical energy into heat o Shivering Thermogenesis – muscle contraction to produce heat  groups of antagonistic muscl...