BIO 203 Final Study Guide PDF

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BIO 203 Final Study GuideBasic Principles of PhysiologyWhat is Physiology? “How things work” Formal definition: the biological study of the functions of living organisms and their parts Operational Definition: The study of how cells interact with their “environment” to obtain the things required for...

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BIO 203 Final Study Guide Basic Principles of Physiology What is Physiology? -

“How things work” Formal definition: the biological study of the functions of living organisms and their parts Operational Definition: The study of how cells interact with their “environment” to obtain the things required for life (“vital substances”)

Exchange Systems -

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Any system that allows for the exchange of material (“vital substances”) from external environment to internal environment, vice versa - Examples: - Respiratory system (O2/CO2) - Digestive system (nutrients/H2O) - Urinary system (excretion/H2O) - Circulatory System (distribution) Vital substances = water, salts, oxygen, nutrients, heat, etc.

Organization of Complex Biological Organisms -

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Cellular level - Most basic - Four general cell types - Epithelial, connective tissue, nerve, muscle Tissue level - Groups of cells with common structure and function - Ex: epithelial tissue Organ level - Organization of different tissues to perform specific functions - Ex: heart System level - Most complex - Several organs organized carry out major body functions - Ex: cardiovascular system

Basic Principles of Life 1. All life is aquatic - Body fluids of animals have the same general composition - Water and salts - Water is the major component and is 75% of body weight and 99% of all molecules in humans - Salts are simple inorganic substances and make up 0.75% of molecules - Na+, K+, Cl-, Ca++, Mg++, Zn++, Po4-

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Biochemical substances are proteins, nucleic acids, etc. and make up 0.25% of molecules 2. All life is compartmentalized - Separation of substances in different compartments - The cell is the basic unit (compartment) - There are 2 major fluid compartments - Intracellular fluid (ICF) - inside the cell - Extracellular fluid (ECF) - outside the cell - Interstitial fluid - ECF that is not in the circulatory system - Plasma - liquid portion of blood - There is an asymmetric distribution of ions between different compartments - Sodium: - High in the ECF (100-140 mM) - Low in the ICF (1-10 mM) - Potassium - Low in the ECF (1-10 mM) - High in the ICF (100-140 mM) - Calcium - Low in the ECF (1-3 mM) - Very low in the ICF 3. All life deals with same fundamental problems - Many animals have solved fundamental problems in interesting ways - Comparative physiology - Ex: all life requires the input of energy - Life is energetically unfavorable (need energy to survive) - ATP is principal form of energy used by cells - Aerobic respiration - Oxygen - More efficient - Produces more energy - Anaerobic respiration - No oxygen - Less efficient - Produces less energy - Ex: reproduction - Ex: defense - Ex: maintain asymmetric distribution of ions - Hard to transport substances selectively between compartments - Trade offs (lose water during respiration, lose water during thermoregulation) 4. All life is constrained by laws of physics and chemistry - Ohm’s law, boyle’s law, ideal gas law, gravity, kinetic and potential energy, inertia, momentum, velocity, and drag

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Physical environment goversn what cells can and cannot accomplish Cells can utilize laws to their advantage - Cell signaling - Ex: Size principle is the relationship between surface area and volume - SA/V is an index of relative surface area for exchange - As the radius gets bigger (larger animal), the SA/V ratio gets smaller and relative surface are for exchange decreases - Ex: relationship between animal size and heat exchange with environment - Large animal: low rate of heat exchange per unit volume, and good heat retention per unit volume - Small animal: high rate of heat exchange per unit volume, and poor heat retention per unit volume 5. All life can tolerate only a limited range of conditions - Conditions include: - Salts, water, oxygen, carbon dioxide, nutrients, waste elimination, temperature, pH…. - The process of maintaining these conditions with tolerable ranges is homeostasis - Homeostasis: maintenance of relatively constant internal environment; it fluctuates - Requires cell-to-cell communication - Nervous system, hormonal system, intrinsic system - Requires negative feedback

Metabolic Rate -

Definition: the amount of energy an animal uses in a unit amount of time Measured as oxygen consumption in units of calories or kilocalories (1000 calories) Consume more oxygen when expending more energy Sum of all energy-requiring biochemical reactions - Basal metabolic rate (energy to sustain life) - Movement - Heat production - Anabolic pathways (building biomass)

Feedback Systems -

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Components: - Sensor: measures some aspect of the internal environment - Integrator: compares the sensor measurement to a reference valeu (set point) - effector : the output of the system that changes the internal environment Negative feedback: effector counteracts (is opposite to) stimulus - Critical for maintaining homeostasis - Ex: an increase in temperature measured by the sensor results in the effector causing a decrease in temperature Positive feedback: the effector increases the initial sensor stimulus - Leads to rapid change

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Ex: an increase in temperature measured by the sensor results in the effector causing a further increase in temperature Ex: action potential

Body Temperature Energy Production and Utilization -

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Macromolecules: metabolize energy - Carbohydrates, proteins, fats - They go in the system to produce energy Macromeolcules produce energy that forms ATP, water, carbon dioxide, and nitrogenous waste products (from proteins) The ATP is then used for biosynthesis (increase biomass), cellular work (defending asymmetry), and external work (activity cost) - Increase in biomass leads to growth of new tissue and fat storage - Increase in cellular work leads to signaling, transport, secretion, and muscle contraction - Increase in external work leads to locomotion Biosynthesis, cellular work, and external work all lead to heat production

Nitrogenous Waste -

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Metabolic breakdown of proteins produce ammonia (NH3) - Nitrogenous waste The nitrogenous waste are: - Salvaged for amino acid synthesis - Excreted (high levels if ammonia are lethal) - In some animals, converted to less toxic forms of nitrogen - Urea and uric acid Excretion of nitrogenous waste - Ammonia: - Advantages: no energy required

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- Disadvantages: requires lots of water to eliminate - Water loss per gram of nitrogen: 0.5 L - Animal classification: ammonotelic - Ex: fresh water fish Urea: - Advantages: less toxic - Disadvantages: requires ATP to synthesize - Water loss per gram of nitrogen: 0.05 L - Animal classification: ureotelic - Ex: mammals Uric acid: - Advantages: requires little water to eliminate - Disadvantages: requires ATP to synthesize - Water loss per gram of nitrogen: 0.001 L - Animal classification: uricotelic - Ex: bird

Heat / Energy / Body Temperature -

Heat: kinetic energy (molecular motion) Temperature: an index of molecular motion (average kinetic energy) - Hot: high heat content, high energy content, high molecular motion, high temperature - Cold: low heat content, low energy content, low molecular motion, low temperature

Thermal Budget -

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Passive and regulated - Animal does not have control Heat obtained (In) - Heat gained from external environment - Conduction, convection, radiation - Endogenous heat production - Metabolic rate Heat lossed (Out) - Heat loss to external environment - Conduction, convection, radiation, evaporation Conduction: - Heat transfer through physical contact (solids, liquids) - T1=T2, no net transfer - T2>T1, net flow from T2 to T1 - T1>T2, net flow from T1 to T2 - Factors the influence heat conduction - Driving force is temperature gradient - Surface area of contact (A), length between objects (l), and composition of interface (thermal conductivity, K) influences ease of movement - Equation: (dQ/dt)= (K*A/l)*(T2-T1)

- dQ/dt = flow of heat Conductivity by substance - Metal > tissue > water > air - Ex: exchange of heat between blood and environment - Vasodilation - Exercise - Increase in body temperature - Larger vessels make it closer to skin, decreases length between objects - Increase in heat transfer - Vasoconstriction - Cold (shivering) - Decrease in body temperature - Smaller vessels make it further from the skin, increases length between objects - Decrease in heat transfer Convection: - Occurs when environmental medium (air or water) moves over body surface - No physical contact - Slower than conduction - Transfer equation is the same - Two types of convection: - Free convection: environmental medium not mechanically moved - Passive movement (hot air rises, convective currents) - Boundary layers - Decreased driving force for heat exchange - Body senses environmental temperature as hotter than what it is - Body temperature has more influence than ambient temperature - Forced convection: environmental medium physically moved - Physical movement of environmental medium disrupts boundary layers - Increased driving force of heat exchange - Body senses true environmental temperature - Ex: wind chill, running Evaporation - Transformation of water from liquid to vapor (gas) - Requires energy - Cools down environment - 1 g H2O = 580 cal (heat of vaporization) Liquid water has a low heat content and vapor water has a high heat content - Evaporation cooling: when water moves from liquid phase to vapor phase, it absorbs energy from the body surface that leads to cooling -

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- Ex: sweating (humans), panting (dogs/cats) Radiation - Infrared electromagnetic radiation: longer wavelength = less energy - Absorbed radiation = heat gain - Emitted radiation = heat loss - Incident radiation can lead to absorbed radiation or reflected radiation - Black surfaces absorb radiation - White surfaces reflect radiation in all directions

Countercurrent Exchange -

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Sea-gulls feet on ice - High potential for heat loss - No heat exchange between arterial and venous blood creates a large driving force for heat exchange from foot to ice - counter -current exchange between arterial and venous blood reduces drivinf force of heat exchange from foot to ice - Minimal heat loss to environment Salt-excreting glands in birds Mechanism: - Arteries and veins are in close contact - High surface are of contact between arteries and veins - High rate of heat transfer from arterial to venous blood - Arterial blood cooled - Venous blood warmed

Core Body Temperature -

Birds and mmals need to maintain core body temperature - humans - 37℃ - Birds - 39℃

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Requires lots of energy Extremities get much colder than core body temperature, so returning blood needs to be reheated The reaction rate of virtually every process in the body increases exponentially with temperature

Ectotherm -

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Use of external heat to thermoregulate Poikilotherms and “Cold-blooded” All non-vertebrate species - Insects, and crustaceans Amphibians, reptiles, fishes, and sharks Body temperature varies with ambient temperature - Proportional Metabolic rate and ambient temperature - Metabolic rate varies with ambient temperature because body temperature is approximately equal to ambient temperature - At low ambient temperature, metabolic rate is low - Use less energy - Slower (easy prey) - At high ambient temperature, metabolic rate is high - Use more energy - Faster (better predator) - There is an optimum metabolic rate at a specific optimum temperature

Advantages: - Require less energy - Ectotherms require approximately 17 times less energy than an endotherm of the same size and mass - More suited to variations in food supply

- Can tolerate a less predictable environment Can exploit a broader range of body sizes / shapes - Since body temperature is approximately equal to ambient temperature, freedom from heat-conserving constraints - Ectotherms can function with much smaller body masses than endotherms - Greater length and diameter variability in ectotherms - More efficient in producing biomass - Ingested food/ energy available for producing biomass rather than maintaining high body temperature Behavioral Thermoregulation - Place goldfish in water with temperature gradient and observe behavior - Will explore water until it selects “preferred temperature (fairly narrow range) -

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Anole - Burrows at night to minimize heat loss - Sits in sun on rock to increase metabolic rate and increase body temperature

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- Selecting temperature by behavior Ectotherms will not tolerate rapid temperature changes - Have a maximum critical temperature - Temperature at which some percentage of animals will die when placed in it (denaturation) - Changes with the seasons (not times of day) - Lower in the winter Thermal acclimation - Selective synthesis of multiple forms of the same enzyme - Isoenzymes (isoforms): isoform A and isoform B (only one will be produced at a time) - Have different optimal temperatures - Function at different rates at different temperatures - Maximum critical temperature and optimal temperature will change, but optimal metabolic rate will not - Acute response: rapid drop in metabolic rate - Chronic response (acclimation): slow increase in metabolic rate and left shift in optimum temperature

Endotherms -

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Use of internal heat (MR) to thermoregulate Homeotherms and “Warm-blooded” Birds, mammals, tunas, and dinosaurs Energetically very costly Body temperature remains fairly constant over a wide range of ambient temperatures - Independent - Negative feedback - When body temperature is greater than ambient temperature, there is a potential for heat loss - When body temperature is less than ambient temperature there is a potential heat gain Metabolic rate and ambient temperature - As ambient temperature gets colder, metabolic rate increases to produce heat and maintain body temperature

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- Use of less energy At the thermoneutral zone the endotherm can thermoregulate without an increase or decrease of the metabolic rate At high ambient temperature, sweating occurs - Use of more energy

Metabolic rate vs. Size - Small animal: low whole animal metabolic rate, very high unit metabolic rate - Large animal: high whole animal metabolic rate, very low unit metabolic rate - Use less energy per unit mass to stay warm Thermoregulation - Inside the thermoneutral zone, the endotherm can thermoregulate through vasodilation and vasoconstriction - Outside the thermoneutral zone the changing metabolic rate will thermoregulate - Thermogenesis: convert chemical energy into heat - Shivering thermogenesis: muscle contraction to produce heat - Groups of antagonistic muscles are activated - little net movement other than shivering - Muscle contraction is only 25% efficient - 75% of energy expended is released as heat - Nonshivering thermogenesis: metabolism of fat to produce heat - Very little energy is conserved in the form of ATP - Brown fat: brown adipose tissue - A specialization for fat-fueled thermogenesis - Found in mammals usually in neck and between shoulders - Adaption for rapid, massive heat production (heats up very quickly) - highly vascularized - Heat spreads to other parts of the body via circulation - Change thermal conduction (passive) in the cold - Decrease driving force

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- Countercurrent exchange mechanism in limbs - Pulsatile blood flow to limbs (arctic fox) Decrease surface area (small ears, short limbs) - Less heat loss - Huddling Increase size - Smaller surface area/volume ratio Increase insulation - fur , feathers, fat - Piloerection - Fluffing feathers - Expand thermoneutral zone and less increase in metabolic rate needed to maintain body temperature Avoidance - Great savings cost in terms of energy - Hibernation: regulat body temperature but at lower value - bears

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Torpor: suspend thermoregulation and allow body temperature to get very low - Small mammals and hummingbirds

Thermoregulation when ambient temperature is greater than body temperature - Moderate heat stress - Vasodilation - Thermal windows - Change posture

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Extreme heat stress - sweating/panting - Evaporative cooling - Water loss is a significant problem - Allow body temperature to high - Avoidance - Desert animals are typically active at night - Estivation (summer sleep equivalent to hibernation)

Heterothermy -

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Use of both internal and external heat to thermoregulate Animals capable of varying degrees of endothermic heat production Temporal heterothermy: body temperature varies over time - Hibernation (bears), torpor (hummingbirds), body temperature fluctuations during the day (camels) Regional heterothermy: different parts of body at different temperatures - Ectotherms that can maintain core temperature higher than ambient temperature (tune, large sharks) - Counter-current heat exchange between venules and arterioles maintains core temperature higher than ambient temperature - Testes in some mammals (canines, humans)

Behavioral Thermoregulation -

behavioral / physiological thermoregulation: facilitate heat transfer to external environment with little or no increase in metabolic rate Heliotherm: heat source is the sun Thigmothermy: heat source is the substrate (earth) Heat gained through conduction, convection and radiation Energetically very cheap Ex: putting sweater on, sitting in the sun

The Hypothalamus -

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Henry G. Barbour - Implanted a small temperature controlled probe into different parts of the rabbit brain - Evoked strong thermal responses only when used to heat or cool the hypothalamus - Cooling: increase in metabolic rate and body temperature - heating : panting and decrease in body temperature - Highly sensitive Hypothalamus integrates all of the temperature-related information and orchestrates the systemic response - Temperature of hypothalamus most important The preoptic / anterior hypothalamus is the integrator - Thermal receptors are sensors

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Autonomic nervous system, pituitary gland/endocrine system, and higher brain centers are effectors - Autonomic nervous system produces vasotone, metabolic rate, and sweat - Pituitary gland/endocrine system produces vasotone and metabolic rate - Higher brain centers produce behavior

Fever -

Hypothalamic thermoregulatory center is very sensitive to pyrogens - Pyrogens: fever-producing substances - Raise the set point in the hypothalamic thermoregulatory center - vasoconstriction - Exogenous pyrogens: polysaccharides produced by gram negative bacteria - Very potent - Raise body temperature by acting directly in hypothalamic regulatory center and indirectly stimulating the release of endogenous pyrogens - Endogenous pyrogens: heat-labile proteins produced by the animal’s own leukocytes (white blood cells) - Released in response to circulating exogenous pyrogens

Water and Ion Balance Biological Need -

All cells need to exist in aqueous environment Water and salts (ions) need to keep relatively constant Tightly associated with temperature regulation - Evaporative cooling critical to maintaining body temperature under conditions of high ambient temperature and/pr high metabolic rate

Body Fluids -

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40 L of water in the whole person Intracellular fluid- 25 L - 2 L in RBC - 23 L in other cells Extracellular fluid - 15 L - Interstitial fluid - 12 L - Pla...