Class Notes (808,122)
Canada (493,016)
Biology (2,220)
BIO270H1 (61)

Thermal Physiology.docx

8 Pages
Unlock Document

University of Toronto St. George
Chris Garside

Lecture 11 Thermal Physiology Thermal Physiology: - Influences all chemical reactions (ex: enzymes) - All animals have a strategy: behabioral biochemical or physiological - Ambient Temperature: environmental temperature (spatial and temporal variation) - Body Temperature: Thermal energy in body - Thermal Energy moves down gradient - Thermal Balance Equation: : main source of thermal energy; from chemical breakdown : Transfer through direct contact : transfer between object and moving media: usually negative : electromagnetic, infrared = sunlight : heat loss through vaporization of water, usually negative Surface Area: Volume Ratio - Larger animal, ratio decreases - Low ratio = less heat exchange - Bergman: animals in cold = larger - Allen: animals in cold = shorter extremeties - Mole rats huddle to use SA:V ratio to keep warm Insulation: - Internal: o Marine: Blubber - External: o Fur and Feathers (thicker = better insulation External insulation increases the distance of conduction so less heat is loss and minimizes air flow on skin so there’s less convection Thermal Strategies - Tolerance: body allowed to vary with ambient (at mercy to environment) - Regulation: body temperature doesn’t vary (energetic cost) - Poikilotherm: Variable body temperature - Homeotherm: stable body temperature - Ectotherm: source of temperature is the environment - Endotherm: generate and maintains its own heat - Stenotherm: narrow range of ambient temperature tolerated - Eutytherm: wider range of ambient temperature tolerated Heterotherms: - Temporal: changes over time (hibernation, pythons with meals, Torpor (night time) - Regional: changes over body (bill fish eye and tuna red muscle – heat in veins) Thermal Tolerance: - Homeothermic Endotherm: o Thermoneutral zone: Body temperature range is minimal o Upper and lower critical limits - Ectotherm/Poikilotherm: o Preferred optimal temperature o Incipient limit: body temperature where 50% chance of dying o Larger range of tolerance between upper and lower incipient limits Effects of body temperature Change - Macromolecular: o Hydrogen bonds and van der waal forces are disrupted at high temperatures  Protein folding disrupted o Hydrophobic bonds are stabilized at high temperatures - Membrane Fluidity: o Van der waal forces cause it to solidify at low temperatures o Increase in protein movement in high temperature (fluidity increases) Homeoviscous Adaptation: maintaining fluidity - Fatty chain length: shorter so more fluid - Saturation: double bonds=kinks=more fluid - Phospholipid o Phospholipidcholine decreases fluidity o Phospholipidethanolamine increases fluidity - Cholesterol inhibits solidifying at low temperatures Enzyme Kinetics - As temperature increases by 10 degrees: rate of biochm reactions doubles - Protein structure o Weak bonds affect 3D structure (disrupted at high temperature) o Ionization of amino acids results in change in active site o Enzymes undergo changes: i. Protein breathing: proteins need perfect temperature and thus need a specific space. Too cold= contract. Too warm = expand ii. Low temperatures means strong weak bonds iii. Low temperatures decreases enzyme efficiency Cold Adaptaion: - Psychotrophs: cold temperature thrivers - Mesotrophs: thrive at moderate temperatures - Polar fish are psychotrophs o Cold-adapted enzymes o Less weak bonds o Enzymes breath easily o Easily denature though Freezing Survival - Water: Supercooling: if the water is pure, no ice is formed till -40 degrees without nucleator - This is awesome because ice can pierce membranes or remove free water - Freeze Tolerance: freeze mofo4 o Secrete nucleators outside of cell i. Control location and kinetics of ice growth ii. Protects cell iii. Intracellular is liquid while extracellular freezes o Produce solutes: i. Counter water movement out ii. Depress freezing point of water with colligative properties - Freeze Avoidance: avoid freezing – secrete antifreeze: glycoproteins that depress freezing point by noncolligative actions by binding to small crystals to prevent them from growing Maintaining Constant Body Temperature - Endothermy: o Thermogenesis: High metabolic rate: heat production o High temperature: increased growth, development, and digestion o Endotherms regulate thermogenesis and exchange of heat o Ectotherms cant retain the heat o Futile Cycles: reactions solely to produce heat from oxidative phosphotelation by increasing ATP turnover and decreasing ATP synthesis Shivering - Unique to birds and mammals - Uncoordinated contraction (no gross contraction) - Can only last a short period before being depleted of nutrients - No locomotion of muscles: save for fight or flight Insect Thermogenesis: - Generate heat to warm flight muscles to allow muscle performance and allow take off - Mechanisms: o Futile cycle in carbohydrate metabolism o Antagonistic flight muscles act simultaneously o Wing movement but no lift o Bu
More Less

Related notes for BIO270H1

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.