Chapter 10 Flashcards
- Endotherm
- Thermoregulation
- Homeotherm
- Ecotherms
- Poikilotherms
- Heterotherms
- regional- temp change from region to another in the body of 1 individual
- temporal- hometherms through out the year then exhibit neither thermoregular or endothermy when hibernating
- An animal that can warm itself through metabolic heat production
- Maintenance of a constant tissue temp
- An animal that can thermoregulation by physiological means (rather than just by behavior)
- thermal conditions outside their bodies determine their body temps
- is an ectotherms that has variable body temps. ex. body temp is high in warm environments
- Nonthermoregulating poikilotherm or ectotherms
- Thermoregulating poikilotherm or ectotherms
- Behavioral thermoregulators
- Nonthermoregulating endotherms
- Thermoregulating endotherms
- Homeotherms
- Can’t control body temp by any mechanism
- Control temp but cant alter metabolic rate so they do it by changing behavior
- Can warm itself through metabolic heat production, but tissue temps can change
- Can maintain a constant tissue temp and can warm itself through metabolic heat production
6.
Heat vs Temperature
Temperature is ?
Heat is ?
a measure of the speed of random atomic motion
a form of energy. Depends on the speed and number of moving atoms
Mechanisms of Heat Transfer
- Convection
- Conduction
- Radiation
- Heat loss or gain to the environment
- Heat transfer from one surface to another through touching
- Heat loss
Poikilothermy
- Most common type of thermal relation
- Poikilotherms have ____ body temperatures
- Temps of aquatic animals are ___ to water temp than terrestrial animal temps to air temp
- Ectotherms have body temperatures that are determined by ____
- variable
- closer
- outside temperatures
Poikilotherms
- Poikilotherms may have ___ control over body temperature
- Animal may move to a spot with a more appropriate temperature (under shade or in sun)
- In cages the environmental temps are far more homogenous – this has implications for pet care
- Behavioral thermoregulation is ?
- behavioral
- the poikilotherm maintains a relatively constant temp via moving
Poikilothermy
Must function over a wide temperature range
- Eurythermal ?
- Stenothermal ?
Physiologically respond to temperature changes in 3 time frames. What are they?
- temperature range is large
- temperature range is small
- Acute
- Chronic
- Evolutionary
Acute poikilothermic responses
- As body temperature increases, metabolic rate increases exponentially (approximately)
- Temperature coefficent
- Q10 = RT/R(T-10)
- Usually between 2 and 3
- Not truly constant
Chronic poikilothermic responses
What is a chronic response?
- 33°-acclimated animals were exposed to temps of 16, 28, and 33°
- An acute response
- 16°-acclimated animals were exposed to temps of 16, 28, and 33°
- Acclimation alters the acute metabolism-temperature relationship
The response to long-term temperature changes
Chronic poikilothermic responses
- Acclimation tends to return the metabolic rate towards its levels prior to a drop in body temperature
- The restoration of metabolic rate is called compensation
- Partial compensation (y to z) is more common
Chronic poikilothermic responses
Acclimation blunts the response to temperature changes
- How?
- Control amounts of rate limiting enzymes increased
- Krebs
- Electron-transport
- This takes time!
Thermal limits
Critical temps: temperature is acutely raised until function failure (death)
thermoregulating then conforming
Pejus temperature – Where there is any sign of chronic weakness
- Heat can’t perform work, but…
- It affects the rates of tissue processes
- It affects the conformation of molecules
- Enzyme-substrate affinity is altered by temperature
- Affinity is roughly equal when looked at preferred body temps
- Climate change could have a major impact on animal survival
Pagothenia lives at -2°C. It dies of heat stress at 4-6°C
Acetylcholinesterase loses all affinity for substrate at 5- 10°C
Antarctic fish (Pagothenia )- Stenothermal
Mullet- Eurythermal
- Lipid function is altered by temperature
- Membrane fluidity
- Homeoviscous adaptation
- Maintenance of membrane fluidity regardless of temperature
- Fatty acids are not saturated at cold temperatures
How is membrane fluidity maintained?
Changing the amount of saturated and unsaturated fats in the membrane.
More sats- makes membrane more solid
More unsats- makes membrane more liquid
Animal tissues freeze at lower temperatures than water (-.1 to -1.9° C). Why?
Because of the salts
- Freezing
- When aqueous solutions are progressively cooled, they can remain liquid even below the freezing point. 1. This is called what?
- May spontaneously freeze at any time
- When aqueous solutions are progressively cooled, they can remain liquid even below the freezing point. 1. This is called what?
2. The temperature at which spontaneous freezing is most likely to happen?
3. ___exposure induces freezing of supercooled soln’s
4. A supercooled solution will immediately freeze if exposed to a tiny ___?
-
If a solution at 0°C is cooled in the presence of an ice crystal, the crystal will prevent supercooling
- This determines the soln’s freezing point
5. Freezing ____ cells usually kills them
6. Cells are tolerant of ____freezing
- Ice formation usually begins in extracellular soln’s
- Supercooling
- Supercooling point
- Ice
- Ice crystal
- Within
- Extracellular
Before freezing, the intracellular & extracellular osmotic pressures are ___
Slow extracellular freezing is made of nearly ___?
Solutes excluded from the ice ____ the extracellular osmotic pressure
Water leaves the cell
- Cell shrinks
- Osmotic pressure increases
equal
pure water
increase
Three methods of coping with freezing?
- Production of antifreeze compounds
- Supercooling
- Tolerance of freezing
Antifreeze compounds
What are the 2 types of antifreeze compounds?
1.
- Increase solute concentration, reducing freezing point (chemical)
- Polyhydric alcohols (e.g. glycerol, sorbitol, mannitol)
2.
- Proteins & glycoproteins that weakly bind to ice crystals in specific ways; thereby, preventing further water molecules from crystallizing
- Depress freezing point 100x more than colligative properties
- Do not depress melting point; allows thermal hysteresis (freezing pt is much less than melting pt)
Colligative antifreezes
Noncolligative antifreezes
Noncolligative antifreezes
- Mainly found in teleost fish and insects
- The winter flounder makes more antifreeze protein as ___ approaches
winter
Supercooling
Animals modify the probability of freezing during supercooling
- Alter quantity/quality of ice-nucleating agents. Reduce molecules that causes foci
- Dissolved/undissolved substances that act as foci for the initiation of freezing. Changing the ratio and make less ice nucleating agents
- Lots of these cause the animal to freeze sooner
Tolerance of freezing
- Sessile or slow-moving invertebrates (like?) on rocks are frequently exposed to freezing conditions when exposed to air
- Some can survive after 60-80% of their body water was ice
- Generally limit supercooling in extracellular fluids, so that freezing happens there (a safe location) (allows for freezing)
- Depends on addition of organic solutes to body fluids
- In both extracellular and intracellular compartments
- Amphibians – glucose
- Insects – polyhydric alcohols
Barnacles, mussels, and snails
Homeothermy
Is?
Body temperature is not constant: daily fluctuations of 1-2°C
Cellular functions are able to be specialized to take place especially reliably at certain temperatures
Requires what 3 things?
Regulation of body temperature by physiological (metabolism )means
- Neurons to sense current body temperature
- Thermoregulatory control centers in the brain
- Heat producing and voiding systems (sweating; negative feedback)
