Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BMS107 > Thermal Physiology > Flashcards

Thermal Physiology Flashcards

1
Q

Q10 and Reaction Rate

-where most reactions occur

A
  • Q10 = 3
    • for every 10 deg. C increase, reaction rate triples
  • Q10 = 2
    • For every 10 deg. C. increase, reaction rate doubles
  • Between Q10 =2 and Q10 = 3 is where most biochemical reactions occur

-Most organisms are highly dependent on temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What happens when temperature goes outside optimum ranges (either high or low)
(4)

A
  • The Van Der Waal’s forces holding membrane lipids together are affected by temperature
  • Temperature changes membrane fluidity -> affects protein movement
  • Low temps cause membrane lipids to solidify
  • High temps increase membrane fluidity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Definitions;

  • Heat
  • Temperature
  • Differences
A
  • Heat: Total kinetic energy of all molecules in system
    - any system w/ temp. above absolute zero will contain some heat
  • Temperature: Mean kinetic energy of molecules in a system
    - Determines the direction of heat flow (from more to less)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Physics of Heat Transfer

-4 methods heat transfer occurs (list)

A
  • Convection
  • Conduction
  • Radiation
  • Evaporation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Total Heat equation

A

H(total) = H(Metabolic) + H (conduction) + H(Convection) + H(radiation) + H(evaporation) + H(stored)

*can rearranged so equation equals Stored heat (just remove H(total))

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Conduction -> Definition

-4 things it is influenced by

A
  • Conduction: Movement of heat from high to low temperature by interaction of adjacent molecules
  • Influenced by;
    • Thermal Conductivity (k)
    • Area (A) through which heat flows
    • Temperature gradient
    • Separation distance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Convection -> Definition

-2 things it is influenced by

A
  • Convection: Movement of heat through a fluid (liquid or gas) by mass transport in currents
  • Influenced by:
    • Temperature Gradient
    • Convection coefficient (which is dependent on body shape (i.e. SA), wind speeds (or water current))
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Radiation -> Definition

-2 things it is affected by

A
  • Radiation: energy transfer by means of electromagnetic energy - travels at speed of light and needs no medium of propagation
  • Influenced by;
    • Absolute Temp.
    • Surface Area
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Radiation;

  • Direct and reflected solar radiation (what is dependent on)
  • Re-radiated radiation
A
  • Direct and reflected solar radiation;
    • in visible range (400-700nm)
    • Heat gain affected by colour)
  • Re-radiated Radiation;
    • mainly in mid infra-red range
      - colour is not important for heat loss
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Evaporation -> Definition

-4 factors it is influenced by

A
  • Evaporation: Evaporation of water requires a lot of heat (removes that heat from the body)
  • Influenced by;
    • Temp Gradients
    • Vapour pressure gradients
    • Surface Area
    • Wind speeds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Heat exchange in bodies - what system is used? why?

A
  • Countercurrent Mechanisms used as tissues are poor conductors
  • Is a countercurrent multiplier
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Thermal Strategies

-Effect of temperature on reactions and performance

A
  • Effect of temperature: as temp increases, no. of molecules that have a high enough activation energy increases (is a max.)
  • Effect on performance: Depends on organism, but all have a temperature where performance is maximised
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Terminology;
-Based on stability of Stored heat (2 terms)

-Based on source of thermal energy (2 terms)

A
  • Based on stability of stored heat;
    • Poikilotherm: Tb changes with Ta (body temp and ambient temp)
    • Homeotherm: Regulates Tb by physiological means (NOT just behaviour)
  • Based on source of thermal energy:
    • Ectotherm: Thermal balance depends on external sources of heat (conduction, convection etc.)
      - Endotherm: Thermoregulation depends on metabolic heat production as major source of heat

*animals fall into 4 categories based on whether they display endothermy or thermoregulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Exceptions to Thermal strategies (2)

A
  • Temporal heterotherms: Undergo prolonged changes in Tb
    - e.g. hibernating animals or pythons after a large meal (or female with eggs - increase body temp)
  • Regional heterotherms: Retain heat in specific regions of the body
    - billfish w/ heat organs near eyes (thru brown adipose tissue)
    - Tuna retain myogenic heat within red muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Body Temperature and Metabolism: Poikilotherm and Homeotherm

A
  • Poikiotherm: VO2 increases with increase in Ta (= Q10 effect)
  • Homeotherm: VO2 decreases with Ta, then independent after critical point (= Thermal neutral zone)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Defintions;

  • Thermoneutral zone
  • Upper Critical Temperature
  • Lower critical Temperature
    • Eurythermic and Stenothermic
A
  • Thermoneutral zone: Range of temperatures that are optimal for physiological processes; metabolic rate is minimal
  • Upper critical Temp: Metabolic rate increases to induce a physiological response to prevent overheating
  • Lower Critical Temp: Metabolic rate increases to increase heat production
    • Eurythermic: have a wide thermoneutral zone
    • Stenothermic: have a narrow thermoneutral zone
17
Q

Amphibians and Reptiles vs. Birds and mammals

A
  • Amphibians and reptiles: Ectotherms (low energy approach to life)
    • low MR
    • Growth and reproduction based on food, water and O2 availability
      - elongated and small bodies
  • Mammals and Birds: Endotherms
    - High MR
    - Independent of Ta
18
Q

Internal Thermostat in Mammals and Birds

A
  • Mammals: thermal sensory information integrated in the hypothalamus
  • Birds: thermostat is located in the spinal cord

*are negative feedback systems

19
Q

Variations in body temperature (4)

-Effect

A
  • Circadian rhythm of Tb (fluctuates over the day)
  • Rise in Tb associated w/ menstrual cycle
  • Postmenopausal hot flashes
  • Fever

*causes new set point to be higher - is why we shiver even though hot

20
Q

Effect of amphetamines on Vertebrate thermostat

A
  • Amphetamines associated with significant morbidity and mortality; largely due to the disturbances it causes in thermoregulation
  • In rats; ambient temp 30 deg.: dose dependent hyperthermic action (generate too much heat)
    • ambient temp 7 deg.: hypothermic (body temp decreases)
21
Q

How to increase heat if cold

-3 things that can be done

A

M + K + C + R + E = Tb

  • Can only change 3 things;
    1. Heat production (M)
    2. Insulation (K + C + R + E)
    3. stored heat (Tb)
22
Q

Heat production

  • Shivering
  • Non-shivering Thermogenesis (NST)
  • Increased Basal Metabolic rate
A
  • Shivering: Uncoordinated skeletal muscle contraction producing heat
  • Non-shivering Thermogenesis (NST): Enzyme systems for fat metabolism activated to produce energy (heat)
    - occurs in both regular (in cells) and brown fat (intracellular structures - such as many blood vessels) (mitochondrial uncoupling)
    - promoted by thyroid hormones
  • Increased Basal Metabolic rate: generates energy and therefore heat
23
Q

Insulation to deal with cold

  • Definition
  • 2 types (and e.g. of these types)
  • What effectiveness depends on
A

-A layer of material that reduces thermal exchange

Types;

  • Internal insulation:
    - blubber
  • External insulation:
    - Hair
    - feathers
    - animals get fluffier when it is cold (Via piloerection)
    - air
    - water
  • effectiveness depends on its thickness
24
Q

Insulation to deal with cold in wet conditions

A
  • Fur thickness doesn’t help when wet

- Blubber used -> beneficial as can control degree of insulation by opening/closing blood vessels

25
Q

Behavioral changes to deal with Cold (3)

A
  • Huddling (Decreases SA:V ratio)
  • Hibernation: seasonal, body temp is a controlled physiological state (used to save energy)
    - as it gets cold, decrease set point
26
Q

Critical Thermal Maximum (CTM)

-definition and what occurs

A
  • Is the maximum temperature that animals can be exposed to, above which long-term exposure can be fatal
    - e.g. protein denaturation, decreased affinity of Hb for O2, membranes become fluid
27
Q

Dealing with heat -> heat balance

A
  • 3 things that can be done;
    1. Decrease heat production
    2. Increase conductance
    3. Tb (allow to store more heat)
28
Q

Conductance to deal with heat

-What animals do

A
  • e.g. altering blood flow to the body surface -> can change the effectiveness of heat exchange
    • in heat, can dilate capillaries to allow blood to get under skin
  • Most mammals, rise of 0.5 deg. C. causes peripheral vasodilation
    - in rabbits, heat loss through ear
29
Q

Evaporative cooling to deal with heat

A
  • If ambient temp is greater than Body temp, or metabolic production is high, then K + C + R all positive
    • need mechanism to move heat against thermal gradient
  • Evaporative cooling = 1 g water removes 2.4 kJ of heat
30
Q

Diurnal Heterothermy to deal with the heat

A

-Goes through cycles of heating and then decreasing heat -> can allow the body to store heat

31
Q

Selective brain cooling

A
  • Carotid rete: countercurrent heat exchange
  • cool blood from nasal passage passes blood going to brain (e.g. in black wildebeest)
  • Is turned off when running; can save on evaporative water loss

-horses also have gutteral pouches - is a countercurrent system for cooling carotid blood

32
Q

Effect of size on heat (5)

A
  • Height off the ground (elevation decreases heat loading)
  • Ability to move to more suitable habitat
  • More efficient locomotion
  • Thermal Inertia
  • EWL would be extreme for small endotherms
  • Small mammals rely mostly on behavioural thermoregulation (permanently, daily and periodically)
    • e.g. microclimate selection (burrow deep to find low temp soil)

*Larger animals have advantage of size in desert (if they obtain food to sustain them)

BMS107 (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions