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LS 2 > Chapter 40: Homeostasis > Flashcards

Chapter 40: Homeostasis Flashcards

1
Q

What does homeostasis depend on?

A

function of organs and organ systems

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2
Q

What does homeostasis do?

A

regulates body temperature and maintains a “constant” environment, functional range of intracellular milieu, and dynamic control (thermostat)

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3
Q

What are the two types of organisms homeostasis regulates?

A

ectotherms and endotherms

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4
Q

What is the vertebrate thermostat?

A

the neutral control of body temperature

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5
Q

What are 4 characteristics of homeostasis?

A
  1. maintaining various aspects of internal environment of an organism at a steady level
  2. needs of cells are exhibited by whole organism
  3. cells are surrounded by extracellular fluids, interacts w/ circulatory system
  4. depends on functions of organs/organ systems of the body
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6
Q

What is the compartmentalization component of homeostasis?

A
  • skin separates the internal and external environments.
  • circulatory system moves materials to and from all parts of internal environment
  • fluids of internal environment bathe all cells of organism and differ in composition
  • cells of organs exchange materials via internal environment
  • some organs exchange materials between internal/external environment
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7
Q

when is compartmentalization useless?

A

if activity isn’t coordinated

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8
Q

What is the composition of fluids in the body?

A

1/3 ECF: 20% Plasma/80% Interstitial Fluid

2/3 Intracellular Fluid (ICF)

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9
Q

What is the pathway for regulatory control?

A

Receptor (Sensor percieves magnitude of parameter)–>Control Center (Integrator compares sensor input with set point then instructs effectors)–>Effector (changes parameter to return it to set point)

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10
Q

Negative Feedback

A

detect direction of change and reverse it

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11
Q

Examples of negative feedback (2)

A

temperature and insulin

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12
Q

Positive Feedback

A

detect direction of change and enhance it (once begun, quickly complete)

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13
Q

Feed-forward

A

internal circadian clock; behavior change to avoid challenging event

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14
Q

Example of feed-forward

A

temperature regulation

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15
Q

Negative Feedback Regulation Pathway

A
  1. Receptors obtain info about internal environment
  2. Receptors send info to central neural processing center where info about current internal state is compared to that of the desired state (set point)
  3. Neural processing center stimulates effectors which generate an adaptive response that changes the internal state to the desired state
  4. The establishment of desired state is detected by receptors and info (by neg FB) is directed to the processing center which turns off adaptive response
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16
Q

What are organs made up of?

A

Tissues (cells with similar structures and function)

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17
Q

What are the 4 types of tissues?

A
  1. epithelial tissues (tightly connected)
  2. connective (embedded in ECM)
  3. Muscle (can contract)
  4. nervous (neurons, process/convey info)
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18
Q

What temperatures damage cells?

A

below 0 degrees C and above 45 degrees C

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19
Q

What do rates of biological reaction depend on?

A

temperature

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20
Q

What is the Q10 for biological systems?

A

between 2 and 3

reaction rate increases 2-3 times as the temperature increases by 10 degrees C

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21
Q

What season is the metabolic rate higher in ?

A

summer

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22
Q

What is the actual rates of the seasons?

A

the same

23
Q

Acclimization is reached by…

A

metabolic compensation

24
Q

What is metabolic compensation?

A

expressing similar enzyme with different temperature optimum

25
Q

Homeotherm

A

maintains relatively constant body temperature with changes in environmental temp

26
Q

Poikilotherm

A

changes body temp with changes in environmental temp

27
Q

Heterotherm

A

regulates body temp at constant level some of the time

28
Q

Endotherms - how do they generate heat

A

generate heat internally by metabolic processes; use metabolic active mechanisms for heat loss (birds/mammals)

29
Q

Ectotherms - how do they generate heat

A

depend largely on external source of heat (fish, frog, lizard)

30
Q

Endotherms - how do they respond to outside temp

A

metabolic rate raises when temperature falls below or above set point of body temperature

31
Q

Ectotherms - how do they respond to outside temp

A

metabolic rate increases with a temperature increase

32
Q

How do ectotherms regulate their body temperature?

A

with their behavior; control blood flow to skin, produce metabolic heat during active muscle use, countercurrent exchange

33
Q

Countercurrent exchange

A

helps keep body heat in core of some ectotherms

34
Q

Countercurrent flow

A

small gradients are maintained

35
Q

Concurrent flow

A

large gradients disappear quickly

36
Q

How do Endotherms regulate body temperature?

A
  1. Behavior
  2. Control of blood flow to skin
  3. Pilomotor control regulates insulation of fur and feathers
  4. countercurrent heat exchanger
37
Q

What is the relation between metabolic rate and body mass?

A

As body mass increases, metabolic rate increases.

38
Q

What is the relation between body size and metabolic rate?

A

As body size increases, metabolic rate decreases.

39
Q

Basal metabolic rate of endotherm v. ectotherm

A

endotherm: 6 times greater than ectotherm at rest/same temp

endotherm generates more internal heat

40
Q

Neutral zone endotherm

A

regulate body temp without changing metabolic rate and can maintain metabolism at basal metabolic rate

41
Q

What happens below a critical temperature?

A

endotherm metabolic rate increases as environmental temp decreases since animal must produce more internal heat to maintain constant body temp as heat loss to environment increases

42
Q

Do endotherms also use countercurrent heat exchange?

A

yes

43
Q

Shivering Thermogenesis

A

muscle contraction with little movement

44
Q

Nonshivering Thermogenesis

A

mostly occurs in brown fat cells & thermogenin uncouples oxidative phosphorylation, leak across inner mitochondrial membrane

45
Q

Thermogenin

A

uncouples oxidative phosphorylation

46
Q

How does evaporative water loss happen?

A

-sweating or -panting (dissipate heat from body @ environmental temp above upper critical temp.)

47
Q

What adaptations to hot and cold climates are there?

A
  • increase in thermal insulation (fur, feathers, fat)

- change in volume/surface ratio

48
Q

Hypothalamus

A

structure that controls body temp

49
Q

How does the hypothalamus control body temp?

A

contains temp sensing receptor cell–>establishes temp set point–>sends signals to turn on or off the adaptive response

50
Q

Fever

A

pyrogens/viruses cause increase to the set point which leads to increased body temp

51
Q

Shallow torpor

A

animals drop body temp on a daily basis at times when they are not usually active

52
Q

Hibernation

A

certain animals lower their set point and body temp for weeks; conserves energy

53
Q

Sleep

A

set points are lower than during wakefulness

LS 2 (6 decks)

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