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Biology > B 13.2 - Homeostasis > Flashcards

B 13.2 - Homeostasis Flashcards

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1
Q

3 internal conditions that are kept constant

A

-body temperature
-blood glucose concentration
-water potential of the blood

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2
Q

internal environment

A

whats going on inside an organism (outside of cells)

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3
Q

external environment

A

whats going on outside an organism’s body (surroundings)

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4
Q

why does the internal environment need to be kept constant?

A

so cells can work efficiently

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5
Q

what is homeostasis?

A

maintenance of a constant internal environment

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6
Q

how do mammals maintain a constant internal body temperature?

A

-insulation
-sweating
-shivering
-vasodilation of arterioles
-vasoconstriction of arterioles

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7
Q

what are cells in blood surrounded by?

A

plasma

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8
Q

what are other cells surrounded by?

A

tissue fluid

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9
Q

where are the optimum conditions for the internal environment maintained within?

A

plasma and tissue fluid

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10
Q

how is homeostasis brought about?
(homeostatic control)

A

negative feedback:
-sensory receptors send body information to brain continuously
-if level is beyond the normal range, brain initiates a response to bring level back to within set points
-receptors inform brain that the level has been restored

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11
Q

what is negative feedback

A

detect
–>change from set point
correct
–>triggers response that brings level back to its set point

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12
Q

effect in cells of blood glucose levels are being too high?

A

cells lose water due to osmosis
–>outside has lower water potential (high concentration of glucose)
–> cell shrivels up / gets crenated

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13
Q

effect of blood glucose levels being too low for cells?

A

-cells cant respire, can’t release energy needed
-brain cells die quickly

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14
Q

how does glucose get into blood?

A

-starch broken down into glucose by enzymes (in mouth and duodenum)
-gets absorbed out of small intestines into blood

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15
Q

why is glucose needed when you exercise?

A

-muscles need to contract more
-more energy is needed
-more respiration needs to happen
-more oxygen + glucose needed

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16
Q

role of pancreas in controlling blood glucose levels

A

-detects blood glucose levels
-secretes insulin and glucagon

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17
Q

process of homeostasis if blood glucose levels are too high

A

-detected by pancreas
-insulin is released into blood
-insulin decreases blood glucose levels by:
–>causing cells to take up more glucose for respiration
–>causing glucose to turn into glycogen in liver cells

18
Q

why does glycogen not affect blood glucose levels?

A

it’s insoluble so it doesn’t affect osmosis (water potential of cytoplasm or blood)

19
Q

process of homeostasis if blood glucose levels are too low

A

-pancreas detects blood glucose levels
-glucagon is released into blood
-glucagon increases blood glucose levels by:
–>making liver change glycogen to glucose

20
Q

why should body temperature be kept constant? (enzymes)

A

enzymes work best at optimum temperatures (gets denatured if temperature is too high)

21
Q

why should body temperature be kept constant? (cell membranes)

A

membranes become more fragile as temperature increases

22
Q

why should body temperature be kept constant? (diffusion rates)

A

rates increase at a higher temperature and decrease at a lower temperature
-affects gas exchange and absorption

23
Q

why should body temperature be kept constant? (liquids like blood)

A

liquids become more viscous (thick and sticky, no flow) as temperature decreases

24
Q

how does the body gain heat? specific examples as well

A

-metabolism (respiration, chemical reactions in the liver)
-movement (respiration, friction within muscles)

25
Q

how does the body lose heat? reason why? specific examples?

A

-urine & faeces (when expelled from body, heat is lost)
-evaporation of water (when water evaporates, it takes heat with it
–>sweat on skin
–>exhaled air

26
Q

how does the body retain heat?

A

apidose (fat) tissue under the skin

27
Q

what do sensory receptors in skin detect?

A

external temperature

28
Q

what do sensory receptors in brain detect?

A

internal temperature (blood)

29
Q

4 effectors that control body temperature

A

-sweat glands
-skeletal muscle
-muscles in wall of skin arterioles
-erector muscles

30
Q

4 ways heat is lost

A

-evaporation
-radiation
-conduction
-convection

31
Q

what is evaporation

A

loss of heat by evaporation of water (sweat)

32
Q

what is radiation

A

emission of electromagnetic radiation

33
Q

what is conduction

A

direct transfer by contact

34
Q

what is convection

A

moving air removes radiated heat

35
Q

4 responses to the body being too cold

A

–retain heat loss
-hairs stand on end
-sweat glands stop making sweat
-shivering
-vascoconstriction

36
Q

hairs standing on end
-effector?
-how it works

A

-hair erector muscles contract
-warm still air is trapped that acts as an insulator (convection)
–> less heat lost by radiation

37
Q

shivering
-effector?
-how it works

A

-skeletal muscles
-muscles repeatedly contract, generating heat

38
Q

vascoconstriction
-effector?
-how it works

A

-muscles in wall of skin arterioles
–skin arterioles (blood vessels near skin surface) constrict (get narrow)
–shunt vessels dilate (get wide)
–less blood flows to the skin –> decreases heat loss (from skin surface to the environment) by radiation

39
Q

3 responses if the body is too hot

A

-hairs lie flat
-sweating
-vascodilation

40
Q

hairs lie flat
-effector?
-how it works

A

-hair erector muscles relax
-no trapped air –> convection increases –> heat lost by radiation

41
Q

sweating
-effector?
-how it works

A

-sweat glands make sweat
-sweat released onto skin surface –> sweat evaporates –> heat is lost when sweat evaporates

42
Q

vascodilation
-effector?
-how it works

A

-muscles in wall of skin arteriole
–skin arterioles (blood vessels near skin surface) dilate (get wide)
–shunt vessel constrict (get narrow)
–more blood flows to skin –> increases heat loss (from skin surface to the environment) by radiation

Biology (20 decks)

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