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Biology > B13.3 - Homeostasis > Flashcards

B13.3 - Homeostasis Flashcards

1
Q

What is meant by external environment? [1]

A

things going on outside our body

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2
Q

What is meant by internal environment? [1]

A

things happening inside our body and organisms

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3
Q

Why does the internal environment need to remain constant? [1]

A

so they can work efficiently

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4
Q

What are examples of things needed to remain constant in the internal environment? [5]

A
  • pH levels
  • temperature
  • oxygen levels
  • keeping the water level constant
  • keeping carbon dioxide levels low
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5
Q

What are cells in blood surrounded by? [1]

A

plasma

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6
Q

What are other cells surrounded by? [1]

A

tissue fluid

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7
Q

What is homeostasis? [2]

A

the maintenance of a constant internal environment

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8
Q

What are some examples of internal conditions which are kept constant? [3]

A
  • body temperature
  • blood glucose concentration
  • water potential of the blood
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9
Q

Where does information about conditions in the body go and how? [2]

A
  • goes to the BRAIN
  • from SENSORY RECEPTORS
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10
Q

What does the brain do if the level has gone beyond the normal range? [2]

A
  • initiates a response
  • to bring the level back to within the set points
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11
Q

How does the brain know that the level has been restored? [1]

A
  • receptors inform the brain
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12
Q

What is the mechanism by which homeostasis operates? [1]

A

negative feedback

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13
Q

What is negative feedback? [2]

A

a mechanism that detects a change from the set point and triggers a response that brings the level back to its set point

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14
Q

What is negative feedback in short? [2]

A

detects and corrects

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15
Q

What’s the equation for respiration? [2]

A

glucose + oxygen –> carbon dioxide + water

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16
Q

Why do we need glucose? [2]

A
  • for respiration
  • for energy
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17
Q

What happens if blood glucose levels are too high? [1]

A

plasma loses water by osmosis

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18
Q

What happens if blood glucose levels are too low? [2]

A
  • cells cannot respire and release the energy they need
  • brain cells are especially dependent on glucose for respiration and die quickly if deprived of it
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19
Q

How does glucose get into your blood? [2]

A
  • starch gets broken down by enzymes into glucose
  • gets absorbed out of small intestine into blood
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20
Q

Where does starch get broken down? [2]

A
  • mouth
  • duodenum
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21
Q

Why do you need more glucose when you exercise? [4]

A
  • muscles contract more
  • energy is needed more
  • more respiration needs to happen
  • more oxygen & glucose needed
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22
Q

How is the pancreas involved in controlling blood glucose levels? [2]

A
  • detects the blood glucose levels
  • secretes 2 hormones
23
Q

Which two hormones does the pancreas secrete? [2]

A
  • insulin
  • glucagon
24
Q

What does insulin do? [1]

A

lowers blood glucose

25
What does glucagon do? [1]
increases blood glucose
26
What is the process taken when blood glucose levels are too high? [3]
- detected by pancreas - insulin is released into the blood - insulin lowers the blood glucose levels in 2 ways
27
What are the 2 ways insulin lowers the blood glucose levels? [2]
- more glucose is taken up by cells of the body from the blood for respiration - causes glucose to be converted into glycogen in the liver cells
28
What is the process taken when blood glucose levels are too low? [4]
- detected by pancrease - glucagon released into the blood - glucagon increases blood glucose levels - glucagon makes the liver change glucogen back into glucose
29
What are facts about Type 1 Diabetes? [2]
- people have this from birth/early childhood - own immune system attacks the cells that make insulin in pancreas
30
What are facts about Type 2 Diabetes? [3]
- linked with obesity - not enough insulin is produced or doesn't work - overweight people need to exercise more and eat less food
31
Why must body temperature be kept constant? [4]
- enzymes - cell membranes - diffusion - liquids e.g. blood
32
Why must body temperature be kept constant for enzymes? [2]
- works best at optimum temperature - denatured if temperature too high
33
Why must body temperature be kept constant for cell membrane? [1]
- becomes more fragile as temperature rises
34
Why must body temperature be kept constant for diffusion? [2]
- increases at higher temperature - decreases at lower temperature
35
Why must body temperature be kept constant for liquids? [1]
- become more viscous as temperature drops
36
What does viscous mean? [1]
sticky/thick
37
What happens if there is more heat gain than heat loss? [2]
hyperthermia = increase in temperature
38
What happens if there is more heat loss than heat gain? [2]
hypothermia = decrease in temperature
39
How does the body gain heat? [2]
- metabolism - movement
40
How does the body gain heat through metabolism? [2]
- respiration - chemical reactions in the liver
41
How does the body gain heat through movement? [2]
- respiration - friction within the muscles
42
How does the body retain (keep) the heat it has? [1]
- adipose (fat) tissues under the skin
43
What does adipose tissues help with? [1]
helps insulate against heat loss
44
How does the body lose heat? [4]
- evaporation of water - in exhaled air - sweat on the skin - urine and faeces
45
How is heat lost from the skin? [1]
radiation
46
What do sensory receptors in the skin and brain detect? [2]
- skin: external changes in temperature - brain: internal changes in temperature
47
What are the effectors when body temperature is being controlled? [3]
- sweat glands - skeletal muscle - skin arterioles
48
What are responses that occur when the temperature falls below 37 degrees celcius? [3]
- hairs stand on end - shivering - vasoconstriction
49
What are the effectors for each response when temperature drops? [3]
- erector muscles - skeletal muscles - muscles in the skin arteriole
50
How does hairs standing on end help keep heat in the body? [2]
- hair traps a layer of air - acts as an insulator - reduces heat loss by convection
51
What are responses that occur when the temperature rises above 37 degrees celcius? [3]
- hairs lie flat - sweating - vasodilation
52
What is the process that occurs when vasoconstriction happens? [5]
- body needs to keep heat - skin arterioles constrict (get narrower) - shunt vessel dilates - less blood flows to skin - less heat lost by radiation from skin surface
53
What is the process that occurs when vasodilation happens? [5]
- body needs to lose heat - skin arterioles dilate - shunt vessel constricts - more blood flows to skin - more heat lost by radiation

Biology (26 decks)

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