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Biology > B13.3 - Homeostasis > Flashcards

B13.3 - Homeostasis Flashcards

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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
Q

What does glucagon do? [1]

A

increases blood glucose

26
Q

What is the process taken when blood glucose levels are too high? [3]

A
  • detected by pancreas
  • insulin is released into the blood
  • insulin lowers the blood glucose levels in 2 ways
27
Q

What are the 2 ways insulin lowers the blood glucose levels? [2]

A
  • 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
Q

What is the process taken when blood glucose levels are too low? [4]

A
  • detected by pancrease
  • glucagon released into the blood
  • glucagon increases blood glucose levels
  • glucagon makes the liver change glucogen back into glucose
29
Q

What are facts about Type 1 Diabetes? [2]

A
  • people have this from birth/early childhood
  • own immune system attacks the cells that make insulin in pancreas
30
Q

What are facts about Type 2 Diabetes? [3]

A
  • linked with obesity
  • not enough insulin is produced or doesn’t work
  • overweight people need to exercise more and eat less food
31
Q

Why must body temperature be kept constant? [4]

A
  • enzymes
  • cell membranes
  • diffusion
  • liquids e.g. blood
32
Q

Why must body temperature be kept constant for enzymes? [2]

A
  • works best at optimum temperature
  • denatured if temperature too high
33
Q

Why must body temperature be kept constant for cell membrane? [1]

A
  • becomes more fragile as temperature rises
34
Q

Why must body temperature be kept constant for diffusion? [2]

A
  • increases at higher temperature
  • decreases at lower temperature
35
Q

Why must body temperature be kept constant for liquids? [1]

A
  • become more viscous as temperature drops
36
Q

What does viscous mean? [1]

A

sticky/thick

37
Q

What happens if there is more heat gain than heat loss? [2]

A

hyperthermia = increase in temperature

38
Q

What happens if there is more heat loss than heat gain? [2]

A

hypothermia = decrease in temperature

39
Q

How does the body gain heat? [2]

A
  • metabolism
  • movement
40
Q

How does the body gain heat through metabolism? [2]

A
  • respiration
  • chemical reactions in the liver
41
Q

How does the body gain heat through movement? [2]

A
  • respiration
  • friction within the muscles
42
Q

How does the body retain (keep) the heat it has? [1]

A
  • adipose (fat) tissues under the skin
43
Q

What does adipose tissues help with? [1]

A

helps insulate against heat loss

44
Q

How does the body lose heat? [4]

A
  • evaporation of water
  • in exhaled air
  • sweat on the skin
  • urine and faeces
45
Q

How is heat lost from the skin? [1]

A

radiation

46
Q

What do sensory receptors in the skin and brain detect? [2]

A
  • skin: external changes in temperature
  • brain: internal changes in temperature
47
Q

What are the effectors when body temperature is being controlled? [3]

A
  • sweat glands
  • skeletal muscle
  • skin arterioles
48
Q

What are responses that occur when the temperature falls below 37 degrees celcius? [3]

A
  • hairs stand on end
  • shivering
  • vasoconstriction
49
Q

What are the effectors for each response when temperature drops? [3]

A
  • erector muscles
  • skeletal muscles
  • muscles in the skin arteriole
50
Q

How does hairs standing on end help keep heat in the body? [2]

A
  • hair traps a layer of air
  • acts as an insulator
  • reduces heat loss by convection
51
Q

What are responses that occur when the temperature rises above 37 degrees celcius? [3]

A
  • hairs lie flat
  • sweating
  • vasodilation
52
Q

What is the process that occurs when vasoconstriction happens? [5]

A
  • 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
Q

What is the process that occurs when vasodilation happens? [5]

A
  • body needs to lose heat
  • skin arterioles dilate
  • shunt vessel constricts
  • more blood flows to skin
  • more heat lost by radiation

Biology (20 decks)

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