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A2 Biology > 5.1.1 Communication And Homeostasis > Flashcards

5.1.1 Communication And Homeostasis Flashcards

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1
Q

Why do multicellular organisms need communication systems

A

Animals and plants need to respond to changes in their internal and external environment

Also need to coordinate the activities of different organs

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2
Q

Why do we need to keep our water potential constant

A

If our blood has lower WP than tissue fluid water moves into blood by osmosis- the tissues dehydrate

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3
Q

Why do we need to keep our pH constant

A

pH affects amount of H+ ions- causes 3D structure of enzyme to change, active site changes, fewer ESC

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4
Q

Define stimulus

A

A change in internal or external environment that causes a response

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5
Q

What is a response

A

A change in behaviour or physiology due to a stimulus

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6
Q

Define cell signaling

A

Communication between cells that allows cells to work together to trigger a response or a reaction inside the cell

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7
Q

What is hormone cell signaling

A

Involves hormone released into the blood that binds only to specific target cells with matching receptors

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8
Q

What is homeostasis

A

Maintenance of a a stable internal environment within a narrow range despite external environment changes so that enzymes can function optimally

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9
Q

What is negative feedback

A

Corrective homeostatic mechanism that works to restore any detected change in the internal environment to optimum state

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10
Q

Give an example of negative feedback

A

Vasodilation
Sweating
= cool body

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11
Q

What is positive feedback

A

A process that increase any change detected by receptor

Taking it further away from a set point

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12
Q

Give a positive example of positive feedback

A

Oxytocin- as cervix stretches during labour

Ethylene gas in fruit

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13
Q

Explain how hypothermia is an example of positive feedback

A

1) person is cold
2) enzyme slow down (less kinetic energy)
3) less metabolic reaction
4) less energy produced
5) less heat
6) person gets colder
7) enzymes slow further
…

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14
Q

What is an endotherm

A

An animal that can regulate and maintain core body temperature

They generate heat from respiration and metabolism

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15
Q

Evaluate the pros and cons of being an endotherm

A

Advantages:

  • constant body temp independent of external temp
  • organism can be active despite external conditions
  • can live in colder environments

Disadvantages:

  • large energy intake
  • less food used in growth
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16
Q

How do we as humans loose heat

A

Radiation to the environment
Evaporation of water to vapour
Convection of heat into air currents
Conduction of heat through skin

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17
Q

What part of the brain is responsible for monitoring blood temp

A

Thermoregulatory centre

In the area of the hypothalamus

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18
Q

What are the two centres that are activated in response to a change in temp

A

Heat gain centre- activated by a fall in blood temp

Heat loss centre- activated by a rise in blood temp

19
Q

Describe the two sets of receptors involved in detecting heat

A

Thermoreceptors in the hypothalamus measure blood temp

Peripheral thermorecpetors in the skin monitor external temp - send impulses to the hypothalamus

20
Q

What happens if your body temperature decreases

A

Heat gain centre activated by a fall in blood temp

This is detected by receptors in the hypothalamus and peripheral thermoreceptors in the skin

21
Q

Name three methods of conserving heat

A

Physiological:

  • vasoconstriction
  • raising of hair

Behavioural:

  • shelter from wind
  • animals huddle together
22
Q

How does the raising of hair cause the body to conserve heat

A

Erector muscles in the skin contract raising hair to trap a layer of insulating air to trap heat and reduce the cooling of skin

23
Q

How does vasoconstriction conserve heat

A

Decrease of arterioles lumen to reduce blood flow to the capillaries in the skin of the organisms- reducing heat loss by radiation

24
Q

3 ways heat is lost from the skin

A

Conduction
Convection
Radiation

25
Q

What happens when external body temp decreases

A

Peripheral thermoreceptors in the skin are stimulated, thermoregulatory centre in hypothalamus detects change in blood

Vasoconstriction

Erector pilli muscled contract raising hair to trap a layer of insulating air to trap heat

26
Q

How are penguins adapted to withstand heat

A

Arteries in penguins legs that are able to adjust blood flow to feet based off of temperature

Penguin feathers are highly specialised to keep water away from the skin and insulate

27
Q

4 ways to generate heat

A

Physiological:
Shivering
Release of adrenaline and thyroid hormones
Increased metabolic rate

Behavioural:
Basking in the sun

28
Q

What happens if your body temperature increases

A

Heat loss centre activated by a rise in blood temperature

Receives input from peripheral thermoreceptors and receptors in hypothalamus

29
Q

Explain the process of vasodilation

A

Increase in the diameter of the arterioles lumen beaut the surface of the skin, increasing blood flow to the skin surface

30
Q

What do hairs do in order to loose heat

A

Erector pilli muscles relax in the skin reduces the layer of insulation provided

31
Q

Behavioural mechanisms of losing heat

A

Avoid the heat of the day, sheltering in burrows or shade to prevent body heat from rising

32
Q

How is heat lost from the skin surface

A

Conduction convection and radiation

33
Q

What happens if we get too hot

A

External temperature increases

Peripheral thermoreceptors stimulates

Impulse sent to hypothalamus

Vasodilation

More blood at surface of capillaries

34
Q

Describe the process of sweat

A

Sweat produced from glands
Kinetic heat energy passes to sweat
Which evaporates removing heat from the body
And cools the body down

35
Q

List 2 behavioural adaptations

A

Digging burrows

Basking in sun

36
Q

List 2 anatomical adaptations

A

Blubber

Thin large ears

37
Q

What is an ectotherm

A

Organisms that mainly rely on external/ environmental sources of heat to regulate their body temperature

38
Q

Give an example of ectotherm

A

Reptiles, fish, and amphibians are all ectotherms

39
Q

Why do ectotherms living in water not need to thermoregulate

A

Water has a high specific heat capacity- water temp is constant

40
Q

3 advantages of being an ectotherm

A

Use less food in respiration

Survive long periods without eating

Greater proportion of energy used for growth

41
Q

3 disadvantages of ectotherms

A

Less active In cooler temps

May need to warm up in the morning- basking- predators?

Not capable of activity in winter

42
Q

3 ways ectotherms gain heat

A

Basking in sun

Change body shape to maximise exposure

Alter colour to increase absorption

43
Q

3 ways to lose heat

A

Bathe in water or find shade in a burrow

Reduce contact with ground

Increase breathing movements

A2 Biology (8 decks)

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