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Biology > 5.1.1 - Communication and homeostasis > Flashcards

5.1.1 - Communication and homeostasis Flashcards

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1
Q

What type of equilibrium does the body maintain ?

A
  • Dynamic equilibrium
    • There are fluctuations over a narrow range of conditions
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2
Q

What is the maintenance of dynamic equilibrium called ?

A

Homeostasis

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3
Q

What two things are essential for the body to maintain a dynamic equilibrium ?

A

Receptors and effectors

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4
Q

What is the role of sensory receptors ?

A

They detect changes in the internal and external environment of an organism

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5
Q

What things are monitored in homeostasis ?

A
  • pH of the blood
  • Core body temperature
  • Concentration of ions in the body
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6
Q

Where is information from the sensory receptors sent ?

A

It is transmitted to the brain

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7
Q

What happens when information reaches the brain ?

A

Impulses are sent along the motor neurones to the effectors to bring about changes to restore the equilibrium in the body

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8
Q

What are effectors ?

A

Effectors are the muscles or glands that react to the motor stimulus to bring about a change in response to a stimulus

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9
Q

What are the two types of feedback systems ?

A
  • Positive feedback systems
  • Negative feedback systems
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10
Q

What do feedback systems allow to happen ?

A

They allow for a maintenance of a relatively steady state around a narrow range of conditions

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11
Q

What are most of the feedback systems in the body ?

A

Negative feedback systems

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12
Q

Describe the overall role of a negative feedback system

A
  • A small change in one direction is detected by sensory receptors
  • As a result, effectors work to revers the change and restore conditions back to their base levels
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13
Q

What do negative feedback systems work to do ?

A

They work to reverse the initial stimulus

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14
Q

Give an example of a negative feedback in action

A

The control of blood sugar levels by insulin and glucagon

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15
Q

Describe the overall role of a positive feedback system

A

A change in the internal environment of the body is detected by sensory receptors, and effectors are stimulated to reinforce that change and increase the response

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16
Q

What are some examples of positive feedback systems ?

A
  • Blood clotting cascade
  • Production of oxytocin during childbirth
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17
Q

What is thermoregulation ?

A

The maintenance of a relatively constant core body temperature to maintain optimum enzyme activity

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18
Q

What are some of the processes involved in heating up and cooling down ?

A
  • Exothermic chemical reactions
  • Latent heat of evaporation
  • Radiation
  • Convection
  • Conduction
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19
Q

What is radiation ?

A

The transmission of EM waves to and from the air, water or ground

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20
Q

What is convection ?

A
  • The heating and cooling by currents of air or water
  • Warm air rises
  • Cool air sinks
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21
Q

What is conduction ?

A

Heating as a result of the collision of molecules

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22
Q

What can animals be classified as ?

A
  • Ectotherms
  • Endotherms
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23
Q

What does ectotherm mean ?

A
  • Outside heat
  • They use their surroundings to warm their bodies
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24
Q

What is the core body temp of ectotherms dependent on ?

A

The environment

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25
Q

What species fall under the ectotherm term ?

A
  • All invertebrate animals
  • Fish
  • Amphibians
  • Reptiles
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26
Q

Why do ectotherms that live in water not need to thermoregulate ?

A

The high heat capacity of water means that the temperature of the environment does not change much

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27
Q

Why do ectotherms that live in water have to thermoregulate ?

A
  • The temperature of the air is constantly changing
  • Can be very different between both seasons and days
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28
Q

Why do ectotherms that live in water have to thermoregulate ?

A
  • The temperature of the air is constantly changing
  • Can be very different between both seasons and days
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29
Q

What does endotherm mean ?

A
  • Inside heat
  • They use their internal responses to warm their bodies
30
Q

What is the core body temp of endotherms dependent on ?

A

They rely on their metabolic processes to warm up and they usually maintain a very stable core body temp regardless of the environment

31
Q

Why do endotherms have to consume more food than ectotherms ?

A

This is because the metabolic rate of endotherms is very high

32
Q

What behavioural responses have ectotherms developed that increase the radiation they absorb from the sun ?

A
  • They may bask in the sun
  • Orientate their bodies so that the maximum surface area is exposed to the sun
  • Extend areas of their body to increase the surface area exposed to the sun
33
Q

What behavioural responses have ectotherms developed that decrease the radiation they absorb from the sun ?

A
  • Shelter from the sun by seeking shade
  • Hiding in cracks in rocks
  • Press their bodies against cool, shady earth or stones
  • Move into water or mud
  • Orientate their bodies so that the minimum surface area is exposed to the sun
34
Q

What are some of the physiological responses to warming displayed by animals ?

A
  • Animals living in colder climates tend to be darker coloured than lizards living in hotter countries so they get warmer
  • They can alter their heart rates to increase or decrease their metabolic rate
35
Q

Who is more vulnerable to fluctuations in the environment ?

A

Ectotherms

36
Q

Why do ectotherms need less food than endotherms ?

A

This is because they use less energy regulating their temperatures, and so they can survive in some very difficult habitats where food is in short supply

37
Q

What is the role of peripheral temperature receptors ?

A

They are in the skin and detect changes in the surface temperature

38
Q

What do temperature receptors in the hypothalamus detect ?

A

They detect the temperature of the blood deep in the body

39
Q

What do the temperature receptors in the hypothalamus act as ?

A

The thermostat of the body

40
Q

What is the core temp of the body ?

A
  • 37 degrees
    • between 36-38
41
Q

What do endotherms use to keep warm ?

A

Their internal exothermic metabolic activities

42
Q

What do endotherms use to cool down ?

A

Energy requiring physiological responses

43
Q

What are some of the behavioural responses of endotherms ?

A
  • Basking in the sun
  • Pressing themselves to warm surfaces
  • Wallowing in water and mud to cool down
  • Digging burrows to keep warm or cool
44
Q

What is hibernation ?

A

Becoming dormant through the coldest weather

45
Q

What is aestivation ?

A

Period of prolonged or deep sleep similar to hibernation but occurs in the summer or during dry seasons to avoid heat stress

46
Q

What are some of the behavioural adaptations of humans to help control body temperature ?

A
  • Clothes are worn
  • Houses are built
  • Heating in houses
47
Q

What are some of the ways that endotherms cool down ?

A
  • Vasodilation
  • Increased sweating
  • Hair/feathers lying flat
48
Q

What happens to the arterioles when the temperature rises ?

A

Arterioles near the surface of the skin dilate

49
Q

What happens to the arteriovenous shunt vessels when the temp rises ?

A

They constrict

50
Q

What are arteriovenous shunt vessels ?

A

They are the vessels that provide a direct connection between the arterioles and the venules

51
Q

What does the constriction of the arteriovenous shunt vessels cause ?

A
  • This forces blood through the capillary networks close to the surface of the skin
  • The skin flushes and cools as a result of radiation
52
Q

How does sweating differ as core temp increases ?

A

Sweating increases as the core temperature starts to increase

53
Q

What happens as the sweat evaporates from the surface of the skin ?

A

Heat is lost, controlling the blood below the surface of the skin

54
Q

What happens to the erector pili muscles as body temperature increases ?

A
  • The erector pili muscles in the skin relax
  • The hair or feathers of the animal lie flat to the skin
  • This avoids trapping an insulating layer of air
55
Q

What are some of the adaptations that endotherms have to cool down ?

A
  • Large SA:V ratio to maximise cooling
  • Pale fur or feathers to reflect radiation
56
Q

What are some of the ways that endotherms warm up ?

A
  • Vasoconstriction
  • Decreased sweating
  • Raising body hair or feathers
  • Shivering
57
Q

What happens to the arterioles when the temperature decreases ?

A

Arterioles near the surface of the skin constrict

58
Q

What happens to the arteriovenous shunt vessels when the temp decreases ?

A

They relax

59
Q

What does the relaxing of the arteriovenous shunt vessels cause ?

A
  • Very little blood flows through the capillary networks close to the surface of the skin
  • The skin looks pale and very little radiation takes place
60
Q

How does sweating differ as core temp decreases ?

A
  • Sweating decreases as the core temperature starts to decreases
  • Sweat production will stop entirely
61
Q

What is the effect of no sweat being produced ?

A

It reduces cooling by the evaporation of water from the surface of the skin

62
Q

What happens to the erector pili muscles as body temperature decreases ?

A
  • The erector pili muscles in the skin contract
  • The hair or feathers of the animal are erect
  • This traps an insulating layer of air and so reduces cooling through the skin
63
Q

What is shivering ?

A

It is the rapid involuntary contracting and relaxing of the large voluntary muscles in the body

64
Q

How does shivering warm someone up ?

A

The metabolic heat from the exothermic reactions warm up the body

65
Q

What are the adaptations of a polar bear to stay warm ?

A
  • Small ears
  • Fur on their feet to insulate from ice
  • Hairs are hollow so trap a permanent layer of insulating air
  • Skin is black, so absorbs radiation
  • Thick layer of fat under the skin
66
Q

What are the two centres of thermoregulation ?

A
  • Heat loss centre
  • Heat gain centre
67
Q

When is the heat loss centre activated ?

A

When the temperature of the blood flowing through the hypothalamus increases

68
Q

What does the heat loss centre do ?

A
  • It sends impulses through autonomic motor neurones to effectors in the skin and muscles
  • Triggering responses that act to lower the core temperature
69
Q

When is the heat gain centre activated ?

A

When the temperature of the blood flowing through the hypothalamus decreases

70
Q

What does the heat gain centre do ?

A
  • It sends impulses through autonomic nervous system to effectors in the skin and muscles
  • Triggering responses that act to raise the core temperature
71
Q

What does the heat gain centre do ?

A
  • It sends impulses through autonomic nervous system to effectors in the skin and muscles
  • Triggering responses that act to raise the core temperature

Biology (30 decks)

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