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Biology > 5.1.1 - Communication and homeostasis > Flashcards

5.1.1 - Communication and homeostasis Flashcards

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
What species fall under the ectotherm term ?
- All invertebrate animals - Fish - Amphibians - Reptiles
26
Why do ectotherms that live in water not need to thermoregulate ?
The high heat capacity of water means that the temperature of the environment does not change much
27
Why do ectotherms that live in water have to thermoregulate ?
- The temperature of the air is constantly changing - Can be very different between both seasons and days
28
Why do ectotherms that live in water have to thermoregulate ?
- The temperature of the air is constantly changing - Can be very different between both seasons and days
29
What does endotherm mean ?
- Inside heat - They use their internal responses to warm their bodies
30
What is the core body temp of endotherms dependent on ?
They rely on their metabolic processes to warm up and they usually maintain a very stable core body temp regardless of the environment
31
Why do endotherms have to consume more food than ectotherms ?
This is because the metabolic rate of endotherms is very high
32
What behavioural responses have ectotherms developed that increase the radiation they absorb from the sun ?
- 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
What behavioural responses have ectotherms developed that decrease the radiation they absorb from the sun ?
- 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
What are some of the physiological responses to warming displayed by animals ?
- 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
Who is more vulnerable to fluctuations in the environment ?
Ectotherms
36
Why do ectotherms need less food than endotherms ?
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
What is the role of peripheral temperature receptors ?
They are in the skin and detect changes in the surface temperature
38
What do temperature receptors in the hypothalamus detect ?
They detect the temperature of the blood deep in the body
39
What do the temperature receptors in the hypothalamus act as ?
The thermostat of the body
40
What is the core temp of the body ?
- 37 degrees - between 36-38
41
What do endotherms use to keep warm ?
Their internal exothermic metabolic activities
42
What do endotherms use to cool down ?
Energy requiring physiological responses
43
What are some of the behavioural responses of endotherms ?
- 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
What is hibernation ?
Becoming dormant through the coldest weather
45
What is aestivation ?
Period of prolonged or deep sleep similar to hibernation but occurs in the summer or during dry seasons to avoid heat stress
46
What are some of the behavioural adaptations of humans to help control body temperature ?
- Clothes are worn - Houses are built - Heating in houses
47
What are some of the ways that endotherms cool down ?
- Vasodilation - Increased sweating - Hair/feathers lying flat
48
What happens to the arterioles when the temperature rises ?
Arterioles near the surface of the skin dilate
49
What happens to the arteriovenous shunt vessels when the temp rises ?
They constrict
50
What are arteriovenous shunt vessels ?
They are the vessels that provide a direct connection between the arterioles and the venules
51
What does the constriction of the arteriovenous shunt vessels cause ?
- 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
How does sweating differ as core temp increases ?
Sweating increases as the core temperature starts to increase
53
What happens as the sweat evaporates from the surface of the skin ?
Heat is lost, controlling the blood below the surface of the skin
54
What happens to the erector pili muscles as body temperature increases ?
- 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
What are some of the adaptations that endotherms have to cool down ?
- Large SA:V ratio to maximise cooling - Pale fur or feathers to reflect radiation
56
What are some of the ways that endotherms warm up ?
- Vasoconstriction - Decreased sweating - Raising body hair or feathers - Shivering
57
What happens to the arterioles when the temperature decreases ?
Arterioles near the surface of the skin constrict
58
What happens to the arteriovenous shunt vessels when the temp decreases ?
They relax
59
What does the relaxing of the arteriovenous shunt vessels cause ?
- 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
How does sweating differ as core temp decreases ?
- Sweating decreases as the core temperature starts to decreases - Sweat production will stop entirely
61
What is the effect of no sweat being produced ?
It reduces cooling by the evaporation of water from the surface of the skin
62
What happens to the erector pili muscles as body temperature decreases ?
- 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
What is shivering ?
It is the rapid involuntary contracting and relaxing of the large voluntary muscles in the body
64
How does shivering warm someone up ?
The metabolic heat from the exothermic reactions warm up the body
65
What are the adaptations of a polar bear to stay warm ?
- 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
What are the two centres of thermoregulation ?
- Heat loss centre - Heat gain centre
67
When is the heat loss centre activated ?
When the temperature of the blood flowing through the hypothalamus increases
68
What does the heat loss centre do ?
- It sends impulses through autonomic motor neurones to effectors in the skin and muscles - Triggering responses that act to lower the core temperature
69
When is the heat gain centre activated ?
When the temperature of the blood flowing through the hypothalamus decreases
70
What does the heat gain centre do ?
- It sends impulses through autonomic nervous system to effectors in the skin and muscles - Triggering responses that act to raise the core temperature
71
What does the heat gain centre do ?
- 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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