5.1 - Communication and homeostasis Flashcards

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1
Q

What is negative feedback?

A
  • A response that is opposite to the stimulus, returning conditions back to the optimum.
  • Brought about by an effector
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2
Q

What is positive feedback?

A
  • A response that increases the stimulus, taking conditions further away from the optimum
  • For example child birth
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3
Q

What is the difference between endotherms and ectotherms?

A
  • Endotherms generate their own heat by metabolic reactions

- Ectotherms rely on the environment to control their body temperature

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4
Q

What is an ectotherm? (Cold-blooded)

A

An organism that is unable to control its body temperature and is reliant on external sources of heat

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5
Q

What is an endotherm? (Warm-blooded)

A

An organism that controls its body temperature in a narrow range using physiological or behavioural adaptations

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6
Q

What is homeostasis?

A

Maintaining a relatively stable internal

environment/state within narrow limits even when the environment is changing

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7
Q

What factors need to be kept constant?

A
  • Body temperature
  • Blood PH
  • Blood glucose
  • Water potential, to ensure cells function properly
  • Levels of: salt, O2 & CO2
  • Blood pressure
  • Blood volume
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8
Q

How do endotherms regulate their internal temperature?

A

Their body will be able to regulate the internal temperature

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9
Q

How do ectotherms regulate their internal temperature?

A

Ectotherms will rely on sitting in the sun (basking) or sitting in the shade

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10
Q

Why must internal temperature be maintained? (Enzymes)

A
  • To ensure that enzymes have optimal temperature
  • This is so they can work properly and not denature if too hot
  • Or have a slower reaction rate due to colder temperatures
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11
Q

Why must internal temperature be maintained? (Aerobic respiration)

A
  • Ectotherms may warm themselves up is so that they can undergo aerobic respiration
  • This means they will be able to produce ATP needed for the active metabolic processes in the body, such as muscle contractions or active transport
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12
Q

How do endotherms regulate internal temperature?

A
  • The thermoregulatory centre inside of the hypothalamus is used
  • The thermoreceptors inside this centre will monitor the temperature of the blood and will send messages to parts of the body (Via the autonomic nervous system) to increase or decrease the body temperature depending upon what it is at the time
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13
Q

How is vasodilation used to regulate temperature?

A
  • Vasodilation is when more blood flows closer to the skin in the capillaries
  • The shunt vessel narrows and prevents the blood from flowing away from the surface of the skin, so the blood is redirected to the capillaries closer to the skin
  • This means more heat is lost through radiation through the skin
  • This causes body temperature to decrease
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14
Q

How is vasoconstriction used to regulate temperature?

A
  • Vasoconstriction is when less blood flows closer to the skin in the capillaries and the blood goes through the shunt vessel further away from the skin instead
  • This means less heat is lost through radiation through the skin
  • This causes body temperature to increase
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15
Q

How do hair erector muscles work to regulate body temperature?

A
  • The hair erector muscle contracts or relaxes to cause the hairs to stand on-end or lie flat
  • If the hairs stand up it traps an insulating layer of air causing an increase in body temperature
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16
Q

How is the body temperature returned back to normal if it increases?

A
  • Change in body temperature is detected by the peripheral temperature receptors in the skin
  • The increase in body temperature would be detected by thermoreceptors in the thermoregulatory centre inside the hypothalamus
  • Neuronal impact: Motor neurones will bring about a response causing either vasodilation, sweating or relaxation of the hair erector muscles
  • Hormonal impact: A decrease in adrenaline production causing a decrease in metabolism which generates heat as a by product of aerobic respiration
  • This will bring temperature back to normal
17
Q

How is the body temperature returned back to normal if it decreases?

A
  • Change in body temperature is detected by the peripheral temperature receptors in the
  • The decrease in body temperature would be detected by thermoreceptors in the thermoregulatory centre inside the hypothalamus
  • Neuronal impact: Motor neurones will bring about a response causing either vasoconstriction, decrease in sweating or contraction of the hair erector muscles
  • Hormonal impact: An increase in adrenaline production causing an increase in metabolism which generates heat as a by product of aerobic respiration
  • This will bring temperature back to normal
18
Q

What is a receptor?

A

-Receptors detect a change in the body

19
Q

What is an effector?

A

-A muscle or gland that is responsible for bringing about a change

20
Q

What is the PH in the blood?

A

-Blood PH is 7.4 +/- 0.1, a shift of 0.4 leads to death

21
Q

Why must blood glucose concentration be regulated?

A
  • Glucose is used as a respiratory substrate by cells so a constant supply of glucose is needed
  • Keeping the blood glucose level constant also ensures a constant water potential
22
Q

Why must the water potential of the blood be regulated?

A
  • Changes in water potential of the blood may cause cells to shrink or expand as water enters or leaves by osmosis
  • The water potential must be kept constant otherwise cells cannot function properly
23
Q

How do effectors bring about negative feedback?

A

-The effector causes a change that brings the internal conditions of the body back to normal (Optimal conditions)

24
Q

How is positive feedback brought about?

A
  • A stimulus causes the conditions of the body to be changed so they are further away from the normal conditions
  • The stimulus causes nerve impulses to go to the brain which stimulates the release of hormones to amplify the change and bring about a response