5.1 Flashcards

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1
Q

Define cell signalling.

A

The way in which cells communicate with each other.

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2
Q

What are conditions that need to be maintained in the body?

A
  • pH
  • Temperature
  • Aqueous environment for products and substrates in solution
  • Free from toxins and excess inhibitors
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3
Q

Define stimulus.

A

Change in internal or external environment.

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4
Q

Define response.

A

Change in behaviour and physiology as a result of stimulus.

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5
Q

What makes a communication pathway good?

A
  • Rapid communication
  • Covers whole body
  • Enables specific response
  • Enables short/long term responses
  • Enables cell to cell communication
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6
Q

Define effector.

A

Cells, tissue or organs which bring about a response.

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7
Q

Define homeostasis.

A

Maintaining constant internal environment despite changes in the internal or external environment.

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8
Q

Define Negative Feedback.

A

A mechanism which reverses a change bringing the system back to the optimum.

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9
Q

Define Positive Feedback.

A

A mechanism which increases a change moving a system further away from the optimum.

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10
Q

Define Sensory receptor.

A

Cell/sensory nerve endings which can detect a stimulus in internal or external environment and create an action potential in response.

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11
Q

What does homeostasis regulate?

A
  • Body temperature
  • Blood glucose concentration
  • Blood salt concentration
  • Blood pressure
  • Carbon dioxide concentration
  • Blood water potential
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12
Q

Explain the standard communication pathway.

A

Stimulus -> Receptor -> Communication pathway (cell signalling) -> effector -> response

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13
Q

What part of brain controls temperature?

A

Thermoregulatory centre in the hypothalamus.

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14
Q

Example of useful positive feedback?

A

Cervix dilates causing posterior pituitary gland to produce oxytocin which causes uterine contractions further dilating cervix producing more oxytocin. Stops when birth complete.

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15
Q

Define ectotherm?

A

An organism that relies on the external sources of heat to regulate its body temperature.

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16
Q

Define endotherm?

A

An organism that relies on metabolic reaction to regulate body temperature.

17
Q

How do ectotherms react to low temperature?

A
  • Move into sunny area
  • Expose greater surface area to sun
  • Lie on warm surface
18
Q

How do ectotherms react to high temperature?

A
  • Move to shade area
  • Decrease surface area exposed to sun
  • Go underground
19
Q

How does a snake regulate body temperature?

A

Basks in the sun next to vegetation allow direct contact with skin increasing body temperature.

20
Q

How does a locus regulate body temperature?

A

Start of the day puts his body side on to sun allowing large surface area exposed to sun.

Mid day faces sun head on decreasing surface area.

Moves to top of plants as soil releases heat through radiation as a result of being warmed up by the sun.

Also they can change depth and rate of breathing

21
Q

How does a lizard regulate temperature?

A

Goes into burrows or crevices in the coolest and warmest points of day as crevice has constant temperature.

22
Q

How does a horned lizard regulate temperature?

A

Expands and contracts rib cage controlling surface area exposed to sun.

23
Q

What are the advantages of ectothermy?

A
  • Less food used for respiration.
  • Nutrient and energy from food used for growth.
  • Less time/energy spent on finding food.
  • Can survive longer without food.
24
Q

Disadvantage of ectothermy?

A
  • In cold temperatures they are inactive therefore at threat of predation.
25
Q

What is the hypothalamus?

A

The part of the brain which controls homeostatic responses.

26
Q

What happens to your skin when body is too hot?

A
  • Sweat glands produce fluids which evaporate using heat from blood as latent heat of vaporisation.
  • Hairs and feathers lie flat to stop insulation
  • Vasodilation occurs causing arterioles and pre capillary sphincters to direct blood to skin surface which leaves through radiation.
27
Q

What happens to skin when too cold?

A
  • Sweat glands will stop production of fluids.
  • Hair and feathers erect to trap hair and insulate skin
  • Vasoconstriction diverts blood away from skin surface to stop heat loss through radiation.
28
Q

What happens to gaseous exchange system when too hot?

A

Animals pant which causes water in airways to evaporate using heat from blood for latent heat of vaporisation.

29
Q

What happens to gaseous exchange system when too cold?

A

Less panting to avoid heat loss.

30
Q

What happens in liver when body is too hot?

A

Liver cells stop respirating so that less heat is lost.

31
Q

What happens in liver when body is too cold?

A

Increased respiration of liver cells causing energy from food to be turned into heat.

32
Q

What happens to skeletal muscles when body is too hot?

A

Less contraction to stop release of energy via respiration.

33
Q

What happens to skeletal muscles when body is too cold?

A

More contractions occurs (shivering) generating heat through respiration.

34
Q

What happens to blood vessels when too hot?

A

Vasodilation causing blood to be diverted to extremities to cause heat loss.

35
Q

What happens to blood vessels when too cold?

A

Vasoconstriction diverts blood away from extremities to stop heat loss which can cause frostbite in extreme conditions.

36
Q

What are the advantages of endotherms?

A
  • Body temperature fairly constant despite external temperature
  • Can take advantage of prey
  • Can inhabit colder places
37
Q

What are the disadvantages of endotherms?

A
  • Need constant supply of food to regulate body temperature
  • Most nutrients and energy from food used for growth.
  • Can overheat in hot places