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1014MSC - Sem 1.5 > WEEK 10 - Topic 1 - Homeostasis (Intro) > Flashcards

WEEK 10 - Topic 1 - Homeostasis (Intro) Flashcards

1
Q

What is a feedback?

A

A response

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2
Q

What is a stressor?

A

The stimulus

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3
Q

What is the difference between a negative feedback mechanism and a positive feedback mechanism?

A

Negative feedback: A homeostatic control mechanism in which the effector response negates the effects of the original stimulus.

Positive feedback: A process in which the effector response enhances the effects of the original stimulus.

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4
Q

What are the components of a feedback mechanism?

A
  • Stimulus (change in variable)
  • Receptor/Sensor (detects the stimulus and sends info to the control centre)
  • (Info sent along the afferent pathway to control centre)
  • Control centre (determines set point, analyses the information and determines response)
  • (Info sent along the efferent pathway to effector)
  • Effector (causes the response; negates or enhances effects of stimulus)
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5
Q

Examples of some important homeostatic variables

A

Body temp
Blood pressure
Blood Ca2+ levels

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6
Q

What are changes in a variable termed as?

A

Stimulus

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7
Q

What is a stimulus

A

Change in variable

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8
Q

Define homeostasis

A

Homeostasis is a state of stable internal environment of the body or a tendency towards such a state

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9
Q

Is a variable in a system controlled by negative feedback maintained perfectly?

A

No, the variable oscillates between an acceptable range - the normal range of function

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10
Q

Who coined the word homeostasis?

A

Walter Cannon

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11
Q

Can the set point of function be reset? Give example.

A

Yes. For eg, the set point for GH increases at night, and more GH is secreted.

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12
Q

What is the set point of function?

A

A set point is the baseline level at which functions can operate efficiently and the variables oscillate around this point (usually the midpoint of a narrow range of values).

It is also the value towards which the system is returned if a disturbance is detected.

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13
Q

For homeostasis what conditions are observed?

A

The variables in the blood are measured as the composition of blood reflects the status of the ECF, which in turn affects cell functions

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14
Q

What is the range of values at which functions operate efficiently called?

A

Normal range of function

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15
Q

What is the internal milieu of the body?

A

The ECF

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16
Q

Which systems are involved in directing homeostatic responses?

A

Nervous and endocrine system

17
Q

Why are variables in the blood measured to maintain homeostasis?

A

The composition of the blood plasma reflects the status of the ECF, which in turn affects cell functions

19
Q

What does humoral mean?

A

Pertaining to the fluids of the body

20
Q

(REVISION) ECF includes:

A
  • Interstitial fluid
  • Blood plasma
  • Transcellular fluid
21
Q

Who is the father of homeostasis?

A

Claude Bernard

23
Q

What is an error signal?

A

Deviation from original value of a variable due to the maintained environmental perturbation

24
Q

What is an error?

A

Deviation from a set point

25
Q

What is a gain?

A

The gain describes how well a system copes with a stressor; how well the system can correct deviations from the original set point.

Correction/error

26
Q

Hot day, 45C
Body temperature may only rise to 38C from 37.5C.

What is the correction, error and gain?

A

Correction: -7C
Error: 0.5C
Gain: 14

27
Q

What does a big gain indicate?

A

A crucial/important variable

28
Q

Another term for circadian rhythm?

A

Diurnal rhythm

29
Q

Define circadian rhythm

A

A daily cycle of biological activity, based on approx. 24 hour intervals

30
Q

What are examples of variables that follow a circadian rhythm?

A

Core body temperature

Cortisol secretion

31
Q

What can cause the set point to change?

A

Because of changing physiological conditions or demands

e.g. fever

32
Q

An efficient homeostatic system minimises what? (In terms of variables)

A

The size (amplitude) of the oscillations of the variable

33
Q

What did Walter Cannon determine?

A

He determined that numerous agents/processes act together (i.e. show integrated activity) to control particular variables.

34
Q

What did Claude Bernard recognise?

A

He recognised that organs systems of the body create and control the composition of the internal milieu, and that this constancy is required for cells of the body to operate.

35
Q

What can cause slight over-corrections and under-corrections of variables?

A

Time lag between the receptor and response

1014MSC - Sem 1.5 (3 decks)

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