Homeostasis Flashcards

1
Q

Homeostasis

A

The maintenance of a relatively constant internal environment

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2
Q

Factors that need to be kept stable

A

Intersitial fluid plasma
Ph
Temperature
Hormone levels
Blood gases such as o2 or co2

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3
Q

Normal levels of potassium

A

3.5-4.5 mM

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4
Q

What’s considered Hyperkalaemia

A

Concentration of k+ ions exceeds 5.0mM

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5
Q

Above what concentration of K+ is considered a medical emergency

A

6.5mM

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6
Q

Elements of a control centre

A

-detector
-comparator/control centre
-effectors which make a change such as a muscle contraction

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7
Q

Regulated variable

A

Sensor exists to keep this variable within limits

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8
Q

Non regulated variable

A

Can change to achieve control of regulated variable. Eg Herat rate changing which affects blood pressure

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9
Q

Equation for dissociation of co2

A

Co2 +h20=h202=h+ +hco3-

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10
Q

Examples of pyrogens

A

Eg bacteria

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11
Q

Positive feedback mechanism

A

Amplifies the change eg child birth, the fetus pressing the cervix causes afferent signal to the hypothalamus which caused the secretion of the oxytocin by posterior pituitary causing more contractions.( positive reinforcement|)

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12
Q

Feedforward

A

Limits change
Anticipatory behaviour =acts to minimise disruption to set points

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13
Q

What does loss of homeo stasis results in

A

Disease

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14
Q

Negative feedback example

A

Sensors such as carotid and aortic baroreceptots detect change
Comparator such as brain stem and The nucleus of the tract is solitarius
Effectors such as cardiac or smooth muscle result in vasoconstriction and incresed co which reduces body pressure back to 120/80

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