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FPP > Homeostasis and physiological variables > Flashcards

Homeostasis and physiological variables Flashcards

1
Q

What is physiology?

A

The study of how organisms function and how function is controlled and maintained in order to keep us alive and healthy.

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2
Q

What does normal function equate to?

A

Normal function = physiological = health

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3
Q

What does abnormal function equate to?

A

Abnormal function = pathophysiological = illness & disease.

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4
Q

What is a physiological variable?

A

A measure of a bodily condition or bodily function.

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5
Q

What is homeostasis?

A

The dynamic maintenance of physiological variables within a predictable range.

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6
Q

What is the set-point?

A

It is the normal ‘basal’ or ‘at rest’ value for a physiological variable

Set points may be temporarily over-ridden or may need to be adjusted to suit changing circumstances.

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7
Q

What is core temp and arterial CO2

A
  • Core temperature = 37 degrees Celsius
  • Arterial carbon dioxide = 5.3 KPa
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8
Q

what is the most common mechanism for the maintenance of physiological variables.

A

negative feedback

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9
Q

what are 2 types of homeostasis and why do we need them

A
  • Short term - immediate survival.
  • Medium - long term - health and well being reproductive capability.
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10
Q

What happens is a physiological variable is out of its normal range for too long?

A

Illness, disease or death.

E.g.
- Hypertension
- Hypoxemia
- Acidosis/alkalosis
- Hyperglycemia (diabetes)
- Excess cortisol (cushing syndrome)
- Hyperthyroidism (Grave’s disease)

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11
Q

What are two examples of physiological variables?

A

Blood glucose concentration
Blood pressure

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12
Q

in blood glucose concentration what is the set point

A

~90 mg/ml

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13
Q

what is the mean bp when diastolic and systolic

A
  • diastolic = 80 mmHg
  • systolic = 120 mmHg
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14
Q

when is the set point of blood pressure lower?

A

during sleep

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15
Q

what is more important to immediate survival than blood pressure

A

Osmolality (salt/water balance) is more important to immediate survival than blood pressure

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16
Q

3 types of control mechanisms

A

Negative feedback
Feed-forward
Positive feedback

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17
Q

what is negative feedback

A

A change is sensed, and a response is initiated to reverse that change,

The effect is therefore to maintain physiological variables within a predicted range

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18
Q

what is feed forward

A

Anticipation of a change brings about the response to that change before the change can be detected by negative feedback sensors

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19
Q

what is positive feedback

A

A change in a variable triggers a response that causes further change in that variable

The effect is therefore amplification of the change rather than normalisation

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20
Q

What are the key features of all negative feedback loops?

A

A physiological variable drifts away from it’s normal set-point

Sensors detect the change in the variable

Afferent pathway carries signals from sensors to integrating centre

integrating centre compares input from sensors against physiological set point and elicits a response

efferent pathway carries signals from integrating centre to effectors

effectors produce responses that tend to bring the variable back towards its set-point

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21
Q

What are the 3 main types of negative feedback?

A
  • Neuronal
  • Endocrine
  • Paracrine
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22
Q

Where are many neuronal integrating centres found?

A

In the midbrain or brain stem.

23
Q

What 4 things are neuronal integrating centres essential for in negative feedback?

A
  • Temperature control
  • Osmolality control
  • Blood pressure/flow control
  • Blood gas/breathing control
24
Q

What is communication with effectors usually via? what does this result in?

A

Communication with effectors is usually via the sympathetic and parasympathetic nervous systems as they tend to have opposing actions on bodily functions.

This results in a fine tuning of physiological variables.

25
Q

what are 4 examples of communication with effectors

A
  • Cardiac output and blood pressure
  • lung ventilation
  • GI tract motility and bladder control
  • exocrine and endocrine secretions
26
Q

feed forward mechanisms are often …

A

neuronal

27
Q

What are the 5 human endocrine organs in a female?

A

hypothalamus

posterior pituitary

anterior pituitary

pancreas

ovaries

28
Q

what are the 4 human endocrine organs in a male

A

thyroid gland

adrenal gland

kidney

testes

29
Q

What are two tyrosine derivatives and where are they found?

A

Thyroxine (T4) - THYROID

Adrenaline - ADRENAL MEDULLA

30
Q

what are 3 hormone classes

A

peptides, polypeptides and glycopeptides

31
Q

what are 2 examples of a peptide

A

Anti-diuretic hormone (posterior pituitary)
Oxytocin (posterior pituitary)

32
Q

what is an example of a polypeptide

A

Insulin (pancreas)

33
Q

what are 4 examples of glycopeptides

A

Growth hormone (anterior pituitary)
Luteinizing hormone (anterior pituitary)
Follicle-stimulating hormone (anterior pituitary)
Thyroid-stimulating hormone (anterior pituitary)

34
Q

What 5 things is cholesterol used to make

A
  • Cholesterol
  • Estradiol
  • Testosterone
  • Cortisol
  • Aldosterone
35
Q

what steroids are found in the liver

A

cholesterol

36
Q

what steroid is found in the ovaries

A

estradiol

37
Q

what steroid is found in the testes

A

testosterone

38
Q

what steroid is found in the adrenal cortex

A

cortisol
aldosterone

39
Q

What are 5 types of hormones?

A

peptides, proteins

Glycoprotein

catecholamines

Steroids

thyroid hormones

40
Q

where are

peptides/ proteins, Glycoprotein, catecholamines

found?

A

Cell surface:
plasma membrane

41
Q

where are

Steroids, thyroid hormones

found?

A

Intracellular:
cytoplasm or nucleus

42
Q

what is the mechanism of action for

peptides/ proteins, Glycoprotein, catecholamines

A

second messengers
to change enzyme activity

Rapid, often transient response

43
Q

what is the mechanism of action for

Steroids, thyroid hormones

A

Alter gene transcription

Slow, prolonged response

44
Q

how does paracrine homeostatic control operate?

A

locally

45
Q

in paracrine homeostatic control, where are Sensors, integrating centres and effectors located in

A

same tissue

46
Q

paracrine homeostatic control involves the secretion of what

A

Usually involves secretion of diffusible substances (autocoids) from one group of cells to act on another group of cells in the same or adjacent tissue

47
Q

what is the stimulus in paracrine homeostatic control

A

stimulus = may operate in parallel or independently of neuronal and endocrine control.

48
Q

what is the effect in paracrine homeostatic control

A

Effect = diffusible substances may act on cell surface receptors or intracellular targets of effector cells.

49
Q

give 4 examples of paracrine homeostatic control

A

Nitric Oxide (NO) in Blood Vessels
^ Blood flow and blood pressure control

Histamine Release in Inflammation
^ Facilitates access of immune cells to affected tissue

Neurotransmitter Release at Synapses
^ A component of neuronal control

Growth Factors in Tissue Repair
^ Promotion of cell division and matrix regeneration

50
Q

give an example of positive feedback

A

Parturition (contraction of uterus to expel fetus)

51
Q

negative feedback loops are typically …. or …

A

Negative feedback loops are typically (but not exclusively) neuronal or hormonal

52
Q

Where are the sensors in a simple hormonal negative feedback found?

A

Pancreatic b-cells

Within the b-cell, change is compared against set-point

53
Q

Parturition is the contraction of uterus to expel fetus, its a type of positive feedback, does it have neuronal or hormonal control?

A

both

FPP (9 decks)

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