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Principles of pharmacology and physiology > Physiological Homeostasis > Flashcards

Physiological Homeostasis Flashcards

1
Q

Definition of homeostasis

A

Dynamic maintenance of physiological variables within a predictable range

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2
Q

Definition of dynamic

A

Variable fluctuates, still within normal range, average value will be predictable over longer periods of time

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3
Q

Definition of negative feedback

A

Change in variable being regulated compared against set point causing a response that tends to move the variable back to the set period. Normalization to set point

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4
Q

Definition of feed forward

A

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

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5
Q

Definition of positive feedback

A

Change in variable triggers response that causes further change in variable. Amplification of change

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6
Q

Definition of sensors

A

Detect changes in physiological variable

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7
Q

Definition of afferent pathway

A

Carry signals from sensors to integrating center

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8
Q

Definition of integrating center

A

Compare inputs from sensors against physiological set point and elicit a response

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9
Q

Definition of efferent pathway

A

Carry signals from integrating center to effectors

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10
Q

Definition of effectors

A

Produce response that tends to normalize physiological variable

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11
Q

What is physiological homeostasis

A

Dynamic maintenance of physiological variables within a predictable range
Variable may fluctuate, still within a normal range
Average value will be predictable over longer periods of time
Size and frequency of fluctuations depends on variable

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12
Q

Effects of homeostasis

Short term and medium long term

A

Immediate survival

Health, wellbeing, reproductive capability

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13
Q

Hierarchy of importance of physiological variables

A

Variable that is of greater immediate importance, maintained at expense of other variables that are of importance in the long term

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14
Q

What is a negative feedback

A

Change in variable compared set point, causes normalization response
When physiological circumstances change, set points can change

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15
Q

Types of negative feedback

A

Neuronal
Endocrine
Local (chemical/physical)

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16
Q

What is feed forward

A

Anticipation of change, brings about response before change detected by negative feedback sensors

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17
Q

What is positive feedback

A

Change in variable triggers response that amplifies change

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18
Q

Where is the neuronal integrating center in nervous negative feedback

A

Midbrain and brain stem

Hypothalamus, pons, medulla

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19
Q

Function of nervous control in negative feedback loops

A

Temperature control (acts on muscles and skin)
Osmolarity control (acts on kidneys)
Blood pressure/flow control (acts on heart, blood vessels)
Blood gas/ventilation control (acts on respiring muscles/lungs)

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20
Q

Uses of the sympathetic and parasympathetic nervous system

A

Opposing actions on various functions

Results in fine tuning of physiological variables

21
Q

What does the autonomic nervous system control

A 
Heart rate
Blood vessel diameter
GI tract motility
Salivary secretion
Sweat gland secretions
Endocrine secretions
22
Q

What neurotransmitters are being used

A

Sympathetic, noradrenaline

Parasympathetic, acetylcholine

23
Q

Describe the negative feedback loop

A

Stimulus
Receptors, along afferent pathway
Integrating center, sends response along efferent pathway
Effector, elicits response

24
Q

Example of using negative feedback loops

A

Control of body temperature

25
Q

Common features of endocrine control mechanisms

A

Endocrine gland/tissue secretes hormones
Released into the blood
Transoprted in the blood to distant target tissues
Act on target tissues through specific receptors
Response of target tissue depends on type of hormone receptor expressed

26
Q

Location of endocrine glands

A 
Hypothalamus
Pituitary
Thyroid
Parathyroid
Adrenal (cortex and medulla)
Pancreas
Ovaries
Testes
27
Q

Endocrine organs

A 
Hypothalamus (neuroendocrine)
Posterior pituitary (neuroendocrine)
Anterior pituitary (endocrine)
28
Q

What hormones are released from the hypothalalmus

A 
Releasing hormones
Growth hormone releasing (GHRH)
Corticotrophin releasing (CRH)
Thyrotropin releasing (TRH)
Gonadotrophin releasing (GnRH)

Inhibitory hormones
Somatostatin
Dopamine

29
Q

What hormones are released from the posterior pituitary

A

Oxytocin

ADH

30
Q

What hormones are released from the anterior pituitary

A 
Growth hormone (GH)
Prolactin
FSH
LH
Thyroid stimulating hormone (TSH)
Adrenocorticotrophic hormone (ACTH)
31
Q

What is the function of releasing hormones

A

Releasing hormones released from hypothalamus

Encourages release of specific hormones in anterior pituitary

32
Q

Types of hormones

A 
Peptides
Polypeptides
glycoproteins
Amino acid dericatives
Steroids
33
Q

Examples of peptide hormones

A

ADH

Oxytocin

34
Q

Examples of polypeptide hormones

A

Growth hormone

Insulin (pancreas)

35
Q

Examples of glycoprotein hormones

A

LH
FSH
TSH

36
Q

Examples of amino acid derivative hormones

A

Derived from tyrosine
Adrenaline (from adrenal medulla)
Thyroxine (from thyroid)

37
Q

Examples of steroid hormones

A 
Cholesterol, precursor to
Pregnolone, precursor to
Progesterone
Estrogen
Androgens
Glucocorticoids
Mineralcorticoids
38
Q

Types of hormone receptors

A

Peptides
Proteins
Glycoproteins
Catecholamines

Steroids
Thyroid hormones

39
Q

Location of peptide, protein, glycoprotein and catecholamine receptors

A

Plasma membrane

40
Q

Mechanism of peptide, protein, glycoprotein and catecholamine receptors and speed of response

A

2nd messenger, change enzyme activity

Rapid, transient response

41
Q

Location of steroid and thyroid hormones

A

Intracellular cytoplasm/nucleus

42
Q

Mechanism of steroid and thyroid hormones and speed of response

A

Alter gene transcription

Slow, prolonged response

43
Q

Endocrine reflex arc

A

Stimulus
Receptors and integrating center in same cell, sent down efferent pathway
Response, causes negative feedback

44
Q

Example of a use of the endocrine reflex arc

A

Control of blood glucose conc

45
Q

Features of local homeostatic response

A

Negative feedback reflex operating locally
Independent of neuronal, hormonal response
Sensors, afferent pathway, integrating center efferent pathway, effectors all in same tissue/organ

46
Q

Local negative feedback reflex arc

A

Stimulus
Receptors, afferent pathway, integrating center and effector in same cell
Response sent down efferent pathway
Triggers a second response, send down another efferent pathway

47
Q

Feedforward control mechanism

Instinctive reflex arc in terms of fight and flight response

A

Threat stimuli
Anticipation of physical exertion
Sympathetic activation
Noradrenaline, adrenaline release
Increased HR, blood flow to skeletal muscles
Preparation for increased O2 and fuel demand from muscles

48
Q

Feedforward control mechanisms

Conditioned reflexes

A

Anticipation of meal
Parasympathetic activation
Stimulation of saliva, gastric juive production
Preparation for food intake

49
Q

Positive feedback arc

Parturition

A

Pregnancy alters estrogen/progesterone balance
Increases excitability of uterus (hormonal)
Uterine contractions (mechanical)
Fetus presses on cervix (neuronal)
Signal sent to hypothalamus for more oxytocin secretion

Loop continues until birth ends

Principles of pharmacology and physiology (25 decks)

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