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pharmacology > Endocrine system > Flashcards

Endocrine system Flashcards

1
Q

What does the endocrine system consist of?

A
  • Specialised ductless glands (or neurones) scattered throughout the body
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2
Q

What do the glands of the endocrine system secrete and how do they travel in the body and what is the response?

A
  • They secrete biologically active chemical messengers
    (hormones) into the blood stream.
  • The hormones are carried in the blood stream to interact with distant target cells.
  • Interaction leads to specific target cell response in terms of metabolism, growth or reproduction.
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3
Q

What are the anatomical divisions of the endocrine system and what does each one consist of?

A

THE CENTRAL ENDOCRINE GLANDS: Hypothalamus, Pituitary gland, Pineal gland

THE PERIPHERAL ENDOCRINE GLANDS: Thyroid glands, Adrenal glands, Endocrine pancreas, Parathyroid glands

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4
Q

State the functions of the endocrine system.

A
  • Regulate & Control Important Cellular & Body Functions.
  • Cellular Metabolism and water & Electrolyte balance.
  • Cell Growth & Development and Reproduction.
  • Adaptive changes to help the body cope with stressful
    situations.
  • Control & Integration of circulatory and digestive
    systems.
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5
Q

Describe the synthesis of hormones.

A

Vesicle-mediated pathway
* Synthesised in rER & packaged in vesicle
* Amine/AA/Peptide/Protein hormones

Non-vesicle-mediated pathway
* Synthesised in sER & directly released
* Steroid hormones

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6
Q

Describe the transport of hormones.

A

Free & unbound
* Amine/AA/peptide hormones
Protein career-bound
* Steroid & thyroid hormones

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7
Q

How do hormones produce their effects on target cells?

A
  • By interacting with specific receptors
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8
Q

What are the two broad types of hormonal receptors?

A
  • Cell surface receptors:
    Receptor-ion channels
    G-protein coupled receptors
    Tyrosine kinase-linked receptors
  • Intracellular or nuclear receptors
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9
Q

What may endocrine disorders result from?

A
  • Hyposecretion
    – Endocrine secretes too little of its hormone
    – Primary, Secondary or Tertiary
  • Hypersecretion
    – Endocrine secretes too much of its hormone
    – Primary, Secondary or Tertiary
  • Abnormal Target Cell Responsiveness
    – Receptor down regulation (hypo responsiveness)
    – Receptor up regulation (hyper responsiveness)
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10
Q

Where are the hypothalamus and pituitary glands located?

A

In diencephalon: the pituitary gland lies in a pocket of bone at the base of the brain

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11
Q

State the function of the hypothalamus & pituitary gland.

A

Function cooperatively as ‘master regulators’ of the endocrine system - control of critical homeostatic & metabolic functions

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12
Q

State the two lobes the pituitary gland consists of and their functions?

A
  • Anterior pituitary: secretes and releases 6 major hormones
  • Posterior pituitary: stores and releases 2 hormones
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13
Q

What is the hypothalamus?

A

Brain’s coordinating centre for endocrine, behavioural & autonomic nervous system function

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14
Q

What does the hypothalamus act as?

A

A neuroendocrine transducer or bridge:
– receives & integrates multiple brain signals
– converts signals into chemical messages
– releases chemical messengers (hormones) to control secretion of pituitary hormones
– pituitary hormones control activity of peripheral endocrine glands

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15
Q

Describe the transport of hypothalamic releasing hormones.

A
  • Hypothalamus makes releasing hormones
  • Action potentials cause release of hormones into portal vessels which are carried to anterior pituitary
  • The anterior pituitary releases its stored tropic hormones into systemic circulation
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16
Q

Describe the role of the hormones GH (ANTERIOR PITUITARY HORMONE)

A

– Important role in intermediary metabolism
* Exerts largely anti-insulin effects
* Increases lipolysis - increases free fatty acid (FFA)
mobilization & use as fuel
* Inhibits peripheral cellular glucose uptake - increases blood glucose levels & decreases use of
glucose as fuel

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17
Q

What is the secretion of the growth hormone modulated by?

A
  • GHRH & somatostatin from hypothalamus
  • Ghrelin from gastric fundus
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18
Q

What does GH output increase with?

A

Size - to maintain the concentration of GH pulses needed to sustain growth during childhood

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19
Q

Describe the pathology of GH.

A

*undersecretion BEFORE puberty will cause dwarfism
*overproduction BEFORE puberty will cause
gigantism
*AFTER puberty over-production causes acromegaly

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20
Q

State the role of the follicle-stimulating hormone FSH (ANTERIOR PITUITARY HORMONE)

A

– stimulates growth & development of ovarian follicles (F)
– promotes ovarian secretion of oestrogen (F)
– Required for sperm production (M)

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21
Q

How is FSH stimulated?

A

– Secretion stimulated by GnRH from the hypothalamus

22
Q

Describe the role of the luteinising hormone (LH) (ANTERIOR PITUITARY HORMONE)

A

– Responsible for ovulation & development of the corpus luteum (F)
– Regulates ovarian secretion of sex hormones (F)
– Stimulates testes to secrete testosterone (M)

23
Q

What is the secretion of LH stimulated by?

A

GnRH from hypothalamus

24
Q

Describe the role of prolactin (PRL) (ANTERIOR PITUITARY HORMONE)

A

– Enhances breast development & milk production in females;
elevated in pregnancy and lactation
– Overproduction leads to infertility

25
Q

What is the secretion of PRL inhibited by?

A

DA from hypothalamus (drugs – dopamine antagonist)

26
Q

Describe he role of thyroid-stimulating hormone (TSH) (ANTERIOR PITUITARY HORMONES)

A

– Stimulates secretion of thyroid hormones
– Promotes vascularisation & growth of the thyroid gland

27
Q

What is the secretion of TSH stimulated by?

A

TRH from hypothalamus

28
Q

Describe the role of adrenocorticotropic hormone (ACTH)

A

– Stimulates secretion of cortisol by adrenal cortex
– Controls growth of the adrenal cortex

29
Q

What is the secretion of ACTH stimulated by?

A

CRH from hypothalamus
- Inhibiting pain/stress signal

30
Q

Describe the role of vasopressin (posterior pituitary hormone)

A

– Antidiuretic hormone (ADH)
– Controls water balance in the body
– Promotes renal water re-absorption - regulation of plasma volume & osmotic pressure

31
Q

State the role of oxytocin. (posterior pituitary hormones)

A
  • Stimulates uterine contraction during childbirth & milk ejection during breast-feeding
32
Q

What is the secretion of oxytocin inhibited by?

A

DA from hypothalamus

33
Q

What is the pineal gland?

A
  • Tiny, pine cone-shaped gland – located in diencephalon
  • Secretes melatonin – ‘hormone of darkness’
  • Production stimulated by suprachiasmatic nucleus (SCN) – body’s master ‘biological clock’
34
Q

What are the main functions of the pineal gland?

A

– synchronizes body’s circadian rhythms
with light-dark cycle
– Promotes sleep
– Influences reproductive activity – onset of puberty

35
Q

Describe the structure of MSH?

A

Similar to that of ACTH

36
Q

What is the role of MSH in animals?

A

It plays a role in skin pigmentation through
stimulation of melanocytes in the epidermis & in control of
sodium excretion.

37
Q

Describe the binding of MSH and its effect

A

a-MSH binds to receptor (MC-1) on melanocyte membrane activating tyrosinase, an enzyme required for melanin synthesis

38
Q

Where is the thyroid gland?

A
  • Located in the neck, just below larynx
  • Two lobes of endocrine tissue joined in middle by narrow strip of gland
39
Q

What 2 cell types make up the thyroid gland?

A

– Follicular cells
– Secrete two iodine-containing hormones
* Tetra-iodothyronine (T4 or thyroxine)
* Tri-iodothyronine (T3)

– Parafollicular or C cells
* Secrete calcitonin (peptide hormone)

40
Q

Describe the effect of the thyroid hormone on normal growth and CNS development.

A

– Effects on normal growth mediated via GH & IGF-1
* Stimulates GH secretion & hepatic production of IGF-1
* Promotes GH & IGF-1 effects on protein synthesis &
skeletal growth
– Required for normal development of nervous system in infants & children
– Promotes normal CNS activity in adults

41
Q

Describe the effect of the thyroid hormone on metabolic rate and heat production.

A

– Increases the overall basal metabolic rate & heat
production (‘calorigenic effect’)
– main regulator of resting O2 consumption & energy
expenditure

42
Q

Describe the effect of the thyroid hormone on intermediary metabolism.

A

– Biphasic effects on carbohydrate, fat & protein metabolism

43
Q

Describe the effect of the thyroid hormone on sympathetic activity.

A
  • Increase cellular responsiveness to catecholamines via β-
    receptor upregulation
44
Q

What are the adrenal glands?

A

Paired organs that cap the kidneys

45
Q

What do the adrenal glands consist of?

A

– an outer adrenal cortex
Secretes 3 types of steroid hormones:
*Mineralcorticoids (aldosterone)
*Glucocorticoids (cortisol)
*Sex hormones (DHEA)
– an inner adrenal medulla
*Secretes catecholamines – AD & NA

46
Q

Describe the role of mineralcorticoids (aldosterone) - adrenocortical hormone

A

– essential for life
– maintain Na + & K+ balance and ECF (extracellular fluid) volume

47
Q

Describe the role of glucocorticoids - adrenocortical hormone

A

– involved in the regulation of carbohydrate, protein & fat
metabolism
– play a key role in adaptation to stress
– exert anti-inflammatory & immunosuppressive effects

48
Q

Describe the role of sex hormones - adrenocortical hormone.

A

– supplement sex hormones secreted by gonads
– exert minor effects on reproductive function
– promote protein anabolism & growth

49
Q

What does the adrenal medulla secrete?

A
  • Adrenaline and Noradrenaline
50
Q

What are the main functions of the adrenal medulla?

A

– Reinforce “fight-or-flight” responses
* Maintenance of arterial blood pressure
* ↑ respiratory rate, HR & CO
* ↑ glycogenolysis -↑ glucose mobilisation
* ↑ lipolysis -↑ mobilisation of free fatty acids

51
Q

Describe the cells of the pancreas.

A
  • Consists of clusters or ‘islands’ of secretory cells, called Islets of Langerhans
  • Comprise 3 types of secretory cells:
    – α (alpha) cells
  • Secrete glucagon
    – β (beta) cells
  • Secrete insulin
    – δ (delta) cells
  • Secrete somatostatin
52
Q

What are secretion of the endocrine pancreas regulated by?

A

Changes in blood glucose concentration.

pharmacology (40 decks)

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