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203 endocrinology and reproduction > T1 L3 endocrine system nuts and bolts > Flashcards

T1 L3 endocrine system nuts and bolts Flashcards

1
Q

endocrine system

A

system of hormone-secreting ductless glands

  • essential for normal growth and development
  • adaptation to internal and external environment
  • contribute to the process of sexual reproduction
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2
Q

hormones

A

mediator molecules (greek= excite)

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3
Q

neuroendocrine system

A
  • nervous system and endocrine system interact

- at hypothalamus (major controlling centre of ANS, temp, circadian rhythms, hunger)

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4
Q

communication of NS

A

via neural impulse transmission

  • NTs, v fast (1-2 ms)
  • act locally from pre to post synapse (microns)
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5
Q

communication of endocrine system

A

via release of hormones

  • much slower (sec/min/days)
  • acts anywhere in body via circ system
  • each hormone elicits a response from any cell carrying a receptor sensitive for that hormone
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6
Q

properties of endocrine glands

A
  • ductless
  • highly vascularised
  • surrounded by blood vessels, hormones secreted into blood
  • hormone is released to interstitial space -> blood stream or lymphatic system
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7
Q

hormones affect other cells metabilsim according to

A

number of molecules available
number of receptors available
affinity of hormone -> receptor

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8
Q

chemical classification of some hormones

A
  1. steroid (oestradiol, testosterone)
  2. protein/ peptide (ADH, oxytocin, insulin)
  3. amine (adrenaline, noradrenaline, dopamine)
    NO (nitric oxide) is both neurotransmitter and hormone
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9
Q

endocrine sources

A
  1. discrete glands:
    (discrete= separate/distinct)
    -hypophysis, thyroid, parathyroid, adrenal
  2. Larger glands have both endocrine and exocrine functions
    - kidneys, ovaries/testis, placenta
  3. diffuse neuroendocrine system:
    scattered nerve cells w/ endocrine function
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10
Q

hypophysis

A

aka pituitary gland

  • compound gland suspended from the hypothalamus by stalk or infundibulum
  • located in the sella turcica (Turkish saddle), sphenpid bone
  • function: master endocrine gland, produces several hormones that influence activity of other endocrine glands (e.g. liver)
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11
Q

hypophysis gross anatomy

A

adenohypophysis: anterior lobe
neurohypophysis: posterior lobe
- no larger in size than that of a pea

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12
Q

hypophysis divisions

A
  1. adenohypophysis: glandular part, outpouching of ectoderm of oral cavity (Rathke’s pouch) FSH, LH, TSH, GH
  2. Neurohypophysis: neural part, downgrowth from diencephalon of brain - Oxytocin, ADH
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13
Q

hypophysis: arteries

A
  • supplied by 2 blood vessels (branches of internal carotid)
    1. superior hypophyseal: supplies median eminence, upper part of stalk (arteries supplying these end as capillary plexus)
    2 inferior hypophyseal: neurohypophysis, lower part of stalk
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14
Q

hypophysis- veins

A

capillary plexuses in median eminence and stalk ending are drained by portal veins
- these veins pass to anterior lobe of pituitary
- veins then form a secondary capillary plexus
This set up provides a route for neurosecretory substances released from hypothalamus to also reach the anterior lobe

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15
Q

hypophysis control (activity)

A

signals from the hypothalamus are responsible for hormone release from ADENOHYPOPHYSIS and NEUROHYPOPHYSIS

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16
Q

Thyroid gland

A
  • bilobed gland in neck
  • 2 lateral lobes connected by isthmus that courses anterior to trachea
  • from just below oblique line of thyroid cartilage to 5/6 tracheal ring, immediately anterior to trachea
17
Q

thyroid gland derivation and control

A

derived from endoderm, develops as a growth from floor of pharynx, near base of tongue

  • under control of:
  • hypothalamus TRH (thyrotropin releasing hormone)
  • hypophysis ( thyroid stimulating hormone)
18
Q

role of thyroid gland

A

essential role in regulating tissue metabolism, growth and development

  • T3 (triiodothyronine)
  • T4 (thyroxine)
19
Q

thyroid gland arteries

A
  1. superior thyroid (from external carotid)

2. Inferior thyroid (from subclavian)

20
Q

thyroid gland veins + N

A
  • blood drainage from an extensive plexus into
    1. internal jusgular vein
    2. brachiocephalic vein

vagus nerve

21
Q

parathyroid glands

A
  1. para (to the side of thyroid glands)
  2. 2 superior, 2 inferior
  3. embedded in capsule of thyroid, posterior aspect
  4. v small, about the size of a grain of rice (40 mg)
22
Q

parathyroid glands derivation

A
  • develop mostly from cells originating from 3rd/4th pharyngeal pouches, migrate caudally w’ the thymus
  • inferior parathyroids travel further to lie lower compared to superior parathyroids
23
Q

parathyroid gland role

A
  • secrete parathyroid hormone: regulates calcium and phosphate levels w/I homeostasis
  • must be preserved during thyroidectomy bc if blood calcium levels fall -> muscles including respiratory and laryngeal go into tetanic contraction => death
24
Q

parathyroid glands arteries

A

-inf. thyroid (also superior)

25
Q

parathyroid glands veins

A
  • superior, middle + inferior thyroid
26
Q

parathyroid nerve

A

-from middle and inf cervical glanglions

27
Q

adrenal glands

A
  • hormone released in response to stress
  • superior poles of kidneys (T12), retroperitoneal
  • coronal cut: outer capsule, cortex and medulla
  • pyramidal (r) or semilunar (l)
28
Q

adrenal glands: origins of the cortex and medulla

A

cortex: derived from mesoderm (mesothelium)
medulla: derived from neural crest cells

29
Q

adrenal gland cortex

A
  • Adrenal cortex secretes corticosteroids:
    cells subjacent to capsule secrete mineralocorticoids e.g. aldosterone function to maintain electrolyte balance
  • Deeper part of cortex: secrete glucocorticoids e.g. hydrocortisone affect metabolism and electrolyte balance
  • cortex also produces adrenal androgens e.g. testosterone
30
Q

adrenal gland medulla

A

secretory cells of medulla: chromaffin cells develop from same embryonic tissue as sympathetic glanglia

  • The medulla is regarded as a modified sympathetic ganglion (ANS)
  • medulla cells secrete CATECHOLAMINES (adrenaline and smaller amounts of noradrenaline)
  • affects HR, blood pressure and smooth muscle of viscera
31
Q

adrenal glands: arterial supply

A
  • superior (from inf phrenic)
  • middle (from aorta)
  • inf suprarenal arteries (from renal)
  • arteries branch before entering capsule and the rami supply the cortex and medulla of gland
  • cortical arteries give rise to subcapsular plexus and in turn to cortical sinusoids that distribute blood to cortical cells
32
Q

adrenal glands- blood course

A

medullary arteries pass through cortex to supply the medulla (receives blood from 2 sources)
- Hormones produced by cortical cells incluence activity of cells in the medulla e.g. cortisol mediates NA conversion to Adrenaline

33
Q

adrenal glands: venous drainage

A

adrenal veins drain into IVC (r) or renal vein (L)

34
Q

adrenal glands activity control:

A

is under control of hypothalamus (ACTH release of hypophysis)

  • sympathetic division of ANS: coeliac plexus, splanchnic nerves
  • ACTH: adrenocorticotropic hormone
  • ACTH stimulates secretion/ release of corticosteroids
35
Q

adrenal glands medulla control

A
  • under direct control from ANS (symp) => fast response
  • release is initiates by impulses from preganglionic sympatheric fibres that end in the chromaffin cells of the medulla
  • chromaffin cells then release catecholamines into adjacent circulation

203 endocrinology and reproduction (6 decks)

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