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Year 2 - T2 Theme 1 > L3 - Nuts and bolts of the endocrine system > Flashcards

L3 - Nuts and bolts of the endocrine system Flashcards

1
Q

What are hormones

A
  • Mediator molecules
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2
Q

What are hormones essential for

A
  • Normal growth and development
  • adaptation to internal and external environment
  • contribute to the process of sexual reproduction
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3
Q

Features of nervous system

A

• Nervous system via neural impulse transmission
Mediator molecules => Neurotransmitters
Very fast (1-2ms)
Act locally from pre to post synapse (microns)

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4
Q

Features of endocrine system

A

• Endocrine system via the release of hormones
Mediator molecules => Hormones
Much slower (seconds/minutes/days)
Act anywhere in the body via the circulatory system
• Each hormone elicits a response from any cell carrying a receptor sensitive for that hormone

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5
Q

Properties of endocrine glands

A
  • Ductless
  • Hormone is released to interstitial space –> blood stream or lymphatic system
  • Highly vascularised
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6
Q

What determines how hormones affect other cells metabolism

A

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

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7
Q

Chemical classification of hormones

A
  • Steroid (oestradiol; testosterone)
  • Protein/peptide (ADH; oxytocin; insulin)
  • Amine(adrenalin; noradrenalin; dopamine)
  • NO (nitric oxide) is both neurotransmitter and hormone
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8
Q

What are the germ layers

A
  • Ectoderm
  • Mesoderm
  • Endoderm
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9
Q

Discrete glands

A
  • Hypophysis; thyroid; parathyroid; adrenal
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10
Q

Larger glands

A
  • Kidneys; ovaries/testis; placenta

- Have both endocrine and exocrine function

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11
Q

What is the diffuse neuroendocrine system

A
  • Scattered nerve cells with endocrine function
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12
Q

What is the hypophysis

A
  • Compound gland suspended from the hypothalamus by stalk or infundibulum
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13
Q

Where is the hypophysis located

A
  • Sella turcica (turkish saddle), sphenoid bone
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14
Q

Function of pituitary gland

A
  • Master endocrine gland

- Produces several hormones that influence activity of other endocrine glands(eg liver)

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15
Q

What is adenohypophysis

A
  • Glandular part
  • Outpouching of ectoderm of oral cavity
  • Rathke’s pouch
  • FSH, LH; TSH, etc
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16
Q

Divisions of hypophysis

A
  • Adenohypophysis

- Neurohypophysis

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17
Q

What is neurohypophysis

A
  • Neural part

- Downgrowth from diencephalon of brain (oxytocin; ADH)

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18
Q

Blood supply to the hypophysis

A
  • Superior hypophyseal
  • Inferior hypophyseal
  • Branches of int carotid
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19
Q

What does the superior hypophyseal supply

A
  • Median eminence

- Upper part of stalk

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20
Q

What does the inferior hypophyseal supply

A
  • Neurohypophysis

- Lower part of stalk

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21
Q

What do arteries supplying median eminence and stalk end as

A
  • Capillary plexuses
22
Q

What are capillary plexuses in median eminence and stalk ending drained by

A
  • Portal veins
23
Q

Where do the portal veins in the hypophysis pass to

A
  • Pass to anterior lobe of pituitary
  • Veins then form a secondary capillary plexus
  • This setup provides a route for neurosecretory substances released from the hypothalamus to also reach the anterior lobe
24
Q

What causes release of hormones from adenohypophysis and neurohypophysis

A
  • Signals from the hypothalamus
25
Q

What are the two lateral lobes of the thyroid gland connected by

A
  • By an isthmus that courses anterior to the trachea
26
Q

Location of the thyroid gland

A
  • From just below oblique line of thyroid cartilage to 5/6 tracheal ring; immediately anterior to trachea
27
Q

What is the thyroid gland derived from

A
  • Derived from endoderm, develops as a growth from floor of pharynx, near base of tongue
28
Q

What is the thyroid gland regulated by

A

· Under control from hypothalamus (thyrotropin-releasing hormone) and hypophysis (thyroid stim hormone)
· Essential role in regulating tissue metabolism, growth and development

29
Q

Blood supply to the thyroid gland

A
  • Superior thyroid (from external carotid)

- Inferior thyroid (from subclavian)

30
Q

Blood drainage of thyroid gland

A
  • From an extensive plexus into the internal jugular vein and brachiocephalic vein
31
Q

Features of parathyroid glands

A

· 4 parathyroid glands: 2 superior and 2 inferior; embedded in capsule of thyroid; posterior aspect
· Very small, about the size of a grain of rice; 40 mg

32
Q

What do the parathyroid glands mostly develop from

A
  • Develop mostly from cells originating from 3rd/4th pharyngeal pouches; migrate caudally with the thymus
  • Inferior parathyroids travel to lie lower compared to superior parathyroids
33
Q

Role of the parathyroid gland

A
  • Secrete parathyroid hormone
34
Q

Function of parathyroid hormone

A
  • Regulates calcium and phosphate levels
35
Q

Why do the parathyroid glands have to be preserved during thyroidectomy

A
  • If removed, blood calcium levels fall –> muscles, inc respiratory and laryngeal, go into tetanic contraction –> death
36
Q

Parathyroid glands - VAN

A

Artery - primarily inferior thyroid (also superior)

Vein - superior, middle + inferior thyroid

Nerve - from middle and inferior cervical ganglions

37
Q

Location of adrenal glands aka suprarenal glands

A
  • Sup pole of kidneys (T12); retroperitoneal
38
Q

What is the adrenal cortex derived from

A
  • Mesoderm(mesothelium)
39
Q

What is the adrenal medulla derived from

A
  • Neural crest cells
40
Q

What does the adrenal cortex secrete

A
  • Corticosteroids
41
Q

What do cells subjacent to capsule in the adrenal glands secrete

A
  • Mineralocorticoids eg. aldosterone

- Function to maintain electrolyte balance

42
Q

What does the deeper part of cortex in the adrenal glands secrete

A
  • Secrete glucocorticoids eg. hydrocortisone

- Affect metabolism and electrolyte balance

43
Q

What does the cortex also produce

A
  • Adrenal androgens eg testosterone
44
Q

What do the secretory cells of the medulla develop from

A
  • Chromaffin cells develop from same embryonic tissue as sympathetic ganglia
45
Q

What do the medulla cells secrete

A
  • Secrete adrenaline and smaller amounts of noradrenaline - i.e catecholamines
46
Q

Blood supply to the adrenal glands

A
  • Superior (from inferior phrenic)
  • Middle (from aorta)
  • Inferior suprarenal arteries (from renal)
  • Arteries branch before entering capsule and the rami supply the cortex and medulla of gland
47
Q

What do the cortical arteries give rise to

A
  • Subcapsular plexus and in turn to cortical sinusoids that distributes blood to cortical cells
48
Q

Venous drainage of adrenal glands

A
  • Drain into IVC (R)

- Renal vein (L)

49
Q

What is the activity of adrenal glands under control of

A
  • Hypothalamus eg. ACTH release from hypophysis

- Symp division of ANS: coeliac; splanchnic nerve

50
Q

What does ACTH stimulate the secretion/release of

A
  • Corticosteroids
51
Q

What is the adrenal medulla under the control of

A
  • Under direct control from ANS (symp) –> fast response
52
Q

What are adrenal gland secretions initiated by

A

Impulses from preganglionic sympathetic fibres that end in the chromaffin cells of the medulla

Chromaffin cells then release catecholamines into adjacent circulation

Year 2 - T2 Theme 1 (20 decks)

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