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203-T1 > Nuts and bolts of the endocrine system > Flashcards

Nuts and bolts of the endocrine system Flashcards

1
Q

Hormones are…..
involved in…
forming part of ……systems

A

mediator molecules

sexual reproduction, normal growth and development, adaptation to internal and external environment

endocrine and nervous (neuroendrocrine) - these two systems interact at the hypothalamus

NO is an example of a neuroendocrine transmitter

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2
Q

Hormones are…..
involved in…
forming part of ……systems

A

mediator molecules

sexual reproduction, normal growth and development, adaptation to internal and external environment

endocrine and nervous (neuroendrocrine) - these two systems interact at the hypothalamus

NO is an example of a neuroendocrine transmitter

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3
Q

Generally outline the path of a hormone

A

Hormone –> interstitual space –> blood stream/lymphatic system

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4
Q

State the three determents of the affect of hormones

A
  1. Number of molecules available (concentration)
  2. Number of receptor available
  3. Affinity hormone-receptor
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5
Q

Give an example for the following hormone types (and their origins):

  1. Steroid:
  2. Peptide:
  3. Amine:
A
  1. oestradiol, testosterone (from ovaries, testes, adrenal cortex-mesodermal origin)
  2. ADH, oxytocin, insulin (from thyroid (endorm), adrenal medulla- ectodermal origin)
  3. adrenaline, NA, DA (adenohypophysis - ectodermal orgin; thyroid/parathyroid, pancreas- endodermal origin; scattered endocrine cells in epithelium of GIT and lungs)
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6
Q

Why is the hypophysis (pituitary gland) describes as a compound gland?

Location?
Function?
Size?
Blood supply?
Venous drainage?
Control?
A
  • Compound as it has 2 origins: adenohypophysis - glandular outpouch of ectoderm of oral cavity, neurohypophysis- neural, downgrowth from diencephalon)
  • Sella turcica, sphenoid bone
  • Produces hormones that influence acitivity of other endocrine glands
  • no larger than a pea
  • Superior hypophyseal supplies median eminence, upper part of stalk; inferior hypophyseal supplies neurohypophysis, lower part of stalk
  • Capillary plexuses drained by portal veins –> anterior lobe of pituitary –> veins form secondary plexus
  • Controlled by signals from the hypothalamus
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7
Q

What is the benefit of having a portal vein system in the pituitary gland?

A

! Provides a route for neurosecretory substances released from hypothalamus to also reach anterior lobe

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8
Q

Consider the thyroid gland

Appearance?
Location?
Germ layer origin?
Function?
Blood supply?
Venous drainage?
Control?

Why must care be taken during cricothyrotomy?

A
  • Bilobed in neck, 30g (2 lateral lobes connected by an isthmus that course anterior to the trachea)
  • Below oblique line of thyroid cartilage to 5/6 tracheal ring; immediately anterior to trachea
  • Endoderm origin, develops as growth from floow or pharynx
  • Function: regulates tissue metabolism, growth and development
  • Blood supply: superior thyroid (from external carotid) and inferior thyroid (from subclavian)
  • Venous drainage: (from an external plexus) into IJV and BCV

-Control: hypothalamus –> thyrotrophin releasing hormone / hypophysis –> TSH

Recurrent nerve (from vagus) damage –> loss of speech

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9
Q

Consider the parathyroid glands

Appearance? Location?
Germ layer origin?
Function?
Blood supply?
Venous drainage?
Innervation?

Why must care be taken during thyroidectomy?

A
  • 4 glands (2 superior, 2 inferior) embedded in capsule of thyroid. Very small (rice), 40mg
  • Develop from cells originating from 3rd/4th pharyngeal pouches (migrate caudally with the thymus, inferior parathyroids travel further)
  • Secrete parathyroid hormone - regulates calcium and phosphate levels within homeostasis
  • Blood supply: Primarily, inferior thyroid (+sup)
  • Venous drainage: Sup+ middle + inf thyroid
  • Innervation: middle and inf cervical ganglion

If parathyroid glands removed–> blood [Ca2+] drops –> muscles (including those involve din respiratory and laryngeal) go into tetanic contraction –> death

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10
Q

Generally outline the path of a hormone

A

Hormone –> interstitual space –> blood stream/lymphatic system

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11
Q

State the three determents of the affect of hormones

A
  1. Number of molecules available (concentration)
  2. Number of receptor available
  3. Affinity hormone-receptor
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12
Q

Medullary functions/ secretions?

A

Chromaffin cells (secretory cells) develop from same embryonic tissue as symp. ganglia. Stimulation of them causes secretion of adrenaline and small amounts of NA ie catecholamines into adjacent circulation

Modified symp. ganglia (ANS)

Function: fight or flight response (HR, BP, increased b/g,SM of viscera)

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13
Q

Why is the hypophysis (pituitary gland) describes as a compound gland?

Location?
Function?
Size?
Blood supply?
Venous drainage?
Control?
A
  • Compound as it has 2 origins: adenohypophysis - glandular outpouch of ectoderm of oral cavity, neurohypophysis- neural, downgrowth from diencephalon)
  • Sella turcica, sphenoid bone
  • Produces hormones that influence acitivity of other endocrine glands
  • no larger than a pea
  • Superior hypophyseal supplies median eminence, upper part of stalk; inferior hypophyseal supplies neurohypophysis, lower part of stalk
  • Capillary plexuses drained by portal veins –> anterior lobe of pituitary –> veins form secondary plexus
  • Controlled by signals from the hypothalamus
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14
Q

What is the benefit of having a portal vein system in the pituitary gland?

A

! Provides a route for neurosecretory substances released from hypothalamus to also reach anterior lobe

How well did you know this?
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15
Q

Consider the thyroid gland

Appearance?
Location?
Germ layer origin?
Function?
Blood supply?
Venous drainage?
Control?

Why must care be taken during cricothyrotomy?

A
  • Bilobed in neck, 30g (2 lateral lobes connected by an isthmus that course anterior to the trachea).
  • Below oblique line of thyroid cartilage to 5/6 tracheal ring; immediately anterior to trachea
  • Endoderm origin, develops as growth from floow or pharynx
  • Function: regulates tissue metabolism, growth and development
  • Blood supply: superior thyroid (from external carotid) and inferior thyroid (from subclavian)
  • Venous drainage: (from an external plexus) into IJV and BCV

-Control: hypothalamus –> thyrotrophin releasing hormone / hypophysis –> TSH

Recurrent nerve (from vagus) damage –> loss of speech

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16
Q

Consider the parathyroid glands

Appearance? Location?
Germ layer origin?
Function?
Blood supply?
Venous drainage?
Innervation?

Why must care be taken during thyroidectomy?

A
  • 4 glands (2 superior, 2 inferior) embedded in capsule of thyroid. Very small (rice), 40mg
  • Develop from cells originating from 3rd/4th pharyngeal pouches (migrate caudally with the thymus, inferior parathyroids travel further)
  • Secrete parathyroid hormone - regulates calcium and phosphate levels within homeostasis
  • Blood supply: Primarily, inferior thyroid (+sup)
  • Venous drainage: Sup+ middle + inf thyroid
  • Innervation: middle and inf cervical ganglion

If parathyroid glands removed–> blood [Ca2+] drops –> muscles (including those involve din respiratory and laryngeal) go into tetanic contraction –> death

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17
Q

Consider the adrenal glands

Appearance? Location?
Germ layer origin?
Blood supply?
Venous drainage?
Control?

Why must care be taken during thyroidectomy?

A
  • Right (pyramidal), left (semi-lunar)
    Retroperitoneal from superior pole of kidney, 2-3cm x 1, 3.5-5g
  • Cortex derived from mesoderm; medulla derived from neural crest cells
  • Blood supply: superior (from inf. phrenic), middle (aorta) and inferior suprarenal arteries
    • 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
    • Medullary arteries pass through cortex to supply medulla
  • Venous drainage: adrenal veins, drain into IVC (R) or renal vein (L)
  • Hypothalamus (ACTH release from hypophysis) symp division of ANS (fast response at medulla): coeliac plexus, splanchnic nerves
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18
Q

What is the relevance that the blood vesseld supplying the medulla traverse the cortex?

A

Hormones produced by cortical cells influence activity of cells in medulla, cortisol mediates NA conversion to adrenaline.

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19
Q

Cortex secretions?

A

Cells subjacent to capsule secrete mineralcorticoids e.g. aldosterone function to maintain electrolyte balance

Deep cortex = glucocorticoids e.g. hydrocortisione affect metabolism and electrolyte balance

Produces adrenal androgens e.g. testosterone

20
Q

Medullary secretions?

A

Chromaffin cells (secretory cells) develop from same embryonic tissue as symp. ganglia

Modified symp. ganglia (ANS)

Secretes adrenaline and small amounts of NA ie catecholamines

Function: fight or flight response (HR, BP, SM of viscera)

21
Q

Describe the innervation of the blood vessels and chromaffin cells of the cortex and medulla

A

Preganglionic symp fibres:

  1. synapse at coeliac ganglia, postganglionic fibres supply blood vessels supplying medulla and cortex
  2. ramify around cells of medulla

Medulla is under direct control from ANS (symp) –> FAST RESPONSE
C

22
Q

What is the overall structure of endrocrine glands?

A

Functional unit consists of cuboidal secretory cells with a lumen (pituitary and parathyroid glands cells have no lumen!)

Secretory cells supported by myoepithelial cells

23
Q

Is the pancreas exocrine or endrocrine?

A

Both

24
Q

What does neuroendocrine mean?

A

Neural stimulation of endocrine cells to secrete hormones e.g. the medulla of adrenal gland is stimulated by preganglionic fibres of the ANS

25
Q

What are the clinical manifestations of endocrine disease?

A
  1. Hormone overproduction/underproduction
  2. Tumour/mass lesion which can be:
    - non functional –> pressure effect
    - associated over production
26
Q

State the cell types found in the adenohypophysis (anterior pituitary gland) and their reaction to dyes

How can we identify specific cells?

A

Acidophils - take up acidic dyes

Basophils - take up basic dyes

Chromophobe - no specific staining techniques

**ACTH is secreted by both chromophobes and basophils (no specific pattern for hormones)

Immunocytochemistry assists in identifying specific cells e.g. antibodies to GF

27
Q

For each adenohypophysis cell, provide the hormone and target organ

  1. Somatotroph
  2. Lactotroph
  3. Corticotroph
  4. Gonadotroph
  5. Thydotroph
A
  1. GH, Bones
  2. Prolactin, Breasts,
  3. ACTH, adrenal glands
  4. FSH, Ovaries, testes
    LH, Ovaries, testes
  5. TSH, thyroid gland
28
Q

What drug has the opposite effect of ADH?

A

Alcohol

29
Q

Describe pituitary adenomas

A
  • Benign tumours arising from anterior lobe
  • Can be function or non-functional. Productive adenomas cause hyperpituitarism. Non-producive adenomas cause hypopituitarism
  • Space occupying effect of both types cause: headaches, vomiting nausea and diplopia, impaired vision (bitemporal hemianopia)
  • Constitute 10% of intra-cranial neoplasms
30
Q

Which hormones does the thyroid gland secrete?

Why is iodine important for this? What happens in a lack of iodine?

A

Thyroxine (T4) and Triiodothyronine (T3) which stimulate metabolic rate

Synthesis of these hormones requires iodine

Sea salt is rich in iodine. Lack of iodine leads to an enlarged thyroid gland –> goitre. This happens to absorb maximum concentration of iodine.

Goitre is due to hyperplasia and hypertrophy. The increase in size overcomes the hormone deficiency and the patients are euthyroid

31
Q

Describe the appearance of a normal thyroid gland?

Other features?

A

35-45g
Bilobed with isthmus
Composed of follicles with variable-sized lumina

Follicles contain colloid with eosinophillic/pink appearance. They are lines by cuboidal cells

  • Highly vascularised
  • Endothelial cells lining the captillaries are fenestrated allowing passage of hormones into circulation
  • Para-follicular cells (C cells) found between the follicles which secrete calcitonin which promotes reduction of calcium concentration in the blood
32
Q

State 5 pathological states of the thyroid gland and whether they produce too uch, too little or just enough thyroid hormone/

A
  1. Goitre- Euthyroid
  2. Graves disease- Hyperthyroid
  3. Hashimoto’s disease- Hypothyroid
  4. Adenoma- Euthyroid
  5. Cancer- Euthyroid
33
Q

Why is it important to assess the radiology of a patients goitre before thyroidectomy?

A

Multi-nodular goitre compressing the trachea removal can lead to tracheomalacia –> cardiac arrest

The trachea collapses due to it becoming flaccid and therefore obstructs the airway

34
Q

What is Grave’s disease?

A

Autoimmune disease where the TSH receptor is stimulated by auto-antibodies

Diffuse enlargement of the thyroif gland goitre due to hyperplasia of thyroid cells

Leads to:

  1. Infilitrative opthalmopathy- accumulation of soft tissue and inflammatory cells behind the eye leading to proptosis (protruding eyes)
  2. Infiltrative dermopathy- thickening and induration of the skin on the anterior shin –> pre-tibial myxoedema
35
Q

What does Graves’s look like microscopically?

A

The colloid has “soap bubble” appearance due to hyperacivity

36
Q

What is Hashimoto’s Thyroiditis?

A

Autoimmune disease

  • Progessive depletion of thyroif cells by inflamation and replaced by fibrosis.
  • Decreased T3/T4
  • Increased TSH
  • Most common cause of hypothyroidism in areas where iodine is readily available
37
Q

What does Hashimoto’s look like microscopically?

A

Prominent lymphocytic infiltration

The gland is irregular with a solid cut surface

38
Q

Follicular adenomas are….

There are 4 thyroid carcinomas. Give their names, prevalence and description

A

Benign tumour of the thyroid follicular cells

  1. Papillary (75-85%); increased risk of lymph node metastasis
  2. Follicular (10-20%); increased metastasis to bone, lung and liver
  3. Medullary (5%); arises from C cells, 20% with MEN2 syndrome
  4. Anaplastic (<5%) older patients, poorer prognosis
39
Q

What do parathyroid glands do ?
Histological appearance?

Pathology?

A

Secrete PTH

  • Control the levels of calcium in the blood
  • Decrease in blood calcium stimulates PTH secretion

Chief cells with no lumen
Highly vascularised

Adenoma- involves one gland
Hyperplasia- involves all four glands
** Both cause hypercalcaemia

40
Q

What colour does a normal adrenal gland appear in the lab? WhY?

A

Orange/yellow

Cells are rich in lipid

41
Q

For each zone of the adrenal cortex, which hormones are secreted?

A

Zone glomerulosa

  • Mineralocorticoid
  • Aldosterone
  • *for absorption of sodium

Zone fasciculata

  • Glucocorticoids
  • Cortisol and cortisterone
  • Sex hormones

Zone reticularis

  • 17 ketosteroids
  • sex hormones
42
Q

How does the histology differ between the cells of the adrenal cortex?

A

ZG- Closely packed round cells

ZF- Clear cells arranged in cords

ZR- Smaller, darker staining cells

43
Q

Adrenocortical hyperactivity and adrenocortical insufficiency are both examples of adrenal gland pathology.

What causes them?

A

Adrenocortical hyperactivity:

  • Due to hyperplasia, adenoma, cancer (rare)
  • Cushing’s syndrome (excess cortisol)
  • Conn’s Syndrome (excess aldosterone)
  • Adrenogenital syndrome (excess androgenes)

Adrenocortical insufficiency
- Addison’s disease

44
Q

How does the histological appearance of the adrenal medulla differ to that of the cortex?

A

Adrenal medulla cells are neuroendocrine- darker staining that the cortex cell
- “Looser”

45
Q

What is a phaechromocytoma?

Why is is describe as a 10% tumour?

A

Tumour of the adrenal medulla
- Cause of treatable hypertension (0.1-0.3%)

  • Due to high levels of catecholamines
  • Precipitous increase in BP, tachycardia, palpitations, headache, sweating, tremor and sense of apprehension
  • Complications of high BP : CCF, IHD, arrrhythmias, CVA
10% familial (MEN2)
10% extra-adrenal
10% bilateral
10% malignant
10% arise in childhood

203-T1 (15 decks)

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