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Functional Anatomy and Embryology > Hormonal Secretions > Flashcards

Hormonal Secretions Flashcards

1
Q

Give 4 functions of hormones.

A

Development - proliferation, growth, differentiation
Metabolism - carbohydrate storage, metabolic rate etc.
Reproduction - sexual maturation
Fluid balance - water balance, plasma osmolarity

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2
Q

Name six endocrine glands.

A 
Pituitary (anterior and posterior)
Thyroid
Parathyroid
Adrenal
Islets of Langerhans (Pancreas)
Gonads
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3
Q

Name four other tissues that secrete hormones.

A

Kidney (Erythropaetin)
Vascular endothelium
Gut cells
Adipocytes

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4
Q

What is endocrine secretion?

A

Secretion of hormone from endocrine cell into blood.

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5
Q

What is neuroendocrine secretion?

A

Secretion of hormone from nerve cells into the blood.

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6
Q

How does neuroendocrine secretion occur?

A

Nerve endings store hormones in vesicles which are released by exocytosis when stimulated by an action potential.

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7
Q

What is paracrine secretion?

A

Secretion of hormones which act locally of neighbouring cells.

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8
Q

What is autocrine secretion?

A

Secretion of hormones which act on the same cell that secreted it.

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9
Q

Name the 4 different types of hormone.

A

Proteins/peptides
Steroids
Amine
Eicosanoids

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10
Q

What are the characteristics of protein/peptide hormones?

A

Synthesised from prohormones which are stored as granules in secretory vesicles.
Circulate in blood ‘unbound’ as they are water.
Hence have a short half-life.

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11
Q

Where are peptide hormones produced?

A

ALL hormones of the hypothalamus, pituitary, parathyroids, GI tract and pancreas.

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12
Q

What are the characteristics of steroid hormones?

A

ALL derived from cholesterol - fat-soluble.
Synthesised in mitochondria and smooth ER.
Hormone release dependent on rate of synthesis as they aren’t stored.
Circulate in blood bound to proteins - have long half-lives.

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13
Q

Where are steroid hormones produced?

A

Adrenal glands, gonads, placenta (e.g. oestrogen)

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14
Q

What are the two types of amine hormones?

A

Amine hormones are derived from tyrosine.

  • Thyroid hormones
  • Catacholamines
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15
Q

What are the characteristics of thyroid hormones?

A

Amines.
Lipid-soluble = long half-lives
Stored in the thyroid gland bound to thyroglobin

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16
Q

What are the characteristics of catecholamines?

A

Amines.
Water-soluble = short half life.
Stored intracellularly in secretory granules.

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17
Q

What are eicosanoids?

A

Hormones.
Local messengers - autocrine or paracrine.
Derived from arachnoid acid

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18
Q

What is the mechanism of action of steroids and thyroid hormones?

A

Act intracellularly or in the nucleus.

Alter gene transcription.

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19
Q

What is the mechanism of action of peptide hormones, glycoproteins and catecholamines?

A

Act on cell surface membrane.

Act via secondary messengers to change enzyme activity.

20
Q

Name the 4 types of input/stimulus to endocrine cells.

A
  • Changes in plasma concentration of mineral ions.
  • Changes in organic nutrient concentration.
  • Neurotransmitters released from neurons.
  • Another upstream hormone acting on the endocrine cell.
21
Q

Where is the pituitary gland and what is its structure?

A

Located just infront of the hypothalamus.
Formed of 2 main lobes (anterior and posterior)
Anterior = adenohypophysis
Posterior = neurohypophysis

22
Q

Name the 3 parts of the anterior pituitary gland (adenohypophysis).

A

Pars tuberalis
Pars distalis
Pars Intermedia

23
Q

Name the 2 parts of the neurohypophysis (posterior pituitary).

A

Infundibulum (neural stalk and median eminence)

Pars nervosa

24
Q

What cells is the neurohypophysis (posterior) made of? Where do their cell bodies lie?

A

Consists of axons of modified neurones - supported by pituicytes.
Cell bodies of these neurones lie in the supraoptic and paraventricular nuclei of the hypothalamus.

25
Q

Name the two hormones secreted by the posterior pituitary gland and their function.

A

ADH - increases water reabsorption in the kidney - increasing blood pressure and volume.
Oxytocin - secretion stimulated by stretching of cervix. Increases uterine contraction and stimulates milk ejection.

26
Q

What disease is caused by a deficiency of ADH?

A

Diabetes insipidus

27
Q

How are hormones released from the posterior pituitary?

A

ADH and oxytocin are synthesised in the cell bodies of axons in the supraoptic and paraventricular nuclei of the hypothalamus.
The hormones are transported down axons and are released into fenestrated capillaries on stimulation of cell bodies in hypothalamus.

28
Q

Name the 3 types of cell found in the Pars distalis and the colour they stain.

A

Acidophils - stain red/orange
Basophils - stain blue
Chromophobes - no stain

29
Q

What do the cells of the pars intermedia secrete?

A

Melanocyte stimulating hormone (MSH)

Increases skin pigmentation.

30
Q

How is secretion in the anterior pituitary (adenohypophsis) regulated?

A

Neuroendocrine cells in the hypothalamus - axons project to the median eminence.
Discharge into capillaries of the pituitary portal vessels.

31
Q

What is the pituitary portal system?

A

Two arteries:

  • Superior hypophyseal artery supplies median eminence and stalk.
  • Inferior hypophyseal artery supplies the postior lobe and the anterior lobe via short portal vessels.
32
Q

What is the structure and location of the thyroid gland?

A

2 pear-shaped lobes connected by midline isthmus - associated right infront of the trachea.
Isthmus lies at level of 2nd-4th tracheal ring.

33
Q

What is the cellular organisation of the thyroid galdn?

A

Thyroid epithelial cells are organised into follicles which produces and accumulate thyroglobin.

34
Q

What happens to iodide in thyroid follicular cells?

A

Iodide is oxidised to iodine.
Iodine is covalently attached to thyroglobin .
Iodinated thyroglobin is broken down n lysosomes to release iondinated tyrosine (tetra-iodothyronine(thyroxine) and tri-iodothyronine)

35
Q

What is the function of C-cells/parafollicular cells of the thyroid?

A

Secrete calcitonin which inhibits calcium mobilisation.

36
Q

What is structure/location of parathyroid glands?

A

2 pairs of parathyroid glands (each the size of a pea).

Found on the posterior border of lateral lobes of the thyroid gland.

37
Q

Describe the cellular organisation of the parathyroid glands.

A

Densely packed Chief Cells arranged in irregular cords around blood vessels.
Secretes the 84-amino acid polypetite parathyroid hormone.

38
Q

What does parathyroid hormone do?

A

Stimulates calcium mobilisation.

39
Q

What is the location of the suprarenal glands (adrenal glands)?

A

2 glands - right is pyrimidalshaped, left is crescent-shaped.
In contact with upper pole of each kidney.
Separated from kidneys by connective tissue but surrounded by renal fascia.

40
Q

What is the structure of the adrenal glands?

A

Two types of tissue:
Cortex - drived from coelemic epithelium lining posterior abdominal wall.
Medulla - derived from adjacent sympathetic ganglion. Blood flows from cortex into medulla. Neural origin from neural crest cells.

41
Q

Name the 3 zones of the adrenal cortex.

A

Zona glomerulus
Zona fasciculata
Zona reticularis

42
Q

What is the function of the zona glomerulus?

A

Located beneath tough fibrous capsule. Secrete mineralocorticoids (aldosterone).
Cause Na+ retention in distal convoluted tubule.
Regulated by angiotensin and renin.

43
Q

What is the function of the zona fasciculata?

A

Cells arranged in straight cords.
Secrete glucocorticoids (cortisol).
Target: glucose, lipid and protein metabolism.
Secretion regulated by adrenocorticotrophic hormone (ACTH) from anterior pituitary.

44
Q

What is the function of the zona reticularis?

A

Cells arranged in irregular cords.
Secrete some glucocorticoids and small amounts of sex steroids.
Secretion regulated by adrenocorticotrophic hormones (ACTH).

45
Q

What is the adrenal medulla?

A

Modified sympathetic ganglia.
Receives cholinergic sympathetic input from splanchnic nerves via coeliac ganglion.
Secretes catecholamines - adrenaline and noradrenaline.

46
Q

Name the 4 types of cells in the Islets of Langerhans.

A

alpha cells - secrete glucagon
beta cells - secrete insulin
gamma cells - secrete somatostatin
F or PP cells - secrete pancreatic polypeptide

Functional Anatomy and Embryology (15 decks)

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