6 - Endocrine Tissues Flashcards
Name the major endocrine glands of the body.
- Pituitary gland (hypophysis)
- Thyroid gland
- Parathyroid glands
- Adrenal glands
- Pancreas
What hormones are produced by the pituitary gland?
Anterior (adenohypophysis):
- Thyroid-stimulating hormone (TSH)
- Adrenocorticotrophic hormone (ACTH)
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
- Growth hormone (GH)
- Prolactin
- Melanocyte stimulating hormone (MSH)
Posterior (neurohypophysis):
- Antidiuretic hormone (ADH)
- Oxytocin
What hormones are produced by the thyroid gland?
Thyroxine (T4) and triiodothyronine (T3)
What hormones are produced by the parathyroid glands?
Parathyroid hormone (PTH)
What hormones are produced by the adrenal glands?
- Cortex secretes corticosteroids (cortisol, aldosterone etc.) and androgens (testosterone and oestradiol)
- Medulla secretes catecholamines (adrenaline, noradrenaline and dopamine)
What secretions are produced by the pancreas?
Exocrine - digestive enzymes into the duodenum
Endocrine - islets of Langerhans (α - glucagon, β - insulin)
What non-glandular organs contain endocrine cells? Give some examples.
- Heart
- Stomach
- Liver
- Duodenum
- Kindey
E.g:
- Ghrelin made by stomach - stimulates feeding behaviour in CNS (hunger)
- Angiotensinogen - precursor for angiotensin made in the liver
- Renin - made by kidney - converts angiotensin I to angiotensin II
What are some functions of the hypothalamus?
- Thermoregulation
- Plasma osmolality
- Heart rate and blood pressure
- Feeding and GI regulation
- Circadian rhythms, wakefulness and sleep
- Stimuli from ANS
- Emotion and mood
- Lactation
What does the hypothalamus produce?
- ADH and oxytocin (travel through nerves to posterior pituitary - storage)
- Six hormones that travel through the portal system to act on the anterior pituitary
What is the name of the portal system to the anterior pituitary from the hypothalamus?
Hypothalamo-hypophyseal portal system
Why does the neurohypophysis (posterior) contain neurones but the adenohypophysis (anterior) doesn’t?
- Posterior pituitary invaginates down from neurohypophyseal bud during development (same development as the hypothalamus)
- Anterior pituitary invaginates up from hypophyseal (Rathke’s) pouch
What is ACTH? Where is it made? What does it do?
Adrenocorticotrophic hormone
Secreted from anterior pituitary gland
Acts on adrenal cortex to produce corticosteroids such as cortisol and aldosterone. Acts on adrenal medulla to produce catecholamines such as adrenaline and noradrenaline.
What is TSH? Where is it made? What does it do?
Thyroid stimulating hormone.
Secreted from anterior pituitary gland
Acts on thyroid gland to regulate secretion of T3 and T4.
What is GH? Where is it made? What does it do?
Growth hormone (somatostatin)
Secreted from anterior pituitary gland
Acts on the liver to regulate the release of somatomedins, these act on bone, muscle and other tissues to promote growth and repair.
What are FSH and LH? Where are they made? What do they do?
Follicle stimulating hormone
Luteinising hormone
Secreted from anterior pituitary gland
Act on the testes in males (testosterone and inhibin) or ovaries in females (oestrogen, progesterone and inhibin)
What is MSH? Where is it made? What does it do?
Melanocyte stimulating hormone
Secreted from anterior pituitary gland
Acts on melanocytes to make melanin. Significance of this is still unknown.
What is ADH? Where is it made? What does it do?
Antidiuretic hormone (vasopressin)
Released by neurones in the hypothalamus and stored in the posterior pituitary gland
Acts on the kidney to promote the reuptake of water into the blood from the tubule fluid.
Where is oxytocin made? What does it do?
Released by neurones in the hypothalamus and stored in the posterior pituitary gland
Acts on smooth muscle in:
- the ductus deferens and prostate (males)
- the uterus and mammary tissue (females)
Where is prolactin made? What does it do?
Secreted from anterior pituitary gland
Acts on the mammary glands to stimulate milk production in late pregnancy
Where is the thyroid gland found? How many lobes does it have? What is the name of the narrow part that connects the lobes?
In the neck, anterior to the trachea, just below the larynx
2 lobes (left and right)
Connected by the isthmus
What condition would show the following:
High T3 and T4 and low TSH (no autoantibodies)
Hyperthyroidism
Low TSH as T3/T4 act back on hypothalamus (negatively regulates TRH). TSH production in pituitary drops.
What condition would show the following:
Low T3 and T4 and high TSH (no autoantibodies)
Hypothyroidism
High TSH as low T3/T4 detected by hypothalamus (increases TRH). TSH production in pituitary increases.
What is Hashimoto’s disease? What hormone levels would you expect to see?
Type of hypothyroidism
Low T3, low or normal T4, high TSH
Anti-TPO and anti-TG autoantibodies
TPO - thyroid peroxidase (enzyme in thyroid)
TG - thyroglobulin (substrate of T3/T4 synthesis)
What is Grave’s disease? What hormone levels would you expect to see?
Type of hyperthyroidism
High T3, normal or high T4, low TSH
TSI and anti-TSH autoantibodies
TSI - thyroid stimulating immunoglobulin
What do the parafollicular cells of the thyroid gland produce? What does this do?
Calcitonin (peptide hormone)
Can decrease the plasma levels of calcium (counteracts parathyroid hormone). Inhibits osteoclast activity and inhibits re-absorption of calcium and phosphate in kidney.
What does the parathyroid gland produce? What does this do?
Produces parathyroid hormone when plasma calcium is low
Causes bones to release calcium (osteoclast activity) and absorbs more from the GI tract
Where in the adrenal glands are catecholamines produced?
Which cells produce them and what is special about them?
The adrenal medulla
Chromaffin cells - specialised neurones that release adrenaline and noradrenaline when stimulated
What changes are associated with the stress response?
- Increased awareness
- Improved cognition
- Euphoria
- Enhanced analgesia
- Increased CVS tone
- Increased resp rate
- Increased metabolism
- Decreased vegetative functions (e.g. feeding, digestion, growth etc.)
ACTH acts on the adrenal gland to mediate the stress response. ACTH release is mediated by what hormone?
Where does this come from and where does it act?
Corticotrophin releasing hormone (CRH)
CRH released by hypothalamus and acts on anterior pituitary.
How do the short-term and long-term stress responses differ?
Short-term:
- Nerve impulses direct from hypothalamus to adrenal medulla
- Release of catecholamines
- Increased heart rate, blood pressure, resp rate, bronchodilation etc.
Long-term:
- CRH –> pituitary –> ACTH –> adrenal cortex
- Release of glucocorticoids (cortisol) and mineralocorticoids (aldosterone)
- Retention of sodium and water (increased blood pressure), increased blood sugar and suppressed immune system
The intercalated ducts of the pancreas join to form the pancreatic duct. What type of epithelium lines the intercalated ducts?
Simple cuboidal epithelium
Give some examples of what the exocrine pancreas produces?
- Trypsinogen
- Chymotrypsinogen
- Lipase
- Amylase
- Ribonuclease
- Deoxyribonuclease
- Gelatinase
- Elastase
Give some examples of what the endocrine pancreas produces?
- α cell - glucagon
- β cell - insulin
- δ cell - somatostatin
- PP cell - pancreatic polypeptide
- D-1 cell - vasoactive intestinal peptide
- EC cell - secretin, motilin, substance P
- E cell - ghrelin
- G cell - gastrin
