6. Endocrine Tissues Flashcards
Where is the anterior pituitary and what does it secrete?
Base of brain
TSH, TH, FSH, LH, GH, prolactin, MSH
Where is the posterior pituitary and what does it secrete?
Base of brain
ADH, vasopressin, oxytocin
Where is the thyroid gland and what does it secrete?
Anterior to trachea (2 lobes)
Thyroxine (T4), triodothyroinine (T3)
Where is the parathyroid gland and what does it secrete?
Lie on dorsal surface of thyroid gland
Parathormone (PTH)
Where are the adrenal glands and what do they secrete?
Top of each kidney
Context secretes corticosteroids, small amounts of androgen, estrogen and progestin
Where is the pancreas and what does it secrete?
Left of and behind stomach
Exocrine secretes digestive enzymes into duodenum
Endocrine has islets of langerhans, alpha cells produce glucagon, beta cells secrete insulin
What are the 3 types of hormones?
Glycoproteins (peptide hormones)
Steroid hormones
Amino acid derived hormones
What does the hypothalamus control?
Thermoregulation Plasma osmolality Heart rate, blood pressure Feeding, regulation of GI tract Circadian rhythms
What does the hypothalamus produce?
Vasopressin (ADH) and oxytocin - travel to posterior pituitary through nerves
Six hormones that travel to anterior pituitary
What is a portal system?
Blood travels through 2 sets of smaller vessels before returning to heart
Give 2 examples of the portal system in the body
Hypothalamo-hypophyseal portal system between hypothalamus and anterior pituitary
Liver (hepatic)
What happens in the development of endocrine system at 5 weeks?
Pituitary develops Thyroid develops Parathyroid and thymus develops Pancreas develops Adrenals develop
What mode of secretion do pituitary hormones use?
Constitutive and regulated merocrine secretion
This is why there is always a small concentration of these hormones in the blood
What does hyperthyroidism mean?
High T3 or T4
Has low TSH
What does hypothyroidism mean?
Low T3 or T4
High TSH
What causes the TSH levels in hypothyroidism and hyperthyroidism?
They are due to negative feedback loop on TRH production and release at the hypothalamus
What happens to parafollicular cells in development?
They are neuroendocrine cells that migrate into thyroid during thyroid development in embryo
What is the role of parafollicular cells?
Produce peptide hormone thyrocalcitonin
Monitors plasma calcium concentration and decreases levels
Inhibits osteoclast activity in bone
What is the role of the parathyroid gland?
Constantly monitors plasma calcium concentrations
What happens if plasma calcium low?
Parathyroid gland detects
PTH is made
PTH causes bones to release calcium into blood and absorb more from GI tract
Negative feedback loop
What is the adrenal medulla composed of?
Parenchyma of epithelioid cells called chromaffin cells
Many myelinated presynaptic sympathetic nerve fibres
What is the outer layer of the adrenal cortex?
Zona glomerulosa
Aldosterone regulates BP
What is the middle of the adrenal cortex?
Zona fasciculta
Glucocorticoids (cortisol) mobilise fats, proteins and carbs
What is the inner layer of the adrenal cortex?
Zona reticularis
Androgen precursors
