Endocrine system Flashcards
What is the endocrine system mediated by?
Hormones
Where are receptors found?
Cell surface
Cytosol
Nucleus
Structure of a thyroid gland?
Bow tie shape
What is the extracellular fluid stored in thyroid follicular cells?
Colloid
What role does iodine play in thyroid gland?
Required for the production of essential hormones (T4 to T3)
Where are hormones T4 and T3 produced and stored?
Produced in follicular cells
Stored extracellularly as a prohormone in colloid
Function of thyroid gland?
Regulation of transcription of proteins
What are the hormone effects mediated by?
Nuclear receptors
What are the consequences of hypothyroidism?
Patient will be overweight
What peptide does the parathyroid gland synthesise and secrete?
Parathyroid hormone (PTH)
What does PTH target?
Bones
GI system
Kidneys
What does PTH regulate?
Plasma level of calcium and phosphate
Where is the location of PT glands?
Posterior side of the thyroid gland
If there is a low level of calcium, what is the effect of PTH?
More PTH will be secreted
What are the 2 subsections of the adrenal gland?
The adrenal cortex
The adrenal medulla
Function of adrenal cortex?
Releases steroid hormones
What are 2 steroid hormones the adrenal cortex releases?
Glucocorticoid (cortisol)
Mineralocorticoid (aldosterone)
What cells release adrenaline?
Chromaffin cells
What hormone does the adrenal medulla release?
Catecholamines (adrenaline and noradrenaline)
What cells are mineralocorticoid released from?
Zona glomerulosa
What cells are glucocorticoids released from?
Zona fasciculata
What blood vessel does glucocorticoid travel in?
Medulla vein
What hormone do developing cells in the ovaries produce?
Oestrogen and Progesterone
Function of oestrogen?
Stimulates cell proliferation of endrometrium
Function of progesterone?
Stimulates maturation and secretion of tissues
What hormone spikes prior to ovulation?
LH
When does progesterone spike?
After ovulation in the secretory phase
What cells produce testosterone?
Leydig cells in the testes
Function of the testes?
Stimulate protein synthesis leading to development and growth
Produces testosterone
Produces male gametes
When do plasma testosterone levels spike?
At around 3 months after fertilization
At puberty (age 10ish)
What do beta cells in the endocrine pancreas release?
Insulin
What do alpha cells in the endocrine pancreas produce?
Glucagon
Where are glucagon and insulin released into?
Portal blood
What do glucagon and insulin influence/target?
The liver
Where are beta and alpha cells in the endocrine pancreas?
In the islets of Langerhans
Where is the adenohypophysis located?
Anterior lobe of the pituitary
Where does adenohypophysis develop from?
From an upward projection of the pharynx
Where is neurohypophysis located?
Posterior lobe of the pituitary
Where does neurohypophysis develop from?
A downward projection of the brain
How are troph cells stimulated?
By releasing hormones from small diameter neurons of the hypothalamus
Where are hormones released from in neurohypophysis?
large diameter neurons into the systemic circulation
What hormones are released by neurohypophysis?
Oxytocin and antidiuretic hormone
Function of antidiuretic hormone?
Stops urination to maintain water in the body
Function of oxytocin?
Contraction of uterus
Hormone of love
Function of trophic hormones?
stimulating effect on other hormones
Function of the hypothalamus?
Links neural activity to whole body function
