3 Endocrinology 2 - Hormones and a bit of insulin Flashcards
What growth hormones does the hypothalamus secrete?
What does it act on?
Growth hormone releasing hormone
Growth hormone inhibiting hormone
PRH, PIH, TRH, CRH, GHRH, GHIH and GnRH are all hypothalamic tropic hormones
What are their effects on anterior pituitary tropic hormones, and what system do they act on.
PRH -> activates prolactin -> act on breasts
PIH (dopamine) inhibits prolactin -> breasts
TRH -> activates TSH -> thyroid gland
CRH -> activates ACTH -> adrenal cortex (cortisol)
GHRH -> GH hormones -> liver and other cells (growth factors)
GHIH (somatostatin) -> inhibits GH hormones GnRH -> activates LH and FSH -> gonads
What hormone does the growth hormone stimulate release of in the liver.
Insulin-like growth factors - acts as a hormone and a Paracrine
What effect does increased growth hormone secretion from the anterior pituitary have on adipose tissue and muscle
Adipose tissue - decreases glucose uptake and increases lipolysis
Muscle - decreases glucose uptake and increases amino acid uptake
What is the hormone released from the hypothalamus in control of puberty?
What hormones are released from the anterior pituitary in response to the hormone released from the hypothalamus?
Gonadotrophin releasing hormone (GnRH)
Anterior pituitary - luteinising hormone and follicle stimulating hormone
Acts on the ovaries which release oestrogen and progesterone and the testes which release testosterone
What is the cause And effect of excess of growth hormone in adults?
Caused by adenoma in anterior pituitary
Causes acromegaly or gigantisism which causes overgrowth of soft tissue and bones - enlarged skull, coarse facial features, enlarged hands and feet and enlarged organs
What are the causes and symptoms of poly cystic ovarian syndrome?
Caused by excess of LH, and deficiency of FSH from anterior pituitary
Causes immature follicles in ovaries
Symptoms : amenorrhea, infertility, hirsutism, acne, weight gain
What are islets of langerhansmand where are they found?
Endocrine tissues/cells which are arranged in spherical clusters within the exocrine tissue in the pancreas.
What are the 2 precursors to insulin?
Preproinsulin -> pro insulin -> insulin
What are the main pancreatic endocrine cells? What do they secrete
Alpha cells - glucagon
Beta cells - 65-80% of total. Insulin secreting
Delta cells - 5-10% of total. Somatostatin.
What are the steps of stimulation of insulin secretion in response to a rise of blood glucose?
1) entry of glucose mediated by GLUT2
2) metabolism of glucose
3) binding of ATP to K-ATP
4) depolarisation of plasma membrane triggers opening of Ca2+ channels
5) influx of Ca2+ ions triggers insulin exocytosis
What is hypothalamic-pituitary axis feedback control?
Hypothalamus -> Anterior pituitary -> Thyroid glad -> negative feedback to hypothalamus
What type of hormones can adipose tissue store?
Lipophilic
What increases the half life of hormones?
Being bound to a carrier protein
What is antagonism?
The effect of 2 hormones oppose each other
e.g. Insulin:Glucagon
What hormone does the anterior pituitary release?
Tropic hormone 2
affects release of other hormones
What is the acronym for remembering hormones of the anterior pituitary gland?
Fresh Pituitary Tastes Almost Like Guinness
FPTALG
What are the hormones of the anterior pituitary gland, where do they act, what do they do?
GH: Acts on liver, up-regulates insulin growth factors and down regulates insulin
TSH: Acts on the thyroid, thyroxin release
ACTH: Acts on the adrenal cortex, glucococortoid and androgen release
LH + FSH: Acts on reproductive organs, up-reg sex steroids
Prolactin: Acts on mammary glands and reproductive organs. Causes growth of repro. organs and lactation
How does sleep and hypoglycaemia affect insulin-like growth factors?
Increases growth hormone releasing hormone
How does stress affect insulin-like growth factors?
Reduces growth hormone inhibiting hormone, causing higher growth hormone secretion
What are the 2 main ways in which puberty is stimulated? What are the characteristics of puberty?
- Body weight (47kg) and leptin
- Growth spurt, secondary sexual characteristics, fertility
How do LH and FSH hormones cause onset of male puberty?
Increased LH causes increased testosterone from Leydig cells
Increased testosterone increases FSH causing spermatogenesis from Sertoli cells
How does oestrogen and progesterone affect the endometrium?
Oestrogen causes growth of the endometrium
Progesterone causes maintenance of the endometrium
What causes polycystic ovarian syndrome?
Excess LH or deficiency of FSH from the anterior pituitary
