Hypothalamus, pituitary, pineal 26 Flashcards
Hypothalamic nerve cells synthesise how many hormones?
At least nine.
Pituitary endocrine nerve cells synthesise how many hormones?
At least seven.
What do both hypothalamus and pituitary cells work together to regulate?
growth, development, metabolism, homeostasis.
What do hypophyseal portal veins do?
They connect capillaries in hypothalamus to capillaries in anterior pituitary.
Where is the pituitary gland found in the body?
Two lobes in the anterior and posterior in the head.
Explain the steps to regulating release of anterior pituitary hormones.
1) Hypothalamic neurosecretory cells end near capillaries of hypothalamus.
2) Secrete releasing hormones or inhibiting hormones through hydrophyseal portal veins
3) Regulates release of anterior pituitary hormones.
What is the anterior pituitary/ adenohypophysis known as?
Human growth hormone (hGH)
What does the human growth hormone do?
Promotes synthesis of insulin-like growth factors (IGFs) = somatomedins, in liver, muscle, cartilage and bone.
How is human growth hormone released?
Released in bursts, 2 hour intervals.
What releases ‘growth hormone releasing hormone’ (GHRH) & ‘growth hormone inhibiting hormone’ (GHIH)?
Hypothalamus.
How does hypoglycaemia do to GHRH & GHIH?
low blood sugar, produces more GHRH & less GHIH
what does hyperglycaemia do to GHRH & GHIH?
high blood sugar, inhibits GHRH & producing more GHIH.
What does the thyroid stimulating hormone do?
Stimulates the synthesis & secretion of thyroid hormones from the thyroid gland.
What regulates the thyrotropin releasing hormone?
Circulating thyroid hormone levels.
Describe follicle stimulating hormone females. (FSH)
FSH initiates follicle development in ovaries.
Describe follicle stimulating hormone in males.
FSH stimulates sperm production in testes.
Describe the role of Luteinising hormone in females.
LH with FSH stimulates ovulation, forms corpus luteum & secretes progesterone.
Describe the role of luteinising hormone in males.
stimulates release of testosterone.
With high levels of oestrogen or testosterone, what happens to the gonadotrophin releasing hormone? (GnRH)
It is suppressed.
What does the anterior pituitary hormone ‘prolactin’ do?
initiates & maintains milk production by mammary glands.
What hormone does not have an inhibiting hormone?
Thyroid.
What stimulates prolactin releasing hormone?
High levels of oestrogen (during pregnancy).
What does adrenocorticotrophic hormone (ACTH) do?
controls production & secretion of glucocorticoids (cortisol) from adrenal cortex.
What hormone stimulates ACTH?
Corticotrophin releasing hormone from hypothalamus.
What inhibits CRH & ACTH release?
Adrenal glucocorticoids - - called negative feedback
what does melanocyte-stimulating hormone (MSH) do?
Appears in small circulating amounts, excess causes skin darkening.
Where are posterior pituitary hormones synthesised?
In the hypothalamus.
Where are posterior pituitary hormones stored prior to release?
They travel down nerve axons to terminals in posterior pituitary gland where they are stored.
What hormones are from the posterior pituitary gland?
oxytocin & antidiuretic hormone (ADH).
Describe the hormone oxytocin.
Allows milk ejecting, enhances smooth muscle uterine contraction during birth, might play a role in emotional connection.
Describe antidiuretic hormone. (ADH) = vasopressin
Causes kidneys to retain more water,
causes vasoconstriction which increases blood pressure.
high blood osmotic pressure (high conc. of solutes detected in hypothalamus = increase in secretion.
What is the Pineal gland?
a small gland attached to the roof of the third ventricle of brain.
What does the pineal gland do?
Produces melatonin, sets the body’s biological clock.
