hypothalamus, pituitary and pineal gland Flashcards
hypothalamus and pituitary is the major link between what
nervous & endocrine systems
Hypothalamic nerve cells synthesise at least how many hormones
9
Pituitary endocrine cells synthesise how many hormones
7
together, hypothalamus and pituitary regulate what
growth, development, metabolism & homeostasis
describe the structures of The Pituitary Gland/Hypophysis
Two lobes; anterior & posterior
Hypophyseal portal veins
- Connect capillaries in hypothalamus to capillaries in anterior pituitary
describe the structure and functions of the hypothalamus control
Axons of hypothalamic neurons (neurosecretory cells) end near capillaries of hypothalamus
Secrete releasing hormones or inhibiting hormones to portal veins
to Regulate release of anterior pituitary hormones
name the anterior pituitary/Adenohypophysis hormones:
- Human Growth Hormone (hGH)
- Thyroid Stimulating Hormone
- Follicle Stimulating Hormone (FSH) & 4.Luteinising Hormone (LH)
- Prolactin (PRL)
- Adrenocortcotrophic Hormone (ACTH)
- Melanocyte-Stimulating Hormone (MSH)
explain the anterior Pituitary/Adenohypophysis hormone:
human growth hormone (hGH)
Promotes synthesis of Insulin-like Growth Factors (IGFs) = somatomedins
- in liver, muscle, cartilage & bone
Released in bursts (~2 hour intervals)
Hypothalamus produces Growth Hormone Releasing Hormone (GHRH) & Growth Hormone Inhibiting Hormone (GHIH )
explain the control of the growth hormone released from the anterior pituitary
Regulated by blood glucose levels
Hypoglycaemia (low blood sugar) : > GHRH and < GHIH
Hyperglycaemia (high blood sugar):<GHRH>GHIH</GHRH>
More GH released during sleep
explain the anterior Pituitary/Adenohypophysis hormone:
Thyroid Stimulating Hormone
Stimulates the synthesis & secretion of Thyroid hormones from the thyroid gland
Hypothalamus has control over Thyrotropin Releasing Hormone (TRH) - no TIH
- Regulated by circulating thyroid hormone levels
explain the anterior Pituitary/Adenohypophysis hormone:
Follicle Stimulating Hormone (FSH) &
FSH initiates follicle development in ovaries
FSH stimulates sperm production in testes
explain the anterior Pituitary/Adenohypophysis hormone:
Luteinising Hormone (LH)
LH together with FSH stimulates ovulation, formation of corpus luteum & secretion of progesterone
LH stimulates release of testosterone
explain what Gonadotrophin releasing Hormone (GnRH) from hypothalamus is suppressed by
high levels of oestrogen in females and testosterone in males.
explain the anterior Pituitary/Adenohypophysis hormone:
Prolactin (PRL)
Initiates & maintains milk production by mammary glands (ejection of milk depends on oxytocin from the posterior pituitary)
Prolactin inhibiting hormone (PIH) suppresses prolactin release
High levels of oestrogens (during pregnancy) stimulate Prolactin Releasing Hormone (PRH) prolactin release (can affect the baby too (to produce some milk) - neonatal milk)
explain the anterior Pituitary/Adenohypophysis hormone:
Adrenocortcotrophic Hormone (ACTH)
Controls production & secretion of glucocorticoids (cortisol) from adrenal cortex
Corticotrophin Releasing Hormone (CRH) from hypothalamus stimulates secretion of ACTH
Stress related stimuli can also stimulate ACTH release
Adrenal glucocorticoids inhibit CRH & ACTH release – negative feedback
explain the anterior Pituitary/Adenohypophysis hormone:
Melanocyte-Stimulating Hormone (MSH)
Only found in Small circulating amounts
Excess causes skin darkening, if too much produced
where are Posterior Pituitary Hormones synthesised and stored prior to release
synthesised in the hypothalamus and travel down nerve axons to terminals in the posterior pituitary where they are stored prior to release.
name the types of Posterior Pituitary hormones
oxytocin
Antidiuretic Hormone (ADH)
explain the Posterior Pituitary hormone:
oxytocin
enhances smooth muscle uterine contraction during birth & milk ejection
- may play role in emotional bonding
explain the Posterior Pituitary hormone:
Antidiuretic Hormone (ADH)
= vasopressin
Causes kidney to retain more water
Causes vasoconstriction which is increase in blood pressure
high blood osmotic pressure i.e. high conc. of solutes detected in hypothalamus causing increase secretion
what pituitary hormones could we potentially live without
Could potentially live without the posterior pituitary hormones but not without the anterior pituitary hormones
explain the pineal
Small gland attached to roof of third ventricle of brain
Produces melatonin
Sets the body’s biological clock
- More released in darkness
