2-Environmental influences Flashcards
What is the central regulatory component of the endocrine system
Pituitary gland
Hypothalamus sends signals down with information from other parts of the brain
Where is it found
Under the hypothalamus in centre of the brain
Optic nerve is very close
Dead centre in the head under the brain
Where does the pituitary send signals
Either to other endocrine glands or directly to tissue
An example of what occurs when temperatures are low
Hypothalamus releases Thyrotropin releasing hormone(TRH)
Anterior pituitary releases Thyroid stimulating hormone(TSH)
Thyroid gland is stimulated
Increases metabolism
2 lobes of the pituitary gland
Physically joined together but no physical interactions
Which nuclei supply the posterior pituitary gland
Supraoptic and paraventricular nuclei (group of neurones with similar functions)
Where are the neurones found
Extend from anterior hypothalamus
Called the magnocellular neurones
Known as the supraoptic-hypothalamic tract where the axons extend
What do the magnocellular release
Oxytocin and vasopressin
Produced in the cell bodies and travels in vesicles down the axons
Which nuclei innervate the anterior pituitary
Hypothalamic-hypophysiotropic nuclei
Small parvocellular neurones pass to median eminence
Which blood system does the anterior pituitary link to
Hypothalamic-portal blood system, no direct nervous connection
Where are the hormones released
Released to the capillary network to the primary plexus (blood supply)
The Anterior pituitary hormones linked with hypothalamic factor
Somatostatin>Growth hormone (inhibits)
TRH>TSH, Prolactin
Dopamine>Prolactin (inhibits)
CRH>Andrencorticotropic hormone
GnRH>Gonadotrophins (LH, FSH)
GHRH>Growth hormone
What are Orexins
neuropeptides that are released from cells in other parts of the hypothalamus (lateral and posterior hypothalamus)
What do Orexins do
Orexin A and B control hunger and tiredness
Also known as hypocretins
Inhibited by glucose and leptin
Involved in narcolepsy
What can abnormalities with the pituitary gland lead to
Craniopharyngioma (tumour) pressing on optic nerve and causes visual abmormalities
