MMED1005 Lecture Notes - Lecture 14: Aldosterone, Cretinism, Goitre
7 Jun 2018
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- Hypothalamic-pituitary axis and their primary endocrine organ effects
- Negative feedback mechanisms
- Adrenal, thyroid, parathyroid and bones and pancreas
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The hypothalamic-pituitary system (hypothalamus – pituitary connection) (hypothalamus is
the brain component of this system and the pituitary is the endocrine component)
- two lobes of the pituitary gland (also known as hypophysis):
o posterior lobe (also known as neurohypophysis, neuro=nerve): neural
▪ neurones originate in the hypothalamus and make 2 hormones
(vasopressin and oxytocin)
o anterior lobe (also known as adenohypophysis, adeno=glandular): glandular,
non-neural
▪ ade up of cell types trophs ad akes horoes ACTH, GH,
TSH, FSH&LH and PRL)
→ do’t lear all of this, just kow that:
different types of neurones exist in the
hypothalamus. Hypothalamic neurons
(shown in green) innovate the posterior
pituitary, they have nerve endings in the
posterior pituitary and from these nerve
endings, vasopressin and oxytocin are
released. Also that (in purple) axons go
to the median eminence to release
factors for the anterior pituitary
→ vasopressin and oxytocin are
synthesised in the cell bodies of the
neurons shown
- they are then trafficked within
vesicles down along these axons and
terminate and synapse directly into
the posterior pituitary area – dumping
oxytocin and vasopressin into the
circulation
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VASOPRESSIN:
In yellow, stimuli
OXYTOCIN:
- positive feedback loop (in nature, usually negative feedback loop)
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Document Summary
Hypothalamic-pituitary axis and their primary endocrine organ effects. Adrenal, thyroid, parathyroid and bones and pancreas. Do(cid:374)"t lear(cid:374) all of this, just k(cid:374)ow that: different types of neurones exist in the hypothalamus. Hypothalamic neurons (shown in green) innovate the posterior pituitary, they have nerve endings in the posterior pituitary and from these nerve endings, vasopressin and oxytocin are released. Also that (in purple) axons go to the median eminence to release factors for the anterior pituitary. Positive feedback loop (in nature, usually negative feedback loop) Negative feedback systems, e. g. growth hormones (cid:894)do(cid:374)"t (cid:374)eed to k(cid:374)ow the differe(cid:374)t zo(cid:374)es, but know that major hormones secreted in the cortex aldosterone, cortisol, androgens) Globulin stabilises hormones and allows them to travel through the circulation without being broken down. Thyroid globulin binds to thyroid hormones. (also anterior pituitary) When lacking in iodine, the body overproduces thyroid globulin in an attempt to capture all the iodine present.
