Pituitary Function and Failure Flashcards
What is the posterior pituitary?
Neurohypophysis
Outgrowth of brain - nervous tissue
Neural link to hypothalamus
What is the anterior pituitary?
Adenohypophysis
From glandular epithelial tissue, ectodermal cells
Vascular link to hypothalamus
In what ways are the anterior and posterior pituitary different?
Embryologically
Structurally
Functionally
What is the infundibulum?
Stalk connecting pituitary to brain
What does the posterior pituitary release?
Vasopressin/ADH
Oxytocin
What does ADH do?
Increases collecting duct permeability
Decreases urine volume
What does oxytocin do?
Breasts - contracts myoepithelial cells along ducts to eject milk
Uterus - contraction
Which hormone makes milk?
Prolactin
From what are the hormones of the posterior pituitary released into the general circulation?
Endings of supraoptic and paraventricular neurons
From what are trophins of the hypothalamus secreted?
Endings of arcuate and other hypothalamic neurons
To where are trophins of the hypothalamus secreted?
Portal hypophysial circulation
Where are the arcuate, supraoptic, and paraventricular nuclei?
Hypothalamus
What is the synthesis, storage, and release of posterior pituitary hormones?
- Hormone made and packaged in cell body of neuron in hypothalamus
- Vesicles transported down cell
- Vesicles containing hormone stored in posterior pituitary
- Hormones released into blood
Describe the steps involved in the activation of the anterior pituitary via the hypothalamic-hypophyseal portal system
- Neurons synthesising trophic hormones release them into capillaries of portal system
- Portal vessels carry trophic hormones directly to anterior pituitary
- Endocrine cells release hormones into second set of capillaries for distribution to rest of body
What is the hypothalamic-hypophyseal portal system?
Vascular system connecting hypothalamus to anterior pituitary
Why don’t you need much trophic hormone to be released from the hypothalamus?
Because hormone concentrated and rapid
What kinds of effects do the hormones released from the hypothalamus have on the anterior pituitary?
Sometimes releasing hormone
Sometimes inhibiting hormone
Both control anterior pituitary function
Is the action of dopamine on the breast direct or indirect?
Direct
What is the target pituitary cell of corticotropin-releasing hormone (CRH)?
Corticotroph
What are the hormone products of corticotrophs?
Adrenocorticotropic hormone (ACTH) Beta-lipotropin
What is the target tissue of ACTH?
Adrenal cortex > cortisol
What is the target tissue of beta-lipotropin?
Adipose tissue
What is the target pituitary cell of thyrotropin-releasing hormone (TRH)?
Thyrotroph
What are the hormone products of thyrotrophs?
Thyrotropin/thyroid stimulating hormone (TSH)
Prolactin
What is the target tissue of TSH?
Thyroid gland > thyroid hormones
What is the target pituitary cell of gonadotropin-releasing hormone (GnRH)?
Gonadotroph
What are the hormone products of gonadotrophs?
Luteinising hormone (LH) Follicle stimulating hormone (FSH)
What is the target tissue of LH and FSH?
Gonads > sex steroids
What is the target pituitary cell of growth hormone-releasing hormone (GHRH)?
Somatotroph
What is the hormone product of somatotrophs?
Somatotropin/growth hormone (GH)?