Introduction To Hormones + GH Flashcards
regulates vital body functions like temperature, thirst, hunger, and controls the release of hormones from the pituitary gland.
It plays a key role in maintaining homeostasis.
hypothalamus
HYPOTHALAMUS
• The part of the brain that is located under the _____ and directly above the
_____
3rd ventricle
pituitary gland
PITUITARY GLAND
Located within the confines of
the_____
Connected to the median eminence of the hypothalamus by the_____
sella turcica
infundibular stalk
• True endocrine tissue
• Secretes classic hormones (OWN)
Anterior Pituitary
Anterior pituitary also known as
• Adenohypophysis
• Neural tissue
• Secretes neurohormones but does not synthesize it (HORMONES FROM HYPOTHALAMUS)
Posterior Pituitary
Posterior Pituitary also known as
Neurohypophysis
• Specialized neurons
• Releasing and inhibiting hormones
• Modify the action of the pituitary gland
NEUROSECRETORY CELLS
is a network of blood vessels that connects the hypothalamus to the anterior pituitary gland, allowing hormones from the hypothalamus to directly influence pituitary hormone secretion.
hypothalamic-hypophyseal portal system
secreted by hypothalamic neurons and transported to the anterior pituitary by the hypothalamic-hypophyseal portal system
NEUROHORMONES
NEUROHORMONES
function as ______to either stimulate or inhibit release of anterior pituitary hormones
trophic hormones
THE NEUROHORMONES (6)
Thyrotropin-releasing hormone (TRH)
Corticotropin-releasing hormone (CRH)
Gonadotropin-releasing hormone (GnRH)
Growth hormone-releasing hormone (GhRH)
Growth hormone-inhibiting hormone (GHIH)
Prolactin-inhibiting hormone (PIH; Dopamine)
are hormones produced by the hypothalamus that regulate the secretion of anterior pituitary hormones.
Examples include thyrotropin-releasing hormone (TRH) and corticotropin-releasing hormone (CRH).
NEUROHORMONES/
hypophysiotropic hormones
Releases TSH and prolactin
TRH
Releases LH and FSH
GnRH
Releases ACTH
CRH
Releases GH
GROWTH HORMONE STIMULATING HORMONE
Releases GH
GROWTH HORMONE STIMULATING HORMONE
Inhibits GH and TSH release (additional effects on
gut and pancreatic function)
Somatostatin
Inhibits prolactin release
Dopamine (prolactin inhibitory factor)
ANTERIOR PITUITARY HORMONES
5 hormone-synthesizing & -secreting cells
• Somatotrophs - GH (Growth Hormone)
• Lactotrophs - PRL (Prolactin)
• Thyrotrophs - TSH (Thyroid-Stimulating Hormone)
• Gonadotrophs - FSH (Follicle-Stimulating Hormone) and LH (Luteinizing Hormone)
• Corticotrophs - POMC (Proopiomelanocortin), including ACTH (Adrenocorticotropic Hormone), MSH (Melanocyte-Stimulating Hormone), β-lipotropin, β-endorphin
Neurohormones
Thyrotropin-releasing hormone - TRH
Corticotropin-releasing hormone - CRH
Gonadotropin-releasing hormone - GnRH
Growth hormone-releasing hormone - GHRH
Somatotropin release-inhibiting hormone (somatostatin) - SRIF
Prolactin-inhibiting factor (dopamine) PIF
Thyrotropin-releasing hormone
TRH
Stimulates secretion of TSH and prolactin
Corticotropin-releasing hormone
Stimulates secretion of ACTH
Gonadotropin-releasing hormone
Stimulates secretion of LH and FSH
Growth hormone-releasing hormone
Stimulates secretion of LH and FSH
Growth hormone-releasing hormone
Stimulates secretion of growth hormone
Somatotropin release-inhibiting hormone (somatostatin)
Inhibits secretion of growth hormone
Somatotropin release-inhibiting hormone (somatostatin)
Inhibits secretion of growth hormone
Prolactin-inhibiting factor (dopamine)
Inhibits secretion of prolactin
is the precursor for adrenocorticotropic hormone (ACTH), B-lipotropin, and B-endorphin in the anterior pituitary.
Pro-opiomelanocortin
is the precursor for adrenocorticotropic hormone (ACTH), B-lipotropin, and B-endorphin in the anterior pituitary.
Pro-opiomelanocortin
LH
Target
Structure
Feedback
Gonad (tropic)
Dimeric glycoprotein
Sex steroids (Ez/T)
FSH
Target
Structure
Feedback
Inhibin
TSH
Taget
Structure
Feedback
Thyroid (tropic)
Dimeric glycoprotein
Thyroid hormones (4/T3)
ACTH
Adrenal (tropic)
Single peptide derived from POMC
Cortisol
Growth hormone
Caster
Multiple (direct effector)
Single peptide
IGF-I
Prolactin
Breast (direct effector)
Single peptide
Unknown
POSTERIOR PITUITARY HORMONES
2 hormones released by the magnocellular neurons of the hypothalamus:
Paraventricular nuclei:
Supraoptic nuclei:
Oxytocin
Antidiuretic hormone (ADH)
POSTERIOR PITUITARY
HORMONES
Oxytocin
Antidiuretic hormone
Milk ejection; uterine contraction
Oxytocin
refers to a control system where a hormone’s production is regulated by its effects on the body, but the feedback does not directly influence the original signal, helping maintain balance in physiological processes.
open loop negative feedback
REGULATION OF HORMONE SECRETION NEGATIVE VS. POSITIVE FEEDBACK MECHANISM
________ is when an increase in a hormone’s level inhibits its further production to maintain balance, such as with thyroid hormone regulation.
________is when an increase in hormone levels stimulates more of its production, as seen in oxytocin release during childbirth.
negative feedback
Positive feedback
ABNORMALITIES OF THE PITUITARY FUNCTION
• clonal expansion of a distinct population of cells
• can also result from an increase in trophic hormones from the hypothalamus or ectopic sites
Hormonal Excess
ABNORMALITIES OF THE PITUITARY FUNCTION
• more varied cause
• deficiency of one or more hormones,
often with continued and progressive
loss of other hormones over time
Hormonal Deficiency
