The HPA Axis and Growth Hormone Flashcards
(44 cards)
What is the major link between the endocrine and nervous systems?
The complex functional unit formed by the hypothalamus and pituitary gland
Where is the pituitary gland located?
Sits beneath the hypothalamus in a socket of bone called the sella turcica
What are some examples of things regulated by the hypothalamus and pituitary gland?
Body growht, reproduction, puberty, milk secretion, lactation, thyroid gland function, adrenal gland function, water homeostasis
What is another name for the anterior pituitary gland?
Adenohypophysis
What is another name for the posterior putuitary gland?
Neurohypophysis
What does the anterior pituitary arise from?
Evagination of oral ectogerm - Rathke’s puch (primative gut tissue)
Where does the posterior pituitary originate from?
Neuroectoderm (primitive brain tissue)
Which part of the pituitary is physically connected to the hypothalamus?
Posterior - hypothalamus drops down through the infundibulum to form the posterior pituitary
What hormones are released by the posterior pituitary?
Oxytocin and ADH
What produces oxytocin and ADH?
Neurosecretory cells in the supraoptic and paraventricular nuclei of the hypothalamus
What is the median eminence?
The median eminence is a part of the hypothalamus from which regulatory hormones are released.
What is the hypophyseal portal system?
The hypophyseal portal system is a system of blood vessels in the brain that connects the hypothalamus with the anterior pituitary.
How do the hormones produced by nerve cells in the hypothalamus act via two distinct neurocrine pathways?
1) Direct effects on distant targets via oxytocin and ADH from posterior pituitary
2) Hormones secreted exclusively into hypophyseal portal system affect endocrine cells within the anterior pituitary
What is oxytocin involved in?
Milk let down and uterus contractions during birth
What does ADH do?
Regulate body water volume
What are tropic hormones?
Tropic hormones are hormones that have other endocrine glands as their target
What are the 6 tropic hormones produced in the hypothalamus (that have direct effects on the release of anterior pituitary hormones)?
Thyrotropin releasing hormone (TRH) Prolactin release-inhibiting hormone (PIH) Corticotropin releasing hormone (CRH) Gonadotropin releasing hormone (GnRH) Growth hormone releasing hormone (GHRH) Growth hormone inhibiting hormone (GHIH)
What hormones are produced by the anterior pituitary?
Thyroid stimulating hormone (TSH) Adrenocorticotrophic hormone (ACTH) Luteinising hormone (LH) Follicle stimulating hormone (FSH) Prolactin Growth hormone
Outline how TRH release from the hypothalamus increases metabolic rate
1) TRH released from hypothalamus to anterior pituitary
2) TSH released from anterior pituitary to thyroid
3) Thyroid hormone released from thyroid
4) Metabolic rate increased
Outline how CRH release from the hypothalamus leads to the stress response and metabolic actions
1) CRH released from hypothalamus to anterior pituitary
2) ACTH released from anterior pituitary to adrenal gland
3) Cortisol released from adrenal gland
4) Stress response, metabolic actions
Outline how TRH or PIH release from the hypothalamus affects breast growth and milk secretion
If TRH released, prolactin released from anterior pituitary which stimulates breast growth and milk secretion
If PIH released, prolactin inhibited
How does GHRH and GHIH affect growth?
If GHRH released from hypothalamus, growth hormone released from anterior pituitary which can stimulate IGF released from liver and lead to growth
If GHIH released from hypothalamus, growth hormone inhibited
How does GnRH have an effect on sex hormone secretion and gamete production?
GnRN released from hypothalamus
LH release from anterior pituitary -> sex hormone secretion from ovaries/testes
FSH release -> gamete production in ovaries/testes
What factors affect growth?
Genetics, nutrition, hormones (eg growth hormone) and environment
