Quest 1 Flashcards
(33 cards)
Endocrinology
- involves hormones and how they communicate
Nervous System
- has a physical connection
- is “wired”
- simple neural reflexes
- neurotransmitters in synapses(a junction btw 2 nerve cells)
Acetylcholine
- a neurotransmitter in the nervous system that functions with rest and digest
Adrenaline/Epinephrine
- a neurotransmitter in the nervous system that functions with fight or flight
How do neurotransmitters in the nervous system input responses?
- afferent neurons carry impulses to -> spinal chord -> efferent neurons carry impulses away from s.c -> elicits body to respond
- “wired” system
Neuroendocrine System
- “wireless”
- neuroendocrine reflexes
Ex: milk letdown- triggered by oxytocin
- there is a physical stimulation -> nerves send signals to -> spinal chord which signals the -> brain to trigger the release of the -> oxytocin hormone which causes -> contraction of smooth muscle
Neurohormone
- hormones made from a nerve
Reproductive Factory Parts
1) Brain- manager
2) Hypothalamus
3) Pituitary Glands
4) Reproductive organs- workers
Brain Parts
1) Thalamus
2) Hypothalamus
3) Anterior and Posterior Pituitary Glands
How do messages travel from the hypothalamus directly to the posterior pituitary gland?
- there is an artery connected from the hypothalamus that goes into the posterior pituitary gland
- the artery passes through the first capillary bed in the hypothalamus and picks up hormones to drop into the second capillary bed which is located in the posterior pituitary gland
- to get the hormones from the hypothalamus to the posterior pituitary gland they travel via a portal vein
- the last vein after the second capillary bed will take back the hormones to the general system
Thalamus
- relay center
- located in the brain
- above hypothalamus
Hypothalamus
- start of hormone signaling
- synthesizes and secretes neurohormones
- has separate areas that are responsible for something different
- contains a cluster of neurons that provide different functions within (nuclei)
- neurohormones when secreted dictate what happens next
- also produces releasing hormones
- below hypothalamus
- attached to pituitary glands
Releasing Hormones
- from the hypothalamus
1) Thyrotropin Releasing Hormone
2) Gonadotropin Releasing Hormone**
3) Growth Hormone Releasing Hormone
4) Corticotropin Releasing Hormone
5) Growth Hormone Inhibiting Hormone
6) Dopamine
Gonadotropin Releasing Hormone (GnRH)
- hypothalamus stimulates the gonads using this releasing hormone
- Gonad = testes/ovaries
- tropin = to feed/grow/stimulate
Pituitary Glands
- produce hormones
- connected to hypothalamus
Anterior Pituitary Gland portal system
- connected to the hypothalamus via the hypothalamic portal system
- it is a system that has two capillary beds connected by a portal vein
- portal system formed because derived from the roof of the mouth (Rathke’s pouch)
- purpose of portal system is so hypothalamus can produce less Releasing Hormones with greater affect
Posterior Pituitary Gland
- directly connected to the hypothalamus and interacts through neurons
- nerves extend from hypothalamus to posterior pituitary
- oxytocin(OT) and Antidiuretic Hormone (ADH, or Vasopressin)
- > hormones made in the hypothalamus and sent to posterior pituitary when ready to be released
How did the Posterior Pituitary Gland form?
- derived from brain tissue
- the posterior pituitary gland is connected to the hypothalamus via the infundibulum(hollow stalk that connects hypothalamus and PPG)
- the gland rests in the sella turcica (bone)
How did the Anterior Pituitary Gland form?
- derived from tissue in the roof of the mouth
- epithelial tissue began pinching off and eventually was alone (Rathke’s Pouch)
- it migrated to the brain and attached to form the anterior P.G
Anterior Pituitary Gland secretes what hormones
1) FSH and LH as a result of Gonadotropin*
2) Thyroid Stimulating Hormone
3) Growth Hormone
4) Adrenocorticotropic Hormone
5) Prolactin*
Hypothalamic Pituitary Gonadal Axis (HPG)
1) hypothalamus secretes Gonadotropin(GnRH)
2) GnRH travels to pituitary gland
3) travels to Gonads (to cause effect)
4) Gonads trigger a hormone and function
- crucial to proper reproduction
- feedback systems are used to regulate
Tonic Center
- in hypothalamus
- a minimal amount of hormones that is secreted on a constant basis
Surge Center
- in hypothalamus
- releases much larger amounts of hormones in comparison to the tonic center
Female example of Hypothalamic Pituitary Gonadal Axis (HPG)- Positive Feedback Loop
1) Hypothalamus secretes GnRH
2) Triggers the release of FSH(follicle stimulating hormone) - tonic center involved
3) FSH binds to ovaries(gonads)
4) stimulates follicle growth (gametes/eggs)
5) estrogen is released
- presence of estrogen triggers brain to make more estrogen, loop restarts
- eventually will reach a threshold of estrogen and the hypothalamus will stop the tonic center and trigger the surge center
- a threshold of estrogen must be reached to trigger the surge center of the hypothalamus
