Hypothalamus Flashcards
(73 cards)
where are the major control point of the ANS?
hypothalamus
medulla
pons
what does the hypothalamus integrate?
neural and hormonal responses
what is the role of the hypothalamic nuclei ?
involved in the body, behavior and autonomic nervous system to control tasks like hunger, temperature regulation, sexual behavior, circadian rhythms and hormone release
supraoptic and paraventricular nuclei in the hypothalamus are responsible for producing what two key hormones?
- Arginine Vasopressin (AVP), also known as antidiuretic hormone (ADH)
- Oxytocin
What is another name for the posterior pituitary gland? anterior?
Neurohypophysis
Adenohypophysis
Nuclei like the arcuate nucleus release hormones such as
Dopamine, which inhibits prolactin
How is the anterior pituitary different from the posterior pituitary in terms of communication with the hypothalamus?
The anterior pituitary requires a venous plexus (blood vessel system), while the posterior pituitary uses direct neural connections
Are the vascular connections between the hypothalamus and pituitary inside the blood-brain barrier?
No, they are outside the blood-brain barrier, allowing negative feedback from circulating hormones.
what are the releasing hormones and their targets for the anterior pituitary?
GHRH → Growth Hormone (GH)
GnRH → FSH and LH
CRH → ACTH
TRH → TSH
what are the hormones released from nerve endings that directly enter the blood stream from the posterior pituitary?
- Oxytocin for breast milk ejection, uterine contractions
- AVP/ADH for water retention in kidneys
what are the target sites for GH that is released from the anterior pituitary and what occurs?
- Liver: Stimulates production of IGF-1 (Insulin-like Growth Factor-1)
- Adipose tissue: lipolysis and reduces glucose uptake
- Muscles: Increases glucose and amino acid uptake, protein synthesis
- Bones: Stimulates growth, collagen production, and cell division
what are the two negative feedback pathways for GH release?
Both GH and IGF-1can inhibit the hypothalamus (reducing GHRH and increasing SST) and the anterior pituitary (reducing GH release)
how can cortical centers start hypothalamic activity?
You feel stressed → the prefrontal cortex activates the hypothalamus → triggers the Hypothalamic–Pituitary–Adrenal axis → releases cortisol
how is oxytocin regulated?
positive feedback loop, during labor uterine contractions cause oxytocin release → which causes more contractions → which releases more oxytocin
what does the hypothalamus release when it senses stress?
CRH (corticotropin-releasing hormone)
what does the release of CRH trigger?
the anterior pituitary to release ACTH (adrenocorticotropic hormone) and Beta-endorphins (natural painkillers)
What does ACTH signal the release of?
cortisol from the adrenal medulla
what is cortisol?
a glucocorticoid that causes a delayed increase (6 hours) in blood glucose to defend against hypoglycemia
what is the function of beta-endorphins?
reduce pain response and elevate mood
when are beta-endorphins and cortisol mainly released?
during catabolic states like stress, exercise, starvation, and hypoglycemia
what can happen if an insulin dose is too high for type I/II diabetics?
hypoglycemia will result and cause for the
increase in activity in the NTS and the hypothalamus
what portion of the brain is activated in heightened states of alertness?
locus ceruleus
** (key center for NE release)
what happens when stress activates the sympathetic nervous system?
- positive chronotropism (increased heart rate)
- positive inotropism (increased heart contractility)
- redirection of blood flow to skeletal muscles, heart and brain
- vasodilation in skeletal muscles through beta-2 adrenergic receptors
what can happen if stress causes the over activation of the vagus nerve (increased vagal activity)?
shut-down response (PNS)
- Lower heart rate
- Lower cardiac output
- Reduced blood flow to the brain → which can lead to fainting (syncope) or CNS ischemia