Hypothalamus Flashcards
What is the role of the hypothalamus in homeostasis?
- essential as it directly connects the body to the brain
- hypothalamus neurons make and transmit specialised neurohormones/neuropeptides that regulate other hormones of the body
- feedback loop as these hormones then bind to receptors on the hypothalamus as a messaging system
Why are emotions and motivated behaviour regulated by the hypothalamus?
- Emotions and motivated behaviour are very adaptive in order to respond and survive
- Adaptivity = survival = reproduction
- Works in combo with limbic system
What is means by allostasis?
- regulating the body and its needs as it changes over life
- ‘Resetting optimal points’
- hypothalamus is adaptive to this meaning cells must have some life-long plasticity
List some ways in which the hypothalamus has clinical context
Addiction: many recreational drugs are involved in reward motivated behaviour systems in the limbic system
Fever: detecting temp. Changes to retain or release heat
Obesity: feeding behaviour is massively controlled by the hypothalamus
Where is the hypothalamus located?
- Located in the VENTRAL ANTERIOR aspect of the brain
- directly above the PITUITARY gland
What is the hypothalamus made up of?
- Collection of nuceli which harbour neurons
Three distinct regions:
- Paraventricular region containing the paraventricular nucleus (PVN)
- Tubular region containing the ARCH nucleus and the ventro-medial nucleus (VMH)
- Mammillary region (MB)
What are the nuclei/neurons sat within?
- Glial rich areas called the median eminence
- Sit near the pituitary stalk/posterior pituitary
What is the importance of the glial-rich areas?
It is where the main brain-body interfaces form
Which hormones regulate sleep?
GABA-ergic and hypocretin neurons in the lateral hypothalamus and zona incerta regulate sleep
What hormones regulate trust?
Oxytocin in the PVN regulate trust
What is evidence to show how important the hypothalamus and its functions are?
- Massively conserved throughout evolution
- Necessary for survival, reproduction and survival of species
- Means animal models are pretty generalisable
How does hypothalamic circuitry work?
Hypothalamic nuclei/neurons all form interlinked circuits
- This means one behaviour can affect a second
- E.g. optimal feeding –> optimal sleep
What is the role of PVN and ARCH neurons projecting to the median eminence in hormone regulation?
- Neurons from the PVN (paraventricular nucleus) and ARCH (arcuate nucleus) project to the median eminence.
- Neurohormones are transported to axon endfeet and released into the portal capillary network.
- These hormones are carried to the anterior pituitary, stimulating the release of pituitary hormones (e.g., CRH, TRH).
How do PVN neurons contribute to hormone release in the posterior pituitary?
- Two classes of PVN neurons (e.g., oxytocin-producing neurons) synthesize neurohormones.
- The axons of these neurons project directly to the posterior pituitary, where neurohormones are secreted into the capillary network for general circulation (e.g., oxytocin release).
What are tanycytes, and what is their function in the hypothalamus?
- Tanycytes are specialized cells in the median eminence that line the third ventricle.
- Located near the ARCH, they play roles in regulating feeding, energy balance, and reproduction.
Why are tanocytes described as ‘gatekeepers’
- provide direct link with circulating systems/peripheral body
- direct passage of hormones through directly to brain
