Hypothalamus Summary Flashcards
(26 cards)
Where is the hypothalamus located?
At the base of the brain, part of the diencephalon, below the thalamus and above the pituitary gland.
Connected to the pituitary by a stalk called the infundibulum.
What is the primary role of the hypothalamus?
Maintains homeostasis: balance of temperature, hunger, hormones, etc.
What are the key functions of the hypothalamus?
- Temperature regulation
- Blood pressure & osmolarity
- Food & water intake
- Sexual behavior & hormones
- Aggression, emotion, and motivation
- Circadian rhythms (body clock)
What is the main function of the Preoptic Zone of the hypothalamus?
Reproductive hormones (GnRH), sexual behaviour.
What are the main functions of the Supraoptic Zone?
Circadian rhythms, thirst, body temperature, ADH & oxytocin.
What is the main function of the Tuberal Zone?
Satiety, hunger, hormone release.
What is the main function of the Mammillary Zone?
Memory, arousal, reward, wakefulness.
What sources of input does the hypothalamus receive?
- Sensory neurons → Touch, light, smell
- Visceral neurons → Internal body signals
- Retinal input → Biological clock regulation
- Nucleus of the solitary tract (NTS) → Taste, gut signals
- Blood-borne signals → Hormones, glucose, sodium
- Direct sensors: thermoreceptors, osmoreceptors, chemoreceptors
What are Circumventricular Organs (CVOs)?
Small regions near the brain ventricles that lack a blood-brain barrier.
Why are Circumventricular Organs important?
They allow the hypothalamus to sense changes in the blood (hormones, toxins, osmolarity).
What is the function of the OVLT?
Detects osmolarity → triggers thirst & ADH.
What does the Subfornical Organ (SFO) detect?
Blood-borne hormones like angiotensin II.
What is the function of the Area Postrema?
Detects toxins → triggers vomiting.
What is the Median Eminence’s role?
Where hypothalamic hormones enter portal circulation to reach the anterior pituitary.
What systems does the hypothalamus regulate?
- Autonomic Nervous System (ANS)
- Endocrine System
- Motivation System (and Limbic Integration)
What involuntary functions does the Autonomic Nervous System (ANS) control?
- Heart rate
- Digestion
- Pupil size
What hormones are released by the posterior pituitary?
- Oxytocin
- Vasopressin (ADH)
What is the function of Oxytocin?
Social bonding, childbirth, milk ejection.
What does Vasopressin (ADH) regulate?
Water balance and blood pressure.
What is the HPA Axis pathway?
CRH → ACTH → Cortisol.
What is the function of the HPA Axis?
Stress response.
Fill in the blank: The hypothalamus is the master of _______.
homeostasis.
What does the hypothalamus link to influence behavior?
Emotion and memory via the limbic system.
What is the role of the SCN (Suprachiasmatic Nucleus)?
Biological clock regulator.
