Hypothalamus – Divisions & Functions
HYPOTHALAMUS – DIVISIONS & FUNCTIONS (Brief)
Location:
- Diencephalic structure
- Below hypothalamic sulcus in ventral part of diencephalon.
- Formed by groups of nuclei, scattered in walls & floors of 3rd ventricle
- Forms major & central element of limbic system surrounded by other structures of limbic system.
Anatomical considerations –
- Divided by sagittal & coronal planes into 3 regions & 3 zones each,
By Sagittal plane (regions):
- Anterior – Supraoptic
- Middle – Tuberal
- Posterior – Mamillary
By Coronal plane (zones):
- Lateral
- Medial
- Periventricular (surrounding 3rd ventricle)
NUCLEI OF HYPOTHALAMUS:
Divided into three groups,
- Anterior or preoptic group
- Middle or tuberal group
- Posterior or mamillary group.
1. Anterior/pre-optic group:
- Supraoptic nucleus
- Suprachiasmatic nucleus
- Paraventricular nucleus
- Lateral preoptic nucleus
- Medial preoptic nucleus
- Anterior nucleus
2. Middle or tuberal group:
- Lateral hypothalamic area
- Ventromedial nucleus
- Dorsomedial nucleus
- Arcuate nucleus
3. Posterior or mamillary group:
- Mamillary nucleus
- Posterior hypothalamic nucleus
FUNCTIONS OF HYPOTHALAMUS:
Two types of functional effects majorly,
- Endocrinal effects
- Neuronal effects
REGULATION OF NEURONAL FUNCTIONS:
1. Regulation of body temperature:
- Controlled by Pre-optic nucleus
- Anterior hypothalamus – Respond to heat
- Posterior Hypothalamus – Respond to cold (Shivering center)
2. Regulation of circadian rhythms:
- Suprachiasmatic nucleus
3. Regulation of hunger & food intake:
- Feeding center
- Lateral hypothalamic nucleus
- Satiety center
- Ventromedial nucleus
4. Regulation of thirst:
- Lateral nucleus.
- Supra-optic nucleus
5. Regulation of BP:
- Pressor effect
- Posterior & lateral nuclei
- Depressor effect
- Preoptic nucleus
6. Regulation of sexual function:
Anterior hypothalamus:
In males:
- Medial preoptic nucleus
In females:
- Lateral preoptic nucleus
7.Osmoreceptor:
- Anterior hypothalamus
8. Response to smell:
- Posterior hypothalamus
9. Other centers/neuronal regulations under control of hypothalamus:
Sleep center
- Preoptic (Ventrolateral)
Wakefulness center
- Reticular Activating System (RAS) in brainstem & hypothalamus
Reward center
- Lateral & ventromedial nuclei of hypothalamus
Punishment center
- Periventricular nuclei (mainly)
REGULATION OF ENDOCRINAL FUNCTIONS:
1. Control of anterior pituitary:
Arcuate nucleus
- Releases activator hormone somatostatin
- For Growth hormone secretion.
Preoptic nucleus
- Releases activator hormone Gonadotrophin Releasing Hormone (GnRH)
- For FSH & LH secretion
Paraventricular nucleus
- Releases activator hormone Corticotropin-releasing hormone (CRH)
- For ACTH secretion.
- Releases Thyrotropin-releasing hormone (TRH).
- For thyroxine secretion
Dorsal & posterior nucleus
- Releases activator hormone for Catecholamines secretion
2. Control of posterior pituitary:
- Supraoptic nuclei – ADH (majority)
- Paraventricular nucleus – Oxytocin (majority)
Exam Question
HYPOTHALAMUS – DIVISIONS & FUNCTION
REGULATION OF NEURONAL FUNCTIONS
1. Regulation of body temperature:
- Controlled by Preoptic nucleus
- Anterior hypothalamus – Respond to heat
- Posterior Hypothalamus – Respond to cold (Shivering center)
2. Regulation of circadian rhythms:
- Suprachiasmatic nucleus
3. Regulation of hunger & food intake:
- Feeding center
- Lateral hypothalamic nucleus
- Satiety center
- Ventromedial nucleus
4. Regulation of thirst:
- Lateral nucleus
- Supra-optic nucleus
5. Regulation of BP:
- Pressor effect
- Posterior & lateral nuclei.
- Depressor effect
- Preoptic nucleus
6. Regulation of sexual function:
Anterior hypothalamus:
In males:
- Medial preoptic nucleus
In females:
- Lateral preoptic nucleus
7.Osmoreceptor:
- Anterior hypothalamus
8. Response to smell:
- Posterior hypothalamus
9. Other centers/neuronal regulations under control of hypothalamus:
Sleep center
- Preoptic (Ventrolateral)
Wakefulness center
- Reticular Activating System (RAS) in brainstem & hypothalamus
Reward center
- Lateral & ventromedial nuclei of hypothalamus
Punishment center
- Periventricular nuclei (mainly)
REGULATION OF ENDOCRINAL FUNCTIONS:
1. Control of anterior pituitary:
Arcuate nucleus
- Releases activator hormone somatostatin
- For Growth hormone secretion.
Preoptic nucleus
- Releases activator hormone Gonadotrophin Releasing Hormone (GnRH)
- For FSH & LH secretion
Paraventricular nucleus
- Releases activator hormone Corticotropin-releasing hormone (CRH)
- For ACTH secretion.
- Releases Thyrotropin-releasing hormone (TRH)
- For thyroxine secretion
Dorsal & posterior nucleus
- Releases activator hormone for Catecholamines secretion
2. Control of posterior pituitary:
- Supraoptic nuclei – ADH (majority).
- Paraventricular nucleus – Oxytocin (majority).
Don’t Forget to Solve all the previous Year Question asked on Hypothalamus – Divisions & Functions
👨⚕️
Chat Support
❌