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Hypothalamus


ANATOMY

Hypothalamus is situated just above the Brainstem below the thalamus in the Brain. It forms the ventral part of the Diencephalon. The size of human Hypothalamus is the same as that of an Almond. Hypothalamus is made up of distinct nuclei and is found in the Nervous Systems of humans.

 

FUNCTION

The hypothalamic nuclei with their functions are the following.

  • Medial Preoptic Nucleus is involved in regulation of the release of Gonadotropic Hormones

  • Supraoptic Nucleus causes Vasopressin release.

  • Paraventricular Nucleus releases Thyrotropin, Corticotropin hormones and Oxytocin.

  • Anterior Hypothalamic Nucleus is responsible for thermoregulation, panting, sweating.

  • Suprachiasmatic Nucleus controls the  Circadian rhythms.

  • Lateral Preoptic Nucleus is related to thirst and hunger.

  • Dorsomedial Hypothalamic Nucleus controls Blood pressure, heart rate and GI stimulation.

  • Ventromedial Nucleus controls satiety and neuroendocrine system.

  • Arcuate Nucleus is involved in functions like feeding, Dopamine and growth hormone releasing hormone (GHRH).

  • Mammillary Nucleus plays its role in memory.

  • Posterior Nucleus increases blood pressure, causes pupil dilation, shivering and Vasopressin release.

 

Output of the Hypothalamus is divided into two categories i.e.

(i)     Neural projections

Fiber system of Hypothalamus runs in two directions. The fiber systems are as follows.

  • Projection caudal to Hypothalamus go through Medial Forebrain Bundle, the Mammillotegmental Tract and Dorsal Longitudinal Fasciculus

  • Projections to Hypothalamus’s rostral areas are carried out through Mammillothalamic Tract, the Fornix and the Terminal Stria.

  • Projections to areas of Sympathetic Motor System are carried through Hypothalamic Spinal Tract.

 

(ii)   Endocrine Hormone

Hypothalamus has a central Neuroendocrine function which controls Anterior Pituitary which in turn regulates various endocrine glands and organs.

 

BLOOD SUPPLY

The arteries supplying the blood to Hypothalamus are all derived from the Circle of Willis. The arterial supply to the Hypothalamus is divided into three parts;

  • Anterior; it consists of the Preoptic region and receives blood supply from the branches of Anterior Cerebral Arteries.

  • Middle; beneath this region are two communicating arteries,it receives bulk of the blood supply from branches of these arteries.

  • Posterior; it receives blood supply from the branches of the bifurcation of the Basilar Artery.

 

PATHOLOGY

Many diseases may affect the Hypothalamus resulting in the disability of normal functions. Some of these diseases are as follows.



ANATOMY

Hypothalamus is situated just above the Brainstem below the thalamus in the Brain. It forms the ventral part of the Diencephalon. The size of human Hypothalamus is the same as that of an Almond. Hypothalamus is made up of distinct nuclei and is found in the Nervous Systems of humans.

 

FUNCTION

The hypothalamic nuclei with their functions are the following.

  • Medial Preoptic Nucleus is involved in regulation of the release of Gonadotropic Hormones

  • Supraoptic Nucleus causes Vasopressin release.

  • Paraventricular Nucleus releases Thyrotropin, Corticotropin hormones and Oxytocin.

  • Anterior Hypothalamic Nucleus is responsible for thermoregulation, panting, sweating.

  • Suprachiasmatic Nucleus controls the  Circadian rhythms.

  • Lateral Preoptic Nucleus is related to thirst and hunger.

  • Dorsomedial Hypothalamic Nucleus controls Blood pressure, heart rate and GI stimulation.

  • Ventromedial Nucleus controls satiety and neuroendocrine system.

  • Arcuate Nucleus is involved in functions like feeding, Dopamine and growth hormone releasing hormone (GHRH).

  • Mammillary Nucleus plays its role in memory.

  • Posterior Nucleus increases blood pressure, causes pupil dilation, shivering and Vasopressin release.

 

Output of the Hypothalamus is divided into two categories i.e.

(i)     Neural projections

Fiber system of Hypothalamus runs in two directions. The fiber systems are as follows.

  • Projection caudal to Hypothalamus go through Medial Forebrain Bundle, the Mammillotegmental Tract and Dorsal Longitudinal Fasciculus

  • Projections to Hypothalamus’s rostral areas are carried out through Mammillothalamic Tract, the Fornix and the Terminal Stria.

  • Projections to areas of Sympathetic Motor System are carried through Hypothalamic Spinal Tract.

 

(ii)   Endocrine Hormone

Hypothalamus has a central Neuroendocrine function which controls Anterior Pituitary which in turn regulates various endocrine glands and organs.

 

BLOOD SUPPLY

The arteries supplying the blood to Hypothalamus are all derived from the Circle of Willis. The arterial supply to the Hypothalamus is divided into three parts;

  • Anterior; it consists of the Preoptic region and receives blood supply from the branches of Anterior Cerebral Arteries.

  • Middle; beneath this region are two communicating arteries,it receives bulk of the blood supply from branches of these arteries.

  • Posterior; it receives blood supply from the branches of the bifurcation of the Basilar Artery.

 

PATHOLOGY

Many diseases may affect the Hypothalamus resulting in the disability of normal functions. Some of these diseases are as follows.

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