neuro2(2) - 883 Hypothalamus HYPOTHALAMUS Introduction The...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Hypothalamus 883 HYPOTHALAMUS Introduction The hypothalamus is a very small, but extremely important part of the diencephalon that is involved in the mediation of endocrine , autonomic and behavioral functions. The hypothalamus: (1) controls the release of 8 major hormones by the hypophysis, and is involved in (2) temperature regulation, (3) control of food and water intake, (4) sexual behavior and reproduction, (5) control of daily cycles in physiological state and behavior, and (6) mediation of emotional responses. A large number of nuclei and fiber tracts have been described in the hypothalamus. Some of these are ill-defined and have no known function, while others have been studied in detail both anatomically and physiologically. This handout will attempt to focus your attention on the significant and interesting aspects of the structure and function of the hypothalamus. The hypothalamus is the ventral-most part of the diencephalon. As seen in Fig. 2 of the thalamus handout , the hypothalamus is on either side of the third ventricle, with the hypothalamic sulcus delineating its dorsal border. The ventral aspect of the hypothalamus is exposed on the base of the brain (Fig. 1). It extends from the rostral limit of the optic chiasm to the caudal limit of the mammillary bodies . Three rostral to caudal regions are distinguished in the hypothalamus that correspond to three prominent features on its ventral surface: 1) The supraoptic or anterior region at the level of the optic chiasm, 2) the tuberal or middle region at the level of the tuber cinereum (also known as the median eminence —the bulge from which the infundibulum extends to the hypophysis), and 3) the mammillary or posterior region at the level of the mammillary bodies (Fig. 1) Important components of the 3 rostral to caudal regions of the hypothalamus are as follows: Supraoptic Region . In the supraoptic region (above the optic chiasm) there are a number of named nuclei, the most prominent being the supraoptic and paraventricular (Fig. 2A). Neither of these two nuclei is large, but each is easily recognized because it is made up of relatively large, deeply staining cells. The cells in these two nuclei secrete vasopressin (ADH , antidiuretic hormone), oxytocin, and CRH (corticotropin releasing hormone). ADH and oxytocin are transported down the axons from cells in the supraoptic and paraventricular nuclei through the infundibulum to the neurohypophysis (posterior pituitary), where they are released into the blood stream (Fig. 3A). This pathway is termed the supraopticohypophysial tract. Damage to the anterior hypothalamus blocks the production of ADH, resulting in diabetes insipidus , which is characterized by rapid water loss from the kidneys. CRH is released by the paraventricular and taken up by the portal system where it has its action on the anterior lobe of the pituitary. A recent, interesting development is the finding of a direct projection from the eye to the suprachiasmatic nucleus of the supraoptic hypothalamic region (Fig. 2A). The hypothalamus is
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern