Hypothalamus

Hypothalamic nuclei:

  1. Preoptic area; preoptic nucleus

2. Anterior area:
a. Supraoptic nucleus
b. Suprachiasmatic nucleus
c. Paraventricular nucleus
d. Anterior nucleus

3. Middle area:
a. Venteromedial nucleus
b. Dorsomedial nucleus
c. Arcuate nucleus

4. Posterior area:
a. Mammillary body
b. Posterior nucleus

5. Lateral area; lateral nucleus

Functions of Hypothalamus:
1. Regulation of body temperature
a. Plays an important role in the integrated control of heat production and heat loss from the body

2. Regulation of anterior pituitary gland activity
a. Regulates the activity of the anterior pituitary gland by releasing factors and release inhibiting factors into the hypothalamus-hypophysial tract

3. Regulation of the posterior pituitary hormone secretion
a. ADH and Oxytocin

4. Control of circadian rhythm
a. There is a circadian rhythm for many body functions, which is about 24 hours
b. An important point concerning most bodily rhythm is that they are internally driven.  
c. The Suprachiasmatic nuclei are the main site for many circadian rhythms of the body.   These nuclei receive important inputs from;
i. The eyes via the retinohypothalamic fibers
ii. The lateral geniculate nuclei
d. Their normal function is to synchronize the various body rhythms to the 24 hour light-dark cycle

5. Control of the sleep waking cycle:
a. The basic system is controlled by the biological clock function of the hypothalamic suprachiasmatic nucleus

6. Control of ANS:
a. Stimulation of the anterior hypothalamus causes parasympathetic response like the contraction of the urinary bladder
b. Stimulation of the lateral areas of the hypothalamus causes sympathetic responses
c. Stimulation of the mid-dorsal area of hypothalamus causes cholinergic sympathetic vasodilation
d. Stimulation of the dorsomedial nuclei and posterior hypothalamic areas produces increased adrenal medullary secretion which is one of the physical changes...