So, the next structure in the brain is the diencephalon.
The diencephalon has three major parts to it, the thalamus, the hypothalamus and the epithalamus.
The thalamus is a superior portion of the diencephalon.
It is located superior to the midbrain and contains nuclei
that serve as a relay station for all of our sensory impulses except for our sense of smell.
They send these impulses to our cerebral cortex.
The thalamus actually has seven major groups of nuclei.
These include the reticular nuclei which monitor, filter and integrate activities of the thalamic nuclei.
The midline nucleus which is presumed to function in memory and olfaction.
Next we have the lateral group which is made up of three different nuclei or three different areas.
These are going to receive input from the limbic system, the superior colliculi and the cerebral cortex.
And, it's going to send output to the cerebral cortex.
As well, we have our medial nuclei.
The medial nuclei receive input from the limbic system and the basal nuclei
and send output to the cerebral cortex.
The medial nuclei are important for emotions, memory, learning and cognition.
The next nuclei is the ventral group. This is actually made up of five different groups of nuclei.
They receive input from the basal nuclei and also send output to the motor areas of the cerebral cortex.
Because of this, they function in movement control. The next is the anterior nuclei.
The anterior nuclei receive input from the hypothalamus and send output to the limbic system.
This is important for emotions and memory.
So the next structure in the diencephalon just inferior to the thalamus is the hypothalamus.
The hypothalamus has four major regions and controls many of our body's activities.
The hypothalamus is actually the body's most important regulator of homeostasis.
The four regions of the hypothalamus include, the mammillary region, the tuberal region,
the supraoptic region and the preoptic region.
The functions of these regions include control of our autonomic nervous system
which is going to regulate this or organ activities like heartrate
and the movement of food through our digestive system, our GI tract
and contraction of the bladder.
The hypothalamus is also very important for the production of hormones.
Hormones produced by the hypothalamus are sent to the pituitary gland
where then they are sent throughout the circulatory system to their target organs.
The hypothalamus has structures that are important for regulating emotional and behavioral patterns
such as rage, aggression, pain, as well as pleasure and sexual arousal.
The hypothalamus also regulates eating and drinking,
and contains a feeding center, a satiation center and a thirst center.
The hypothalamus also acts as our body's thermostat and controls our body temperature.
And another very important function of the hypothalamus
is regulation of our circadian rhythm or our body's internal clock
which helps us establish our sleep wake cycle.
The third structure of the diencephalon is the epithalamus.
The epithalamus lies superior and posterior to the thalamus and contains the pineal gland.
The pineal gland is important because it secretes melatonin and also contains the habenular nuclei.
These are involved in olfaction. So just to backtrack.
Melatonin is important because it also helps us regulate our circadian rhythm.
And a lot of times people who are having trouble sleeping
will go and take melatonin supplements in order to supplement the pineal gland.
The habenular nuclei are involved in our emotional response to odors.
So it's involved in olfaction but instead of it being -- telling you what a smell is, it actually --
it is involved in how you respond to smell such as feeling happy
when you smell brownies or feeling stressed or angry
when you smell the cologne of one of your old boyfriends that made you very mad.
Parts of the diencephalon known as the circumventricular organs
or CVO's can monitor chemical changes in the blood because these parts
actually lack a blood-brain barrier.
CVO's are part of the hypothalamus, the pineal gland and the pituitary gland.
CVO's help coordinate homeostatic activities of both the endocrine and the nervous system
and allow for the regulation of blood pressure, fluid balance, hunger and thirst.