7th October 2016 Endocrinology Hypothalamus and Pituitary The Brain The brain consists of the higher centres and the lower centres. The higher centres include: - Basal Ganglia - Cerebellum - Cerebrum (including Cortex of the brain and limbic system) The Higher centres are involved in voluntary control, planning, and imitation. Perception of stress and challenge is done in the higher centres and stimulates the endocrines to produce hormones. The lower centres include: - Brain stem (medulla oblongata, Pons, and Mid brain) - Thalamus - Hypothalamus The lower centres are involved in simple reflexes and autonomic control. Hypothalamus 'Hypo' means below; it means part of the brain below the thalamus. It is the region under the thalamus. It is apart of the brain that is not behind the BBB; it is not protected but has access to the peripheral nervous system and is able to receive chemical messages without it being filtered through or screened by the BBB. BBB is used by the brain to protect it from toxins that could be present in the blood. It is composed of discrete groups of neurones called 'nuclei' or 'areas' e.g. arcuate nucleus and paraventricular nucleus. These are areas that regulate specific bodily functions e.g. regulate hunger, temperature, blood pressure ect ... The hypothalamus has a crucial role in the endocrine system: 1. It is an endocrine organ that controls the anterior pituitary (AP); it is its major function. 2. It innervates the posterior pituitary (PP) via direct nerve fibres.
7th October 2016 Endocrinology 3. It innervates more distant glands (adrenal medulla, pineal, kidney, parathyroid, pancreatic islets) via the autonomic innervations - cause the release of a hormone without the requirement of the pituitary. Central to endocrinology! Celebral Cortex Thalamus Fomix Cerebullum Hippocampus Amygdala Spinal cord Hypothalamic nuclei: Caudate Nucleus Corpus Callosum Hypothalamus Olfactory Bulb Pituitary gland Pons Medulla Paraventricular Nucleus Dorsomedial Nucleus Anterior Nucleus Preoptic Area Suprachiasmatic Nucleus Supraoptic Nucleus Posterior Nucleus Ventromedial Nucleus Mamillary Body Arcuate Nucleus Infundibulum Anterior Pituitary Posterior Pituitary
7th October 2016 Endocrinology Distinct shaded areas that are discret areas that contain groups of neurons that cause specific bodily functions. The main function of the hypothalamus is homeostasis: maintaining the status quo of the body - keeping the internal environment of the body within the hypothalamic set point. The hypothalamus regulates: - Blood pressure - basoreceptors. - Temperature - average is around 37? over a 24hour period. This is a set point, and the hypothalamus regulates the temperature via thermoreceptors over the body to initiate changes in body temperature. - Fluid and electrolyte balance - Body weight - body fat releases hormones that tell the brain the person is full. - Sleep These factors are regulated at what is known as the 'hypothalamic set point'. This point can migrate over time, due to aging, but is relatively fixed. Homeostasis is endocrinologically derived. Pituitary gland It is not part of the brain. It is also referred to as the hypophysis and acts as a second in command to the