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Physiology 1021
Bob Larose

Neurology Hypothalamus and Limbic System: A major function of the nervous system is to maintain the constancy of the internal environment; homeostasis. Neurons controlling the internal environment are concentrated in a region of the brain called the hypothalamus. The hypothalamus is greatly influenced by, and operated in the conjuction with, higher control systems located in the limbic system. The hypothalamus is critical for survival The brain: Has 4 lobes: 1. Frontal cortex 2. Occipital cortex 3. Parietal cortex 4. Temporal cortex Some functions of the hypothalamus are essential to life, where others contribute to the overall adaptation of the animal to its normal, changing external environment. Because of the importance to all life processes, information about the hypothalamus is found in almost every chapter of the text. Functions of the hypothalamus: 1. Controls the Autonomic nervous system.  Deals with the “fight or flight” response 2. Neuroendocrine control  Posterior pituitary glands, receives from adrenal medulla 3. Reproduction  Behavior and pituitary function 4. Water balance and exchange 5. Sodium balance and exchange 6. Body energy balance and exchange  Nutrients intake- metabolism 7. Drives and emotion  Feelings, Attach 8. Circadian rhythms 9. Body temperature regulation There are specialized sections in the hypothalamus There is nucleus within the brain, not normal nucleus like in cell.  1. Collections of neurons that look the same  2. Have the same function The hypothalamus is not homogenous and is made up of many different neurons. Different hypothalamic nuclei: Supraoptic nucleus: water balance Suprachiasmatic nucleus: biological clock Ventromedial hypothalamus: Tells you when to stop eating Paraventricular Nucleus: Water balance, food + eating Lateral Hypothalamus: feeding Preoptic/ Anterior hypothalamic region: blood pressure regulation and controls body temperature Basomedial hypothalamus: The Autonomic Nervous System: The ANS is part of the peripheral nervous system. It is involved in the actions that you do not need to think to do such as breathing. Works with smooth muscles, cardiac muscles and the secretion of glands. Two divisions of the autonomic nervous system: 1. Parasympathetic 2. Sympathetic Parasympathetic Cell body sends neurons directly to target cell Causes fast transport however it cannot be intervened  Cannot change path mid signal Sympathetic: Cell body sends to a relay of cells Causes slower transport but allows the ability to change direction once signal sent. Sympathetic Parasympathetic Rhyming Time Fight vs Flight Rest and Digest Specification Cant change direction/ Can go to multiple cells target Speed Fast Slow Preganglionic Short axon Long axon Located in spinal cord and Located in brain/ spinal grows out cord Postganglionic Long axon Short axon Cell body far from target Cell body close to target cell cell 5 Morphological characteristics of the ANS: 1. PNS has long preganglionic neurons, SNS has short neurons 2. ALL neurons use Ach as a transmitter 3. All PNS neurons use Ach, SNS neurons use NE 4. PNS works faster and is more specific. SNS is slower, with a more global response 5. PNS branches out from cranial and sacral divisions, SNS branches from thoracic and lumbar divisions Usually the Sympathetic and Parasympathetic nervous systems work together. They offer opposite/ Complementary effects Posterior Hypothalamus Anterior Hypothalamus (Sympathetic) (Parasympathetic) Blood Pressure Increase Decrease Heart Rate Increase Slow Gastrointestinal Slows Stimulated for digestion Mobility Pupil Size Dilute Constrict Pituitary Gland: The pituitary gland is made up of the axons from the periventricular and the Supraoptic nuclei. The hypothalamus produces different hormone releasing factors, which activate the anterior pituitary gland to release hormones in to circulation Releasing hormones secreted by the Basomedial Hypothalamus reach the anterior pituitary gland via a specialized component of the circulatory system called the hypophyseal portal system. Hormones produced
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