Chapter 3 - The Centrak Nervous Systen (CNS)

Chapter 3 The central nervous system (CNS) includes the brain and spinal cord. The spinal cord connects the brain to the peripheral nervous system (PNS) PNS CONSISTS of the nerves that innervate the muscles (motor unit), skin and internal organs, and sensory neurons & nociceptors AUTONOMIC nervous processing there is usually done automatically organs of the body in conscious control from planning areas of brain, heart rate, breathing, digestion PNS Somatic contains those neurons that control your muscles and cause the movement of them Autonomic Sympathetic Activates systems in the body Parasympathetic restores systems to resting state Directions Dorsal Toward the back Ventral toward the stomach Rostral toward the head/nose Caudal toward the tail Medial towards midline Lateral toward the side Distal distant, far Proximal near it, close Anterior toward the front (head) Posterior toward back and tail Superior above Inferior below Ipsilateral same side Contralateral opposite side Nucleus a large group of neuron somas Ganglia a group of neuron somas example Ventro medial hypothalamus satiety center maintains The seven major divisions of the central nervous system (CNS) Spinal cord, medulla, pons, cerebellum, midbrain, diencephalon and telencephalon Spinal cord Medulla Pons Cerebellum Midbrain Diencephalon Thalamus Hypothalamus Telencephalon Limbic system Basal ganglia Cerebral cortex Spinal cord much of sensory information that reaches our brain enters through sensory neurons and nociceptors from the dorsal horns of the spinal cord. Sensory neurons convey information about muscle position, temperature and touch •Nociceptors respond to chemicals that are produced by damaged cells (which the brain interprets as pain) 1). The information is sent to the brain through bundles of nerves in the ascending pathways along the sides of the spin cord 2). A reflex can be triggered. A reflex occurs when a sensory neuron synapses on an interneuron that activates a motor neuron to cause a muscle to move Lateral ascending pathway damage patient may lose the ability to detect sensations and nociception at and below the level of damage Chapter 3 Medulla contains cell bodies of neurons that make up some of the cranial nerves there are separate nuclei that control autonomic nervous system functions such as digestion, breathing, HR. vagus nerve regulates excitation of smooth muscles within blood vessels in the arms, legs and digestive organs. upper medulla damage: leave a patient in a coma that is characterized by irregular and uneven breathing Pons convey information about movement between the cortex and cerebellum, and also between these areas in the spinal cord pons play a role in sleep cholinergic neurons in the pontine nucleus of the pons activate dreams of REM (rapid eye mane) sleep. cholinergic neurons during REM sleep to prevent us from moving Damage to pons cause a condition called "REM without atonia" in which patients act out their dreams (get sleep walking) Cerebellum connected to the brain stem (pons) by fiber tracts. General function: make adjustments to the force and range of our movements while they occur Le also controls our sense of balance and is involved in some types of motor skill learning Damage to the cerebellum DOES NOT impair a patient's ability to initiate movement DOES impair the ability to correct errors made during movement. MIDBRAIN Controls many sensory and motor functions including eye movement, and the coordination of visual and auditory reflexes The substantia nigra, located in the midbrain, provides the basal ganglia with the neurotransmitter dopamine in parkinsons disease 80 or more of the neurons in the substantia nigra die, leaving the patient unable to carry out voluntary movements.   periaqueductal gray: plays an important role in the brain's response to pain, and drugs that target this area can produce analgesia Although morphine produces several effects in the central nervous system, one effect is to inhibit neurons in the periaqueductal gray area. DIENCEPHALON Includes the thalamus and hypothalamus Thalamus: major relay center Le connects incoming information from sensory, motor and pain systems to the correct areas in the telencephalon Hypothalamus. controls much of the output from the brain to other systems in the body and also monitors feedback from those systems (e.g., autonomic, endocrine, and stress response) and contains nuclei for expressing emotions and motivations