Nervous System PDF

 “communication center” of the body  Receiving sensory signals  Integration of information  Controls muscular & glandular activities  Regulates and maintains homeostasis  Establishment & maintenance of mental activities  Receives stimuli Conducts action potential Transmits s...

 “communication center” of the body  Receiving sensory signals  Integration of information  Controls muscular & glandular activities  Regulates and maintains homeostasis  Establishment & maintenance of mental activities  Receives stimuli Conducts action potential Transmits signals to other neurons  surround neurons  provide support and insulation between them  most abundant cell types in CNS.  Types of glial cells: o oligodendrocyte o astrocytes o ependymal cells o Schwann cells, o Microglia o satellite cells.  Resting membrane potential (RMP) ◦ Charge difference across the cell membrane  ACTION POTENTIAL ◦ the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell. ◦ STEPS:  Resting potential  Na+ outside ; K+ inside  Channels closed  Stimulus/threshold  Some Na+ opens ; Na+ enters  If threshold is passed they all open  Depolarization  Na+ channels open; Na+ enters ; cell becomes positive  Chain reaction of Na+ channels opening the axon  Repolarization  Na+ gates close ; K+ gates open  K+ moves out & the cell becomes negative.  SYNAPSE  also called neuronal junction  the site of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector).  Presynaptic terminal  Postsynaptic membrane  Synaptic vesicles (neurotransmitter) Excitatory Inhibitory Excitatory Inhibitory Inhibitory Excitatory Inhibitory Excitatory Inhibitory Inhibitory Inhibitory  REFLEXES  Involuntary reaction in response to a stimulus transmitted to CNS.  Neuronal pathway where reflex occurs  Basic functional unit of NS since it is the simplest pathway capable of receiving stimulus producing immediate response  Mostly occur in the spinal cord  Components: ◦ Sensory receptor motor neuron ◦ Sensory neuron effector organ ◦ interneurons  Central Nervous System (CNS) ◦ Brain (cranium) ◦ Spinal cord (vertebral column)  Peripheral Nervous System (PNS) ◦ Nerves and ganglia outside the CNS ◦ Collects information from numerous sources both inside & outside of the body ◦ Relays it through sensory neurons to CNS where information is either ignored, triggered reflex or evaluated. ◦ Motor neurons relay information from the CNS to effector/s (muscles or glands) to regulate activities ◦ 12 pairs of cranial nerves ◦ 31 pairs of spinal nerves Extends from foramen magnum to the L2  Knee Jerk Reflex (Patellar Reflex) ◦ sudden kicking movement of the lower leg in response to a sharp tap on the patellar tendon, lying just below the kneecap.  Withdrawal Reflex (Flexor Reflex) ◦ Remove a limb or other body part from painful stimulus (pain receptors)  originate in the spinal cord and form part of the peripheral nervous system  mixed nerve is one which transmits motor, sensory, and autonomic signals between the spinal cord and the body.  31 pairs act as “telephone lines,” carrying ◦ Cervical (C1 – C8) messages back and forth between ◦ Thoracic (T1 – T12) your body and spinal cord to control ◦ Lumbar (L1 – L5) sensation and movement. ◦ Sacral (S1 – S5) Each spinal nerve has two roots The ◦ Coccygeal ventral (front) root carries motor impulses from the brain and the dorsal (back) root carries sensory impulses to the brain.  Flexus - (branching network) of intersecting nerves.  Cervical plexus - serves the head, neck and shoulders.  Brachial plexus - serves the chest, shoulders, arms and hands.  Lumbar plexus - serves the back, abdomen, groin, thighs, knees, and calves.  Sacral plexus - serves the pelvis, buttocks, genitals, thighs, calves, and feet.  PLEXUSES AND DERMATOMAL MAP  Muscles are attached to the bones by TENDONS CEREBRUM  Brainstem ◦ Connects the spinal cord to the brain ◦ Controls heart rate, blood pressure and breathing Part of Brainstem Function ▪ Regulation of heart rate ▪ Blood vessel diameter Medulla Oblongata ▪ Breathing, swallowing ▪ Vomiting, coughing, sneezing ▪ Balance & coordination ▪ Breathing, swallowing and PONS balance ▪ movements of the eye MIDBRAIN/Mesencephalon ▪ auditory and visual processing.  Function ▪ regulates motor movements. ▪ coordinates voluntary Cerebellum movements such as posture, balance, coordination, and speech. Diencephalon ▪ relaying of sensory signals, including motor signals to the THALAMUS cerebral cortex ▪ regulation of consciousness, sleep, and alertness. Epithalamus ▪ Emotional and visceral response to odors Hypothalamus ▪ Hormonal secretion (GH, GoH ▪ Thermoregulation  is the largest part of the brain and is composed of right and left hemispheres.  interpretation of touch, vision and hearing, speech, reasoning, emotions, learning, and control of movement. Lobes of Cerebrum Function Frontal ▪ controls emotional expression, problem solving, memory, language, judgment, and sexual behavior. ▪ “control panel” of our personality and our ability to communicate.  is the largest part of the brain and is composed of right and left hemispheres.  interpretation of touch, vision and hearing, speech, reasoning, emotions, learning, and control of movement. CEREBRUM Lobes of Cerebrum Function ▪ controls emotional expression, problem solving, memory, Frontal language, judgment, and sexual behaviour. ▪ “control panel” of our personality and our ability to communicate. ▪ Center for receiving and perceiving Parietal most sensory information like touch, pain, temperature & balance Occipital Interpretation of visual input ▪ Involved in olfaction (smell) Temporal ▪ auditory (hearing) sensations ▪ Plays a role in memory  Right and Left Cerebral Hemispheres  The left hemisphere of the brain is responsible for controlling the right side of the body. It also performs tasks that have to do with logic, such as in science and mathematics.  the right hemisphere coordinates the left side of the body, and performs tasks that have do with creativity and the arts.  (EEG) is a test used to find problems related to electrical activity of the brain.  tracks and records brain wave patterns. Small metal discs with thin wires (electrodes) are placed on the scalp, and then send signals to a computer to record the results.  is the faculty of the brain by which data or information is encoded, stored, and retrieved when needed.  It is the retention of information over time for the purpose of influencing future action.  Long term Memory ◦ Declarative ◦ Procedural  Working Memory  Short Memory The main parts of the brain involved with memory: amygdala, hippocampus, cerebellum, prefrontal cortex The LIMBIC SYSTEM  involved in motivation, emotion, learning, and memory.  The limbic system is where the subcortical structures meet the cerebral cortex.  operates by influencing the endocrine system and the autonomic nervous system.  Responds to olfactory stimulation (hunger, thirst)  Disorder of Limbic system: voracious eating, increased sexual activity, loss of normal fear and anger. ▪ inflammation of the membranes (meninges) surrounding the brain and spinal cord. These structures are responsible for the production, transport and removal of cerebrospinal fluid, which bathes the CNS.  clear, colorless body fluid found in the brain and spinal cord.  FUNCTION: ◦ CSF cushions the brain within the skull ◦ serve as a shock absorber for the CNS ◦ circulates nutrients and chemicals filtered from the blood. ◦ removes waste products from the brain.  excess cerebrospinal fluid (CSF) builds up within the ventricles (fluid- containing cavities) of the brain and may increase pressure within the head. 12 CRANIAL NERVES  Carries action potential from the CNS to PNS  Present in smooth muscle, cardiac & glands  Controlled unconsciously (involuntary)  regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal.  Division: ◦ Sympathetic – body under physical activity ◦ Parasympathetic – body at rest ◦ Acetylcholine  Parasympathetic neurotransmitter involved in muscular activities  sensation of pain, learning and memory formation  the regulation of the endocrine system  rapid eye movement (REM) sleep cycles. ◦ Norepineprine and Epinephrine epinephrine has slightly more effect on heart, norepinephrine has more of an effect on your blood vessels Both play a role in your body's natural fight-or-flight response to stress  sudden interruption in the blood supply of the brain  caused by an abrupt blockage of arteries leading to the brain (ischemic stroke).  bleeding into brain tissue when a blood vessel bursts (hemorrhagic stroke)  Symptoms: ◦ numbness or weakness in the face, arm or leg (one side of the body). ◦ trouble speaking or understanding speech. ◦ vision problems in one or both eyes. ◦ difficulty walking or dizziness, loss of balance or problems with coordination. ◦ Severe headache with no known cause.  Transmission of Nerve Impulses by Neuron  STROKE (Symptoms and Treatment)  TOP 5 DISORDERS of the Nervous System  Assignment : Cranial nerves and SPINAL NERVES Functions  Diseases and Disorders of Nervous System ◦CONTINUATION GRADED RECITATION