The Nervous System PDF

THE NERVOUS SYSTEM Prepared by : Jennifer M. Sunga, LPT, MATS Updated by: Audelle B. Camaya, RN, LPT, MATc  CLOUD CYTOMA IS A TYPE OF BRAIN CANCER?  THOUGHTS TO PONDER “Be very careful to KEEP YOUR MIND SAFE. The thoughts that you think make you the person that you are.” –...

THE NERVOUS SYSTEM Prepared by : Jennifer M. Sunga, LPT, MATS Updated by: Audelle B. Camaya, RN, LPT, MATc  CLOUD CYTOMA IS A TYPE OF BRAIN CANCER?  THOUGHTS TO PONDER “Be very careful to KEEP YOUR MIND SAFE. The thoughts that you think make you the person that you are.” – Proverbs 4:23 EASY LESSON OBJECTIVES Explain 01 The functions Of the nervous system Describe 02 Divisions of the nervous system Discuss 03 Cells and organization of the nervous system  OVERVIEW AND ORGANIZATION OF THE NERVOUS SYSTEM  FUNCTIONS OF THE NERVOUS SYSTEM 01 02 Sensory input 03 Integration Motor output  FUNCTIONS OF THE NERVOUS SYSTEM 04 05 Regulation of Homeostasis 06 Control of Voluntary Control of Movement Involuntary Functions  FUNCTIONS OF THE NERVOUS SYSTEM 07 08 Learning & 09 Memory Cognition of 10 higher Brain Emotional functions Responses Reflexes  FUNCTIONS OF THE NERVOUS SYSTEM 1. SENSORY INPUT - gathering of information to monitor changes occurring inside and outside of the body 2. INTEGRATION - to process and interpret sensory input and decide if action is needed 3. MOTOR OUTPUT - a response to integrated stimuli - the response activates muscles or glands FUNCTIONS OF THE NERVOUS SYSTEM  FUNCTIONS OF THE NERVOUS SYSTEM 4. REGULATION OF HOMEOSTASIS - the nervous system works closely with the endocrine system to maintain homeostasis. 5. CONTROL OF VOLUNTARY MOVEMENTS - allows conscious control over skeletal muscles, enabling activities like walking, talking, or picking up objects.  FUNCTIONS of the NERVOUS SYSTEM 6. CONTROL OF INVOLUNTARY FUNCTIONS - regulates involuntary functions such as heartbeat, digestion and respiratory rate 7. LEARNING AND MEMORY - for processing and storing information 8. COGNITION AND HIGHER BRAIN FUNCTIONS - nervous system governs higher brain functions like thinking, reasoning, problem-solving, language, emotions, and consciousness  FUNCTIONS of the NERVOUS SYSTEM 9. EMOTIONAL RESPONSES - controls emotional reactions and mood through interactions between the brain's limbic system and neurotransmitters 10. REFLEXES - quick, automatic responses to certain stimuli that are controlled by the spinal cord and do not require conscious thought  LION’S MANE MUSHROOM SUPPLEMENT 1. Cognitive Health and Neuroprotection Lion’s mane contains compounds, such as hericenones and erinacines, that may stimulate the production of nerve growth factor (NGF) supporting brain cell growth and potentially enhancing memory, focus, and cognitive performance.  LION’S MANE MUSHROOM SUPPLEMENT 1. Cognitive Health and Neuroprotection Research suggests it may help prevent age-related cognitive decline and aid in recovery from neurological injuries.  LION’S MANE MUSHROOM SUPPLEMENT 2. Mood and Mental Health Support Studies indicate that lion's mane may reduce symptoms of anxiety and depression. Its neuroprotective properties could help regulate brain chemistry and promote a sense of well-being, potentially reducing inflammation linked to mental health conditions.  TWO MAJOR DIVISIONS OF THE NERVOUS SYSTEM 01 02 Central nervous system (CNS) Peripheral nervous system (PNS) Nerves (outside the brain & Brain & spinal cord spinal cord), neurons & glial cells  STRUCTURAL CLASSIFICATION NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM SENSORY DIVISION MOTOR DIVISION AUTONOMIC SOMATIC NERVOUS SYSTEM NERVOUS SYSTEM SYMPATHETIC PARASYMPATHETIC  1. CENTRAL NERVOUS SYSTEM 1. BRAIN 2. SPINAL CORD  1. CENTRAL NERVOUS SYSTEM A. BRAIN - The brain is the most complex organ in the body and consists of several parts  CNS: PARTS OF THE BRAIN 1. CEREBRUM The largest part, divided into left and right hemispheres. Responsible for higher cognitive functions like thinking, memory, emotion, and sensory perception.  CNS: PARTS OF THE BRAIN LOBES OF THE CEREBRUM 1. Frontal Lobe - Involved in decision- making, problem-solving, and planning 2. Parietal Lobe - Processes sensory information like touch, temperature, and pain.  CNS: PARTS OF THE BRAIN LOBES OF THE CEREBRUM 3. Temporal Lobe - Responsible for hearing, language, and memory. 4. Occipital Lobe - Processes visual information.  CNS: PARTS OF THE BRAIN 2. CEREBELLUM Located below the cerebrum at the back of the brain. Coordinates balance, posture, and fine motor movements.  CNS: PARTS OF THE BRAIN 3. DIENCEPHALON Located deep within the brain, it includes: o Thalamus - acts as a relay station for sensory information.  CNS: PARTS OF THE BRAIN 3. DIENCEPHALON o Hypothalamus - Regulates homeostasis, controlling hunger, thirst, sleep, and body temperature.  CNS: PARTS OF THE BRAIN 3. DIENCEPHALON o Epithalamus (including the Pineal Gland) - Involved in regulating sleep- wake cycles and producing melatonin.  CNS: PARTS OF THE BRAIN 4. BRAINSTEM Connects the brain to the spinal cord and controls basic life functions. Parts include: o Midbrain - Controls eye movements and auditory/visual processing.  CNS: PARTS OF THE BRAIN 4. BRAINSTEM Connects the brain to the spinal cord and controls basic life functions. Parts include: o Pons - Assists in regulating breathing and serves as a relay station.  CNS: PARTS OF THE BRAIN 4. BRAINSTEM Connects the brain to the spinal cord and controls basic life functions. Parts include: o Medulla Oblongata - Controls vital functions like heartbeat, blood pressure, and respiration.  CNS: PARTS OF THE BRAIN 5. LIMBIC SYSTEM Involved in emotions, memory, and behavior. Key structures include: o Amygdala - Processes emotions, particularly fear and pleasure. o Hippocampus - Critical for memory formation and spatial navigation.  CNS: PARTS OF THE BRAIN 6. BASAL GANGLIA Group of structures involved in coordinating movement and regulating voluntary motor control.  CNS: SPINAL CORD B. SPINAL CORD A long, cylindrical structure of nerve tissue that extends from the brainstem down through the vertebral column.  CNS: SPINAL CORD B. SPINAL CORD The spinal cord transmits signals between the brain and the body and controls reflex actions.  CNS: SPINAL CORD B. SPINAL CORD It is a crucial pathway for sending motor instructions and receiving sensory input.  STRUCTURAL CLASSIFICATION NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM SENSORY DIVISION MOTOR DIVISION AUTONOMIC SOMATIC NERVOUS SYSTEM NERVOUS SYSTEM SYMPATHETIC PARASYMPATHETIC  PERIPHERAL NERVOUS SYSTEM 1. SENSORY DIVISION (AFFERENT NEURONS) - Nerve fibers that carry impulses to (towards) the central nervous system  PHERIPHERAL NERVOUS SYSTEM 2. MOTOR DIVISION (EFFERENT NEURONS) - Nerve fibers that carry impulses away from the central nervous system  PHERIPHERAL NERVOUS SYSTEM 2. MOTOR DIVISION - AUTONOMIC - SOMATIC  MOTOR DIVISION A. AUTONOMIC - SYMPATHETIC - PARASYMPATHETIC - ENTERIC NERVOUS SYSTEM  AUTONOMIC NERVOUS SYSTEM 1. SYMPATHETIC Prepares the body for “fight or flight” responses by increasing heart rate, dilating pupils, and inhibiting digestion.  AUTONOMIC NERVOUS SYSTEM 2. PARASYMPATHETIC Supports “rest and digest” activities by lowering heart rate, stimulating digestion, and promoting relaxation.  AUTONOMIC NERVOUS SYSTEM 3. ENTERIC NERVOUS SYSTEM Often called the "second brain," it controls functions within the gastrointestinal tract and operates independently of the brain and spinal cord.  MOTOR DIVISION B. SOMATIC The SNS controls voluntary movements and transmits sensory and motor information to and from the CNS. It includes: 1. Sensory (Afferent) Neurons - Carry sensory information from receptors in the skin, muscles, and organs to the CNS.  MOTOR DIVISION B. SOMATIC The SNS controls voluntary movements and transmits sensory and motor information to and from the CNS. It includes: 2. Motor (Efferent) Neurons - Send signals from the CNS to skeletal muscles to facilitate voluntary movements.  MOTOR DIVISION FUNCTIONS OF THE SOMATIC NERVOUS SYSTEM 1. Voluntary Muscle Control 2. Reflex Arcs 3. Sensory Processing  CRANIAL NERVES The cranial nerves are a set of 12 paired nerves that emerge directly from the brain and brainstem, primarily responsible for transmitting information between the brain and parts of the head, neck, and upper body.  CRANIAL NERVES They play essential roles in sensory, motor, and autonomic functions, such as vision, smell, taste, hearing, facial sensation, and movement.  CRANIAL NERVES 1. Olfactory Nerve (CN I) Function: Sense of smell. Type: Sensory. Pathway: Transmits smell information from the nasal cavity to the brain.  CRANIAL NERVES 2. Optic Nerve (CN II) Function: Vision. Type: Sensory. Pathway: Carries visual information from the retina to the brain.  CRANIAL NERVES 3. Oculomotor Nerve (CN III) Function: Controls most of the eye's movements, pupil constriction, and eyelid elevation. Type: Motor. Pathway: Moves the eye up, down, and inward, and controls the size of the pupil and eyelid movement.  CRANIAL NERVES 4. Trochlear Nerve (CN IV) Function: Controls the superior oblique muscle, which rotates the eye downward and outward. Type: Motor Pathway: Assists in eye movement, especially downward gaze.  CRANIAL NERVES 5. Trigeminal Nerve (CN V) Function: Facial sensation and motor functions for chewing. Type: Mixed (Sensory and Motor). Pathway: Has three branches (ophthalmic, maxillary, mandibular) that relay sensory information from the face and control chewing muscles.  CRANIAL NERVES 6. Abducens Nerve (CN VI) Function: Controls the lateral rectus muscle, which moves the eye outward. Type: Motor Pathway: Enables outward movement of the eye (lateral gaze).  CRANIAL NERVES 7. Facial Nerve (CN VII) Function: Controls muscles of facial expression, taste on the front two-thirds of the tongue, and certain salivary and tear glands. Type: Mixed (Sensory and Motor). Pathway: Responsible for facial expressions, taste, and some autonomic functions.  CRANIAL NERVES 8. Vestibulocochlear Nerve (CN VIII) Function: Hearing and balance. Type: Sensory Pathway: Transmits sound and equilibrium information from the inner ear to the brain.  CRANIAL NERVES 9. Glossopharyngeal Nerve (CN IX) Function: Taste on the back third of the tongue, swallowing, and salivary gland function. Type: Mixed (Sensory and Motor) Pathway: Assists with taste, swallowing, and salivation.  CRANIAL NERVES 10. Vagus Nerve (CN X) Function: Controls muscles in the voice box, throat, and regulates functions of the heart, lungs, and digestive tract. Type: Mixed (Sensory and Motor). Pathway: Involved in autonomic control of the heart, lungs, and digestive organs, as well as some taste and sensory functions in the throat.  CRANIAL NERVES 11. Accessory Nerve (CN XI) Function: Controls muscles in the neck and shoulders. Type: Motor. Pathway: Supplies the sternocleidomastoid and trapezius muscles to enable head rotation and shoulder movement.  CRANIAL NERVES 12. Hypoglossal Nerve (CN XII) Function: Controls tongue movements for speech, chewing, and swallowing. Type: Motor. Pathway: Responsible for tongue muscle control.  CELLS OF THE NERVOUS SYSTEM  CELLS OF THE NERVOUS SYSTEM 1. NEURONS Also known as nerve cells Receive stimuli, conduct action potentials & transmits signals to other neurons or effector organs.  CELLS OF THE NERVOUS SYSTEM PARTS OF A NEURON 1. Cell Body (Soma) Contains the nucleus and other organelles. It’s responsible for maintaining the cell and processing information received from other neurons.  CELLS OF THE NERVOUS SYSTEM PARTS OF A NEURON 2. Dendrites Branch-like extensions from the cell body that receive signals from other neurons and convey them toward the cell body.  CELLS OF THE NERVOUS SYSTEM PARTS OF A NEURON 3. Myelin Sheath A fatty layer that covers the axon in segments, insulating it and helping to speed up electrical signal transmission.  CELLS OF THE NERVOUS SYSTEM PARTS OF A NEURON 3. Myelin Sheath It's formed by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system.  CELLS OF THE NERVOUS SYSTEM PARTS OF A NEURON 4. Nodes of Ranvier Gaps between sections of the myelin sheath where the axon membrane is exposed.  CELLS OF THE NERVOUS SYSTEM PARTS OF A NEURON 4. Nodes of Ranvier These gaps allow for the rapid "jumping" of signals, known as saltatory conduction, which speeds up nerve impulse transmission.  CELLS OF THE NERVOUS SYSTEM PARTS OF A NEURON 5. Axon Terminals (Synaptic Terminals or Boutons) Endings of the axon where the neuron connects with other cells at synapses. Neurotransmitters are released from here to send signals to the next neuron or effector cell. CELLS OF THE NERVOUS SYSTEM  CELLS OF THE NERVOUS SYSTEM TYPES OF NEURONS 1. Multipolar Neurons Have many dendrites and 1 single axon. Most the neurons are within CNS, nearly all motor neurons are multipolar.  CELLS OF THE NERVOUS SYSTEM TYPES OF NEURONS 2. Bipolar Neurons 1 dendrite & 1 axon. Located in some sensory organs like retina of the eye and nasal cavity  CELLS OF THE NERVOUS SYSTEM TYPES OF NEURONS 3. Pseudo-unipolar 1 process extends to the periphery & the other extends to the CNS. Two functions as a single axon, with small dendrite like sensory receptors at the periphery  CELLS OF THE NERVOUS SYSTEM 2. GLIAL CELLS Also known as neuroglia or simply glia, are non- neuronal cells in the nervous system that play essential supporting roles for neurons.  CELLS OF THE NERVOUS SYSTEM 2. GLIAL CELLS They are critical for maintaining homeostasis, providing support and protection, and facilitating communication within the nervous system.  CEREBROSPINAL FLUID Cerebrospinal fluid (CSF) circulation plays a vital role in supporting brain function and maintaining neurological health. CSF is a clear, colorless liquid that surrounds the brain and spinal cord, cushioning them and providing essential nutrients.  CEREBROSPINAL FLUID Produced mainly in the choroid plexus within the brain's ventricles, CSF flows through a carefully orchestrated pathway before being reabsorbed into the bloodstream.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 1. Protection and Cushioning CSF acts as a protective buffer, absorbing shocks and minimizing impact to the brain during head movements or injury.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 2. Nutrient Transport and Waste Removal CSF provides a medium for the exchange of nutrients and waste products between blood vessels and brain cells.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 2. Nutrient Transport and Waste Removal The brain’s metabolic activities generate waste products that must be efficiently cleared to maintain healthy function.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 2. Nutrient Transport and Waste Removal CSF circulation helps remove toxins and metabolic waste, such as beta-amyloid, which is implicated in Alzheimer’s disease if it accumulates abnormally.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 3. Regulation of Intracranial Pressure CSF circulation helps regulate intracranial pressure by maintaining an equilibrium between CSF production and absorption.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 3. Regulation of Intracranial Pressure Increased or decreased CSF levels can disrupt this balance, impacting brain function and causing symptoms like headache, nausea, and, in severe cases, impaired consciousness.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 3. Regulation of Intracranial Pressure Conditions like hydrocephalus arise when CSF builds up due to blockages or reabsorption issues, leading to elevated intracranial pressure and potentially damaging brain tissue.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 4. Immune Defense and Homeostasis CSF contains immune cells that help protect the brain against infections.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 4. Immune Defense and Homeostasis Its circulation assists in distributing immune cells throughout the central nervous system (CNS), allowing them to respond to infections or injury.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 4. Immune Defense and Homeostasis Furthermore, CSF helps maintain homeostasis in the CNS by regulating the brain’s extracellular environment, including pH and electrolyte balance, which is critical for proper neuronal function.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 5. Influence on Sleep and Brain Health Emerging research shows that CSF circulation is strongly linked to the glymphatic system, a waste clearance pathway that becomes more active during sleep.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 5. Influence on Sleep and Brain Health This system helps remove toxins from the brain, including proteins like tau and beta-amyloid, which accumulate in neurodegenerative diseases.  IMPORTANT FUCTION OF CEREBROSPINAL FLUID 5. Influence on Sleep and Brain Health During sleep, CSF flow increases, suggesting that sleep plays a crucial role in brain detoxification and maintaining cognitive health. PATHWAY OF CEREBROSPINAL FLUID FLOW  ACTION POTENTIAL: NERVOUS SYSTEM An action potential is a rapid and temporary electrical impulse that travels along the membrane of a neuron, allowing it to communicate with other neurons, muscles, or glands.  ACTION POTENTIAL: NERVOUS SYSTEM It is a fundamental process in the functioning of the nervous system, enabling the transmission of information over long distances within the body.  KEY PROCESSES DURING ACTION POTENTIAL 1. Resting Potential Neurons have a resting membrane potential of approximately -70 mV, maintained by the sodium- potassium pump and passive ion channels. The inside of the neuron is more negatively charged than outside.  KEY PROCESSES DURING ACTION POTENTIAL 2. Threshold When a neuron receives a strong enough stimulus, it reaches a threshold potential (typically around -55 mV). This triggers the action potential to begin.  KEY PROCESSES DURING ACTION POTENTIAL 3. Depolarization Voltage-gated sodium (Na⁺) channels open, allowing Na⁺ ions to rush into the cell. This causes the membrane potential to become more positive, rapidly shifting to around +30 mV.  KEY PROCESSES DURING ACTION POTENTIAL 4. Peak and Repolarization Once the membrane potential reaches its peak, the Na⁺ channels close, and voltage-gated potassium (K⁺) channels open. K⁺ ions move out of the cell, making the inside more  KEY PROCESSES DURING ACTION POTENTIAL 4. Peak and Repolarization Once the membrane potential reaches its peak, the Na⁺ channels close, and voltage-gated potassium (K⁺) channels open.  KEY PROCESSES DURING ACTION POTENTIAL 4. Peak and Repolarization K⁺ ions move out of the cell, making the inside more negative and bringing the membrane potential back down (repolarization).  KEY PROCESSES DURING ACTION POTENTIAL 5. Hyperpolarization Sometimes, the membrane potential temporarily becomes more negative than the resting potential, known as hyperpolarization, due to the K⁺ channels remaining open longer than necessary.  KEY PROCESSES DURING ACTION POTENTIAL 6. Refractory Period The neuron enters a refractory period, during which it cannot fire another action potential immediately. This period ensures that the action potential only travels in one direction along the axon.  KEY PROCESSES DURING ACTION POTENTIAL 7. Return to Resting Potential The sodium-potassium pump helps restore the original ion distribution, bringing the neuron back to its resting state.  IMPORTANCE OF ACTION POTENTIAL 1. Signal Transmission Action potentials allow neurons to send signals to other neurons or target tissues rapidly and efficiently.  IMPORTANCE OF ACTION POTENTIAL 2. All-or-Nothing Response An action potential is an all-or-nothing event— once the threshold is reached, the neuron will fire an action potential of consistent size and duration.  IMPORTANCE OF ACTION POTENTIAL 3. Propagation In myelinated neurons, action potentials travel faster through saltatory conduction, where the impulse jumps from one node of Ranvier to the next, increasing the speed of signal transmission.  SYNAPSE A synapse is the junction where communication occurs between two neurons or between a neuron and another type of cell, such as a muscle or gland cell.  SYNAPSE It is essential for transmitting signals throughout the nervous system and plays a key role in all aspects of brain function, including movement, thought, memory, and emotion.  TYPES OF SYNAPSE 1. Chemical Synapses The most common type in the brain, where a neuron releases neurotransmitters to communicate with the next cell.  TYPES OF SYNAPSE 2. Electrical Synapses Less common and involve direct electrical connections between neurons through structures called gap junctions, allowing the electrical current to pass directly from one cell to another  STRUCTURE OF A CHEMICAL SYNAPSE 1. Presynaptic Neuron The neuron that sends the signal. It contains synaptic vesicles filled with neurotransmitters.  STRUCTURE OF A CHEMICAL SYNAPSE 2. Synaptic Cleft The small space between the presynaptic and postsynaptic cells. 3. Postsynaptic Neuron The cell that receives the signal, which has receptors on its membrane to detect the neurotransmitters.  HOW CHEMICAL SYNAPSE WORKS 1. Action Potential Arrival An action potential reaches the axon terminal of the presynaptic neuron.  HOW CHEMICAL SYNAPSE WORKS 2. Neurotransmitter Release Voltage-gated calcium (Ca²⁺) channels open, allowing Ca²⁺ to enter the neuron. This influx triggers synaptic vesicles to fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.  HOW CHEMICAL SYNAPSE WORKS 3. Binding to Receptors The neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic membrane.  HOW CHEMICAL SYNAPSE WORKS 4. Postsynaptic Response Binding of neurotransmitters to receptors can result in an excitatory or inhibitory response in the postsynaptic neuron.  HOW CHEMICAL SYNAPSE WORKS 4. Postsynaptic Response Excitatory neurotransmitters (Ex: glutamate) can depolarize the postsynaptic membrane, potentially triggering an action potential, while inhibitory neurotransmitters (Ex: GABA) can hyperpolarize the membrane, making action potentials less likely.  HOW CHEMICAL SYNAPSE WORKS 5. Termination The neurotransmitter's action is terminated by reuptake into the presynaptic neuron, enzymatic breakdown, or diffusion away from the synapse.  IMPORTANCE OF SYNAPSES 1. Information Processing Synapses allow for complex processing and integration of signals in the brain, enabling learning, memory, and decision-making.  IMPORTANCE OF SYNAPSES 2. Neuroplasticity Synapses can strengthen or weaken over time in response to activity, a process known as synaptic plasticity. This underlies learning and the formation of memories.  IMPORTANCE OF SYNAPSES 3. Neurotransmitter Balance Proper functioning of synapses depends on the right balance of neurotransmitters. Imbalances can lead to neurological disorders such as depression, anxiety, and schizophrenia.  DISORDERS RELATED TO SYNAPTIC FUNCTION 1. Alzheimer’s Disease Associated with synaptic dysfunction and loss of synapses. 2. Parkinson’s Disease Involves reduced dopamine signaling at synapses. 3. Epilepsy Characterized by abnormal electrical activity that can result from synaptic malfunction.  THANK YOU FOR LISTENING!