Human Nervous System PDF

HUMAN NERVOUS SYSTEM Neurons Neurons Neurons are the nerve cells of the central nervous system that transmit information through electrochemical signals throughout the body. Neurons contain a soma, a cell body from which the axon extends. Axons are nerve fibers that are the longest part of t...

HUMAN NERVOUS SYSTEM Neurons Neurons Neurons are the nerve cells of the central nervous system that transmit information through electrochemical signals throughout the body. Neurons contain a soma, a cell body from which the axon extends. Axons are nerve fibers that are the longest part of the neuron, which conduct electrical impulses away from the soma. There are dendrites at the end of the neuron, which are branch-like structures that send and receive information from other neurons. A myelin sheath, a fatty insulating layer, forms around the axon, allowing nerve impulses to travel down the axon quickly. There are different types of neurons. Sensory neurons transmit sensory information, motor neurons transmit motor information, and relay neurons allow sensory and motor neurons to communicate. Neurons Neurons The communication between neurons is called synapses. Neurons communicate with each other via synaptic clefts, which are gaps between the endings of neurons. During synaptic transmission, chemicals, such as neurotransmitters, are released from the endings of the previous neuron (also known as the presynaptic neuron). These chemicals enter the synaptic cleft to then be transported to receptors on the next neuron (also known as the postsynaptic neuron). Once transported to the next neuron, the chemical messengers continue traveling down neurons to influence many functions, such as behavior and movement. Brain Parts The brain is composed of the cerebrum, cerebellum, and brainstem Cerebrum The cerebrum is the largest and most recognizable part of the brain. It consists of grey matter (the cerebral cortex ) and white matter at the center. The cerebrum is divided into two hemispheres, the left and right, and contains the lobes of the brain (frontal, temporal, parietal, and occipital lobes). The cerebrum produces higher functioning roles such as thinking, learning, memory, language, emotion, movement, and perception. Cerebrum Right Brain vs. Left Brain The cerebrum is divided into two halves: the right and left hemispheres. The left hemisphere controls the right half of the body, and the right hemisphere controls the left half. The two hemispheres are connected by a thick band of neural fibers known as the corpus callosum, consisting of about 200 million axons. The corpus callosum allows the two hemispheres to communicate and allows information being processed on one side of the brain to be shared with the other. Left and Right Brain Brain Hemisphere Hemispheric lateralization is the idea that each hemisphere is responsible for different functions. Each of these functions is localized to either the right or left side. The left hemisphere is associated with language functions, such as formulating grammar and vocabulary and containing different language centers (Broca’s and Wernicke’s area). The right hemisphere is associated with more visuospatial functions such as visualization, depth perception, and spatial navigation. These left and right functions are the case in most people, especially those who are right-handed. Lobes of the Brain Frontal lobes The frontal lobes are located at the front of the brain, behind the forehead Their main functions are associated with higher cognitive functions, including problem-solving, decision-making, attention, intelligence, and voluntary behaviors. The frontal lobes contain the motor cortex responsible for planning and coordinating movements. It also contains the prefrontal cortex, which is responsible for initiating higher- lever cognitive functioning, and Broca’s Area, which is essential for language production. The frontal lobe is the anterior (front) part of the brain that is located right behind the forehead inside the skull. There are two frontal lobes: one on the right side of the brain and one on the left side. What Happens When the Frontal Lobe Is Damaged? Frontal lobe damage results in drastic behavioral and personality changes as well. Damage to the frontal lobes can affect one or several of their functions and may be permanent or transient, depending on the cause. Any injury, stroke, infection, tumor, or neurodegenerative disease that affects the brain can affect the frontal lobe too, damaging it. Treatment varies depending on the cause of the damage and involves a team of various healthcare professionals. What are the functions of the frontal lobe? The frontal lobe is responsible for the following functions: Voluntary movements of the body Complex sequence or multistep movements, such as wearing clothes or making toast Speech and language Concentration Memory Motivation Reasoning skills Inhibitions and judgments Planning and problem solving Regulation of mood and emotions Expression of emotions and personality Management of social behavior What happens when the frontal lobe is damaged? Some common symptoms of frontal lobe damage can include: Paralysis (partial or complete loss of movement) Difficulty in performing tasks that require several steps or sequence of movements such as dressing up or making coffee Speech and language difficulty Inability to concentrate Poor planning and problem-solving skills Poor judgment Loss of inhibition or impulse control Inability to control mood and emotions Changes in personality and behavior Inappropriate social behavior Irritability Decreased motivation Inability to function normally in school or at work What can cause damage to the frontal lobe? There are several factors that can cause damage to the frontal lobe: Trauma to the frontal lobe of the brain Stroke Infection of the brain involving the frontal lobe Tumors of the frontal lobe Multiple sclerosis Alzheimer’s disease Parkinson’s disease Iatrogenesis (injury to the frontal lobe during surgery) Things to know about multiple sclerosis (MS) Multiple sclerosis (MS) is a disease that causes demyelination (disruption of the myelin that insulates and protects nerve cells) of spinal nerve and brain cells. The exact cause is unknown, it's considered an autoimmune disease. Risk factors for the disease include being between 15-60 years of age; women have about two to three times the risk for multiple sclerosis than men. Rarely, do MS in children and teens (pediatric MS) get MS. Symptoms, causes, and treatments for MS in children and teens are similar to those for adults, except children and teens may also have seizures and/or mental status changes. Things to know about multiple sclerosis (MS) Multiple sclerosis symptoms and signs depend on where the nerves are demyelinated and may include: Visual changes including double vision or loss of vision Numbness Tingling or weakness (weakness may range from mild to severe) Paralysis Vertigo or dizziness Erectile dysfunction (ED, impotence) Pregnancy problems Incontinence (or conversely, urinary retention) Muscle spasticity Incoordination of muscles Tremor Painful involuntary muscle contractions Slurred speech Fatigue TYPES OF MS There are four types of MS: Relapsing-remitting multiple sclerosis (RRMS), Secondary-progressive multiple sclerosis (SPMS), the most common type Primary-progressive multiple sclerosis (SPMS) Progressive-relapsing multiple sclerosis (PRMS) How is frontal lobe damage treated? Treatment of frontal lobe damage varies based on the cause. Some factors may cause permanent frontal lobe damage, and the treatment mainly involves rehabilitation therapies to learn new coping mechanisms. The treatment plan usually includes a team of several different healthcare professionals. Treatment options include: Physical therapy: To maintain or regain mobility, muscle strength, and flexibility Occupational therapy: To learn new skills and perform daily tasks and activities more easily Vocational counseling: To help return to work or studies Speech-language therapy: To improve communication How is frontal lobe damage treated? Cognitive therapy: To learn skills to help improve memory, planning, and judgment Psychological therapy: To help improve relationships and manage emotions and mood swings Surgery: Surgery may be advised in cases of a trauma or brain tumor involving the frontal lobe Medications: Medications may be prescribed in case of infections or neurodegenerative diseases such as Parkinson’s References Purves, D., Augustine, G., Fitzpatrick, D., Katz, L., LaMantia, A., McNamara, J., & Williams, S. (2001). Neuroscience 2nd edition. sunderland (ma) sinauer associates. Types of Eye Movements and Their Functions. Mayfield Brain and Spine (n.d.). Anatomy of the Brain. Retrieved July 28, 2021, from: https://mayfieldclinic.com/pe-anatbrain.htm Robertson, S. (2018, August 23). What is Grey Matter? News Medical Life Sciences. https://www.news-medical.net/health/What-is- Grey-Matter.aspx Guy-Evans, O. (2021, April 13). Temporal lobe: definition, functions, and location. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/temporal-lobe.html Guy-Evans, O. (2021, April 15). Parietal lobe: definition, functions, and location. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/parietal-lobe.htm Guy-Evans, O. (2021, April 19). Occipital lobe: definition, functions, and location. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/occipital-lobe.htmll Guy-Evans, O. (2021, May 08). Frontal lobe function, location in brain, damage, more. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/frontal-lobe.html Guy-Evans, O. (2021, June 09). Gyri and sulci of the brain. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/gyri-and- sulci-of-the-brain.html