The Nervous System The Basic Functions of the

The Nervous System

The Basic Functions of the Nervous System • Sensation – The ability of the nerves to detect stimuli, such as pressure, temperature changes, taste, smell or light, and send a message in the form of impulses to the brain and spinal cord. – Example: touching a hot stove, tasting something sweet

Movement • The ability of the brain to send impulses to muscles to cause movement, or a change in position. • Example: bending your knee, scratching your nose

Coordination • The nervous system controls and coordinates functions throughout the body and responds to internal and external stimuli. • Example: walking, running, swimming

The Basic Structures of the Nervous System

The Brain • The brain contains approximately 100 billion neurons. The brain weighs about 3 pounds. About 20% of blood leaving the heart circulates through the brain. • The brain is responsible for analyzing information, processing information and relaying messages to the rest of the body. It is the main control center of the body. • Along with the spinal cord, it forms the body’s Central Nervous System or CNS.

Brain Structure Two hemispheres joined by the corpus callosum Sulcus= grooves (valleys) Gyrus = bumps (mountains) Ventricles = spaces for CSF

The Spinal Cord • Along with the brain, it is part of the Central Nervous System. • It is the major communication link between the brain and the rest of the body. • It can process many reflexes – unconscious, automatic responses to stimuli.

There are 31 pairs of spinal nerves which branch from the spinal cord to control such processes as breathing, arm movement, and leg movement.

Spinal Column Cross Section Spinal Cord is protected by the vertebrae The Spinal Cord is made up of gray matter and white matter

Cerebrospinal Fluid • CSF is a clear, watery fluid which bathes the brain and the spinal cord to protect it by acting as a shock absorber. • CSF allows for the exchange of nutrients and waste products between the blood and the nervous tissue. • CSF circulates between the two layers of the meninges, through the center of the spinal cord, and through large openings in the brain (ventricles).

Meninges • A set of three layers of connective tissue that enclose the brain and spinal cord. They are located under the skull and attach directly to the brain. • Meninges help to provide a small amount of protection to the brain and spinal cord. • Cerebrospinal fluid circulates between two layers of the meninges.

Dura Mater = “tough mother”; outermost layer Pia Mater= inner most layer; follows the sulci and gyri Arachnoid Mater = middle layer; resembles a spider web

Nerves • Nerves (neurons) are the basic units of structure and function for the nervous system. • Nerves are capable of sending electrical messages called impulses.

Types of Nerves • Sensory nerves which detect changes and carry impulses to the brain and spinal cord from the sense organs. • Interneurons which are located between sensory and motor nerves and carry impulses between those nerves. • Motor nerves which detect changes and carry impulses away from the brain and spinal cord to muscles.

Neuron Structure Axon – part of the neuron that sends impulses away from the cell body Body – main portion of the nerve cell Dendrites – part of the neuron that conducts the impulse to the cell body Synapse – area where the impulse is passed from one neuron to another Myelin Sheath – the electrically insulating layer around the axon Nodes of Ranvier – gaps between the myelin sheath

Brain Structures and Functions • Cerebrum – The cerebrum is the largest part of the brain. It has two distinct halves called hemispheres. They are connected by a band of tissue called the corpus callosum. The cerebrum has man folds and grooves on the brain hemisphere to increase the number of nerves found in the brain.

The cerebrum is divided into four lobes. • Frontal Lobe – The frontal lobe controls skeletal muscle movement, interprets the sense of smell, is responsible for our personalities, and our ability to learn, think, problem solve and concentrate. • Parietal Lobe – The parietal lobe interprets many of our senses including taste, touch, temperature, and pain.

• Occipital Lobe – The occipital lobe interprets the sense of sight. • Temporal Lobe – The temporal lobe interprets the senses of balance and hearing. It also contains structures (such as the hippocampus) which store memory.

Cerebellum • The cerebellum is the second largest part of the brain. In fact, cerebellum means the “little cerebrum. ” It is located at the back of the head below the cerebrum. • It functions to coordinate the muscular movements and helps the muscles move gracefully and efficiently. It also helps with the body’s ability to balance.

Brainstem • The brain stem is located below the cerebellum and connects the spinal cord to the brain. • The brain stem is composed of two structures – the medulla oblongata and the pons. • The medulla oblongata is continuous with the spinal cord and helps to regulate the heart beat, blood pressure, breathing, swallowing, hiccupping, and vomiting. It also relays nerve impulses between the brain and the spinal cord. • The pons is a small bulge above the medulla oblongata. It is important to help us regulate the rate and depth of breathing.

Diseases/Disorders of the Nervous System • Meningitis – Meningitis is an infection that causes the inflammation of the brain and spinal cord coverings.

Epilepsy • Epilepsy is a brain disorder involving repeated seizures of any kind. Seizures are episodes of disturbed brain function that cause changes in attention or behavior.

Traumatic Brain Injury • A brain injury is any trauma that leads to injury of the scalp, skull, or brain. The injuries can be minor or major. A closed injury means that you have received a hard blow to the head an open injury means that the skull has been broken and the brain is exposed. There are several millions of head injuries annually.

Headache • A headache is pain or discomfort in the head, scalp, or neck. • Most people can find relief from headache by making lifestyle changes, learning to control stress, and occasionally, by the use of medications. • There are several types of headaches including tension headaches and migraines

Stroke • Stroke, also known as a CVA or cerebrovascular accident, occurs when there is an interruption of the blood supply to any part of the brain.

Careers Associated With the Nervous System • Occupational Therapist – Occupational therapists (OTs) help people improve their ability to perform tasks in their daily living and working environments. They work with individuals who have conditions that are mentally, physically, developmentally, or emotionally disabling. They also help them to develop, recover, or maintain daily living and work skills

Occupational Therapist Assistant • Occupational therapist assistants and aides work under the direction of occupational therapists to provide rehabilitative services to persons with mental, physical, emotional, or developmental impairments. The ultimate goal is to improve clients’ quality of life and ability to perform daily activities

Toxicologist • Toxicologists plan and carry out laboratory and field studies to identify, monitor and evaluate the impact of toxic materials and radiation on human and animal health, and on the health and current status of the environment, as well as the impact of future technology

Pharmacist • Pharmacists give medicine to people when a doctor says that they need it. They tell people how to use the medicine correctly. Pharmacists are experts in medicine and its side effects. They sometimes help doctors choose which medicines to give patients. Pharmacists also warn doctors if the doctors have asked their patients to take any medicine that might hurt their patients. Sometimes, pharmacists mix the medicine themselves

Pharmacy Technician • Pharmacy technicians help licensed pharmacists provide medication and other health care products to patients. Technicians usually perform routine tasks to help prepare prescribed medication for patients, such as counting tablets and labeling bottles. Technicians refer any questions regarding prescriptions, drug information, or health matters to a pharmacist.

Social Worker • Social work is a profession for those with a strong desire to help improve people’s lives. Social workers help people function the best way they can in their environment, deal with their relationships, and solve personal and family problems. Social workers often see clients who face a life-threatening disease or a social problem, such as inadequate housing, unemployment, a serious illness, a disability, or substance abuse. Social workers also assist families that have serious domestic conflicts.

Psychologist • Psychologists study the human mind and human behavior. Research psychologists investigate the physical, cognitive, emotional, or social aspects of human behavior. Psychologists in health service provider fields provide mental health care in hospitals, clinics, schools, or private settings.