Station 9 : THE SPINAL CORD The spinal cord is a long thin bundle of nerve cells that extends from the medulla of the brainstem all the way down the vertebral column. The spinal cord is made up of gray matter and white matter. Gray matter is made up of nerve cell bodies, and white matter is made up of axons. CROSS SECTION OF SPINAL CORD SPINAL CORD (SHOWN IN YELLOW) The gray matter looks like a butterfly, the white matter is found in the space that surrounds it. The spinal cord connects the sensory neurons of the peripheral nervous system to the brain.. The vertebral column protects the spinal cord.
Station 10 : BRANCHES OF NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM Relays messages, processes info, analyzes data. Involves the brain and spinal cord. PERIPHERAL NERVOUS SYSTEM Receives information from the environment and relays commands from CNS to organs and glands Motor Division Transmits impulses from CNS to muscles and glands Sensory Division Transmits impulses from sense organs to the CNS Somatic Regulates activities under conscious control ex) movement of skeletal muscles Parasympathetic Autonomic Regulates involuntary activities ex) heartbeat, smooth muscle contractions Sympathetic Controls organs at rest Controls organs in stress
Station 11 : CENTRAL NERVOUS SYSTEM The central nervous system (CNS) consists of the brain and spinal cord. The CNS is like the headquarters of the nervous system. Functions of the CNS: Interpret information received from all parts of the body Coordinate and influence all parts of the body. The central nervous system is protected by the cranium and vertebral column.
Station 12 : THE PERIPHERAL NERVOUS SYSTEM The Peripheral Nervous System (PNS) consists of all the nerves that are located outside the brain and spinal cord. (Peripheral meaning outside or surrounding.) The function of the PNS is to connect the central nervous system to the limbs and organs. THE PERIPHERAL NERVOUS SYSTEM IS BRANCHED: MOTOR DIVISION: SOMATIC Voluntary control that communicates with skeletal muscle. SENSORY DIVISION: AUTOMATIC Involuntary control that communicates with cardiac muscle and smooth muscle.
Station 13 : BRAIN SURGEONS AND NEUROSCIENCE Neuroscience is the study of the brain and nervous system. Brain surgeons are known in the medical field as neurosurgeons. They perform surgeon on not only the brain, but the spinal cord and nerves as well. Neurosurgeons may be responsible for repairing blood vessels in the spine or brain, responding to trauma, operating on tumors, or treating infections. The average yearly salary for a neurosurgeon is $360,000 Neurosurgeons must complete a 4 year undergraduate degree Followed by 4 years of medical school. Followed by 7 years of residency under the guidance of an experienced neurosurgeon.
Station 14 : NEURONS Nerves are cable- like bundles of axons that communicates the brain to the rest of the body. Nerves are made up of neurons, which are the cells of the nervous system. DENDRITES NEURON AXON TERMINAL SOMA NODE OF RANVIER AXON SCHWANN CELL NUCLEUS MYELIN SHEATH Neurons are the core of the nervous system. They can transit chemical and electrical information in order to communicate. There are three categories of neurons: 1. Sensory neurons- carry impulses from the sensory organs to the spinal cord and brain. 2. Motor neurons- carry impulses from spinal cord and brain to muscles and glands. 3. Interneurons- carry impulses between sensory and motor neurons.
Station 14 : NEURONS CONTINUED DENDRITES AXON TERMINAL SOMA NODE OF RANVIER AXON SCHWANN CELL NUCLEUS MYELIN SHEATH The nodes of Ranvier are gaps in the myelin sheath that were discovered by French pathologist Louis Antoine Ranvier Schwann cells are named after Theodore Schwann. They are the main glial cells of the peripheral nervous system. They help maintain homeostasis and produce the myelin sheath. The soma is the scientific term for the cell body, which contains the nucleus. Dendrites are projections of the cell body that can receive electrical stimulation from other neurons via synapses. The myelin sheath acts as in insulator which helps speed up the rate of impulses.
Station 15 : GLIAL CELLS Glial cells are helpers of neural cells. Functions of glial cells: 1. To surround neurons and help hold them in place. 2. To supply nutrients and oxygen to neurons. 3. To insulate neurons so that they are not directly touching. 4. To remove dead neurons and destroy foreign invaders. The function depends on the type of glial cells.
Station 15 : GLIAL CELLS CONTINUED Glial cells were discovered by Rudolf Virchow in 1856. R The size and number of glial cells are directly proportional to intelligence. Albert Einstein had significantly more glial cells in the area of the brain related to mathematical language processing. Glial cells shown in red and blue. Neuron in gold. Astrocytes are glial cells that help with blood flow to the neurons. Oligodendrocytes help produce myelin sheath.
Station 16 : NEURON COMMUNICATION DENDRITES AXON TERMINAL SOMA NODE OF RANVIER AXON SCHWANN CELL NUCLEUS MYELIN SHEATH HOW DO NEURONS COMMUNICATE? The dendrites pick up electrochemical signals from other neurons. The signal travels down the axon to the axon terminal, where NEUROTRANSMITTERS are released. The electrochemical signals between each neuron occur within SYNAPSES, which are specialized connections between the neurons.
Station 17 : NEUROTRANSMITTERS NEUROTRANSMITTERSare brain chemicals that communicate information throughout our brain and body. They relay signals between neurons. The brain uses neurotransmitters for Involuntary actions, such as your heart beating, breathing, digesting, releasing adrenaline Voluntary movements Regulating your mood and sleep cycle Enforcing positive and negative behavior NEUROTRANSMITTERS CAN BE EXCITATORY Excitatory neurotransmitters are chemicals that simulate the brain INHIBITORY Inhibitory neurotransmitters are chemicals that calm the brain. EXAMPLES: Dopamine Norepinephrine Epinephrine Adrenaline EXAMPLES: Dopamine Serotonin Gaba. DOPAMINE HELPS US FOCUS, WHICH CAN BE EXCITATORY OR INHIBITORY. THOSE WITH ADHD MAY TAKE MEDICATION THAT HELPS STIMULATE PRODUCTION OF DOPAMINE.
Station 17 : NEUROTRANSMITTERS CONTINUED Neurotransmitters are communicated from neuron to neuron. They are released through the axon terminal of one neuron and attached to receptors on the dendrite of another neuron. The neurotransmitters are simply messengers. They can deliver messages from the brain to other body parts and vice versa. The message depends on which type of neurotransmitter it is. For example, adrenaline usually means fight or flight.
Station 18 : NERVE IMPLUSE A NERVE IMPULSE is an electrical transmission across neurons. DIRECTION OF NERVE IMPULSE Nerve impulses travel from AWAY from the cell body towards the axons. Nerve impulses begin when a neuron is stimulated by another neuron or its environment. Threshold- the minimum level of stimulus that must be reached in order for an impulse to occur. All impulses are the same strength. If the stimulus reaches the threshold, there will be an impulse. If it is not enough, it will not reach the threshold and nothing will happen. This is called the ALL OR NOTHING rule. The all or nothing rule is like playing dominoes. As long as you push on the domino just enough, they will fall. However, if you don t push enough, they will not move.
Station 19 : MEMBRANE POTENTIAL Neurotransmitters communicate electrochemically. An ion is an element or molecule that has a charge (+) or (- ). Neurotransmitters use ions of sodium (+), potassium (+), calcium (++) and chloride (- ) Ions travel through the semi- permeable membrane of neurons. When an neuron is not sending a signal it is at rest and its membrane is said to be at resting potential. When a neuron is sending a message, it is in action and its membrane is said to be in action potential. RESTING POTENTIAL ACTION POTENTIAL Inside of neuron is negative compared to the outside. Inside of neuron is positive compared to the outside. - Average neuron has resting potential of - 70mV (equivalent to 1/20 of flashlight battery).
Station 20 : RESTING POTENTIAL Opposite charges cancel each other out. For example, all the salt molecules you see (NaCl) do NOT have a charge. NO CHARGE! SODIUM Na+ POTASSIUM K+ CHLORINE Cl- PROTEIN (negatively charged) The word POTENTIAL stems from the fact that there is a difference of charge across the membrane. The outside of the membrane has more positively charged sodium ions, which gives the outside a more positive charge than the inside. Resting potential- difference in electrical charge across a cell membrane - Potassium ions (K+) diffuse out of a cell more easily than sodium ions (Na+) can diffuse in. Result= negative charge inside the neuron relative to the outside. Resting potential is created!
Station 21 : ACTION POTENTIAL A stimulus causes sodium ions to flow through the cell membrane into the neuron. When the charges on either side of the neuron membrane are switched, the term we use describe this is reversed polarity). When the polarity is reversed, the inside of the neuron is now positive relative to the outside. This sudden change in polarity generates electricity to fire nerve impulses. We call this action potential. Action potential is important because our neurons cannot communicate without this process! SODIUM Na+ POTASSIUM K+ CHLORINE Cl- PROTEIN (negatively charged) Special gates that allow sodium through the cell membrane are generally closed. A stimulus from the environment or another neuron causes these gates to open. This allows sodium to pass through the membrane, which leads to action potential.
Station 22 : INTERESTING FACTS A neuron can impulse once every 5 milliseconds (or in other words, 200 times per second!) The human brain contains approximately 100 billion neurons. The sciatic nerve is the biggest in the human body. It extends from the spinal cord down the thighs and all the way into the feet. Worms have the simplest type of nervous system. Some primitive animals, such as sponges, do not have nervous systems. Neurons are the largest type of cell in the human body (though they are still microscopic). Most neurons in the body do not regenerate. Neurons are generated from stemmed cells that can also grow to become glial cells. Nerve impulses can travel up to 320 mph. If your hand touches a hot stove, sensory neurons on the skin will the brain a message. Your brain will send a message back to your skeletal muscles telling them to move your hand off the stove. This whole process takes about 1/10 th of a second.