Functions of the Nervous System A network of _______ of nerve cells linked together in a highly organized fashion to form the rapid ______ center of the body. Functions include: Integrating center for __________, movement, and almost all other body ___________. The mysterious source of those traits that we think of as setting humans apart from animals

Basic Functions of the Nervous System Sensation Monitors changes/events occurring in and outside the body. Such changes are known as _________and the cells that monitor them are ___________. ________________ The parallel processing and interpretation of sensory information to determine the appropriate response Reaction Motor output. The activation of muscles or glands (typically via the release of _______________________ (NTs))

Nervous Tissue Highly Cellular Two types: ____________ Functional, signal conducting cells Supporting cells

Neurons The functional and structural unit of the ____________ system Specialized to ___________ information from one part of the body to another Most contain the following: Cell body (__________) One or more specialized, slender processes (_______________) An input region (______________) A conducting component (________) A secretory (output) region (________ __________)

Neurons ___________ _______________ Contains __________ plus most normal organelles Responsible for producing _________ and secreations needed for communication _______________ Thin, branched processes whose main function is to receive incoming _______. increase the surface area of a neuron to increase its ability to communicate with other neurons

Neurons ___________ Most neurons have a _______ axon a long (up to 1m) process designed to convey info away from the cell body Originates from a special region of the cell body called the ______ ________ Transmit signals from the soma toward the end of the axon where they cause neurotransmitter release Often branch sparsely, forming ________________. Each collateral ends in a ________ ________, which contains _______ _____________ – membranous bags of neurotransmitters.

Axons Surrounded by a ____________ _____________, a wrapping of lipid which: Protects the axon and electrically isolates it ________________ the rate of signal transmission The myelin sheath is made by ________________ for nerves found in the brain and spinal cord and by ___________ ________ for nerves found outside brain and spinal cord This wrapping is never complete. Interspersed along the axon are gaps where there is no myelin – these are ________ ___ __________.

Neuroglia Outnumber neurons by about ________ to 1 6 types of supporting cells 1. ________________ Star-shaped, abundant, and versatile Maintain the chemical _____________ of neurons (i.e. K+) Involved in the formation of the blood brain barrier Control the types of materials that pass from blood to neurons

Neuroglia _____________ ___________________ Specialized immune cells Carries out ________________ Repairs nerve cell damage Basis of many nervous system disorders ___________________ Line the cavities of the brain and spinal cord Produces _______________ fluid (bathes, nourishes and protects) Have cilia to help circulate cerebrospinal fluid

Neuroglia 4. _____________________ 5. _________________ 4. _____________________ Form an insulating cover called the _________ _________ for neurons found in the brain and spinal cord Helps the transmission of stimuli along the axon 5. _________________ Found in the ______________ nervous system Provides a framework for neurons to create connections

Neuroglia 6. __________________ 7. _________________ Small cells that cover the surface of neurons of the brain and spinal cord Maintain _________ environment and assist in nerve cell repair 7. _________________ Form __________ _________ around nerves located outside of the brain and spinal cord Gaps between Schwann cells are called _______ ___ _________

Communication Begins with the _____________ of a neuron. One neuron may be stimulated by another, by a __________ cell, or even by some physical event such as pressure. Different types neurons include: Sensory neurons (________)- provide info about internal and external environment Association neurons (_________)- integrate information and send commands Motor neurons (____________)- synapse with muscles or glands

Communication Thus, neurons need to be able to conduct information in 2 ways: From one end of a neuron to the other end. - Accomplished with __________ using action potentials Across the minute space (_________) separating one neuron from another. - Accomplished using chemicals via ____________________

Resting Potential Chemically unstable condition in which the neuron is highly polarized (charge inside the cell is __________ millivolts) This is due to the Na+/K- pump which keeps a higher concentration of sodium ions __________ of the cell than on the __________ of the cell Changes in mV allow for the generation of ________ potentials and thus informative intercellular communication

Action Potential Is a chain reaction that causes the neuron to lose its ___________ potential It is the _____________ signal that rapidly travels the along the axon Its started by an influx of ________ ions into the neuron The action potential takes place as follows:

Action Potential __________ receive stimulus causing the sodium channels to open and allowing Na+ to rapidly enter cell. If enough channels open the cytoplasm's charge will reach __________ mV The cell now reaches its _____________ A threshold must be obtained for the action potential to travel (___________) across the cell membrane

Action Potential 2. At threshold, many more Na+ channels open causing the charge of the cytoplasm to ______ mV. The cell is now in ___________ (has lost its resting potential -70mV) 3. Depolarization continues down length of axon producing AP propagation down the axon to the ____________

Action Potential 4. Sodium channels close/___________ channels to leave the cell open causing positive charges Loss of positive charges inside causes cell to become more negatively charged which is called ____________ 5. ______________________ is the event where repolarization goes beyond the resting potential to a charge of ________mV and has 2 purposes: 1. __________ ______________- prevents the neuron from receiving another stimulus during repolariazation 2. Prevents AP from traveling in the opposite direction

Action Potential 6. ___________ phase- Na+/K- pumps work to return cell to _________ potential by pumping out Na+ and in K- 7. The cell will remain in the refractory period and cannot ____________ with another cell until recovery phase is complete

Action Potential Conduction The manner and speed in which it travels depends on whether the neuron is ____________ or __________. Unmylinated axons Slow (5 to _______ m/sec) The wave of de- and repolarization simply travels from one patch of membrane to the next adjacent patch. (like falling ___________) Mylinated axons Fast (10 to _______ m/sec) Depolarization occurs only in the _________ (nodes of Ranvier) which decreases the total area of membrane that depolarized AP __________ from node to node

Chemical Signals One neuron will transmit info to another neuron or to a -_________ or gland cell by releasing chemicals called ________________. The site of this chemical interplay is known as the ______________. An axon terminal (_________ _________) will abut another cell, a neuron, muscle fiber, or gland cell. This is the site of _______________ – the conversion of an electrical signal into a chemical signal.

Synaptic Transmission An AP reaches the axon terminal of the ____________ cell and causes Voltage-gated _______ channels to open. Ca2+ rushes in, binds to regulatory proteins & initiates NT ____________. NTs diffuse across the synaptic cleft and then bind to receptors on the ______________ membrane and initiate some sort of response on the postsynaptic cell.

Effects of Neurotransmitters Different neurons can contain different ________________ Different postsynaptic cells may contain different _______________ There are two types of neurotransmitters: ___________- helps the post-synaptic cell reach threshold, making it more likely to produce an AP (i.e. catecholamines, acetylcholine) _____________- make it more difficult for a neuron to produce an action potential (i.e. serotonin)

Reflexes A ________ is a rapid, predictable motor response to a stimulus. Unlearned and _____________. Reflexes involving skeletal muscles and somatic motor neurons are _________. (i.e. knee-jerk, balance, ducking) Reflexes controlled by autonomic neurons are ____________. (i.e. urinating, vomiting, sneezing, breathing) Spinal reflexes are integrated within the spinal cord while cranial reflexes are integrated in the brain. Reflexes may be inborn or learned.