Functions of the Nervous System

1. 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

2. 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))

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

4. 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 (________ __________)

5. 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

6. 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.

7. 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 ________ ___ __________.

8. 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

9. 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

10. Neuroglia 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

11. Neuroglia 6. __________________ • 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 _______ ___ _________

12. 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

13. 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 ____________________

14. 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

15. 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:

16. 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

17. 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 ____________

18. 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

19. 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

20. 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

21. 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.

22. 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.

23. 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)

24. 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.