1. Nervous System

2. Mosby items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. The nervous system is the communication and control system of an animal’s body. Composed of two main divisions: ____________ Nervous System (CNS) Composed of brain and spinal cord _______________ Nervous System (PNS) Consist of nerves that come off of the CNS and innervate rest of body Function of nervous system activities: _____________ (sense changes within or outside the body and sends it to the spinal cord and brain) _____________ (brain and spinal cord receive, analyze, store, and integrate the info to produce a response) _____________ (an instruction of the body to do something) Introduction

3. Mosby items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Neuron: basic functional units of nervous system High requirement for ____________. Brain must always have O 2 supply Cannot ___________ but can _____________ cell processes if the cell body remains intact Neuroglia (glial cells; these are not neurons): provide structural and functional support and protection to neurons

4. Neuron Soma/Perikaryon Central cell body Cell processes _____________ – receive stimuli/impulses from other neurons and transmit information_____soma. Can also be sensory receptors for heat, cold, touch, pressure, stretch or other physical changes inside or outside the body Short and branched ________ - conducts nerve impulses _______ from soma towards another neuron or an effector cell (muscle, gland) Long, single process

5. Myelin Axons are often covered in myelin (fatty/protein substance) Nervous tissue containing myelinated axons is called ___________ matter. Myelin sheath: cell membrane of glial cells tightly wrapped around the axon _____________________ in the brain and spinal cord ____________ ______ in the nerves outside the brain and spinal cord Myelinated axons conduct impulses faster than unmyelinated ones

6. Nodes of Ranvier Multiple Schwann cells or oligodendrocytes cover the entire length of the axon _____________________: gaps in the myelin sheath between adjacent glial cells Myelin sheath and nodes of Ranvier work together to enhance the ___________ of conduction of nerve impulses along the axon.

7. Organization of Nervous System 1. Anatomical _________ nervous system (CNS) Brain and spinal cord ___________ nervous system (PNS) Extends outward from the central axis toward the periphery of the body Cranial nerves originate directly from the brain Spinal nerves emerge from the spinal cord

8. Organization of Nervous System 2. Direction of Impulses _____________ nerves - conduct impulses TOWARD CNS a.k.a. sensory nerves - conduct sensations from sensory receptors in skin and other locations to CNS ______________ nerves - conduct impulses AWAY from CNS a.k.a. motor nerves - cause skeletal muscle contraction/movement Some nerve fibers are sensory (optic), motor (oculomotor), or both (glossopharyngeal)

9. Organization of Nervous System 3. Function: Autonomic vs. Somatic _________________ nervous system - actions under conscious, or voluntary, control Motor nerves lead to skeletal muscle and cause limb or body movement Example: turning your head when your name is called _________________ nervous system - controls and coordinates automatic functions Motor nerves lead to smooth muscle, cardiac muscle, and glands Example: slowing of the heart rate in response to an increased blood pressure, stomach releasing HCl when food is present ______________________ Division (fight or flight) ______________________ Division (feed or breed)

10. Neuron Function: DEPOLARIZATION AND REPOLARIZATION Resting __________ - when neuron is not stimulated But, it’s still working to maintain a resting state (Na/K pump) Resting __________ ____________- difference in electrical charge across neuronal membrane Due to differences in distribution of positive and negative charges from sodium, potassium, proteins, and other charged ions on either side of neuronal membrane Inside of the neuron ends up having a more negative charge than the outside Resting membrane potential is a negative number (-70 mV), indicating the negative charge inside the cell The Na/K pump maintains a negatively charges resting membrane potential

11. Neuron Function Na + /K + pump: specialized molecules located in the neuron’s cell membrane that maintains cell resting state. Pumps ____ (Na + ) out of neuron Pumps ____(K + ) into neuron Cell membrane becomes ________________

12. Depolarization STEPS: Neuron receives external stimulus ______ channel opens on cell membrane Na + flow into cell by passive _____________ Down the concentration gradient Electrical gradient (opposites attract)

13. Depolarization STEPS: During depolarization, inside of neuron goes from being __________ to _________ charged due to inflow of Na + ions ACTION POTENTIAL = significant change in electrical charge

14. Neuron Function: Depolarization

15. Repolarization STEPS: Na + channels close ______ channels open K + diffuses out of cell Electrical and concentration gradient, just like Na Resting potential (charge) restored Cell is ___________________ But, Na + is inside, K + outside

16. Repolarization

17. AFTER Repolarization Na + /K + pump moves ions back to their original sides Resting state restored