Nervous System

1. Nervous System Priscilla Rocha, Pamela Mercado, Ana Ruballos Anatomy & Physiology Period 3

2. Anatomy & Function of Classic Neuron • Composed of neural tissue • Nerve cells or neurons and neurological cells • Neurons • React to physical and chemical changes in their surroundings • Dendrites receive input • Longer process (axon or nerve fiber) carries the information away from the cell with nerve impulses

3. Anatomy & Function of Classic Neuron Continued… • Nerves • Bundles of axons • Synapse • Small space between a neuron and the cell(s) with which it communicates • Dendrites • Small cellular processes that receive input • Myelin sheaths • an electrical insulator that speeds nerve impulses to muscles and other effectors

4. Neuron

5. Classification of Neurons: Structural Differences • Neurons are classified into three groups • Each is specialized to send a nerve impulse in one direction • Bipolar, Unipolar, pseudounipolar, pyramidal, and Multipolar

6. Bipolar neurons • 1. Bipolar Neurons- A cell body with 2 processes. One process serves as the axon and the other like a dendrite. Located in specialized parts of the ears, nose, and eyes. 

7. Unipolar neurons • 2.Unipolar Neurons- Cell body with a single process that divides into 2 axonal branches. The peripheral process which deals with peripheral parts of the body, like skin. Secondly, the central process which enters the brain and spinal cord. 

8. Pseudounipolar neurons • Psuedounipolar neurons is a sensory neuron in the peripheral nervous system. The two processes form a single process. One branch is structurally an axon, however, functions as a dendrite. • Afferent conduction originiating in a nerve ending.

9. Pyramidal neurons • Pyramidal neurons are large triangular-shaped neurons in the cerebral cortex that transmit impulses to voluntary muscles

10. Multipolar neurons • 3. Multipolar Neurons- Cell body with many processes, one axon and the rest dendrites. These are commonly found in the brain and spinal cord.  

11. Classification of Neurons: Functional Differences • These neurons are classified by the information carried to the central nervous system (CNS), completely within the CNS or out of the CNS. 

12. Function Continued… • Sensory neurons- conduct nerve impulses from receptors in peripheral body parts into the brain and spinal cord • Their specialized to detect changes in the outside world or within your body • Most of the sensory neurons are found to be unipolar, but some are bipolar

13. Motor neurons • 2. Motor Neurons- Transmit nerve impulses from the CNS toward the effectors- target cells that produce responses. Types of effectors are: muscles which are being contracted and glands that are being secreted. These are found to multipolar. 

14. interneurons • 3. Interneurons- transmit impulses between neurons within the brain and spinal cord. Usually between sensory neurons where the signal is being interpreted and the other being sent to the motor neurons. Found to be multipolar neurons. 

15. Introduction to nervous system • The nervous system consist of 2 major system, the peripheral nervous system (PNS) and the central nervous system (CNS). The peripheral system is subdivded into the stomatic nervous system and the autonomic nervous system.  

16. Nervous system continued… • 1. The peripheral nervous system consist of the nerves and ganglia outside of the brain and spinal cord. Its function is to connect the CNS to limbs and organs serving as a communication relay going back and forth between your brain and your exteremities.  

17. Nervous system continued • 2. The autonomic nervous system is the system that influences the functional of internal organs. ANS has 2 branches: the sympatheic nervous system is one and is responsible for the fight-or-flight response in the body. The second is the parasympatheic which is responsible for the rest and digest response in the body.  

18. Cns and pns • The central and peripheral nervous systems work together • The pns receives information from the environment and carries stimuli via action potential • The cns analyzes the information and formulates a response • Response is conveyed to proper organ through pns or motor neurons • Cns brain • Pns spine/nerve endings

19. Central nervous system neuroglia • CNS: • astrocytes (star shaped cells) found between neurons & blood vessels • oligodendrocytes (smaller version of astroctyes) found along myelinated axons • microalgia found scattered throughout the CNS • ependymal (cuboidal) found in the central canal

20. Peripheral nervous system neuroglia • Schwann cells produce myelin • Satellite cells support clusters of neurocell bodies called ganglia

21. Classification of Neurological Cells Cont.

22. Action Potential • Resting: nerve cell • Sodium and potassium ions (in neuron membrane) follow the laws of diffusion and show a net movement from areas of high concentration to areas of low concentration • pump • Membrane more permeable to potassium ions than sodium ions • Cytoplasm of cells is negatively charged (anions such as phosphate, sulfate and proteins) • Outside of membrane gets positively charged, inside is negatively charged

23. Action Potential Continued… • Action Potential • If signal is strong and the voltage reaches a threshold, it will trigger the action potential • Peak voltage • Gated sodium channels close and potassium channels open • Neuron becomes hyperpolarized • More potassium ions on the outside than sodium ions on the inside

24. Refactory • Refractory • Returns potassium to the inside of the cell and sodium to the outside of the cell

26. Neurotransmitters • Neurotransmitters • Carriers of electrochemical messages • Neuron to neuron • Acetylcholine stimulates skeletal muscle contractions • Monoamines (modified amino acids) • Unmodified are short chained amino acids

27. Neurotransmitters continued… • Peptide neurotransmitters are synthesized in the rough endoplasmic reticulum • They travel down the axon to the nerve terminal • Other neurotransmitters are synthesized in the cytoplasm of the nerve terminals and are stored in vesicles • When an action potential passes along the membrane of a synaptic knob it increases permeability allowing calcium ions in by opening channels • Calcium diffuses inward • The more calcium that enters the knob, the more vesicles release neurotransmitters

28. Neurotransmitter

29. Bibliography Shier, David, Jackie Butler, and Ricki Lewis. "Nervous System I: Basic Structure and Function." Hole's Human Anatomy & Physiology. 11th ed. New York: Mc GrawHIll, 2007. 355+. Print. "Pseudounipolar Neuron." Academic Dictionaries and Encyclopedias. N.p., n.d. Web. 14 Apr. 2015. "Pyramidal Neuron." Academic Dictionaries and Encyclopedias. N.p., n.d. Web. 14 Apr. 2015.