1. Nervous Tissue A. Nervous system divisions B. Functional anatomy of nervous tissue B. Functional anatomy of nervous tissue 1. Neuroglia 1. Neuroglia a. Types of neuroglia a. Types of neuroglia b. Myelination b. Myelination 2. Neurons 2. Neurons a. Parts of a neuron a. Parts of a neuron b. Classification of b. Classification of neurons neurons 3. Gray and white matter 3. Gray and white matter C. Neurophysiology 1. Resting membrane potential 1. Resting membrane potential 2. Ion channels 2. Ion channels 3. Action potential (impulse) 3. Action potential (impulse) a. Depolarization a. Depolarization b. Repolarization b. Repolarization c. Refractory period c. Refractory period d. Propagation (conduction) of d. Propagation (conduction) of action potentials action potentials e. The all-or-none principle e. The all-or-none principle f. Saltatory conduction f. Saltatory conduction 4. Transmission at synapses 4. Transmission at synapses a. Chemical synapses a. Chemical synapses b. Excitatory and inhibitory postsynaptic potentials b. Excitatory and inhibitory postsynaptic potentials c. Spatial and temporal c. Spatial and temporal summation of PSPs summation of PSPs d. Removal of neurotransmitter d. Removal of neurotransmitter 5. Neuronal circuits 5. Neuronal circuits

2. The nervous system is the body's control center and communicates network. It serves three broad functions: 1. senses changes in the environment 2. integrates and interprets 3. responds

3. Nervous Systems Divisions 1. central nervous system a. brain a. brain b. spinal cord b. spinal cord 2. peripheral nervous system a. somatic division a. somatic division b. autonomic division b. autonomic division (1) sympathetic vs (1) sympathetic vs (2) parasympathetic (2) parasympathetic

4. Neuroglia 1. astrocytes 2. oligodendrocytes 3. microglia 4. ependyma 5. neurolemmocytes (Schwann cells) (Schwann cells) 6. satellite cells

5. Neuron 1. cell body a. nucleus a. nucleus b. nucleolus b. nucleolus c. Nissl substance c. Nissl substance 2. dendrite 3. axon a. axon hillock a. axon hillock b. trigger zone b. trigger zone c. axon collaterals c. axon collaterals d. telodendrion d. telodendrion e. end bulbs e. end bulbs

6. Myelination 1. PNS = neurolemmocytes CNS = oligodendrocytes CNS = oligodendrocytes 2. process 3. myelin sheath 4. neurolemma 5. nodes of Ranvier

7. Structural Classification of Neurons 1. multipolar neuron 2. bipolar neuron 3. unipolar neuron a. central process a. central process b. receptor b. receptor

8. Functional Classification of Neurons 1. sensory (afferent) neurons 2. association neurons (interneurons) 3. motor (efferent) neurons

9. Some Terminology 1. nerve fiber 2. nerve vs. tract 3. tract 4. ganglion vs. nucleus (center) 5. gray matter 6. white matter Gray matter White matter

10. Neurophysiology Communication by neurons depends upon two basic properties of their cell membranes: 1. There is an electrical voltage, called the resting membrane potential, across the cell membrane. 2. Their cell membranes contain a variety of ion channels (pores) that may be open or closed.

11. Resting Membrane Potential 1. build-up of ions 2. separation of charges = potential energy (mV) potential energy (mV) 3. membrane potential = -70 mV 4. polarized membrane +++++ --------- +++++ --------

12. Two Main Factors Contribute to the RMP 1. distribution of ions across the cell membrane. a. extracellular fluid is rich in Na+ and Cl- a. extracellular fluid is rich in Na+ and Cl- b. intracellular fluid is rich in K+ and anions b. intracellular fluid is rich in K+ and anions such as organophosphates and proteins such as organophosphates and proteins 2. relative permeability of the cell membrane to Na+ and K+ Na+ and K+ a. moderately permeable to K+ and Cl- a. moderately permeable to K+ and Cl- b. slightly permeable to Na+ b. slightly permeable to Na+ c. impermeable to the intracellular anions c. impermeable to the intracellular anions

13. Ion Channels(Pores) 1. non-gated (leakage) 2. gated (regulated) a. open in response to stimulus a. open in response to stimulus (chemical, voltage change, light, mechanical) (chemical, voltage change, light, mechanical) b. excitable cells have them b. excitable cells have them c. found in trigger zones c. found in trigger zones

14. How do chemically gated ion channels open? intracellular fluid extracellular fluid +++++++ +++++++++++++ - - - - - - - - - - - - - - - - - - -- cell membrane Na+ ACh CHEMICALLY-GATED Na+ CHANNEL closed intracellular fluid extracellular fluid +++++++ +++++++++++++ - - - - - - - - - - - - - - - - - - -- cell membrane Na+ ACh CHEMICALLY-GATED Na+ CHANNEL open

15. Chemically gated channel

16. How do voltage-gated channels open? intracellular fluid extracellular fluid +++++++ +++++++++++++ - - - - - - - - - - - - - - - - - - -- cell membrane Na+ VOLTAGE GATED Na+ CHANNEL open intracellular fluid extracellular fluid +++++++ +++++++++++++ - - - - - - - - - - - - - - - - - - -- cell membrane Na+ VOLTAGE-GATED Na+ CHANNEL closed Voltage 3. Mechanically-gated channels, light-gated channels

17. An Action Potential

18. Action Potential-Depolarization 1. threshold stimulus 2. voltage-gated Na+ channels open 3. Na+ influx (-70 ---> +30 mV) _____________________________ 4. positive feedback

19. Action Potential-Repolarization 1. voltage-gated K+ channels open 2. K+ efflux (-90 <--- +30 mV) 3. hyperpolarization 4. Na-K pumps restore ions

20. Action Potential Summary

21. Refractory Period 1. absolute 2. relative

22. POSITIVE FEEDBACK OF AN ACTION POTENTIAL CONTROLLED CONDITION A stimulus or stress disrupts membrane homeostasis by causing a threshold depolarization RECEPTOR The receptors in this case are voltage-gated Na+ channels in their resting state CONTROL CENTER The shape of the voltage-gated Na+ channel depends on membrane voltage change EFFECTORS Voltage-gated Na+ channels are also effectors. Threshold depolarization causes shape changes in the channel NO RETURN TO HOMEOSTASIS Opening of the voltage-gated Na+ channels causes depolarization in adjacent membrane, opening more voltage-gated Na+ channels

23. All of None Principle Each time an action potential is formed, it has a constant and maximum strength for the existing conditions.

24. Continuous Conduction 1. trigger zone to synapse 2. propagation 3. one direction only

25. Saltatory Conduction 1. myelin sheath 2. nodes of Ranvier 3. "jumping" impulse 4. 0.5 vs 130 m/sec 5. energy conservation

26. Transmission at Synapses 1. "synapsis" means connection 2. synapses integrate and filter information 3. signals are transmitted or inhibited 4. presynaptic vs postsynaptic neurons

27. Chemical Synapses 1. arrival of action potential 2. Ca++ influx 3. synaptic vesicle rupture 4. NT release 5. NT diffusion 6. NT/receptor interaction 7. postsynaptic potential

28. Postsynaptic Potentials can be excitatory or inhibitory 1. excitatory (EPSP) a. facilitation a. facilitation b. summation b. summation (1) spatial (1) spatial (2) temporal (2) temporal 2. inhibitory (IPSP) a. hyperpolarization a. hyperpolarization

29. Postsynaptic Potentials

30. Facilitation and Summation 1. spatial 2. temporal ___________ net effects 1. facilitation 2. summation (impulses) 3. inhibition (hyperpolarization)

31. EXAMPLE OF SYNAPTIC INTEGRATION postsynaptic neuron inhibitory presynaptic neuronexcitatory presynaptic neuron Threshold = +3

32. TYPES OF NEUROTRANSMITTERS Acetylcholine Most common neurotransmitter; In a class by itself chemically; Mostly excitatory, depending on location and function; Brain, spinal cord, neuromuscular and neuroglandular synapses of the periphery Excitatory amino acids Glutamate – 75% of excitatory synapses in brain Asparate – spinal cord Inhibitory amino acids Glycine – most common in spinal cord GABA (gamma amino butyric acid) – most common in brain Monoamines (biogenic amines) Catecholamines – norepinephrine, epinephrine, dopamine Other amines – serotonin, histamine Neuropeptides – substance P, enkephalines and endorphins, cholecystokinin

33. Removal of Neurotransmitter from Synaptic Cleft 1. diffusion 2. enzymatic degradation 3. uptake into the cell

34. Neuronal Circuits 1. simple series 2. diverging 3. converging 4. reverberating 5. parallel after-discharge