1. Nervous System Overview of the Nervous System Neurons and Neuroglia
Physiology of Nerve Conduction
Synapse and Synaptic Transmission

2. Key terms Central nervous system Peripheral nervous system
Autonomic nervous system
Somatic nervous system
Parasympathetic Nervous system
Sympathetic nervous system
Afferent nerves
Efferent nerves
Neurons (dendrite,body, axon, myelin sheath)
Neuroglia
Synapse
Action potential

3. Organization of the nervous system

4. Two major divisions: Central Nervous System (CNS)
Brain and spinal cord
Directs activity of entire nervous system
Peripheral Nervous System (PNS)
Spinal nerves
cranial nerves
Sensory receptors

5. Functional division (PNS)
Somatic nervous system (voluntary)
Stimulates and controls skeletal muscles
Autonomic nervous system (involuntary)
Controls cardiac and smooth muscles, and glands
Includes sympathetic and parasympathetic branches
Parasympathetic nervous system – controls all automatic day-in-and- day-out functions of circulatory, respiratory, and digestive systems
Sympathetic nervous system – activate fight or flight

6. Organization of nervous system

7. Functions of the nervous system
Uses millions of sensory receptors to monitor changes (STIMULI)occurring inside and outside the body; this gathered information is called SENSORY INPUT
Processes and interprets the sensory input and decides what should be done – a process called INTEGRATION
It then effects, or causes, a response by activating muscles or glands (EFFECTORS) via MOTOR OUTPUT

8. Review organization of the nervous system

10. Nervous tissue
Two categories exist: neurons and neuroglia

11. Look up and record the description and function of each type of cell
Neurons and neuroglia
neurons
neuroglia
Cells that transmit information in the form of nerve impulses
Three types depending on function: sensory (afferent), motor(efferent), interneurons
Provide support and protection
CNS (4 types):
- astrocytes, microglia, ependymal cells, oligodendrocytes
PNS (2 types):
Schwann cells, satellite cells
Look up and record the description and function of each type of cell

12. Nervous tissue
neurons
neuroglia

14. Review cells of the nervous system

16. Transmission of nerve impulses
Action Potential
Synapse

17. Action potential
In an inactive neuron (at rest), there are K+ ions inside the cell and Na+ ions outside the cell
The inside of the membrane is more negatively charged than outside = polarized
When stimuli activates a neurons, hundreds of Na channels open, allowing Na ions to rapidly diffuse into the cell/neuron
As a result, electrical charge inside the cell becomes more + = depolarized
Depolarization opens more ion channels, generating a wave of depolarization
This electrical charge is known as nerve impulse, or action potential
Following the discharge of the action potential, the membrane becomes permeable to K+ ions, which rapidly diffuse out of the cell and begin the process of restoring the membrane to its resting state = repolarization
The time between the completion of the action potential and repolarization is = refractory period and the cell cannot respond to another stimulus
Note: cell membrane is essentially impermeable to large negatively charged ions that are present inside the neuron, therefore fewer negatively charged ions move out than positively charged particles;

18. Action Potential review

19. Impulse transmission
Speed at which nerve transmission travels is determined by 3 things:
1. axon diameter- the larger the axon, the greater the number of ions to conduct current
2. presence of myelin sheath – conduction in nonmyelinated axons is much faster because fatty myelin is an electrical insulator and action potentials jump over the myelinated regions (from node (of Ranvier) to node) where the axon is exposed= salutatory conduction ; this results in significantly faster impulse transmission than is possible in nonmyelinated axons
3. body temperature – warmer temperatures increase ion diffusion rates
Limb position – 119m/s
Information/impulses from objects we touch – 76m/s
Thought signals – m/s
Pain – less than 1m/s

20. Synapse Communication between neurons occurs at the synapse
The synapse is the site where the neurotransmitter is released from the nerve axon terminal
Transmission of nerve impulses is an ELECTROCHEMICAL event (action potential=electrical and synapse=chemical)

21. synapse
Action potential reaches axon terminal and Ca++ gates and Ca ions enter the terminal
Influx of Ca causes vesicles to join cell membrane adjacent to synaptic cleft forming pores
Release and diffusion of neurotransmitter across synaptic cleft to receptor sites on the next nerve or to a muscle fiber (postsynaptic)

22. Synapse

24. Functional Anatomy of the central nervous system