1. Nervous System Communication

2. Kid Concussions In The News

3. Neurons Nerve cells Parts of neurons Message = nerve impulse Cell body
Long extensions
Message = nerve impulse

4. Animal Nervous Systems
Sponges – no nervous system
Other animals all have neurons in systems

5. Nerve Net
In all cnidarians
Interconnected nerve cells
No brain

6. Ringlike Nervous System
In echinoderms
Ring with 5 radiating nerves

7. Ladderlike Nervous System
In many Platyhelminthes
Some have distinct brain

8. Annelid Nervous System
Segmental ganglia
Ganglia = aggregations of nervous tissue
Ventral nerve cord & brain

9. Vertebrate Nervous System
Central nervous system
Brain & spinal cord
Peripheral nervous system
Nerves to & from CNS

10. Nerve Cells Cell body Axon Dendrites Contains nucleus
Organelles necessary for cell
Axon
Long cell extension
May have myelin covering
Dendrites
Cell extensions
No myelin covering

11. Sensory Neurons Receive information
Transmit to the central nervous system

12. Motor Neurons
Transmit commands away from CNS
To muscles & glands

13. Interneurons Located within brain & spinal cord Integrate information
Axons may not be myelinated

14. Neuroglia Nerve support cells
Provide support, protection, & nutritional stability
Schwann cells
Found around axons
Produce myelin sheath

15. Myelin Sheath
Insulates axon
Nodes of Ranvier
Uncovered areas

16. Nerve Impulses
Electrical signals transmitted along membranes of nerves

17. Resting Potential Neuron is electrically charged at rest
Outside is positively charged
Inside is negatively charged

18. Sodium-Potassium Pump
Proteins embedded within cell membrane
Moves sodium to the outside
Moves potassium to the inside
Maintains resting potential
Requires energy

20. Action Potential Nerve impulse is started by a stimulus
Stimuli cause movements of ions through membrane
Threshold potential
Sufficient stimulation to depolarize membrane
Action potential
Rapid reversal of membrane electric potential

22. Nerve Transmission Action potential at one point depolarizes next area
Depolarization moves in self-propagating wave

23. Saltatory Conduction
Nerve impulse jumps & moves faster along myelinated axon

24. Synapse Area where nerve communicates Transfers message Another neuron
An effector

25. Synaptic Cleft Neurons do not touch other neurons or effector cells
Nerve impulse must cross gap

26. Neurotransmitters Organic molecules (> 60 different chemicals)
Transfer message across synaptic cleft
Attach to receptors on target cell

27. Neuromuscular Junctions
Synapse between neuron & skeletal muscle
Neurotransmitter is acytylcholine

28. Neuron to Neuron Connections
Uses many different neurotransmitters
Some cause different effects
Excitatory synapse – continuation of impulse
Inhibitory synapse – reduce ability to depolarize

29. Integration of Nerve Impulses
Summed impulses determine if postsynaptic neuron will depolarize

30. Human Nervous System Central nervous system Peripheral nervous system
Brain
Spinal cord
Peripheral nervous system
Brings messages to & from CNS
Somatic nervous system – voluntary
Autonomic nervous system - involuntary

31. Central Nervous System
Integrates sensory & motor impulses

33. Spinal Cord Connects peripheral nervous system with brain
Receives information via spinal nerves
Includes reflex arcs

34. CNS Protection - Meninges
Layers of membranes
Dura mater
Arachnoid
Pia mater

35. Peripheral Nervous System
Sensory & motor impulses
Cranial nerves communicate directly with brain

36. Spinal Nerves Sensory & motor nerve fibers
Travel directly to spinal cord
Nerves are bundled to form mixed nerves

37. Motor Neuron Systems Somatic Autonomic Voluntary
Movements of skeletal muscles
Autonomic
Involuntary
Reflex = automatic response to nerve stimulation
Involuntary motor pathways

38. Divisions of the Autonomic Nervous System
Parasympathetic
Prevails during periods of inactivity
Housekeeping
Sympathetic
“fight or flight”
Responds to stress
Prepares body for action
Parasympathetic & sympathetic together help to maintain homeostasis

40. Psychoactive Drugs Affect action of nervous system Some are abused
Neurotransmitters
Specific parts of the brain
Some are abused

45. Drug Addiction Chronic use (or abuse) of psychoactive drugs
Person becomes physically dependant
Drug use tends to increase due to drug tolerance

46. End Chapter 32