1. The Nervous System

2. Functions of the Nervous System
1. Monitors internal and external environment
2. Take in and analyzes information
3. Coordinates voluntary and involuntary responses.

3. Organs of the Nervous System
Brain and Spinal Chord (CNS)
Sensory Receptors of Sense Organs (eyes, ears etc)
Nerves connect nervous system with other systems

4. Divisions of the Nervous System
1. Central Nervous System
Spinal Chord and Brain
Processing coordination of stimulus and response
2. Peripheral Nervous System
- All neural tissue outside the CNS
- Delivers sensory information to the CNS and carries motor commands to the effectors

5. Functions of the CNS Are to process and coordinate: - sensory data:
From inside and outside the body
Movement:
Control activities of peripheral organs (e.g. skeletal muscles)
Higher functions of the brain
Intelligence, memory, learning, emotion

6. Functions of the PNS 1. Deliver sensory information to the CNS
2. Carry commands to peripheral tissues and systems

7. Nerves Also called peripheral nerves:
Bundles of axon with connective tissues and blood vessels
Carry sensory information and motor commands in PNS:
Cranial nerves: connects to brain (12 pairs)
Spinal nerves: attach to spinal chord (31 pairs)

8. Divisions of the PNS Afferent Division: Efferent Division:
Carries information from PNS to CNS
Efferent Division:
Carries motor commands from CNS to PNS
Has somatic and autonomic components

9. The Efferent Division of the PNS
Somatic Nervous System (SNS)
Controls skeletal muscle contraction
Voluntary muscle contractions
Reflexes
Autonomic Nervous System (ANS)
Controls subconscious actions
Contraction of smooth and cardiac muscle
Glandular secretions

10. The Autonomic Nervous System Splits
Parasympathetic Nervous System
Sympathetic Nervous System

11. Neural Tissue Contains 2 kinds of cells Neurons Neuroglia
Cells that send and receive signals
Neuroglia
Cells that support and protect nerves

12. Neurons The basic functional units of the nervous system
Parts of a neuron
Cell body (Soma)
Short, branched dendrites
Long, single axon

13. Structure of a Neuron

14. Dendrites Highly branched Dendritic spines:
Receive information from other neurons
80-90% of neuron surface area

15. The Axon Long Carries electrical signal (action potential) to target
Axon structure is critical to function

16. Nodes and Internodes Internodes Nodes Myelinated segments of axon
Also called nodes of Ranvier
Gaps between internodes
Where axons may branch

17. The Synapse
Area where a neuron communicates with another cell

18. Synapse Areas where a neuron communicates with another cell
Presynaptic Cell
Neuron that sends message
Postsynaptic Cell
Cell that receives message
Synaptic Cleft
Gap that separates the presynaptic membrane and the postsynaptic membrane

19. The Synaptic Knob Is expanded area of axon
Contains synaptic vesicles of neurotransmitters
Chemical messengers
Released at presynaptic membrane
Affect receptors of postsynaptic membrane

20. Functional Classifications of Neurons
Sensory Neurons
Deliver information to CNS
Motor Neurons
Stimulate or inhibit peripheral tissues
Interneurons
Located between sensory and motor neurons
Analyze inputs, coordinates outputs

21. Neuroglia Half the volume of the nervous system
Many types of neuroglia in the CNS and PNS

22. Neuroglia Functions
Line of central canal of spinal chord and ventricles of brain
Repair damaged neural tissue
Processes contact between other neuron cell bodies

23. Neuorglia Wrap around axons to form myelin sheaths (Schwann Cells)
Increases speed of action potentials
Myelin insulates myelinated axons
Makes nerves appear white (white matter)

24. White and Grey Matter White Matter Grey Matter
Regions of CNS with many myelinated nerves
Grey Matter
Unmyelinated areas of CNS