1. The NERVOUS System

2. Functions of the Nervous System
Sensory
senses stimuli
Integrative
Analyzes/interprets information about the stimuli it receives
Motor
responds to stimuli by some type of action
muscular contraction
glandular secretion

3. Nervous System Schematic

4. The Central Nervous System
Consists of the brain and spinal cord
Sorts incoming sensory information
Generates thoughts and emotions
Forms and stores memories
Stimulates muscle contractions
Stimulates glandular secretions

5. The Peripheral Nervous System
Connects sensory receptors, muscles, and glands in the peripheral parts of the body to the central nervous system
Consists of cranial and spinal nerves
Afferent Neurons (Sensory)
conduct nerve impulses from sensory receptors toward the CNS
Efferent Neurons (Motor)
conduct nerve impulses from the CNS to muscles and glands

6. The Somatic Nervous System
Sensory neurons that convey information from the body to the CNS
Motor neurons from the CNS that conduct impulses to the skeletal muscles

7. The Autonomic Nervous System
Sensory neurons from the viscera that convey information to the CNS
Efferent neurons that conduct impulses to smooth/cardiac muscle and glands
Unconscious control
Two divisions of the ANS
Sympathetic Division
- stimulatory effect
Parasympathetic Division
- inhibitory effect

8. Neurons
The nerve cells responsible for the special functions of the nervous system
sensing - remembering- thinking
controlling muscle activity
controlling glandular secretions
Synapse - points between two neurons or between a neuron and an effector organ
Neuromuscular Junction
Neuroglandular Junction

9. Parts of A Neuron Cell Body (Soma)
nucleus, cytoplasm, organelles
Dendrites - processes protruding from the cell body. Receive impulses.
usually very short
AFFERENT FUNCTION
Axons - long, thin process that transmits impulses
usually myelinated
EFFERENT FUNCTION

10. Neurons

11. Neuroglia
Nervous system cells that support, nurture and protect the neurons
Types of Neuroglia found in the CNS
Astrocytes
Oligodendrocytes
Microglia
Ependymal Cells
Types of Neuroglia found in the PNS
Neurolemmocytes (Schwann Cells)

13. Astrocytes Star-shaped cells with many processes
Participate in metabolism of neurotransmitters
Maintain K+ balance for generation of nervous impulses
Participate in brain development
Help form the blood brain barrier
Provide a link between neurons and blood vessels

14. Oligodendrocytes
Form a supporting network around the neurons (myelin sheath) within the CNS
Cannot repair if damaged

15. Microglia
Small phagocytic cells that protect the central nervous system by engulfing invading microbes
Clears away debris from dead cells

16. Ependymal Cells Neuroglia cells that line the brain ventricles
Line the central canal of the spinal cord
Helps form and circulate cerebral spinal fluid

17. Neuroglia of the PNS Schwann Cells - Neurolemmocytes
Cells responsible for producing the myelin sheaths around the PNS neurons
Speeds up transmission of impulse
Can repair if damaged

18. Myelination The process of developing or producing a Myelin Sheath
Insulates the axon of a neuron
Increases the speed of nerve impulse conduction
CNS - oligodendrocytes
PNS - neurolemmocytes (Schwann Cells)
Diseases such as Tay-Sachs disease and Multiple Sclerosis involve destruction of the myelin sheaths around the nerve

19. Neurophysiology
The transmission of nerve (electrical) impulses from nervous tissue to other nervous tissue, organs, glands, and muscles.

20. Neuron Membrane Potential
Na+ is in higher concentration outside the cell and K+ is in higher concentration inside the cell.

21. Neuron Action Potential
Na+ moves in and K+ moves out of the cell, causing a change in the polarity of the cell.

22. Transmission of Nerve Impulses
An electrical event due to movement of ions across a membrane
Also called an action potential
Lasts about 1 msec (1/1000 of a second)
Dependent upon diameter of the axon
larger diameter axons msec (1/2500 sec)
2500 impulses per second
smaller diameter axons - 4 msec (1/250 sec)
250 impulses per second

23. Neuron Impulse “Ion Exchange”

24. Types of Impulse Conduction
Continuous Conduction - step by step depolarization of each area of the nerve
typical of unmyelinated nerve fibers
Saltatory Conduction - the jumping of an action potential along the axon
Nodes of Ranvier

25. Gray and White Matter
White Matter -myelinated processes from many neurons
Gray Matter - unmyelinated nerve cell bodies, axons, dendrites, ganglia, and axon terminals
Appears gray because of lack of myelin

27. Reflexes
Fast, predictable, automatic responses to changes in the environment
Somatic Reflexes - involve skeletal muscles
Visceral (Autonomic) Reflexes - involve responses of smooth muscles, the heart, and glands
Involve the spinal nerves

28. The Reflex Arc
A response by the body involving only the body segment being affected and the spinal cord
Brain does not have to be involved
5 parts--Sensory receptor--->sensory neuron---> integrating center (processing center)---> motor neuron--->effector (completes action)
Know for test!

29. The BRAIN 1

30. The BRAIN One of the largest organs in the body
Controls all mental functions
Component of the CNS
Composed of over 100 billion neurons
Comprises 2-3% of body weight
Utilizes over 20% of body’s energy 5

31. Major Divisions of the BRAIN
CEREBRUM - occupies most of the cranium and is divided into right and left halves called hemispheres
Cerebral cortex
Gray matter of the brain
Gyrus-elevations
Sulcus-grooves
Fissure-deep grooves
Corpus collosum
connects hemispheres 6

32. CEREBELLUM - the posterior-inferior portion of the brain
Coordinates skeletal muscle movements
Balance

33. DIENCEPHALON - located above the brainstem
Composed primarily of the:
Thalamus (emotional center)
Hypothalamus (connection between brain and endocrine system)
Regulates vitals

34. BRAIN STEM - consists of the:
medulla oblongata (controls vitals; coughing, sneezing, swallowing, vomiting)
the pons (regulates rate and depth of breathing)
the midbrain (reflex center for hearing and vision)
it is continuous with the spinal cord

35. The Brain

36. Ventricles Cavities within the brain that produce and circulate CSF
Lateral ventricles
Third ventricle
Fourth ventricle

37. Choroid Plexus Network of capillaries in the walls of the ventricles
Covered with ependymal cells that form the cerebrospinal fluid
These ependymal cells are so close together they form the blood-brain barrier.
Selectively permeable barrier
Protects the brain and spinal cord from potentially harmful substances in the blood

38. Blood Supply to the Brain
One of the most metabolically active organs in the body
Makes up only 2-3% of body weight but uses about 20% of available O2 at rest
Well supplied with O2 and nutrients
Only nutritional source for brain metabolic activity is glucose
Capillaries in the brain are much less leaky than other capillaries in the body and form a blood brain barrier

40. Lobes of the Cerebrum Named after the bones that cover them
Frontal Lobe -Temporal Lobe
Parietal Lobe -Occipital Lobe 8

41. Frontal Lobe Motor Areas Association Areas
Controls movement of voluntary skeletal muscles
Association Areas
Carry on high level intellectual processing
Problem Solving - Reasoning - Planning
Concentration - Memory - Behavior
Emotions - Expressions 9

42. Parietal Lobe Sensory Areas Association Areas
Interprets sensations such as:
touch - pressure – pain
Association Areas
Understanding of speech
Using words to express thoughts and feelings 10

43. Temporal Lobe Sensory Areas Association Areas Hearing and balance
Interpret sensory experiences
Memory of visual scenes - music - smells and other complex sensory patterns 11

44. Occipital Lobe Sensory Areas Association Areas
Visual processing and interpretation
Association Areas
Combines visual images with sensory experience 12

45. Protection and Coverings of the Brain
Protected by the cranial bones and the cranial meninges
Dura Mater - outer layer
Arachnoid - middle layer
Pia Mater - inner layer
Also protected by cerebrospinal fluid
fluid that nourishes and protects the brain and spinal cord
continuously circulates through the subarachnoid space around the brain and throughout the cavities within the brain

46. Meninges of the Brain

47. Meninges Connective tissue covering the brain and spinal cord
Three layered membrane
Dura Mater – “Tough mother”
dense irregular connective tissue
Arachnoid - middle layer. “Spider web”
spider web arrangement of collagen fibers
Pia Mater - inner most meninges
very delicate layer of thin tissue

48. Spinal Cord Protective Coverings
Dura Mater
Arachnoid
Pia Mater

49. Spinal Nerves / Brachial Plexus

50. Cerebrospinal Fluid Mechanical Protection Circulation Shock absorption
Buoys the brain
Circulation
Medium for exchange of nutrients and waste products between the blood and nervous tissue

51. The End!

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