1. The Nervous System Health Science 1 Ms. Marta Valdes, Instructor

2. Organs and Divisions of the Nervous System
Central nervous system (CNS)—brain and spinal cord
Peripheral nervous system (PNS)—all nerves

3. Division Flowchart

4. Neuron
Neuron-basic cell of the nervous system consist of 3 main parts—
dendrites: conduct impulses to cell body of neuron
cell body & axon: conducts impulses away from cell body of neuron

5. 3 main types of nerve cells
Sensory neuron
Interneuron
Motor neuron

6. Sensory neurons
Function—sensory: conduct impulses to the spinal cord and brain
Carries impulses from receptors e.g. pain receptors in skin to the CNS( brain or spinal cord)

7. Interneuron Carries impulses from sensory nerves to motor nerves.
Interneuron: conduct impulses from sensory neurons to motor
neurons
Carries impulses from sensory nerves to motor nerves.

8. Glia Cell
Glia (neuroglia) - Support cells, bringing the cells of nervous tissue together structurally and functionally

9. Disorders of the Nervous System
Disorders of nervous tissue
Multiple sclerosis—characterized by myelin loss in central nerve fibers and resulting conduction impairments
Tumors
General name for nervous system tumors is neuroma
Most neuromas are gliomas, glial tumors

10. Normal & Partially Destroyed Myelin by Multiple Sclerosis

11. Nerves
Nerve—bundle of peripheral axons
White matter—brain or cord tissue composed primarily of myelinated axons (tracts)
Gray matter—brain or cord tissue composed primarily of cell bodies and unmyelinated fibers

12. Nerves Nerve coverings—fibrous connective tissue
Endoneurium—surrounds individual fibers within a nerve
Perineurium—surrounds a group (fascicle) of nerve fibers
Epineurium—surrounds the entire nerve

13. Nerve Impulses
Definition—self-propagating wave of electrical disturbance that travels along the surface of a neuron membrane
Mechanism
A stimulus triggers the opening of Na+ channels in the plasma membrane of the neuron
Inward movement of positive sodium ions leaves a slight excess of negative ions outside at a stimulated point; marks the beginning of a nerve impulse

14. Impulse Pathway

15. The Synapse
Definition—chemical compounds released from axon terminals (of a presynaptic neuron) into a synaptic cleft
Neurotransmitters bind to specific receptor molecules in the membrane of a postsynaptic neuron, opening ion channels and thereby stimulating impulse conduction by the membrane

16. Transmission of Impulse (conduction) Through the Synapse with Neurotransmitters

17. The Synapse (Neurotransmitters)
Names of neurotransmitters—
Acetylcholine-1st neurotransmitter to be identified, lowers heart rate
Catecholamines - norepinephrine, dopamine, and serotonin
Endorphins-"endorphin rush" refers to feelings of exhilaration brought on by pain, danger, or other forms of stress
Enkephalins- regulate "the neural processes of encoding and processing noxious stimuli that have the potential to damage tissue
Nitric oxide (NO)-signaling molecule involved in many physiological and pathological processes (nitroglycerine)
Example
Parkinson’s disease—characterized by abnormally low levels of dopamine in motor control areas of the brain; patients usually exhibit involuntary trembling and muscle rigidity
Depression - characterized by abnormally low levels of serotonin.

18. Signs of Parkinson’s Disease

19. Central Nervous System
Divisions of the brain
Brainstem
Consists of three parts of brain; named in ascending order, they are the medulla oblongata, pons, and midbrain
Function—gray matter in the brainstem functions as reflex centers (for example, for heartbeat, respirations, and blood vessel diameter); sensory tracts in the brainstem conduct impulses to the higher parts of the brain; motor tracts conduct from the higher parts of the brain to the spinal cord

20. Divisions of the Brain

21. Central Nervous System
Diencephalon
Structure and function of the hypothalamus
Consists mainly of the posterior pituitary gland, pituitary stalk, and gray matter
Acts as the major center for controlling the ANS; therefore, helps control the functioning of most internal organs
Controls hormone secretion by anterior and posterior pituitary glands; therefore it indirectly helps control hormone secretion by most other endocrine glands
Contains centers for controlling appetite, wakefulness, pleasure, etc.

22. Central Nervous System
Structure and function of the thalamus
Dumbbell-shaped mass of gray matter in each cerebral hemisphere
Relays sensory impulses to cerebral cortex sensory areas
In some way produces the emotions of pleasantness or unpleasantness associated with sensations

23. Central Nervous System
Cerebellum
Second largest part of the human brain
Helps control muscle contractions to produce coordinated movements so that we can maintain balance, move smoothly, and sustain normal postures
Recent evidence shows the cerebellum may also have wider coordinating effects, assisting the cerebrum and other regions of the brain

24. Central Nervous System
Cerebrum
Largest part of the human brain
Outer layer of gray matter is the cerebral cortex; made up of lobes; composed mainly of dendrites and cell bodies of neurons
Interior of the cerebrum composed mainly of white matter (that is nerve fibers arranged in bundles called tracts)
Functions of the cerebrum—mental processes of all types, including sensations, consciousness, memory, and voluntary control of movements

26. Central Nervous System
BRAIN DISORDERS
Destruction of brain tissue
Cerebrovascular accident (CVA)—hemorrhage from or cessation of blood flow through cerebral blood vessels; a “stroke”
Cerebral palsy—condition in which damage to motor control areas of the brain before, during, or shortly after birth causes paralysis (usually spastic) of one or more limbs

27. Central Nervous System
Dementia—syndrome that includes progressive loss of memory, shortened attention span, personality changes, reduced intellectual capacity, and motor control deficit
Alzheimer disease (AD)—brain disorder of the middle and late adult years characterized by dementia
Huntington disease (HD)—inherited disorder characterized by chorea (purposeless movement) progressing to severe dementia
HIV (also causes AIDS) can infect neurons and thus cause dementia

28. Central Nervous System
Seizure disorders
Definition
Seizure—sudden burst of abnormal neuron activity that results in temporary changes in brain function
Epilepsy—many forms, all characterized by recurring seizures
Petit mal
Grand mal

29. Electroencephalogram (EEG)—graphic representation of voltage changes in the brain used to evaluate brain activity

30. Central Nervous System
Spinal cord
Outer part is composed of white matter made up of many bundles of axons called tracts; interior composed of gray matter made up mainly of neuron dendrites and cell bodies
Functions as the center for all spinal cord reflexes; sensory tracts conduct impulses to the brain, and motor tracts conduct impulses from the brain

32. Central Nervous System
Coverings and fluid spaces of the brain and spinal cord
Coverings
Cranial bones and vertebrae
Cerebral and spinal meninges—the dura mater, arachnoid mater, and the pia mater
Fluid spaces—subarachnoid spaces of meninges, central canal inside cord, and ventricles in brain

33. Peripheral Nervous System
Cranial nerves
Twelve pairs—attached to undersurface of the brain
Connect brain with the neck and structures in the thorax and abdomen
Spinal nerves
Structure—contain dendrites of sensory neurons and axons of motor neurons
Function—conduct impulses necessary for sensations and voluntary movements

36. Peripheral Nervous System
Peripheral nerve disorders
Neuritis—general term referring to nerve inflammation
Sciatica is inflammation of the sciatic nerve that innervates the legs
Neuralgia, or muscle pain, often accompanies neuritis
Trigeminal neuralgia—recurring episodes of stabbing pain along one or more branches of the trigeminal (fifth cranial) nerve in the head
Bell’s palsy—paralysis of facial features resulting from damage to the facial (seventh cranial) nerve

37. Peripheral Nervous System
HERPES ZOSTER OR SHINGLES
Viral infection caused by chickenpox virus that has invaded the dorsal root ganglion and remained dormant until an episode of shingles
Usually affects a single dermatome, producing characteristic painful plaques or vesicles

38. Autonomic Nervous System
Autonomic nervous system—motor neurons that conduct impulses from the central nervous system to cardiac muscle, smooth muscle, and glandular epithelial tissue; regulates the body’s automatic or involuntary functions
Autonomic neurons—preganglionic autonomic neurons conduct from spinal cord or brainstem to an autonomic ganglion; postganglionic neurons conduct from autonomic ganglia to cardiac muscle, smooth muscle, and glandular epithelial tissue

39. Autonomic Nervous System
Autonomic or visceral effectors—tissues to which autonomic neurons conduct impulses (i.e., cardiac and smooth muscle and glandular epithelial tissue)

40. Autonomic Nervous System
Composed of two divisions: the sympathetic system and the parasympathetic system
Autonomic conduction paths
Consist of two-neuron relays (i.e., preganglionic neurons from the central nervous system to autonomic ganglia, synapses, postganglionic neurons from ganglia to visceral effectors)
In contrast, somatic motor neurons conduct all the way from the CNS to somatic effectors with no intervening synapses

41. Autonomic Nervous System
Sympathetic nervous system
Function
Serves as the emergency or stress system, controlling visceral effectors during strenuous exercise and strong emotions (anger, fear, hate, or anxiety)
Group of changes induced by sympathetic control is called the fight-or-flight response

42. Autonomic Nervous System
Parasympathetic nervous system
Function
Dominates control of many visceral effectors under normal, everyday conditions

43. Divisions of the ANS Sympathetic - “fight or flight”
Catabolic (expend energy)
Mass activation prepares for intense activity.
Heart rate (HR) increases.
Bronchioles dilate.
Blood [glucose] increases.
Parasympathetic - “feed & breed”, “rest & digest”
Maintain homeostasis
Normally not activated as a whole, stimulation of separate parasympathetic nerves.
Relaxing effects:
Decreases heart rate.
Dilates visceral blood vessels.
Increases digestive activity.
Dual innervations of many organs — having a brake and an accelerator provides more control

44. Activity: Paras. vs. Symp.

46. Autonomic Nervous System
Autonomic neurotransmitters
Cholinergic fibers—release acetylcholine
Adrenergic fibers—release norepinephrine (noradrenaline)

47. Autonomic Nervous System
Autonomic nervous system as a whole
Regulates the body’s automatic functions in ways that maintain or quickly restore homeostasis
Many visceral effectors are doubly innervated (that is, they receive fibers from parasympathetic and sympathetic divisions and are influenced in opposite ways by the two divisions)

48. Autonomic Nervous System
Disorders of the autonomic nervous system
Stress-induced disease
Prolonged or excessive response to stress can disrupt normal functioning throughout the body
Examples of stress-induced conditions
Heart disease
Digestive problems
Reduced resistance to disease
Tumors
Neuroblastoma—highly malignant tumor of the sympathetic nervous system, primarily affecting young children

49. Neurological Conditions
Multiple sclerosis
Cerebral Palsy
Bell’s palsy
Migraine
ADHD
Wernicke-Korsakoff Syndrome
Alzheimer's Disease
Encephalitis
Epilepsy
Syncope
Febrile Seizures
Parkinson’s Disease
Phineas Cage
CHOOSE A TOPIC FROM THE LIST OR ON YOUR OWN
Research and write a 3 page APA 6th edition research paper. I will explain the rules for writing in APA. You can find additional information and an example of the format in the class website