THE NERVOUS SYSTEM

1. THE NERVOUS SYSTEM Chapter 7

2. Monitors changes-__________________________--inside and outside the body • Processes and interprets input-________________________________ • Effects a response by activating muscles or glands(effector)via_____________________________________ Stimuli and gathered info is sensory input integration Motor output

4. Organization of the Nervous System

5. Divided by structure and activities • Structural classification • _____________________________________-consists of brain and spinal cord and is integrating command center • __________________________________-part of system outside CNS-nerves extending beyond the brain and SC • _______________________________-carry messages to and from SC and • ______________________________-carry impulses to and from brain CNS Spinal nerves Cranial nerves Peripheral nervous system

6. Functional classification • Divides peripheral nervous sytem into 2 divisions • __________________or afferent division consists of nerves conveying info to CNS via sensory receptors in the body • __________________________-bring in impulses from skin,skeletal muscles and joints • ________________________________bring in messages from inside and outside the body Visceral or sensory fibers or afferents sensory Somatic sensory fibers

7. effect Somatic nervous system Voluntary nervous sysyem • Motor or efferent division carry impulses from CNS to effector organs-muscles and glands-They _________a motor response • a)______________________allows us to consciously,or voluntarily control skeletal musces-so this sytem is also called ______________________________/some skeletal responses are initially involuntary • b) __________________ regulates autonomic or involuntary-like smooth muscle ,cardiac muscle and glands…..commonly called ______________________,which has 2 parts :1)sympathetic-opposes parasympathetic-associated w/ flight or fight 2)parasympathetic division-opposes sympathetic and craniosacral division Involuntary NS Autonomic nervous system

8. Nervous Tissue:Structure and Function • Either supporting cells or neurons • Supporting Cells-limped together as neuroglia and includes cells that generally support,insulate and protect delicate neurons---glial cells have special functions:

9. ______________________________-abundant star shaped cells-swollen ends that cling to neurons,bracing them and anchoring to nutrient supply:________________________/They form a living barrier between capillaries and neurons and help make exchange between the 2-help protect neurons from harmful substances in the blood and also help control brain chemical environment by “mopping”up leaked K ions and recapturing released neurotransmitters • _____________________________-spider like phagocytes to dispose of debris-like dead brain cells and bacteria astrocytes microglia capillaries

10. ependymal oligiodendrocytes • _____________________________-glial cells that line the central cavities of the brain and SC …..beating of cilia to distribute cerebrospinal fluid for those cavities and provide a cushion • _________________________________-glia that wrap flat extensions tightly around nerve fibers-producing fatty myelin sheath(an insulation) • 2 major varieties in PNS:______________________form myelin sheath and ______________________________-positive cushioning cells Schwann cells Satellite cells

15. Neurons-- anatomy-all have cell body,which contains nucleus and is metabolic center and one or slender extending processes • Neurons-- anatomy-all have cell body,which contains nucleus and is metabolic center and one or slender extending processes • Cell Body-metabolic center • Transparent ________________ w/ a conspicuous nucleolus • Cytoplasm has usual organelles except centrioles • Rough ER is called______________________________and _____________________________(intermediate filaments used in maintaining cell shape) Nissal substance nucleus neurofibrils

16. Processes-or fibers- vary greatly in length from microscopic - ~3-4 ft.Our longest reach from lumbar to large toe • ________________________-convey incoming messages(electrical signals) towards cell body-may be many of these for one nerve cell • _____________________- carry messages AWAY from cell body-only 1 axon,but branch much 2 end w/hundreds of axon _____________________________.-they contain 100’s of tiny vesicles,or membranous sacs w/___________________________chemicals-released into extracellular space Axon terminals axons dendrites neurotransmitters

17. _____________________________tiny gap that separates axon terminal from next neuron(synapse) • _____________________________-whitish ,fatty material w/waxy appearance.It functions by insulating or protecting fibers and Increases transmission rate Myelin sheath Synaptic cleft

18. Axons outside CNS are myelinated by ____________________________,which is gradually squeezed tightly enclosing axon • External to Schwann cell is neurilemma- Schwann cells

20. Gaps between Schwann cells are called __________________________ • Myelinated fibers also in CNS as ___________________________-around small segment of 1 nerve fiber-coiling around as many as 60 fibers at one time…Since they lack neurilemma that contributes to non –regeneration property Nodes of Ranvier oligodendrites

21. __________________________________is a neurological disorder causing visual or speech problems as wel as increasingle degenerating muscle …This is all due to an autoimmune response that destroys a protein in the myelin and cause nerves to short ciruit----Interferon is used Multiple sclerosis

22. Terminology- nuclei ganglia • - • cell bodies in CNS are usually called ______________--carrying out metabolic functions/not regenerated • __________________small collections of cell bodies outside CNS-in PNS • ________________________ are bundles of nerve fibers running through CNS • _____________________________________ are bundles of nerve fibers running through PNS • _________________________-collections of myelinated fibers in CNS • ________________________CNS unmyelinated fibers nerves tracts Gray matter White matter

23. Classification Sensory or afferent • Functionally groups neurons according to direction of nerve transmission relative to CNS…if carrying impulse from receptor to CNS-____________________________neurons-found in a ganglion outside CNS;dendrite endings of sensory neurons are usually associated with specialized recptors activated by specific nearby changes-cutaneous sense organs and_____________________________in muscle and tendons proprioreceptors

24. _________________(efferent)neurons carry impulses from CNS to visceraan/or muscles or glands-cell bodies in CNS • ________________________or association neurons connect motor and sensory neurons in neural pathways-cell bodies always in CNS • Structurally based on # of processes extending from cell body---if several:____________________________-inc. all motor and association neurons/__________________neurons have 2 processes-rare in adults/_____________________neurons have single process –sensory neurons in PNS motor interneurons multipolarneuron bipolar Unipolar neurons

25. 6-Physiology

26. NERVE INPULSES:Neurons have 2 major properties-___________________________________________ • __________________________refers to inactive or resting plasma membrane(fewer + ions on inner face(K+ions)-outside are Na+ ions …if the inside is more - ,it is inactive Irritability and conductivity polarized

27. depolarization Action potential repolarization • Action Potential and generation:…many different stimuli excite neurons—eg.light,sound,pressure-most excited by neurotransmitters released by other neurons….changes permeability of membrane changes briefly-gates of Na channels open---changing polarity-_________________________-inside now more +--graded potential • If this strong enough it initiates an_________________________(nerve impulse)-all-or none response • An outflow now of K+ ions will restore resting state-__________________________________

28. UNTIL REPOLARIZATION HAPPENS<A NEURON CANNOT CARRY ANOTHER IMPULSE ! • NA-K pump uses ATP • The above describes unmyelinated impulses –Myeinated sheaths conducts impulses faster-__________________________________-leaps from node to node • Conductivity can be impaired by sedatives and anesthetics by altering permeability Salatory conduction

29. Synapse Transmission-impulse does not traverse- synapse neurotransmitter do and they cause Na+ entry ,depolarization,etc.-brief transmission-electrochemical

30. Reflexes-rapid and predictable and involuntary response to stimuli • Somatic reflexes-stimulate skeletal muscles • _____________________regulate smooth muscles,heart and glands Autonomic reflexes

31. _____________________________is a neural pathway and has at least 5 elements:____________________________________________________________________________________________________ Sensory receptor,effector organ,sensory or motor neurons and synapse-CNS integration center Relex arcs

33. III. CNS gyri sulci • Functional Anatomy of the Brain • Brain is ~ 3 lbs. • 4 regions-cerebral,diencephalons,brain stem,cerebellum • Cerebral hemispheres • Paired • Largest and most superior • ____________-elevated regions of tissue separated by shallow _______ • ______________________are less numerous grooves and separate larger regions of brain fissures

34. Longitudinal fissure • ______________-separates 2 hemispheres by deep fissure • Other fissures or sulci divide into lobes,named for corresponding cranial bone • 3 basic regions to ea hemisphere:_______________________ Superficial cortex of gray matter,internal white matter,and basal ganglia(Gray)

35. Cerebral Cortex:-includes speech,memory,logical and emotional response, consciousness , interpretation of sensation,and voluntary movement • ________________________-posterior to central sulcus-primary somatic sensory area-interprets impulses traveling from body sensory receptors(except for special senses)/allows you to perceive pain,coldness or light touch….as shown in 7-14,p.245…body is represented in an upside down manner in sensory area-such a spatial map is a ___________________-crossed pathways-left primary somatic sensory area receives impulse from right and vice verse Primary somatic sensory area in parietal lobe Sensory homunculus

40. __________________________visual area in posterior • ___________________________has auditory area and has olafactory area • _________________________is primary motor area/the axons of these motor neurons make ________-major voluntary motor tract and it descends to cord-pathways again crossed • _________is map on motor cortex Temporal lobe Occipital lobe Corticospinal or pyramidal tract Motor homunculus Frontal lobe

41. ______________________at base of precentral gyrus-involved in speech-usually only in left hemisphere-damage here can cause inability to say words properly • In anterior frontal lobes is believed to be intellectual reasoning and socially acceptable behavior region • The main _____________________is located at junction of temporal,parietal,and occipital lobes-usually only in 1 hemisphere also • __________________is involved w/word meanings • Cell bodies of neurons involved in cerebral hemisphere are in outermost gray matter Speech area Broca’s area Frontal lobes

45. Cerebral White Matter-deeper,remaining cerebrum-composed of fiber tracts carrying impulses to and from or within cortex • __________________________________-large fiber tract that connects cerebral hemispheres(an example of a commisure)-allows hemispheres to communicate with each other….Association fiber tracts connects areas w/in hemisphere and projection fiber tract connects cerebrum Corpus callosum

48. _______________________________-islands of gray matter buried in white matter of cerebral hemispheres-help regulate voluntary motor activities by modifying instructions-esp. starting or stopping • basal ganglia Basal nuclei

50. ______________________________- genetic disease, middle-age and leads to massive degeneration of basal nuclei and then cerebral cortex-includes jerky movements and an eventual vegetative state w/in 15 years fatal-overdrive in motor stimulation • ______________-has basal nuclei problems-strikes in 50’s-60’s and comes from a degeneration of dopamine releasing neurons-dopamine deprived basal nuclei become overactive-tremors,head nodding etc. Huntington’s disease or Chorea Parkinson’s disease