Nervous System

1. Nervous System Control center & communication network of the body

2. Nervous System • Doctor: Neurologist • Fxn: Communication – through an electrochemical impulse/nerve impulse that works fast to maintain short-term homeostasis Sensory PNS Integrative/Decision PNS Motor Brain CNS Spinal Cord

3. 3 Functions • Sensory – perceives or senses changes as they occur • Integrative – processing/integrating the sensory information to arrive at a desired response • Motor – ability to initiate a response that has a desired effect • Organs: brain, spinal cord, nerves, sensory organs • Specialist: Neurologist

4. Divisions of the Nervous System NS PNS CNS Somatic Autonomic Brain Spinal Cord Sympathetic Parasympathetic

5. Reflex – rapid response to environmental changes / ER situations • Small # of neurons (nerve cells) involved • Fast & autonomic (aka. Automatic) to minimize injury • Reflex arc – conduction pathway for a reflex action

7. Parts to all Reflex Arc’s (pgs. 255-256)*made of either 2 or 3 neurons* • Stimulus • Sensory receptor • Sensory / afferent neuron • CNS • Motor / efferent neuron • Effector

8. Skematic Diagrams for Reflex ARC:Which parts of the reflex represent CNS & PNS? (3 neuron) 1. Stimulus (2 neuron)

9. Tissue Level of Organization Nerve Tissue Consists of nerve cells and interstitial tissue. It has the properties of excitability and conductivity, and functions to control and coordinate the activities of the body.

11. What is a nerve? Neurons – • Structural & functional unit of nerve tissue • sense change, integrate, motor response by way of rapid electrochemical impulses 3 parts to all neurons: • Dendrite – thin, branching extensions originating from cell body. • Receives impulses from adjacent neurons or receptors • Conducts info toward cell body Direction of impulse Saltatory

12. 3 parts to all neurons: 2. Cell body – part of neuron that contains the nucleus, cytoplasm, and many organelles 3. Axon – highly specialized area that conducts impulses away from the cell body toward adjacent neuron, muscle, organ, gland, etc. * myelinated - fast (130 m/s >300 mph) - white matter * unmyelinated - slow (<10 m/s) - gray matter (cell bodies) Direction of impulse Saltatory (skipping)

14. Resting Potential Action Potential Muscle cells or neurons Not contracting Not sending impulse Contracting Sending an impulse Many cells exhibit resting membrane potentials but only muscle & nerve cells are capable of action Potential (uneven distribution of ions) – separation of charges between 2 pts measured in volts ACTION POTENTIAL / NERVE IMPULSE

15. Preparing for action potential Na+ Na+ Na+ Na+ Na+ + + + + + + + + + + + + + + - - - K+ - - - K+ - - - - K+ - Polarized state - proteins Cl- • Cause of Resting Potential: • Sodium-potassium pump – uses energy to unevenly transport ions (3 net Na+ out and 2 K+ into) the cell • Membrane is more permeable to K+, therefore K+ leaks back out faster than Na+ leaks in All results in the outside of the membrane having a positive charge and the inside having a negative charge

16. Allowing cells to respond to changes in the environment = excitability Na+ Na+ Na+ - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + Depolarized state Stimulus reaches threshold and the cell membrane becomes permeable to Na+. Then, Na+ rush into the cell from high to low concentration via diffusion. Na+ Na+ Na+ Na+ Na+ + + + + + + + + + + + + + + - - - K+ - - - K+ - - - - K+ - Polarized state

17. At rest, the inside of the neuron is slightly negative due to a higher concentration of positively charged sodium ions outside the neuron.  When stimulated past threshold, sodium channels open and sodium rushes into the axon, causing a region of positive charge within the axon.  The region of positive charge causes nearby sodium channels to open. Just after the sodium channels close, the potassium channels open wide, and potassium exits the axon.  This process continues as a chain-reaction along the axon.  The influx of sodium depolarizes the axon, and the ourflow of potassium repolarizes the axon.  The sodium/potassium pump restores the resting concentrations of sodium and potassium ions 

18. http://www.youtube.com/watch?feature=player_detailpage&v=U0NpTdge3awhttp://www.youtube.com/watch?feature=player_detailpage&v=U0NpTdge3aw Action potential by MediMationz

19. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html

20. STIMULUS Ions changed • Resting Membrane Potential • no contraction • no impulse being sent • Action Potential • contraction • impulse Na+ + + + + + + + + + + + + + Polarized K+ - - - - - Na+ - - - - - - - - - - - - - - Depolarized + + + + + + Repolarized – back to resting Na+ / K+ pump Membrane is more permeable to K+ than Na+ Cl- inside cell, (-) proteins inside

21. Saltatory conduction – the jumping of the impulse from one node of Ranvier to another

22. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__chemical_synapse__quiz_1_.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__chemical_synapse__quiz_1_.html Impulse transmission from cell to cell Presynaptic neuron Postsynaptic neuron Na+ Receptor sites Ca2+ Exocytosis - ATP Synapse - gap STIMULUS Receptor site: think lock-n-key Na+ Na+ Saltatory conduction Na+ Na+

24. Excitatory – continues impulse / message Na+ channels open Examples… dopamine, seratonin, AcH, etc… Antidepressants work on keeping these in the synapse longer Inhibitory – prevents impulse / message K+ channels open Na+ remain closed Cl- open inside Examples… GABA, endorphins, enkephalins Our bodies natural painkillers Hyperpolarizes (below this level) K+ channels open more Na+ remain closed Cl- open even more inside Neurotransmitters +30 mV -70 mV

25. Neurotransmitters (proteins – a.a.) • Excitatory – continues impulse / message • Na+ channels open • Polarized Depolarized • Resting Action • Inhibitory – prevents impulse / message • K+ channels open • Na+ remain closed • Cl- open inside • Hyperpolarizes (below this level) • K+ channels open more • Na+ remain closed • Cl- open even more inside • Polarized Hyperpolarized • Resting Resting - - - - - - - - - + + + + + + + + + + + + + - - - - - - - - +30 mV -70 mV + + + + + + + + + + + + + - - - - - - - - - - - - - - - - + + + + + + + - - - - - - - -

27. 3 Ways Neurotransmitters are removed from the synapse • Diffusion • Enzymes • Proteins – a.a. provide specificity (lock-n-key) • EX. • EX. • Acetylcholine - Acetylcholinasterase • Neurotransmitter Transporters – “The Bus” • Reuptake A T Lactose lactase

28. Ways to Chemically Modify Synaptic Transmission • Increase/Decrease (Inc/Dec) synthesis of neurotransmitters • Inc/Dec release of neurotransmitters • Inc/Dec removal of neurotransmitters (enzyme… bus) • Inc/Dec activation of receptor site **Excitatory or Inhibitory neurotransmitters • EX. Cocaine use • chemically similar to dopamine – • (excitatory neurotransmitter in the brain) • “bus” affected Agonist – an agent that enhances synaptic transmission or mimics the effect of natural neurotransmitters Antagonist – an agent that blocks the action of a neurotransmitter

29. Project: How does “It” affect communication? • What neurotransmitter? Excitatory or Inhibitory? • Affects synapse by: • Synthesis of neurotransmitters • Release of neurotransmitters • Reuptake • Activation of receptor site • What is supposed to occur? How does “It” alter communication? • Where is the body is the communication taking place? Provide visual. • Does your explanation make sense to explain the feeling achieved, symptoms of disease, etc? • If it’s a drug, picture before drug, picture after drug. • If it’s a disease, picture without disease and one with the disease. • Go through you’re A&P terms for this unit, and what terms could be correctly used?

30. The EYE • Eye Diagram: (10) Terms to be used for labeling • Blind spot / optic disc • Choroid • Cornea • Iris • Lens • Optic nerve • Pupil • Retina • Sclera • Suspensory ligaments

31. Pathway of Light through the Eye** refracts (bends) light ** • ** cornea – static, transparent, “window of the eye” • * aqueous humor – watery fluid between cornea & iris • minor shape, nourishes because fluid is recycled • pupil – hole in center of iris, light passes through • size changes with amount of light available • * lens – changes the amount of refraction • accomodation – concave/convex – lens changes shape to focus light on the retina in one spot • * vitreous humor – thick, jelly-like fluid in posterior cavity that supports eye shape, holds retina in place, & is not recycled • Retina – like a wet piece of tissue paper • Change in light = impulses • Image on retina – smaller, upside down, backwards • Photoreceptors • Rods – black & white (dim) • Cones - color

32. Vision • ROYGBIV – reflected wavelength of light is what is perceived by the viewer • Photorectors • Rods – for Dim light (black & white) • Ex. Owls, dogs, cats • Cones – Color • Ex. Humans • 3 types • Erythrolabe • Chlorolabe • Cyanolabe Trichromatic – 3 Dichromatic – 2 Monochromatic – 1 Achromatic – B/W Sex – linked recessive (usually affects men – from mom) normal = c colorblind = c c c c X Y X X X XC c

33. Vision • Normal Vision (macula) • “blind spot” – optic disc / optic nerve • Nearsighted (myopia) • Focuses before the retina • Farsighted (hyperopia) • Focuses after the retina • Astigmatism • Unequal curvature from lens & cornea • Blurred vision near & far • Drawings

34. Impulse to the Brain • Optic nerve • Impulse leaves eye • Optic chiasma • Where impulses cross (X) • Optic tract • Leads from chiasma to… • Thalamus • Relay switch for sensory impulses • Occipital lobe of Cerebral Cortex • Interprets signal • Larger & right side up (& not reversed)

37. Attach to brain 12 pairs Head & neck Named with Roman numerals such as I, II, III, IV, V, etc… Sensory Toward CNS (attached to sensor Motor Away from CNS (muscles) Mixed Toward/away CNS Attached to spinal cord 31 pairs Neck, trunk, limbs C, T, L, S, C Nerve TypesCranial Nerves vs. Spinal Nerves

40. Protective Coverings of CNS(brain & spinal cord) • Bones • Cranium / skull • Vertebra • CSF (cerebral spinal fluid) • Protection • Nutrients (O2 to CNS) • Wastes (CO2 away from CNS) • Choroid plexus – ventricles • Filtration • Arachnoid villi • Reabsorption **accumulation of fluids in the brain** pg. 259 • Meninges • Dura mater – “tough mother” • Arachnoid – spider-like • Pia mater – “delicate mother”

42. Brain – iTouch items • Cerebrum • Cerebellum • Pons • Medulla oblongata • Midbrain

43. http://ilearn.senecac.on.ca/aahs/health/IHP/ottawa/anatomy/neuron/map/neuron.htmlhttp://ilearn.senecac.on.ca/aahs/health/IHP/ottawa/anatomy/neuron/map/neuron.html

44. http://35.9.122.184/images/40-AnimalStructureAndFunction/

45. Neurons • Made up of a cell body and branches called dendrites and axons • Dendrites receive messages from other neurons and send them to the cell body • Axons carry messages away from the cell body

46. Any message carried by a neuron is called an impulse Any message carried by a neuron is called an impulse

47. Neurons A message carried by a neuron is called an impulse

49. Types of Neurons • Sensory • Motor • Interneuron

50. Sensory Neurons • Receive information • Send impulses to the brain or spinal cord