The document discusses the structure and function of neurons and the nervous system. It covers topics such as sensory input and motor output, signal transmission through neurons via action potentials, synaptic transmission between neurons through neurotransmitters, and the role of glial cells in supporting neuronal function. Key points include that neurons transmit signals through electrical and chemical processes, synaptic transmission involves the release and binding of neurotransmitters, and glial cells provide insulation and structural/metabolic support to neurons.

2. Overlapping functions: Sensory input Integration Motor output

3. Collect information from the environment Internal and external Also called the sensory input Give the specific type of nerves found in the five basic senses

4. Processing of input to be interpreted and associated with the correct response Processed in the CNS Give an example of a correct response from a stimulus

5. Conduction of signals from integration to effector cells Signals are conducted by nerves Nerve= tissue (composed of nerve cells) Neuron= nerve cells

6. Through a combination of chemical and electrical signals

7. Structural and functional unit of the nervous system Axon hillock

8. Dendrites Axons Axon hillock Myelin sheath Synaptic terminals Synapse Presynaptic cell Postsynaptic cell Neurotransmitter

9. Simplest- reflex arc Reflex – an automatic response Simplest reflex arc= two kinds of nerve cells Motor and sensory Effector cells – muscle or gland Knee-jerk= more complex Front thigh contracts/inhibition of back thigh Involves second circuit (three parts) Sensory neurons from quadriceps= synapse with interneuron and motor neuron

11. Always in the CNS Also called association neuron, local circuit neuron Multi-branched Always communicate with each other “ memory”

12. Both are clusters of cell bodies Nuclei- found inside the CNS Ganglion- found outside CNS Take note the difference in structures of sensory neuron, motor neuron and interneuron Relate it to their function

13. Single presynaptic neuron to several postsynaptic neurons Convergent of several presynaptic neuron to a single postsynaptic neuron Circular path (memory)

14. Outnumber neurons 10:1 Then: glial cells do not participate in nerve signalling Now: presence of some synaptic interactions Important in structural integrity of the Nervous system Normal functioning of neurons

15. Embryo: radial glia- form tracks where neurons migrate Mature CNS: astrocytes – structural and metabolic support; stimulate formation of tight junctions between cells lining the capillaries of the brain (blood-brain barrier

16. Glia that form myelin sheath around axons of neurons Oligodendrocytes – CNS Schwann cells- PNS Myelin sheath- provides electrical insulation

21. Change in the voltage across the plasma membrane of neurons Caused by movement ions across the plasma membrane Ion channels

22. All cells have voltage across theri plasma membrane This membrane potential exists because of difference in ion concentration Electrically polarized Anion- inside Cation-outside

23. Animal cell: normally -50V to -100V Resting state of neuron: -70V Resting potential- membrane potential of an unstimulated neuron

24. Presence of special ion channels Selective permeability of the membrane Anions do not diffuse readily outside the membrane

25. Plasma membrane- lipid bilayer Lipid- not electrically charged Ions cannot dissolved readily (do not diffuse easily) Presence of pumps or channels

26. Presence of more K + channels than Na + channels due to high permeability to K +

27. Ion channels do not determine the rate and direction of ion movement Electrochemical concentration is responsible

29. -85mV- amount that can counterbalance concentration gradient of K Called the equilibrium potential of potassium

30. http://images.google.com.ph/imgres?imgurl=http://bp3.blogger.com/_v2GFIISzHOU/SAfTN-3b72I/AAAAAAAAAM0/gxoCzSqXK5o/s400/Action%2BPotential.jpg&imgrefurl=http://katie-humanbio.blogspot.com/2008/04/nerve-impulses.html&usg=__vMf6_WjdaeIWniQU8SyB-39dsQE=&h=324&w=383&sz=25&hl=en&start=1&um=1&tbnid=Co_p3fdsxS3QEM:&tbnh=104&tbnw=123&prev=/images%3Fq%3Daction%2Bpotential%2Bnerve%2Bcell%2Bsodium%2Bpotassium%2Bpump%26um%3D1%26hl%3Den%26rlz%3D1T4PBEA_en-GBPH281PH282%26sa%3DN

31. All cells have membrane potential but only neurons and muscle cells can generate large amount of membrane potential Excitable cells Resting potential- membrane potential of resting cell

32. Nerve impulses are the action potential generated in a cell that travel through pulse-like wave of voltage though membranes Due to stimulus

33. Ungated ion channels- open all the time Gated ion channels Chemically-gated ion channel- stimulus: chemical (e.g. Neurotransmitter) Voltage-gated ion channel- stimulus: change in membrane potential

34. Graded potential: change in membrane potential due to strength of stimulus Hyperpolarization- membrane potential is more negative Depolarization- membrane potential is more positive

35. Recall: muscle contraction at the cellular level Threshold potential Action potential- response when threshold potential is met (generated only in axons) Threshold potential usually -50mV to -55 mV Hyperpolarization do not produce action potentials

36. Voltage-gated ion channels are stimulated Potassium- single voltage-sensitive gate Closed- resting state Opens slowly in response depolarization Sodium- two voltage sensitive gates Activation- closed (resting state); opens rapidly during depolarization Inactivation- open (resting state); closes slowly in response to depolarization

37. Responsible in the restoration of the internal membrane potential Due to low permeability to sodium Inc permeability to potassium Hyperpolarization- responsible for refractory period

39. A domino effect always in a forward direction due to refractory period

40. Diameter of axon- faster if higher diameter Current is inversely proportional to the cross section of a wire Presence of Schwann cells Node of Ranvier- gaps between Schwann cells Ion channels are concentrated, extracellular fluid is in contact with the axon membrane at the node Saltatory conduction

41. Unique cell junction that control communication Between: 2 neurons, sensory receptors and sensory neurons, motor neurons and muscle cell, neurons and gland cell Two types Electrical synapse Chemical synapse

42. Less common than chemical synapse Cells are connected by gap junctions Allows action potential to spread directly from presynaptic terminals to postsynaptic terminals No loss of signal strength and delay Responsible for rapid movement

43. Presence of synaptic cleft (gap) Electrical signals not directly transmitted Signal: electrical-chemical-electrical Presence of synaptic vesicles containing neurotransmitter in the presynaptic axon Presence of chemical-gated ions

44. Recall: structure of a neuron Presence of inhibitory and excitatory synapses

45. Depolarization of the plasma membrane Results from influx of positive ions (e.g. Na ions) Depolarization may lead to an action potential if the threshold potential is met This is called EXCITATORY POSTSYNAPTIC POTENTIAL or EPSP

46. Inc permeability of Cl and K ion channels Hyperpolarization INHIBITORY POSTSYNAPTIC POTENTIAL or IPSP

47. Depends on the type of receptor and ion channel at the receiveing end

48. Region where voltage-gated sodium channels open Production of action potential: Several synaptic terminals acting simultaneously on one postsynaptic terminal Few synaptic terminal discharging neurotransmitter at a greater frequency Summation is produced

49. Temporal: frequency of chemical transmission is great; no time to return to resting potential Spatial: presence of many presynaptic neurons stimulating one postsynaptic neuron Both are present in IPSP and EPSP

50. Effects vary Can be within a few millisecond Can be longer due to signal transduction pathways it enters Can remain active over a long period of time

51. One of the most common among vertebrate and invertebrate Can be inhibitory or excitatory depending on the receptor Excitatory in muscle cell In heart muscle: inhibitory Dec ability to create action potential through hyperpolarization

52. Derived from amino acids Function as transmitters in the CNS Imbalances result in different disorders Parkinson’s disease- low dopamine Schizophrenia-high dopamine Psychoactive drugs like LSD and mescaline- produce hallucinatory effects by binding to receptors of serotonin and dopamine

53. Catecholamines- from tyrosine Dopamine Epinephrine and norepinephrine Also functions as hormones Serotonin- from tryptophan Affects signal transduction pathway Affects biochemical processes

54. GABA- gamma aminobutyric acid Transmitter of most inhibitory synapses Produces IPSPs by inc Cl permeability Present in Valium Glycine Glutamate Aspartate

55. Short chain amino acids Operate via signal transduction pathways Substance P- mediates pain Endorphins- feel good hormone Analgesic; counters pain Dec urine output Also acts as a hormone

56. NO and CO as regulators Release of NO in penis Viagra inhibits enzyme that masks the effect of NO Gaseous messengers are not store rather are synthesized