Nervous System and Tissue Functions Control and communication Sensory input (all changes on the inside and outside of body) Integration (brain, spinal cord, components take bits of info and decisions are made in what should be done in response) (a lot is done unconsciously) Motor output (messages sent to things that is going to produce some response)  Schematic of levels of organization in the nervous system Central nervous system (CNS) Brain and spinal cord (major control centers of body, integration in body) Integrative and control centers Peripheral nervous system (PNS) Cranial nerves and spinal nerves Communication lines between the CNS and the rest of the body Nerves: bundles of axons with other material- Cranial nerves- Spinal nerves Sensory (afferent) division- Somatic and visceral sensory nerve fibers Nerve fibers (individual axons) Somatic (skeletal muscles, skin, joints Visceral (smooth muscles, organs within body- Conducts impulses from receptors to the CNS- Bring info from body  CNS- From body  brain and spinal cord Motor (efferent) division- Motor nerve fibers- Conducts impulses from the CNS to effectors (muscles and glands)- CNS  body- Muscles and glands - Somatic nervous system Somatic motor (voluntary) Conducts impulses from the CNS to skeletal muscles- Autonomic nervous system (ANS) Visceral motor (involuntary) Conducts impulses from the CNS to cardiac muscles, smooth muscles, and glands Sympathetic division Mobilizes body systems during activity Parasympathetic division Conserves energy Promotes house-keeping functions during rest Histology Neuroglia: not neurons, supporting cells  Supporting cells within CNS- Astrocytes (protect neurons from damage, have appendages, detect changes in pH and chemical changes)- Microglia (if something were to invade, these would help protect CNS, defense cells within the CNS, phagocytize - Ependymal cells (circulate cerebrospinal fluid, have cilia- Oligodendrocytes (have several extensions that wrap around to create myelin sheath) Supporting cells within the PNS- Satellite cells (perform a lot of same functs of astrocytes- Schwann cells (same role of oligodendrocytes Structure of a motor neuron Dendrites (receptive regions) Cell body (biosynthetic center and receptive region) (soma) Axon (impulse generating and conducting region) Schwann cell (one internode) Exon terminals (secretory region) Astrocytes (protect neurons from damage, have appendages,  Myelin sheath Other terms White and grey matter Neurofilaments Neurofibrils Ganglia Nuclei Neurons: capable of sending electrical impulses to other cells  Structural Multipolar Bipolar Unipolar Functional  Sensory (afferent) Motor (efferent) Interneurons  Membrane potential Voltage Potential difference Current ( C ) = Voltage (V) / Resistance (R ) Resting membrane potential The concentration of Na+ and K+ o each side of the membrane are different Depolarization Hyperpolarization Graded potentials (the spread and decay of a graded potential Depolarization Spread of depolarization Decay of membrane potential with distance Action potentials Between repolarization and hyperpolarization Transient increase in Na+ permeability Restoration of Na+ impermeability Transient increase in K+ permeability Resting state  depolarization  repolarization  hyperpolarization  The key players- Voltage-gated Na+ channels Closed, opened, inactivated- Voltage-gated K+ channels Closed, opened Propagation Threshold All-or-nothing Refeactory period Conduction velocity- Diameter- Myelination  Membrane proteins Leakage (non-gated) channels Chemically (ligand) gated channels Open when the appropriate neurotransmitter binds to the receptor, allowing (in this case) simultaneous movement of Na+ and K+ Voltage gated channels Open and close in response to changes in membrane voltage Mechanically gated channels Pumps  Synapses Axosomatic synapses Axodendritic synapses Axoaxonic synapses  Presynaptic cell Postsynaptic cell Postsynaptic potentials - Graded potentials on postsynaptic cell Excitatory Inhibitory- Summation Temporal spatial Electrical synapses Chemical synapses  Neurotransmitters Chemical classification Acetylcholine Biogenic amines Amino acids Peptides Purines Gases Lipids Functional classification Excitatory vs. inhibitory Direct vs. indirect  Neurotransmitter receptors Channel-linked receptors- Open in response to binding of ligand- Closed ion channel = ion flow blocked- Open ion channel = ligand and ions flow G-protein linked recpetors- Cause formation of an intracellular second messenger that brings about the cell’s response GRADED POTENTIALS ARE NOT ACION