PET3322 Functional Anatomy and Physiology Exam II Study Guide Photos are taken from Dr Figueroa s powerpoints Nervous System A few definitions Functions Sensory input o o o o o o Ganglion collection of neuron cell bodies outside CNS Plexus extensive network of axons and sometimes neuron cell bodies located outside CNS Monitors both internal and external stimuli Signals CNS Integration Within the CNS Brain and spinal cord process and evaluate sensory input and start the body s responses o Motor Output Controls muscles and glands effectors CNS effectors Central Peripheral Brain and spinal cord Sensory receptors Detection Nerves Ending of neurons or separate specialized cells Cranial from the brain and spinal from the spine A bundle of axons and their sheaths Connects the CNS to sensory receptors muscles and glands Contains both sensory and motor fibers Peripheral Nervous System o Sensory Afferent inward Transmits action potentials from receptors TO the CNS Somatic Fibers Impulses from skin skeletal muscles and joints brain Visceral Fibers Impulses from visceral organs brain o Motor Efferent outward Transmits action potentials AWAY FROM the CNS to effectors muscles glands o Motor Division Somatic Nervous System CNS skeletal muscles Voluntary Single neuron system Synapses Where action potential jumps to the next cell Neurotransmitters are released here in the synaptic cleft Types Electrical faster 2 way don t focus on this Chemical 1 way presynaptic neuron postsynaptic neuron neurotransmitters Autonomic Nervous System CNS smooth cardiac muscle Involuntary Sympathetic flight or flight parasympathetic at rest and enteric digestive tract Don t focus on this for exam 2 o Neurons Nerve Cells Structure Cell body soma single nucleus with prominent nucleolus Nissl body rough E R primary site of protein synthesis Axon output usually long process coming from the soma Branches collaterals Initial segment beginning of axon Dendrites input short and usually highly branched Dendritic spine where axon synapse with dendrite Axon hillock part of trigger zone where action potentials are made Axonal terminals presynaptic terminal buttons Neurotransmitters Action potential Ca2 enters cell neurotransmitters released from synaptic vesicles diffuse across synapse neurotransmitter binds to postsynaptic neuron Ach binds to receptor Na gates open if threshold met another action potential occurs neurotransmitters are removed Causes the transfer of electrical impulses from one nerve to the next Can be excitatory or inhibitory They are the functional unit of the nervous system nerve cells Receive stimuli and transmit action potentials electrical excitability Function of Neurons Myelin Sheath White matter myelinated axons propagation Fully developed at 1 year Degeneration in multiple sclerosis and sometimes diabetes Structure Not continuous Nodes of Ranvier spaces Function Protects and insulates axons Speeds transmission of electrical signals Repair of axons Unmyelinated Axons In invaginations of Schwann cells or oligodendrocytes Gray matter integrative functions No myelin sheaths Has propagated spread widely action potentials Originates in trigger zone Action potential in one location causes one in another and so on Can t go back because initial site depolarized The Action Potential nerve impulse o Graded potential depolarization repolarization possible hyperpolarization back to rest o All or nothing the strength of the impulse doesn t matter as long as it exceeds the threshold 55 mV each impulse is the same Resting Membrane Potential o Exists because the concentration of ions are different inside and out and because permeability is different for Na and K K 50 100 greater At rest 70 mV Outside positive K amino acids and organic phosphate Inside negative Na and Cl o Depolarization Happens first Potential difference b t inside and outside becomes smaller less polar more positive Na gates open Na rushes into cell membrane potential significantly increases Na gates close Positive feedback process o Repolarization Happens after Na gates close K gates open K rushes out potential goes back to rest or becomes too negative hyperpolarization K gates close o Hyperpolarization Afterpotential Happens if too much K exits the cell during repolarization causing more Potential difference becomes bigger more polar of a potential difference lower than 70 mV Ionic Events Na gates open Na rushes in K gates open K rushes out o o o o Axons of the Central Nervous System Tracts Axons of different neurons travelling together in bunches Called nerves in the PNS Synapses Presynaptic and Postsynaptic Neurons Pre post Synaptic Cleft space between pre and postsynaptic neurons o Removal of neurotransmitter Method depends on neurotransmitter synapse Diffusion Enzymatic degradation Acetylcholinesterase splits ACh into acetic acid and choline choline is recycled within presynaptic neuron Norepinephrine Either recycled or diffused Enzyme monoamine oxidase MAO Absorbed into circulation broken down in liver Inhibitory Synapses o Membrane becomes more permeable to K and Cl o Inhibitory postsynaptic potential IPSP Results from the opening of ligand gated molecule binds to receptor Cl or K channels Causes the postsynaptic cell to become more negative hyperpolarized Harder to depolarize stimulate Postsynaptic cell less likely to reach threshold o o o o o Central Nervous System Central Nervous System Components Brain Spinal Cord Gray matter outer cortex and inner nuclei White matter deeper White matter outer Gray deeper PNS gray matter ganglia groups of cell bodies Cerebral Cortex o Motor Areas Primary motor area cortex in the precentral gyrus of the frontal lobe o Sensory Areas Primary somatosensory area in the postcentral gyrus of the parietal lobe Right side of brain controls left side of body and vice versa Some areas of the body have larger cortical areas in the brain because they have more extensive sensory input o Primary Motor Cortex Precentral gyrus of the frontal lobe Detailed motor control larger designation in brain Right in front of it premotor area Gross big movements large motor Precise movements small motor units units Voluntary Movement Motor Homunculus Proportion Concept those pictures to the right of the sensory and motor maps in the brain larger pictures mean larger areas in the brain Somatic Motor Pathway Always involve at least 2 neurons Upper motor neuron in CNS Lower motor neuron in spinal cord Lower motor neurons brainstem
View Full Document
Unlocking...