Human Anatomy & Physiology Notes: Neurology and the Brain

Bio Unit 2 Review

Test Review
• Ions want to get to E(ion)

• Electrical synapses only excitatory

• CSF produced by choroid plexus, in ventricles

• Ionotropic stimulation can result in IPSPs

• H-zone thick filaments only

• Parasympathetic uses muscarinic
• Sympathetic adrenergic

• Depolarizing of axon hillock to threshold = AP
• Hyperpolarizing alone can never generate AP
• Tonic sensory receptor triggers AP for entire duration of stimulus
• 2 APs can never be conducted down axon at same time

• Decreased acetylcholinesterase = more frequent contraction and increased Ach release
in response to AP

• Internodes are made of Schwann cells wrapped around axons

• On axon, CNS has mechanically-gated sodium channel
• Primary sensory neuron VGSC
• Nicotinic receptor on ganglion chemically-gated potassium channel
• Muscarinic receptor has VGCC

• Intrafusal fibers send sensory signals to brain to maintain tonus

• Thalamus is in diencephalon to integrate somatosensory stimuli and relay to cerebrum

• More Na+ ions = Vm closer to 0

M3-1 & M3-2 Notes
• Enteric NS works independently of CNS
• Pseudounipolar only afferent

• Synaptic cleft between terminus and dendritic spine
• Axon hillock is trigger zone

,• Collateral is branch of axon that leads to axon terminus

• CNS
o Interneurons = multipolar and anaxonic
• PNS
o Sensory = pseudounipolar and bipolar
o Motor = multipolar

• ICF slight excess of anions
• ECF slight excess of cations

• Hyperpolarize is more negative
• Depolarize is closer to 0
• Repolarize is return to RMP
o From K+ exiting cell

• Action potentials are regenerative
o Trigger downwards, amplitude same, non dissipative w distance
o Not summable
• When action potential reaches axon terminus, activates VG Ca2+ channels
o Depolarization, Ca2+ enters cell
o Vesicles fuse with cell membrane

• Hypokalemia = decreased [K+] = hyperpolarization
• Hyperkalemia = increased [K+] = depolarization

• Termination of signal
o Back to glial cells or axon terminus
o Enzymes inactivate neurotransmitters
o Diffuse out of synaptic cleft
• Electrical synapses cannot transmit IPSPs

• 6 connexins = 1 connexon/hemichannel
o 2 connexons = 1 gap junction
• Gap junctions are hydrophilic pores
• Direct electrical connection between neurons

• Neurotransmitter/neuromodulator released into synaptic cleft
• Neurohormone released into blood

• EPSP = closes K+ channel or opens Na+ channel
• IPSP = closes Na+ channel or opens K+/Cl- channel

, • Acetylcholine controls skeletal/smooth muscle and glands
• (Nor)epinephrine controls smooth muscle and glands
• GABA controls CNS (inhibitory)
o GABAa opens Cl- channel
o GABAb opens K+, closes Ca2+
• Glutamate controls CNS (excitatory)
o Glutamate ionotropic opens Na+/Ca2+ channels
o Glutamate metabotropic closes K+ channels
• Cholinergic relates to acetylcholine
• Adrenergic relates to (nor)epinephrine

• Botulinum blocks acetylcholine release
• Black widow venom increases intracellular [Ca2+] and neurotransmitter release
• Nicotine mimics acetylcholine and binds to nicotinic cholinergic receptors
• Morphine blocks neurotransmitter release at pain synapses


M3-3 Notes
• Somatosensory neurons part of PNS
• Somatosensory nuclei part of spinal cord

• Cancer usually glial because glial cells rapidly divide
• Neurons do not divide easily
• Oligodendrocytes form myelin sheaths
• Microglia are scavengers

• Ventricles all filled with CSF
• Ventricles connected (contiguous)

• Dorsal root à dorsal horn à ventral/lateral horn à ventral root
• Horns: regions of gray matter within spinal cord
• Roots: cables of efferent axons
• Efferent à visceral use lateral horn
• Efferent à somatic use ventral horn

• Cerebellum does not initiate; cerebrum does
• Cerebellar agenesis born without cerebellum
o Survive because of neuroplasticity

• Cerebrum gray matter
• Gyri are convolutions
• Sulci are grooves