Exam Notes On Nervous System PDF

ONE one TWO THREE functional anatomy - FOUR of the ·erveug fijftem FIVE SIX SEVEN...

ONE one TWO THREE functional anatomy - FOUR of the ·erveug fijftem FIVE SIX SEVEN EIGHT NINE TEN ELEVEN TWELVE @ Sog o Digital Hub Title : Date : ONE Week : organisation of the nervous system : TWO CENTRAL NS OUTPUT TO PNS INPUT TO CNS D brain + Spinal cord * THREE PERIPHERAL NS afferente division efferente division A T T somatic nervous system autonomic nervous system voluntary involuntary FOUR visceral stimuli sensory + # Fibers from environment # T T NS external/internal motor neurons sympathetic NS parasympathetic enteric NS control rest + Flight-fight - hormones response digest = conserves energy * T T heart / rate Skeletal cardiac muscle EFFECTOR muscles digestive FIVE respiration ORGANS organs smooth muscle execrine glands endocrine some glands SIX Functional classes of neurons : SEVEN 1 afferente neurons from efferent division -p PNS receptors ends that AP in sensory at generates response · EIGHT to a stimilus - cell body = X dendrites/presynaptic input · lies next to spinal cord NINE - have a long peripheral axon extends from receptor - b cell body short central axon from cell body - a spinal cord TEN. 2 Interneuron. efferente 3 neurons · facilitate communication btun aff + eff. · cell bodies originate in CNS · within CNS · presynaptic inputs converge on the cell body : influencing ELEVEN · integrate peripheral info + responses its activity · the interconnections btwn internations are responsible for : · convey the integrated output to effector organs thoughts emotions intellect ect. in CNS in effector organs , , , memory · dendrites + cell body , axon TWELVE · axen = PNS (muscle movement + glandular excretion) @ Sog o Digital Hub Title : Date : ONE Week : Glial cells : TWO found in CNS : 1.. Astrocytes : 2. Ependymal cell THREE - forms part of blood brain barrier ~ lines ventricles of brain + central canal of S C.. - regulate If composition ~ assist in preduction + circulation of cerebrospinal fluid ↓ ~ structural support + orginization to CNS absorbs shock , regulate environm + link brain cells and bioed FOUR ~ assist with neuronal development ~ replicates to occupy space of dying neuvers 3. Microglial cell cells ~ phagocytic meves through CNS. 4 Oligodendrocytes : engulve infectious agents harmful substances protection FIVE ~ + : insulates ↳ ~ myelinates + (NS axens synaptic pruning : remove unnessacary neurons ~ Fastens AP propagation along axens in CNS SIX SMEA SEVEN EIGHT (majority NINE TEN ELEVEN TWELVE @ Sog o Digital Hub Title : Date : ONE Week : membrane potential : electrical communication : TWO ~ separation of charges across plasma memb causes MP MP (unequally distributed ( ~ + what causes : Nat + k large intracellular proteins tions · THREE = plasma memb permeability signal transduction · * nerve + muscle cells : excitable tissue FOUR & RMP environmental Stimuli = X signals produced = convert a specific response = used for communication = energy-delectrical energy to receive stimuli : graded pot & afferent ending / pest synaptic heuren FIVE · graded potentials = aff. neuron + post-synaptic neuren changes in memb potential in stimuli (need response to lot change = a to SIX AP TH-petential = X -A represents sub don't long distance = over propogate SEVEN · action potential long distance = along ave n = short+ rapid a in memb pot. EIGHT = propegate along the length of excitable cells = depol/hyperpol/repolarize Hyperpolarization: An increase in the membrane potential, making the NINE inside of the cell more negative than the resting membrane potential. Depolarization: A decrease in the membrane potential, making the inside of the cell less negative than the resting membrane potential. , TEN ELEVEN TWELVE @ Sog o Digital Hub Title : Date : ONE Week : Graded potential : TWO MP in signal is receive/process/iniate/ transmit · when rapidly A a nerve cell-electrical used to a message THREE how AP is generated : FOUR FIVE SIX outside area becomes SEVEN morc - the depolar , Spreads to adj. inactive areas : new active area the new active area = A permeability of plasma memb tion flew : spreading depol. EIGHT the GP is spread to adjacent inactive areas = depolarization = new active areas * in permeability + on mevement during AP causes dep. to spread futher away from original active area NINE TEN ELEVEN TWELVE @ Sog o Digital Hub Title : Date : ONE Week : TWO I THREE ↑ - s & D 1 S 5 g s " - 3i => i & # O & # & - S S & & - e & O r & · - · - [t - 2 & 5 & & & & + G FOUR T I 8- I - ↑ - 3 & S : & 1 D T S & & · S S 3 FIVE 3 · & & S 8 -s · - I - T 4 S SIX & : & & 5 3 8 & & · · & & ⑤S · + SEVEN · g · 7 & S & 8 S & 5 ⑤- & # 6 - j & j & EIGHT 5 & NINE D & & ~ T · : · 5 & · S 3 = - & : S 1 S I · ·↳ · & & I & TEN = & 3 · 8 j S & - 2 Z & & S 5 & -. · 8 G & ↓ S J · S ! · % I C & O B * G - S ↳ & S 8 & & -- & is I - I & T8 s & - ELEVEN 8 S S - ·. 3 8 & - T 3 & 8 I · # & T 3 S TWELVE @ Sog o Digital Hub Title : Date : ONE Week : Chemical synaps : TWO THREE FOUR. 6 neurot. binds to receptors on post-synaptic memb 1. post s Heuren = has receptor channels channel.. : causes to open for ion > MP movem change of - post-s. Heuren -p firing of AP in post- syn - memb if TH pet is reached.i f 2 neuren terminal is on effektor cell L binding FIVE cause 2ndary messenger system : change cellular activity. SIX SEVEN 1. neurotransmitters packaged resides into in terminal are + stered presynaptic EIGHT Ap down aven terminal activates. 2 propogates into den : synaps The voltage-gated Nat. 3 AP channels in influx Nat causes synaptic kneb to open : of 4. F of Not of From resides synaptic cleft via exocytes is causes release neurotransm. synaptic into NINE. 5 released Neurot. diffuse access synaptic cleft + bind to receptors in postsynaptic. memb. 6 neurotransm. receptors are also ion channels = allow in mevement. 7 Flew ofiens through recepter channels a memb pot of postsynaptic neuvers : trigger AP if TH is reached TEN activation of and messenger system : electrical-p chemical signals = slight delay in transfer of signals = synaptic delay ELEVEN TWELVE @ Sog o Digital Hub Title : Date : ONE Week : TWO channels specific · receptor : non binds permeability E + · when neurot. to receptor both Nat + k = small dep THREE · more Not move into cell than 11 out = net movement-p small depolarization excitatory bring post syn. TH · neuven to I synaps not enough to FOUR but brings MP closer to TH inhibitory ↑ permeab of 21 12 + FIVE · + synapses · K" out of cell (linte = mp mere- , ↳ hyperpolarizes cell (less likely to reach TH = small hyperpol SIX Neurotransmitters : SEVEN · acetylcholine released from meter + parasym merves · dopamine B - in active in CNS functioning = involved of CNS + PNS = EIGHT · norepinephrine · glycine released by symp. nerves in = involved functioning of CNS + PNS = majer inhibitory neurot. of spinal cord NINE · serotonin behaviour appetite mood glutamate · , TEN active in CNS found primary = , also in gut + platlets = excitatory neurot - of CNS · GABA ELEVEN majer inhibitory of = neurst brain TWELVE @ Sog o Digital Hub Title : Date : ONE Week : TWO THREE 1. Synaptic Structure: A synapse typically consists of: Presynaptic Terminal: The end of the axon of the presynaptic neuron. Synaptic Cleft: A small gap between the presynaptic and postsynaptic neurons. Postsynaptic Membrane: The membrane of the dendrite or cell body of the postsynaptic neuron. FOUR 2. Synaptic Transmission: Action Potential Arrival: When an action potential reaches the presynaptic terminal, it triggers the opening of voltage-gated calcium channels. Calcium Influx: Calcium ions (Ca2+) enter the presynaptic terminal due to the opening of calcium channels. Neurotransmitter Release: The influx of calcium stimulates the fusion of synaptic vesicles with the presynaptic membrane, releasing FIVE neurotransmitters into the synaptic cleft. Neurotransmitter Diffusion: Neurotransmitters (e.g., acetylcholine, glutamate, GABA) diffuse across the synaptic cleft and bind to receptors on the postsynaptic membrane. 3. Postsynaptic Response: SIX Receptor Activation: Neurotransmitter binding activates receptors on the postsynaptic membrane. Receptors can be ligand-gated ion channels or G protein-coupled receptors. Ion Channel Opening: Depending on the receptor type, ion channels on the postsynaptic membrane open, allowing ions to flow into or out of the cell. Postsynaptic Potential: SEVEN The influx or efflux of ions leads to a postsynaptic potential, which can be excitatory (depolarizing) or inhibitory (hyperpolarizing). 4. Integration and Action Potential Generation: Summation: Postsynaptic potentials summate at the axon hillock, where the decision to generate an action potential is made. Threshold Reached: EIGHT If the summation reaches the threshold, an action potential is generated at the axon hillock. 5. Termination of Signal: Neurotransmitter Removal: Neurotransmitters are removed from the synaptic cleft through reuptake, enzymatic degradation, or diffusion. Reuptake or Enzymatic Breakdown: NINE Neurotransmitters can be actively transported back into the presynaptic terminal (reuptake) or broken down by enzymes. 6. Presynaptic Inhibition and Facilitation: Modulation of Release: The presynaptic terminal can be modulated by other neurons through processes such as presynaptic inhibition (reduced neurotransmitter release) or presynaptic facilitation (increased neurotransmitter release). TEN ELEVEN TWELVE @ Sog o Digital Hub  Title : Date : ONE Week : 1. Contiguous Conduction: Description: TWO In contiguous conduction, the action potential spreads continuously along every portion of the axon membrane. This process occurs in unmyelinated axons, where the entire length of the axon membrane is involved in the propagation of the action potential. Process: Depolarization: The action potential is initiated at the axon hillock and propagates along the entire length of the axon. THREE Voltage-Gated Ion Channels: Voltage-gated sodium and potassium channels along the axon membrane open and close sequentially to allow the propagation of the action potential. Local Current Flow: The influx of sodium ions at one point on the membrane creates a local current that depolarizes the adjacent region, leading to the opening of voltage-gated channels in that region. Characteristics: FOUR Contiguous conduction is relatively slow. It consumes more energy due to the constant movement of ions along the entire length of the axon membrane. Example: Unmyelinated axons in the pain receptors (nociceptors) or some autonomic neurons utilize contiguous conduction. FIVE 2. Saltatory Conduction: Description: In saltatory conduction, the action potential jumps from one node of Ranvier to another, skipping the myelinated regions of the axon. This process occurs in myelinated axons, where the myelin sheath insulates the axon, allowing for faster and more SIX energy-efficient transmission. Process: Nodes of Ranvier: Action potentials are generated only at the nodes of Ranvier, which are small, non-myelinated gaps in the myelin sheath. Saltatory Propagation: The action potential "jumps" from one node to the next, skipping the myelinated regions. SEVEN Local Circuit Currents: At the nodes, local circuit currents depolarize the membrane, allowing the action potential to be regenerated at each node. Characteristics: Saltatory conduction is significantly faster than contiguous conduction. It is more energy-efficient because ion movement is restricted to the nodes of Ranvier. EIGHT Example: Motor neurons and sensory neurons in vertebrates often utilize saltatory conduction due to the presence of myelin. nodes of Ranvier i a xen RMP : - zemV hillock / NINE + + + + t V + · ----- ~ ' depolarise ↓ · + 1 - opens Nat + 1 channels TEN I 0 - Da t + 5 + + + + P p P