Create
Learn
Share

PHYSIOLOGY - Neuro PART 1

rename
tasnimjaisee's version from 2017-10-14 19:40

Section 1

Question Answer
Afferentcarry information towards CNS - Sensory - stimulus to electrical energy
Efferentcarry information away from CNS - Motor
Central Nervous System (CNS)brain – spinal cord
Peripheral Nervous System (PNS)nerve tissue outside the CNS
Number of Brain neurons(80-100 billion neurons)
Number of spinal cord neurons100 million neurons
Afferent division sensors (3)Somatic - Visceral - Special
Efferent divisions (2)Somatic motor - Autonomic
Autonomicinternal organs
MotorSkeletal muscle
Neuronsthe basic functioning units of nervous system
Gliasupport cells of neural functions
Cell body (soma)Control center - extends outward; dendrites and axons
DendritesInput
AxonsOutput
Presynaptic terminalscontain transmitting elements
Sensory neuron structural TYPES (2)Pseudopolar - Bipolar
Psuedopolar structural viewOnly axons, dendrites fused with axon
Bipolar structural view2 equal fibers extends off cell body
Interneurons of CNS structural typesAnaxnic - Multipolar
Anaxonic structural viewNo axons
Multipolar structural category view (3)Branched; lack extension - 5-7 dendrites branch 4-6x - 1 long axon branch several times ending @ axon terminal
Interneuronsfacilitate communication between neurons
NervesBundles of peripheral neurons (Efferent - Afferent - Mixed)
memorize

Section 2

Question Answer
Axons lack ___ and ___; so proteins are produced in ___Ribosomes - ER - Cellbody
Axonal transport (AT) stepsFast AT walks mitochondria & vesicles on network - Exocytosis vesicle release - Synaptic vesicle recycling - Retrograde fast AT - Lysosome digestion
Peptides are ___ on rough ER and ___ by golgiSynthesized - Packaged
Fast axonal transport carries... (3)Membrane bound organelles - Anterograde - Retrograde
AnterogradeAway from cell body to axon terminal (400mm/day)
Retrograde rate200mm/day
What kind of proteins does the Slow axonal transport?Cytoplasmic & cytoskeleton proteins
Slow axonal transport: Anterograde RateUp to 8mm/day
Why are slow axonal transport slow in the first place?Slower due to pausing
KinesinsAnterograde transport - Follow positive charge on microtubules
DyneinsRetrograde transport - Follow negative charge
What do kinesins and dyneins use, to move?ATP hydrolysis
Types of synapses?Chemical (common) - Electrical
Chemical synapse (vid example) (3)Action potential at presynaptic terminal cause voltage-gated calcium ion channels to open - Calcium ions diffuse in cell making vesicle to release acetylcholine - Acetylcholine binds to receptor site ligands opening sodium channels
How do neurons find targets (2)?Chemical signals - Growth Cones
What is Myelin made of?Phospholipid membrane
What does myelin provide (3)Structural stability to axons - insulates axon ↑ electric signals - trophic factors
Demyelination causing multiple sclerosisDemyelination of brain and spinal cord - autoimmune (immune cells attack myelin) - reduced ability of myelin-producing cells
Satellite glial cells functions (2)Neurons capsule (cushion) - Nutrients
Are astrocytes gilas or neuronsGilas
How much of brain cells do astrocytes make up?1/2
What do astrocytes manage? (3)Synapse - ATP - ECF (Take K+ and H2O)
What are cells are part of blood-brain barriers and influence vascular dynamics?Astrocytes
Are Microglia in CNS or PNS?CNS
Microglia function (2)Pathogens protection - Metabolic insult recovery
If activating signals pass a threshold for these immune cells they start detriment (ex. Alzheimer's)Microglia
Which cells helps circulate cerebral spinal fluidEpendymal cells
Neural stem cell sourceEpendymal cells
2 part peripheral neuron injury when axon is cutcell body attached section lives - Other disintegrates
The proximal axon may regrow through which types of cells?Schwann cell sheaths
____ repair less likely to occur naturally. (CNS/PNS)CNS
____ tend to seal off and form scar tissueGila
Which cells create a tube to guide regenerating axons?Schwann cells
What is the rate for which Schwann cells create small nerve tubes?1 mm/day
What is the rate for which Scwann cells create large nerve tubes?5 mm/day
Are satellite glial cells in CNS or PNS?PNS
memorize

Section 3

Question Answer
Why are neurons and muscle cells “excitable”Propagate spreading ability over long distances
Factors influencing membrane potential (2)Uneven ion distribution - Membrane permeability
Nernst equationMembrane potential if membrane was permeable to only one ion
Goldman-Hodgkin-Katz equationPredicts membrane potential from contribution of all ions crossing membrane ○ (concentration x permeability)
Out of K+ ○ Na+ ○ Cl - which are the most available in conducting electrical signals?K+
Out of K+ ○ Na+ ○ Cl - which contribute slightly in conducting electrical signals?Na+
Out of K+ ○ Na+ ○ Cl - which contribute minimally in conducting electrical signals?Cl-
Resting membrane potential in most neurons is at which charge and due to which chemical(s)?~ -70mV due to K+ and Na+ and Cl-
Significant change in membrane potential (i.e. -70mV to +30mV) does not indicate ___concentration gradients change
What is the state of the concentration gradients during alterations?Relatively constant
____ ions need to move to alter the membrane potential (Few/Many)Few
To alter the membrane potential by 100mV, what must be done?1 out of every 100,000 K+ ions must enter/ leave
5 major types of ion channelsNa+ ○ K+ ○ Ca2+ ○ Cl- ○ monovalent cation
Monovalent cation channelsNa+ and K+ passing
Gated channel types (3)Mechanical - Chemical - Voltage
Mechanically gated channels (2)Open response to physical forces (pressure) - In sensory neurons
Chemical channelsRespond to ligands
Voltage channelsrespond to changes in the cells membrane potential
Differences between channels (4)Volage - Speed - de/re-polarization - spontaneous inactivation
What are examples of diseases which are formed by channelopathies? (3)Cystic fibrosis - Insensitivity to pain - Muscle diseases
ChannelopathiesAlter activation/inactivation
Types of channelopathies mutatons (3)Permeation - Activation/Inactivation
"Rm"Membrane resistance
"Ri"Internal resistance of the cytoplasm
Ohm’s law EquationI=V/R
Membrane resistanceresistance of phospholipid bilayer
Internal resistance of the cytoplasm depends on... (2)cytoplasm composition - cell size
2 Sources of resistance in cellMembrane - Cytoplasmic resistance
What does resistance determine?How far current will flow before energy dissipates
Graded potentialsSignals that travel over short distances & lose strength traveling
Which potentials can be depolarizing OR hyperpolarizing?Graded potential
Which potentials can create large enough depolarization to induce action potential?Graded potentials
Actions potentialsBrief, rapid & large depolarizations travel long distances through neuron without losing strength
What is Graded Potentials' proportionalityAmplitude is proportional to stimulus strength
What happens to graded potential as it spreads out from originDecreases its strength
What is graded potentials generated by? (2)Chemically gated ○ Leak channel closure
Graded potentials lose strength as they move through cell due to.. (2)leak and resistance
Graded Potentials: DepolarizationExcitatory Postsynaptic Potential (EPSP)
Graded Potentials: HyperpolarizationInhibitory Postsynaptic Potential (IPSP)
If strong enough (excitatory), what do graded potentials do?Reach the trigger zone and fire an action potential
Subthreshold Graded Potential (Initially, Traveling, Trigger-zone)Initially: Graded potentials above T ○ Traveling: Decreases strength ○ @ Triggerzone→Below T; no AP
Suprathreshold Graded Potential (Initially, Trigger-zone)Initially: Strong stimulus same point creates potential above T - @ Triggerzone→Above T; AP
For high concentration of voltage gated Na+ channels, at which voltage does membrane potential generate?55mV
memorize

Section 4

Question Answer
Which channels help set the resting membrane potential?Voltage-gated Na+ and K+ channels ○ Leak channels
Voltage gated Na+ and K+ channels are both activated by? (depolarization/ polarization)depolarization
Upon depolarization, between Na+ and K+ which channels open slower?K+
Action potential steps: Rising phaseMembrane depolarizes to T ○ Channels open
Action potential steps: Falling phaseK+ enters slow after Na+ enters
Action potential steps: After hyperpolarizationK+ channels stay open until hyperpolarization
During rising phase which voltage causes channels to inactivate?30mV
During rising phase what voltage charge causes channels to activate?-55 mV
Which AP phase is known as depolarization?Rising phase
Which AP phase is known as repolarization?Falling phase
Can Na-K ATPase returns ions to original compartments before another AP trigger?Yes
What happens to the membrane potential when Voltage gated K+ do not immediately close upon reaching -70mVMembrane potential dips below resting membrane potential
How do voltage gated Na+ channels close at peak AP (3)@RMP activation gate closes ○ Stimulus arrives; Activation gate for Na+ enterance ○ inactivation gate closes; Na+ entry stops ○ Repolarization causes K+ to leave; gates reset
Inactivation gates ceases a which kind of loop?Positive feedback loop
Absolute refractory period2nd AP can't be initiated 1-2 msec ○ Na+ channels inactive
Relative refractory periodSecond AP can be initiated but requires a larger than normal stimulus (graded potential) 2-5 msec
During which refractory period some Na+ channels are open?Relative refractory period
Which refractory period must overcome more negative membrane potential (afterhyperpolarization)?Relative refractory period
Which refractory period ensures AP moves in 1 direction onlyRelative refractory period
AP conduction size is identical at?trigger zone and axon terminal
What happens when positive ions enter the neuron?current flows to adjacent sections of the axon
How are action potentials are conducted? (4)Graded potential enter trigger zone ○ Na enters; +ve charge ○ Local current causes depolarization ○ K+ loss re-polarizes membrane
What prevents backward conduction?Refractory period
What are the purposes of refractory periods?AP traveling in one direction - Limits rate which signals are transmitted: Prevents toxicity
memorize

Section 5

Question Answer
What happens if an axon has a large diameter in terms of conduction velocity?Less internal resistance
Conduction velocity resistance of the axon membrane to ion leakageCurrent spread to adjacent sections more rapidly if not lost via leak channels (myelin)
AP conduction is more rapid in axons with?high-resistance membranes
Saltatory conduction1 node to another node conduction
Within Myelinated and unmyelinated axons which has the bigger diameter?Myelinated
Node of Ranvier have which gated channels?Volatage gated Na+ Channels
___um myelinated axon has same velocity of a ___um unmyelinated10 ○ 500
AP cannot be maintained in the unmyelinated region due to?A lack of Na+ channels
When current leaks from unmyelinated region what happens?Depolarization is subthreshold when it reaches the next node containing Na+ channels
What is an example of chemicals that exist interfering with conduction by binding to Na+, K+ or Ca2+Local anesthetics
How can electrical activity be altered?Chemical binding - ECF concentration
How many synapses can a postsynaptic neuron can contain?150,000 synapses
Electrical synapsesIons flow directly from 1 cell to the next
NeurocrineReleased from neurons used for cell-to-cell communication
NeurotransmittersRapid response
NeuromodulatorsSlow response
Which neurocrine acts on a postsynaptic cell in close vicinityNeurotransmitters - Neuromodulators
NeurohormonesSecreted into the blood stream - Act on targets throughout the body
Neurocrine can act as a ____ at one synapse and ____ at another depending on the receptors presentNeurotransmitter - Neuromodulator
2 categories of neurocrine receptorsIonotropic - Metabotropic
Ionotropicligand gated ion channels - Specific for 1 ion or non-selective cation - Fast postsynaptic responses
Metabotropic receptorsG-protein coupled receptors - Receptor tail is a 3 part
G-Protein3 part membrane transducer
Metabotropic receptorsG-Protein responses: Direct with ion channels - Activate membrane-bound enzymes
G-Protein response: Interact directly with ion channelsOpening/closing channels depending on g-protein (gi , gs)
Metabotropic receptorsInteraction with a membrane bound enzyme: signal transduction pathways: Phospholipase C Signal - Adenylyl cyclase
Phospholipase C Signal transduction pathway (5)G activates PLC - PLC converts phospholipids into DAG - IP3 diffuses in cytoplasm - DAG activates PKC - IP3 causes Ca2+ release; signal
Examples of Amplifier enzymePhospholipase (PLC) - Adenylyl cyclase
Protein Kinase C (PKC)Phosphorylates proteins
Adenylyl cyclase signal transduction pathwaySignal molecule binds to GPCR; activating G →Adenylyl cyclase →ATP to cyclic AMP →Kinase A →Cellular response
memorize