Neurophysiology (Struc. Func) Flashcards
2 Categories of Cells in the Nervous System
NEURONS (Greek neuron=nerve)
MAJOR Functional Units of the ? System
? excitable (action potential)
Specialized in ?
? once they reach maturity
Injury leading to neuronal death will ? change the structure & functions of the affected areas
NEUROGLIA/GLIAL CELLS (Greek glia= glue)
The ? Cells, The ? System
Involved in the ? & ? of the nerve cells
? (gives structural shape) ?, ?(both associated with myelin; sphingolipid)
NEURONS (Greek neuron=nerve)
MAJOR Functional Units of the Nervous System
Electrically excitable (action potential)
Specialized in information processing
Do not divide once they reach maturity
Injury leading to neuronal death will permanently change the structure & functions of the affected areas
NEUROGLIA / GLIAL cells (Greek glia= glue) The Helper Cells, The Support System
Involved in the nutrition & maintenance of the nerve cells
Astrocytes, Oligodendrocytes, Schwann cells
NEURON
- DENDRITES – information-? area of the cell membrane, detect ?
- CELL BODY, ? or ? – contains ?
- ? or ? – axon origin; originates ** !! Action
Potential (AP) !! ** - AXON – ? extension of the cell membrane
- ? TERMINAL – end of axon; transmit information ( through ? )
- MYELIN SHEATH – enhances ? of information transfer
- NODE OF RANVIER – gaps in the ?
SENSORY or AFFERENT
* Send (INPUT) information from ? toward the ?
* includes Somatic (skin or skeletal muscles) and ? (? organs)
INTERNEURONS or ASSOCIATION NEURONS
* Found in the ?,
* ? * motor and sensory neurons
MOTOR or EFFERENT
* Send information from the brain/spinal cord to ? (? , command)
* only somatic or somatic and autonomic ?
NEURON
* DENDRITES – information-receiving area of the cell membrane, detect stimuli
* CELL BODY, SOMA or PERIKARYON – contains organelles
* AXON HILLOCK or TRIGGER ZONE – axon origin; originates Action
Potential (AP)
* AXON – information-carrying extension of the cell membrane
* PRESYNAPTIC TERMINAL – end of axon; transmit information (neurotransmiters)
* MYELIN SHEATH – enhances speed of information transfer
* NODE OF RANVIER – gaps in the insulating myelin sheath
SENSORY or AFFERENT
* Send (INPUT) information from receptors toward the brain/spinal cord
* Somatic (skin or skeletal muscles) and visceral (internal organs)
INTERNEURONS or ASSOCIATION NEURONS
* Found in the brain/spinal cord, connecting motor & sensory neurons
MOTOR or EFFERENT
* Send information from the brain/spinal cord to muscle/glands (effectors, command)
* Somatic (voluntary) and autonomic (involuntary)
Bipolar Neuron
- Have 2 ? that connect to the cell body
- 1 ? & 1 ?
- Found in ? areas of the nervous system (? and ? - olfactory epithelium, nasal cavity, inner ear, retina)
- are * ? *
Bipolar Neuron
Have 2 processes that connect to the cell body
* 1 axon & 1 dendrite
* Found in specific areas of the nervous system (retina and nose - olfactory epithelium)
INTERNEURONs
Pseudounipolar Neurons:
1 single stem ? that branches to form 2
- ? and ? NS
- do not have ?, axonal processes will receive and ? information
sensory neurons
- send info. from ? in sensory organs towards the ?
MULTIPOLAR NEURONS
- 1 axon and many ?
- most ? type
- found ? the body
MOTOR NEURONS & INTERNEURONS
Send information from the brain/spinal cord to ?
Pseudounipolar Neurons:
1 single stem axonal process that branches to form 2 processes
- peripheral and central NS (sensory ganglia, and cranial nerves)
- do not have dendrites , axonal processes will receive and transmit information
sensory neurons
- send info. from receptor in sensory organs towards the brain/spinal cord
MULTIPOLAR NEURONS
- 1 axon and many dendrites
- most common type
- found throughout the body
MOTOR NEURONS & INTERNEURONS
Send information from the brain/spinal cord to muscles/glands.
THE NEURON
Dendrites: receive signals from ? terminals of other neurons
Cell body: contains organelles such as:
* Nucleus
* Free ?
* ?
* ?
* ? -> these are contained everywhere in neurons in large quantities as nerve cells require large amounts of ?
Axon hillock and Initial axon segment:
* Integrates ? (often ? each other) &
* ? and ? the AP before it is propagated along the ?
Axon: can be very ?, is the ? unit, adult axons often don’t contain ? and depend on ? from cell body.
Presynaptic Terminals: signaling to ? cells
THE NEURON
Dendrites: receive signals from presynaptic terminals of other neurons
Cell body: contains organelles such as:
* Nucleus
* Free ribosomes
* RER
* GA
* mitochondria -> these are contained everywhere in neurons in large quantities as nerve cells require large amounts of ATP
Axon hillock and Initial axon segment:
* Integrates different signals (often opposing each other) &
* generates and shapes the AP before it is propagated along the axon
Axon: can be very long, is the conducting unit, adult axons often don’t contain ribosomes and depend on protein from cell body.
Presynaptic Terminals: signaling to adjacent cells
NEURON AND SYNAPSE
Neurons communicate via ** ? **
in Greek “Synapsis” means ?
- ? * with other neurons, muscle fibers or glands
- Synapses are formed by:
1. The ? terminal of one cell
2. The ? surface of the ? cell (i.e., ? synaptic cell)
3. Synaptic ? ( i.e., ? b/t the 2 cells) - Action potentials travel * ? * the axon
- Speed varies from 0.5 to 120 meters per second
- Larger axons are * ? *
- Smaller ones (< 1 μm in diameter) are myelinated or nah?
NEURON AND SYNAPSE
Neurons communicate via ** synapses **
in Greek “Synapsis” means connection
- specialized contact areas * with other neurons, muscle fibers or glands
- Synapses are formed by:
1. The presynaptic terminal of one cell
2. The receptive surface of the adjacent cell (i.e., postsynaptic synaptic cell)
3. Synaptic cleft ( i.e., space b/t the 2 cells) - Action potentials travel * along * the axon
- Speed varies from 0.5 to 120 meters per second
- Larger axons are * myelinated *
- Smaller ones (< 1 μm in diameter) are not myelinated
Myelin Sheath
The myelin sheath is a greatly modified ?
Wrapped around the axon in a ? fashion
Originate from and are part of the:
* ? cells in ?
* ? in the CNS
Each myelin-generating cell furnishes myelin for only ? of the axon
The periodic interruptions are the ?
* Critical to the ?
Myelin Sheath
The myelin sheath is a greatly modified plasma membrane (PM)
Wrapped around the axon in a spiral fashion
Originate from and are part of the:
* schwann cells in PNS
* oligodendrocytes in the CNS
Each myelin-generating cell furnishes myelin for only segment of the axon
The periodic interruptions are the NODES OF RANVIER
* Critical to the functioning of myelin
NEURON AND SYNAPSE
The Myelin Sheath Facilitates
?
“? Insulation”
Saltatory Conduction of the impulse
* in Latin, Saltare = to “ ? ”
* Action Potentials “jumps” from ?
to ?
* Depolarization occurs more rapidly in ? axons
saltatory conduction: when AP goes from one ? to another
NEURON AND SYNAPSE
The Myelin Sheath Facilitates
conduction
“Electrical Insulation”
Saltatory Conduction of the impulse
* in Latin, Saltare = to “ jump ”
* Action Potentials “jumps” from node
to node
* Depolarization occurs more rapidly in myelinated axons
saltatory conduction: when AP goes from one nodeS OF RANVIER to another
THE NEURON INFORMATION CONDUCTION
Dendrites: receive signals from ?
terminals of other neurons
Dendritic spines: small ? of the dendritic membrane, they greatly increase the ? of the postsynaptic cell
Contain specialized * ? * to recognize the
* chemical ?* released from the presynaptic terminal
THE NEURON INFORMATION CONDUCTION
Dendrites: receive signals from presynaptic
terminals of other neurons
Dendritic spines: small protrusions of the dendritic membrane, they greatly increase the receptive surface of the postsynaptic cell
Contains specialized receptors to recognize the chemical transmitters released from the presynaptic terminal
NEURAL COMMUNICATION AND SIGNALING
- Receptors (usually dendritic) receive ? signals from ? terminals of just one or many other neurons?
- Receptors convert neurochemical signals into small ?
- All different signals are integrated at * ? * (IPSPs and EPSPs)
- Depending on results of this integration, ? may be generated
- AP travels ?, to the ? terminals and causes release of chemical neurotransmitters onto another ? or ? cell
NEURAL COMMUNICATION AND SIGNALING
- Receptors (usually dendritic) receive neurochemical signals from presynaptic terminals of many other neurons
- Receptors convert neurochemical signals into small voltage changes
- All different signals are integrated at * axon hillock initial axon segment * (IPSPs and EPSPs)
- Depending on results of this integration, AP may be generated
- AP travels rapidly along the axon, to the presynaptic terminals and causes release of chemical neurotransmitters onto another neuron or muscle cell
RESTING MEMBRANE POTENTIAL
The resting membrane potential is determined by the “ ? “ (charged particles) between the inside & the outside of the cell and by the different “ ? “ of the membrane to different types of ions.
→ Especially ? and ?
Although net concentration of + and - charges is similar in both ? and ? fluids:
-> “ ? “ accumulates just “ ? “ the cell membrane, & excess of ? charges immediately ? the cell membrane
-> This makes the inside of cell ? charged compared to outside of cell
-> This electrical difference (voltage) across membrane: ? with cells, in mammalian neurons: ~ ** !!! IMP!! (average) **
RESTING MEMBRANE POTENTIAL
The resting membrane potential is determined by the “ uneven distribution of ions “ (charged particles) between the inside & the outside of the cell and by the different permeability of the membrane to different types of ions.
→ Especially ? and ? ions
Although net concentration of + and - charges is similar in both extracellular and intracellular fluids:
-> “ excess positive charges “ accumulates just “ outside “ the cell membrane, & excess of negative charges immediately inside the cell membrane
-> This makes the inside of cell - ly charged compared to outside of cell
-> This electrical difference (voltage) across membrane: ? with cells, in mammalian neurons: ~ ** !!! IMP!! (average) ** -> ~ - 70 mV (AVERAGE)
RESTING MEMBRANE POTENTIAL
Resting membrane potential is a result of 3 major factors:
- The ? on the inside and outside of the cell.
An ion species will move toward a ? if it can flow across the membrane.
* the concentration difference across the membrane creates a ?, creating an ? to a charge imbalance across membrane = voltage
This is called the ? for that ion. Ions always flow ? it!
- ? (ATPase): this ?-dependent pump in cell membranes pumps ** ? ** of the cell and draws ? ions into the cell ** ? ** their concentration gradients, #? Na+ ions out for each #? K+ ions in
- Differential permeability of the membrane to diffusion of ions: the resting membrane is much more permeable to ? than to ? ions because it has many more ? than ?
RESTING MEMBRANE POTENTIAL
Resting membrane potential is a result of 3 major factors:
- The concentration of ions on the inside and outside of the cell.
An ion species will move toward a dynamic equilibrium if it can flow across the membrane.
* the concentration difference across the membrane creates a chemical driving force, creating an electrical driving force leading to a charge imbalance across membrane = voltage
This is called the equilibrium potential for that ion. Ions always flow towards it!
- Na+, K+ pump (ATPase): this energy-dependent pump in cell membranes pumps ** Na+ ions OUT ** of the cell and draws K+ ions into the cell ** AGAINST ** their concentration gradients, 3 Na+ ions out for each 2 K+ ions in
- Differential permeability of the membrane to diffusion of ions: the resting membrane is much more permeable to K+ than to Na+ ions because it has many more K+ leak channels than Na+ leak channels
MEMBRANE POTENTIAL CHANGES
Resting membrane potential can be changed by synaptic signals
- ? are unique, their membrane potential can be changed by a ? from another cell
neurotransmitters (released from presynaptic axon terminal) bind to receptors on the ? membrane -> open or close ? channels and change the ? of the postsynaptic cell
-> can change it in 2 ways: make more ? or more ?
-> this depends on which ? are activated
-> creating ** ? potential **
Resting membrane potential can be changed by synaptic signals
- neurons and muscle cells are unique, their membrane potential can be changed by a synaptic signal from another cell
neurotransmitters (released from presynaptic axon terminal) bind to receptors on the postsynaptic membrane -> open or close ion-selective channels and change the membrane potential of the postsynaptic cell
-> can change it in 2 ways: make more - or more +
-> This depends on which receptors are activated
-> Creating postsynaptic potential
MEMBRANE POTENTIAL CHANGES
- If postsynaptic potential: more positive than RP (-70 mV) → ? → increases or decreases the chances for reaching the threshold and triggering an AP
- Depolarization (more positive), caused by: ? open, ? ions flow inside the cell
- Chemical transmitter is quickly removed from synapse: change only lasts ? as channels close again
*If postsynaptic potential more negative than RP (-90mV) → ? → decreases or increases the chance for triggering an AP?
Hyperpolarization (more negative), caused by: opening of K+ channels, K+ ions move out
MEMBRANE POTENTIAL CHANGES
- If postsynaptic potential: more positive than RP (-70 mV) → excitatory postsynaptic potential (EPSP) → increases the chances for reaching the threshold and triggering an AP
- Depolarization (more positive), caused by: Na+ channels open, Na+ ions flow inside the cell
- Chemical transmitter is quickly removed from synapse: change only lasts * milliseconds * as channels close again
*If postsynaptic potential more negative than RP (-90mV) → inhibitory postsynaptic potential (IPSP) → decreases the chance for triggering an AP
Hyperpolarization (more negative), caused by: opening of K+ channels, K+ ions move out
THE ACTION POTENTIAL
Resting membrane potential
All cells * ? * (voltage) across
their cell membrane
? and ? are special: the electrical potential can be changed in response to:
* ? from other cells
* ? of environmental energy (sensory organs)
When change in membrane potential (neuron/muscle cells) reaches a ? value, this causes a dramatic change in the ?:
called an ** ? ** (AP)
THE ACTION POTENTIAL
Resting membrane potential
All cells * have an electrical potential (voltage)* across their cell membrane
** neurons and muscle cells ** are special, the electrical potential can be changed in response to:
* synaptic signaling from other cells
* transduction of environmental energy (sensory organs)
When a change in membrane potential (neuron/muscle cells) reaches a threshold value, this causes a dramatic change in the membrane potential:
called an ** ACTION POTENTIAL ** (AP)
(potassium channels open and then potassium ions leave cell until it gets more negative which is the hhyperpolarization part
from the -70 influx of excitatory signals which is incresing voltage of cell and then -55 it depolarizes and when voltage almost +40 then sodium channels open and potassium will leave the cell and then)
ACTION POTENTIALS:
- APs begin at the * ? * and spread down the entire length of the ?
- They result from the * ? * that the postsynaptic cell receives
- If membrane potential becomes ? enough to reach threshold potential: ? is triggered
- APs are the result of sequential opening and closing of ? channels: First to ?, then to ?
Voltage-gated ion channels and action potential:
1. depolarization: ? channels open: ? flows in
2. ?: Na+ voltage gated channels close, K+ voltage gated channels open: K+ flows out
3. Hyperpolarization: K+ flows out through * ? as well as ? *
4. Return to resting potential as ? channels gradually ?
ACTION POTENTIALS:
- APs begin at the * axon initial segment (hillock or trigger zone) * and spread down the entire length of the axon
- They result from the *integration of the various EPSP and IPSP * that the postsynaptic cell receives
- If membrane potential becomes + enough to reach threshold potential: AP is triggered
- APs are the result of sequential opening and closing of voltage gated ion channels: First to Na+, then to K+
Voltage-gated ion channels and action potential:
1. depolarization: Na+ voltage gated channels open: Na+ flows in
2. Repolarization: Na+ voltage gated channels close, K+ voltage gated channels open: K+ flows out
3. Hyperpolarization: K+ flows out through * leak channels as well as voltage-gated channels *
4. Return to resting potential as K+ voltage-gated channels gradually close
PROPAGATION OF ACTION POTENTIALS
APs propagate from their origin down the axon
? passively spread to adjacent resting segments of the membrane and trigger an ? there
In this way, the ? down to the ? terminal at the axon’s far end
ACTION POTENTIALS - CONDUCTION VELOCITY
The speed of AP conduction varies → diameter of ? and ? of myelination
In smaller, unmyelinated axons: conduction velocity is ? (i.e. 0.5 m/s)
Wider axons and myelination can ? velocity > 90 m/s
* In myelinated axons, the current can ‘jump’ from one ? to another (called ?) → Flows very ? under the myelin
THE SYNAPSE
The action potential travels down the axon
It ultimately causes the opening of “ ? “ at the axon terminal:
* “ ? “ enters the cell, high levels of “ ? “ cause fusion of synaptic vesicles with the membrane
* Neurotransmitters contained in those synaptic vesicles are released into the ? by ? and can bind to receptors of the postsynaptic cell
-> known as ? response
PROPAGATION OF ACTION POTENTIALS
APs propagate from their origin down the axon
+ charges passively spread to adjacent resting segments of the membrane and trigger an AP there
In this way, the AP spreads from the axon’s initial segment down to the axon’s terminal at the axon’s far end
ACTION POTENTIALS - CONDUCTION VELOCITY
The speed of AP conduction varies → diameter of axon and degree of myelination
In smaller, unmyelinated axons: conduction velocity is slow (i.e. 0.5 m/s)
Wider axons and myelination can speed up velocity > 90 m/s
* In myelinated axons, the current can ‘jump’ from one node to another (called ?) → Flows very rapidly under the myelin
THE SYNAPSE
The action potential travels down the axon
It ultimately causes the opening of “ Ca+ voltage-gated ion channels “ at the axon terminal:
* “ Ca+ “ enters the cell, and high levels of “ intracellular Ca+ “ cause the fusion of synaptic vesicles with the membrane
* Neurotransmitters contained in those synaptic vesicles are released into the synaptic cleft by exocytosis and can bind to receptors of the postsynaptic cell
-> known as cellular response
(Ca2+ protein complex stimulates fusion and exocytosis of neurotransmitter)
