AP exam 3
Terms
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- what are graded potentials?
- short lived depolarization of the cell membrane to potentially lead to an action potential
- the shift from resting potential (-70 mV) to a more positive potential
- depolarization
- true or false: dendrites are never myelinated
- TRUE
- the CNS contains the
- brain and spinal cord
- the PNS contains the
- things outside the CNS; nerves and ganglia
- what is the CNS responsible for?
- processing and coordinating sensory data and sending out motor commands
- nerves are: (structure)
- bundles of axons
- ganglia are:
- where cell bodies collect
- afferent divisions are sensory or motor?
- sensory
- efferent divisions are sensory or motor?
- motor
- afferent divisions do what?
- take info from receptors to the CNS (arriving info)
- efferent divisions do what?
- take a signal from the CNS to a muscle or gland (exiting info)
- damage to the afferent division would cause what?
- lack of pain reception; loss of senses
- the somatic nervous system is in charge of what?
- voluntary muscles; skeletal muscle contractions
- the autonomic nervous system is in charge of what?
- involuntary; signals to glands, smooth muscle and cardiac muscle
- what are the 2 divisions of the ANS?
- sympathetic and parasympathetic divisions
- what does the sympathetic division do?
- fight-or-flight response, arouses the body for action; increases heart rate, respiratory rate, decreases digestion
- what does the parasympathetic division do?
- rest and digest; calming effect; decreases respirations and heart rate, increases digestion
- what are neurons?
- nerve cells
- how many nucleuses does a neuron have?
- one single nucleus
- can a neuron divide?
- NO
- what do neurons NOT have?
- centrioles - cannot divide
- another word for a neuron's cell body is:
- soma
- the cytoplasm surrounding the nucleus constitutes the _____
- perikaryon
- areas of the perikaryon containing clusters of RER and free ribosomes are called:
- nissl bodies
- what is a dendrite?
- branches that extend out from the cell body that receive information to transmit to the rest of the neuron
- what is an axon?
- process capable of propagating an electrical impulse known as an action potential
- the electrical impulse sent through an axon is called:
- action potential
- the base/initial segment of an axon that is attached to the cell body at a thickened region is called:
- axon hillock
- extensions of the main axon trunk are called the:
- telodendria
- the telodendria of an axon end at the:
- synaptic terminal
- describe an anaxonic neuron
- dendrite and axon are indistinguishable and do NOT produce an action potential
- this type of neuron does not produce an action potential
- anaxonic
- this type of neuron has only one dendrite and one axon and is found in the nose and retina
- bipolar
- describe a unipolar neuron
- cell body is off to the side and looks fused together
- the sensory neurons in the PNS are what classification of neurons?
- unipolar
- the most common type of neuron is?
- multipolar
- describe a multipolar cell:
- one axon, multiple dendrites
- all motor neurons and most neurons in the spinal cord are what kind?
- multipolar
- does the nervous system provide swift and brief responses or swift and long responses?
- BRIEF
- in the CNS, a neuron typically receives information from other neurons at its
- dendrites
- phagocytic cells in neural tissue of the CNS are
- microglia
- the neural cells responsible for the analysis of sensory inputs and coordination of motor outputs are
- interneurons
- depolarization of a neuron plasma membrane will shift the membrane potential toward
- 0 mV
- the primary determinant of the resting membrane potential is
- the membrane permeability to potassium
- receptors that bind acetylcholine at the postsynpaptic membrane are
- chemically gated channels
- if the resting membrane potential is -70 mV and the threshold is -55 mV, a membrane potential of -60 mV will make it EASIER or HARDER to produce an action potential?
- EASIER
- what do sensory neurons detect?
- stimuli - heat, light, pressure, chemical activity
- sensory neurons are also known as
- afferent neurons
- the largest category of neurons are
- interneurons
- what do sensory neurons do?
- deliver information from receptors TO the CNS
- where are sensory neurons located?
- ganglion
- motor neurons are known as
- efferent neurons
- what do motor neurons do?
- carry instructions from CNS to effector (muscle or gland)
- where are most of the interneurons located?
- in the brain
- interneurons are involved in:
- integrative function, emotions, memory, processing/storing/retrieving info
- what are neuroglia?
- supporting cells
- the 4 types of neuroglia in the CNS are
- astrocytes, microglia, ependymal cells, oligodendrocytes
- the most abundant neuroglial cells in the CNS are
- astrocytes
- which neuroglial cell maintains the blood-brain barrier?
- astrocytes
- what is the blood-brain barrier
- keeping blood and the CSF apart
- what do astrocytes do?
- framework, stabilize tissue to prevent further injury, regulate interstitial environment, maintain blood-brain barrier
- these cells keep the CNS free of cellular debris and pathogens
- microglia
- these cells line canals and chambers of brain and spinal cord
- ependymal cells
- what do ependymal cells do?
- line canals and chambers, produce and circulate CSF
- these neuroglial cells are epithelial cells
- ependymal
- these neuroglial cells wrap around the exposed surface of an axon
- oligodendrocytes
- oligodendrocytes do what?
- create a sheath around an axon
- what are the 2 types of neuroglia of the PNS
- satellite and schwann cells
- statellite cells do what?
- surround cell bodies in ganglia, regulate what enters and exits the cell
- schwann cells do what?
- sometimes they wrap around the axon itself to become myelinated, but most are unmyelinated - the cells are incorporated IN it, not AROUND it.
- in an unmyelinated cells, a message must do what?
- go through each individual structure
- in a myelinated cell, a message must do what?
- jump from node to node to send the message
- when do myelinated fibers begin and when are they complete?
- 14th week of fetal development; adolescence
- this is the thick outer surface of a schwann cell
- neurilemma
- gaps between myelinated portions of axons are
- nodes of ranvier
- what is the function of myelination?
- to increase the speed of action potentials
- is white fiber myelinated or unmyelinated
- myelinated
- why is white matter white?
- high white lipid concentration in the myelin
- where do we find unmyelinated fibers?
- short axons or collaterals
- is gray matter myelinated or unmyelinated?
- unmyelinated
- what is demyelination?
- the progressive destruction of myelin sheaths in CNS/PNS
- is myelin in the CNS or PNS
- BOTH
- how permeable is a neuron cell membrane?
- selectively permeable
- what cells help in PNS regeneration?
- schwann cells
- what can cause demyelination?
- metal poisoning, MS, diptheria, guillain-barre syndrome
- what is transmembrane potential?
- the potential energy, possible energy, stored energy
- when a cell is at rest, is it negative or positive?
- negative
- ECF is
- sodium and chlorine ions are at high levels outside the cells
- ICF is
- potassium ion and negatively charged protein are high inside the cell
- ECF is inside or outside the cell?
- outside
- ICF is inside or outside the cell?
- inside
- when does a transmembrane potential exist?
- when positive and negative charges are held apart (outside and inside the cells)
- when does a current occur in transmembrane potential?
- when something happens and the potential difference is eliminated (through charges moving)
- a resting potential of a neuron is
- -70 mV
- is energy required in passive forces?
- NO
- what is happening in a chemical gradient?
- moving from a high concentration to a low concentration
- what is happening in an electrical gradient?
- moving towards the opposite charge (positive to negative)
- in an electrical gradient, the membrane is more permeable to ________
- potassium ions
- _____ ions leave more quickly than _____ ions enter
- potassium; sodium
- what is an electrochemical gradient?
- the sum of chemical and electrical forces acting on the ion across the plasma membrane (potassium and sodium)
- what is the sodium potassium pump?
- when the cells expends energy to remove 3 sodium ions and recaptures 2 potassium ions
- in the sodium potassium pump, what is leaving and what is coming in?
- 3 sodium OUT, 2 potassium IN
- what are leak channels?
- always open, but the permeability varies
- passive channels are also called
- leak channels
- these channels are important in maintaining resting potential
- passive/leak channels
- active channels are also called
- gated channels
- what are chemically gated channels?
- receptors that are in the cell membrane use neurotransmitters to open the channel
- where on the neuron do neurontransmitters open a chemical channel?
- at the dendrites and neuromuscular junction
- what is a voltage gated channel?
- open or close in response to a change in the transmembrane potential
- voltage gated channels deal with the movement of
- sodium, potassium, and calcium ions
- where do voltage gated channels occur?
- along axons or sarcolemma
- these channels are found only where an action potential is produced
- voltage gated channels
- what are mechanically gated channels?
- open of close in response to a physical distortion (touch, pressure, vibration)
- where are mechanically gated channels found?
- sensory receptors
- how long is the spinal cord
- about 18 inches
- what are the 2 main spinal cord enlargements
- cervical enlargement and lumbar enlargement
- this holds the spinal cord in place
- filum terminale
- the conus medullaris is the
- point spot at the spinal cord
- the cauda equina is known as the
- horses tail
- what is the cauda equina made of
- NOT the spinal cord, holds nerves
- what are the 3 spinal meninges
- dura, arachnoid, and pia matters
- what is the purpose of the spinal meninges
- around the cord to protect it
- where is the epidural space?
- between the vertebrae and dura mater
- this is the fibrous connective tissue forming the outer meninges
- dura mater
- this is directly attached to the dura mater
- arachnoid mater
- this is the space that is filled with CSF and acts as a shock absorber
- subarachnoid space
- the blood vessels in the spinal cord are found in this meninge
- pia matter
- this is the innermost meninge
- pia mater
- what is spina bifida?
- when bone and skin doesn't grow correctly over the spinal cord
- where are most spinal taps taken from
- lumbar region
- the central canal receives _______ from the _______
- CSF from the medulla oblongata
- what does the gray commisure connect?
- the 2 halves of the spinal cord
- sensory nuclei are located where in the spinal cord?
- the posterior/dorsal horms
- voluntary motor nuclei are located where in the spinal cord?
- anterior/ventral horms
- visceral motor nuclei are located where in the spinal cord?
- lateral horms
- these roots come from the anterior horm and contain axons of motor nerves
- ventral roots
- these roots come from the posterior horn and contrain axons of sensory nerves
- dorsal roots
- cell bodies of sensory neurons
- dorsal root ganglia
- what is a mixed spinal nerve?
- both motor and sensory axons are in it
- white matter of the spinal cord is divided into
- tracts
- do ventral roots bring info in or send info out
- send info OUT to PNS
- do dorsal roots bring info in or send info out
- bring info IN to the cord
- white mater is divided into 3 columns:
- posterior, lateral, anterior
- what are tracts of the spinal cord?
- axons that share the same function and structural characteristics
- what do ascending tracts do?
- take info from the PNS to the CNS - carry sensory info to the brain
- what does a descending tract do?
- carries info from CNS to the PNS - carries motor commands to the cord (from the brain) and out to the body
- this is the outermost covering of a spinal nerve
- epineurium
- this divides the axons into bundles/fascicles
- perineurium
- this is the covering around each individual axon of a spinal nerve
- endoneurium
- how many pairs of spinal nerves are there?
- 31
- how many pairs of cervical nerves are there?
- 8
- what spinal nerve is between T2 and T3?
- T2
- what spinal nerve is between C7 and T1?
- C8
- what is the length of a spinal nerve
- very short - 1-2 cm long
- branches of spinal nerves are known as
- rami
- where are neural bodies found in the spinal cord?
- the anterior horn
- these rami are the smaller of branches
- dorsal rami
- these rami are for the areas posterior of body trunk and somatic and visceral motor fibers
- dorsal rami
- these rami are for the limbs and anterior body trunk (organs)
- ventral rami
- these rami branch off to deal with skeletal muscles, organs, etc.
- ventral rami
- these are areas of the skin send by a specific spinal nerve
- dermatomes
- what is a nerve plexus?
- a complex interwoven network of nerves formed by ventral rami
- what is an example of a nerve plexus?
- sciatic nerve, ulnar nerve
- what is a reflex?
- a rapid, automatic response to specific stimli
- what are the 5 steps of the reflex arc?
- 1. stimulus arrives and receptor is activated 2. a graded potential leads to an action potential, info is sent to the CNS, sensory neuron is activated 3. information processing to a motor neuron 4. activation of a motor neuron 5. response by the effector
- what is an acquired reflex?
- complex motor patterns like braking your car
- when does an innate reflex form?
- when you are a fetus
- what is a stretch reflex?
- tendon stretches
- what is a flexor reflex?
- a withdrawal reflex
- what is a crossed extension reflex?
- when 1 side is effected, the other reacts (ex: grab on arm back, the other goes forward)
- what are neural pools?
- interconnected neurons with specific connections
- what are the 2 most common types of circuits?
- diverging and converging circuits
- what is a diverging circuit?
- a broad distribution of specific input and sensory neurons in the CNS - when a single presynaptic neuron travels to more than one post synaptic neuron (ex - eye sends a message to several parts of the brain)
- what is a converging circuit?
- when many neurons narrow down to one postsynaptic cell - when lots of neurons stimulate one cell
- what are reverberating circuits?
- follows a pattern - once a stimulus begins at one spot, it will continue to go without much though (ex: we start walking and can continue without thinking about each step)
- what is serial processing?
- information passes in a line from one neuron to another (most reflexes are this)
- what is parallel processing?
- info passes down several channels at the same time and allows for more than 1 response at the same time (ex: smelling cookies evokes many different senses)
- what is paraplegia?
- damage to the thoracic vertebrae or lower - effects lower limbs
- what is quadraplegia?
- damage at or superior to C5 - the higher up the damage, the more problems will occur)
- what is spinal shock?
- when the spinal cord is damaged and experiences temporary paralysis
- what is poliomelitis?
- the virus attacks somatic motor neurons (skeletal muscles) and leads to paralysis
- what is meningitis?
- inflammation of the meninges of the spinal cord or brain - it disrupts the flow of CSF and causes neural tissue death
- what is hansen's disease?
- leprosy - bacterial infection of your sensory nerves - you can't feel anything and tend to damage your limbs - your immune response does not react to the damage and infection occurs
- what is the mid-brain?
- pons and medulla oblongata
- what does the diencephalon do?
- processing center for emotions and hormones - made of thalamus and hypothalamus
- what does the cerebellum do?
- allows for repetition of the same movements - involved in balance
- this is the site of conscious thought, sensations, intellect and memory
- cerebrum
- what does the interventricular foramina do?
- connects lateral ventricles to the 3rd ventricle
- where is the 3rd ventricle found
- diencephalon
- where are the lateral ventricles?
- in cerebral hemispheres - they are in pairs - left and right
- what does the mesencephalic aqueduct do?
- connects the third ventricle with the 4th ventricle
- what does the 4th ventricle become?
- the spinal cord
- where is CSF produced?
- in the ventricles
- what are the functions of CSF?
- surround and cushion all exposed surfaces of the CNS, transports nutrients, allows brain to float in the skull, provides chemical stability
- this is the outermost fibrous covering of the brain
- dura mater
- what is the first layer of the dura mater in the brain that's fused to the periosteum of cranial bones
- endosteal layer
- the innermost layer of the brain meninges
- meningeal layer
- what are the dural sinuses?
- the gap between the the dura mater where blood collects to be returns to the heart
- what are duralfolds?
- area where dura mater dips into the folds of the brain
- arachnoid trabeculae does what?
- helps return CSF via the blood
- what is the final covering of the brain that is everywhere?
- pia mater
- what are the functions of cranial meninges?
- protect the brain, protect the blood vessels, house CSF, partition the brain into individual sections
- what does the medulla oblongata do?
- coordinates the most basic life functions
- where are autonomic nuclei located?
- cardiovascular center and vasomotor center and respiratory center
- what does the vasomotor center do?
- controls smooth muscle tone in blood vessels
- what are the replay stations of the medulla oblongata?
- places where synapses happen and send info to the thalamus or cerebellum
- where are groups of nuclei located in the brain?
- medulla oblongata
- this links the cerebellar hemispheres with the rest of the brain and acts as a bridge
- pons
- where is the respiratory control center located in the brain?
- the pons
- the right and left cerebellar hemispheres are connects by the
- vermis
- where are purkinje cells located?
- the cerebellum
- these cells can receive 200,000 synapses per cell coming from all over the body
- purkinje cells
- tree of life
- arbor vitae
- what is the arbor vitae made of
- white mater - axons
- what does the arbor vitae do?
- sends info to both sides
- what is the function of the cerebellum
- learned movement patterns, coordinate muscles of balance and equillibrium
- what is ataxia
- damage to the cerebellum - it can be temporary (drunk) or permanent (from trauma)
- what are the 2 parts of the corpus quadrigemina
- superior colliculus and inferior colliculus
- what is the superior colliculus in charge of
- visual information and reflex movements of the eye, head and neck
- what is the inferior colliculus in charge of
- reflexes of auditory system
- what is the substantia nigra
- darkly pigmented; inhitis cerebral activities by releasing dopamine and inhibits muscle tone
- what does a red nucleus of the mesencephalon do
- receives info from cerebrum and cerebellum has subconscious control of upper limb position and muscle tone
- what are the 2 specialized structures of the hypothalamus
- mamillary bodies and infundibulum
- what do mamillary bodies of the hypothalamus do
- process olfaction and reflex movements of eating
- what does the infundibulum from hypothalamus do
- narrow stalk of tissue connecting hypothalamus and pituitary gland
- what are the functions of the hypothalamus
- autonomic control to adjust for activities, emotional response and behavior, body temperature, food and water intake, sleep-wake cycle, memory
- what does the thalamus do?
- receives, filters, sorts and relays sensory impulses to the appropriate cortical area, coordinates info from the hypothalamus, cerebellum for motor commands
- what does the pineal gland secrete?
- melatonin (helps with sleep cycle)
- the hippocampus and the ammygdyla is part of the
- limbic system
- where are the hippocampus and ammygdyla found?
- in the temporal lobe
- what does the cingulate gyrus do?
- arches over the corpos collosum
- what is the fornix?
- tract of white mater that connects the hippocampus with the hypothalamus
- what is the main purpose of the limbic system?
- the emotional part of the brain
- the largest part of the brain
- cerebrum
- this is on the outer edge of the cerebrum
- cerebral cortex
- the cerebral cortex is made of
- grey mater
- these are the ridges that you see on the cerebrum
- gyrus/gyri
- this is the deep groove that divides the cerebrum into 2 hemispheres
- longitudinal fissure
- this is the shallow indendation that divdes the parietal and frontal lobes
- central sulcus
- motor commands are sent from this area of the brain
- frontal lobe
- this area is behind the central sulcus and is in charge of primary sensory info
- parietal lobe
- this lobe has auditory and olfactory information
- temporal
- the occipital lobe is in charge of
- visual information
- the insula is in charge of what?
- taste information
- what does cerebral white matter do?
- connects areas of grey matter - white matter are the axons that connect the areas of the cerebral cortex
- commissural fibers do what?
- connect hemispheres for communication - so the left side knows what is happening on the right and vice versa
- this area of the brain has more than 200 million axons
- corpus callosum
- these fibers interconnect areas of the neural cortex within a single hemisphere
- association fibers
- these fibers link the cerebral cortex to the rest of the CNS
- projection fibers
- what are basal nuclei?
- masses of gray matter
- where are basal nuclei found?
- imbeded into the core of the cerebrum
- what are the functions of basal nuclei?
- subconscious control of muscle tone, coordination of learned movement patterns
- will the basal nuclei begin a general pattern?
- NO - the cerebrum will begin it, the basal nuclei have the pattern
- this part of the cerebral cortex is anterior to the central sulcus
- primary motor cortex
- what does the primary motor cortex do?
- directs voluntary motor neurons in the brain stem
- the premotor cortex is for
- coordination of learned movements (like a reading pattern)
- this area is for sensing touch, pressure, pain, vibrations and temperature and is at the parietal lobe
- primary sensory cortex
- the region that monitors and interprets info that arrives at the sensory areas of the cortex
- somatosensory association area
- this area recieves visual information
- primary visual area
- this area interprets the results of the primary visual area
- visual association area
- the gustatory cortex is the info from the
- taste buds
- this area receives info from association areas and direct very complex motor activities
- integrative center
- this area helps with predictions and consequences
- prefrontal cortex
- this area of the brain is where our personality and analysis abilities comes from
- wernicke's area
- what does the broca's area do?
- regulate pattern for breathing and vocalizations for speech
- the left side of your brain functions as
- language, reading, writing, analytical, logic and reasoning
- the right side of your brain is for
- analyzing emotional context, how you say something, facial recognition
- excessive CSF in the brain
- hydrocephalus
- aphasia
- impairs the ability to speak or read
- this happens when the corpus collosum is cut
- disconnection syndrome
- when the brain bangs against the cranial bones and bruising occurs it is
- a concussion
- ALS is also known as
- lou gehrig's disease
- what happens with ALS/lou gehrig's?
- spinal nerve becomes diseased and stops working - death usually occurs because the respiratory muscles stop working
- what does ALS stand for?
- amyotrophic lateral sclerosis
- hyperkalmia
- excess potassium ions in the extracellular fluid decrease the chemical gradient for potassium which interferes with repolarization and inhibits action potentials
- will a fever cause the cell membranes to be more or less excitable?
- MORE
- with hypothermia cause inhibition of excitement of neural activity
- inhibition
- what happens during a stroke?
- oxygen is depleted from the CNS and portions of it die
- what does botox do?
- blocks neurotransmitter release and relaxes the muscle
- what does black widow spider venom do?
- increases the neurotransmitter release and causes spastic paralysis (your muscles can't relax)
- this is the most widespread neurotransmitter used in ALL neuromuscular junctions
- acetylcholine
- where is acetylcholine found?
- PNS and CNS
- what does dopamine do?
- causes excitatory of inhibitory effects - it helps prevent overstimulation
- norepinerphrine does what?
- adrenaline! causes excitatory effects
- what does serotonin do?
- excitatory effect in the CNS
- if you have a decreased level of serotonin, what symptoms might you have
- less concentration and depression
- where is norepinerphrine found?
- the brain and ANS
- where is dopamine found?
- part of the CNS
- what does GABA do?
- inhibitory effect, helps reduce anxiety
- how does GABA work?
- hooks into calcium channels and inactivates them, less neurotransmitter is released so the message doesn't get sent
- this neurotransmitter relays pain sensations and is a vasodilator
- substance P
- opoids are created in the _____ and controlled by the _______
- pituitary gland; hypothalamus
- what do opoids do?
- provide pain relief by inhibiting the release of neurotransmitters
- what are postsynaptic potentials and where do they develop?
- they are graded potentials that develop in the postsynaptic membrane
- EPSPs are
- excitatory post synaptic potentials
- what do EPSPs do?
- cause depolarization of the postsynaptic membrane and move closer to threshold
- excitatory synapses produce
- EPSPs
- IPSPs are
- inhibitory postsynaptic potentials
- what do IPSPs do
- cause hyperpolarization of the postsynaptic membrane - it gets more negative
- excitatory synapses cause depolarization by
- opening the channels that allow both sodium and potassium to cross the cell membrane, which decreases negative ions and gets MORE positive
- how do inhibitory synapses cause hyperpolarization?
- channels that allow potassium and/or chloride ions open and allow them to cross the membrane - potassium will exit or chloride will enter - gets more NEGATIVE
- what happens at the summation of the postsynaptic neurons?
- combo of EPSPs or IPSPs or BOTH
- in this summation, stimuli occur in rapid succession and single synapses are activated repeatedly
- temporal summation
- at this summation, simultaneous stimuli at different locations of the same neron have the same effect
- spatial summation
- facilitation is when
- a neuron is closer to threshold than when it's at rest
- what would caffeine do to a threshold?
- decreases it, the amount of Ach is increased and there are faster action potentials
- is nicotine a EPSP or IPSP
- EPSP
- what causes a graded potential?
- a stimulus opens gated ion channels
- these are changes in transmembrane potential that can't spread far from the site of stimulation
- graded potentials
- this is a shift away from resting potential to becoming MORE negative
- hyperpolarization
- what happens during hyperpolarization?
- potassium gated channels open
- this is when gated channels close and the sodium potassium pump and leak channels return ion concentrations back to normal resting potential
- repolarization
- what is the purpose of a graded potential?
- to initiate an action potential if it's strong enough
- action potential only occur in these cells
- neurons and muscle cells
- once stimulated, can you stop an action potential?
- NO
- this is the rapid reversal of membrane potential
- action potential
- to have an action potential, you must have a stimulus that's great enough to:
- open voltage regulated channels
- what is the all-or-none principle?
- once threshold is reached, you have the same action potential each time
- the difference between graded potentials and action potentials is
- the all-or-none principle
- what is the threshold for a sodium gated channel?
- -60 mV
- what are the 4 steps of an action potential
- 1. graded potential causes depolarization (making more positive) to reach threshold 2. sodium ions rush into the cell to make it positive 3. at +30 mV, sodium channels inactivate and the potassium channels open up and potassium leaves 4. the cell returns to normal permeability (temporary hyperpolarization)
- at the end of an action potential, why is there temporary hyperpolarization?
- -90 mV because potassium ions move out at a faster rate than when at rest.
- the time it takes the cell membrane that has undergone an action potential to stabilize
- refractory period
- what happens in the absolute refractory period
- can't undergo another action potential because the gates are inactivated
- what happens during the relative refractory period?
- if a great enough stimulus comes along, than it will generate another action potential even if it's not at rest
- what is the role of the sodium-potassium pump during the refractory period?
- the channels must open
- where will an action potential travel?
- away from its point of origin until the end - it doesn't fizzle out
- this is when an action potential is "retold" along an entire unmyelinated fiber
- continuous propagation
- this is when an action potential jumps from node to node of a myelinated fiber
- saltatory propagation
- what are type A axons?
- largest, myelinated, responsible for sending info related to position, touch and balance, they move very fast
- what are type B axons?
- smaller, myelinated, responsible for sending info related to temperature, pain, general touch, about 18m/sec
- what are type C axons?
- smallest ones, unmyelinated - smooth and cardiac muscle and glands, travels the slowest at about 1m/sec
- are action potentials in skeletal muscle or muscle tissues?
- muscle tissues
- what is the resting potential in muscle tissue?
- -85 mV
- an action potential will last longer or shorter in muscle cells?
- longer
- are the action potentials in muscle tissue fast or slow?
- slow
- the transfer of information from the axon to a postsynaptic cell is called
- the synapse
- this kind of synapse is when pre and post synaptic cells are locked together in a tight junction
- electrical
- in this synapse, there is no direct connection between pre- and post-synaptic cells
- chemical synapse
- if there is a chemical synapse, will an action potential occur?
- not necessarily
- this is the fluid filled space between the axon terminal and membrane
- synaptic clefts
- if a presynaptic neuron's axon terminal is excitatory, what will happen?
- promote action potential
- if a presynaptic neuron's axon terminal in inhibitory, what will happen?
- action potential will be supressed
- excitatory neurotransmitters cause
- depolarization
- inhibitory neurotransmitters cause
- hyperpolarization
- what happens during a typical cholinergic synapse?
- 1. action potential arrives and depolarizes the synaptic terminal 2. depolarization opens calcium channels in the presynaptic membrane 3. calcium ions flood into presynaptic cytoplasm and triggers the exocytosis of synaptic vesicles 4. synaptic vesicles fuse with the membrane of the axon terminal and ACh is released into the synaptic cleft 5. ACh binds with receptors in the postsynaptic membrane 6. Ion channels open and the postsynaptic membrane is depolarized 7. this creates a graded potential which can lead to another action potential
- what will ACh be degraded by in the postsynaptic membrane and synaptic cleft?
- AChE
- this is the time it takes between the arrival of the action potential to the postsynaptic membrane
- synaptic delay
- all receptors of ACh are _______ and cause ______
- excitatory, cause depolarization
- neurotransmitters will be excitatory or inhibitory dependent on the
- receptor
- why do neurotransmitters have to be removed from the synaptic cleft?
- for future action potentials to occur
- these help influence the release of neurotransmitters by the presynaptic cell or postsynaptic cell's response to the neurotransmitter
- neuromodulators
- do neuromodulators stay a long time?
- YES - they don't go away easily
- most neuromodulators bind to ______ or _______ and activate _______
- presynaptic or postsynaptic and activate enzymes (to influence the chemically-regulated channels)
- A dorsal and ventral root of each spinal segment unite to form a
- spinal nerve
- The white matter of the spinal cord contains
- bundles of axons
- The dorsal root ganglia mainly contain
- cell bodies of sensory neurons
- The specific strip of skin that is innervated by a specific spinal nerve is called a(n) ________.
- dermatome
- The complex, interwoven network formed by contributions from the ventral rami of neighboring spinal nerves is termed a(n)
- plexus
- The ________ plexus supplies innervation to the diaphragm.
- cervical
- Reflexes based on synapses formed during development are ________ reflexes.
- innate
- The part of the peripheral nervous system that carries sensory information to the CNS is designated
- afferent
- The myelin sheath that covers many CNS axons is formed by
- oligodendrocytes
- Cholinergic synapses release the neurotransmitter
- ACh
- If the chemically gated sodium channels in the postsynaptic membrane were completely blocked,
- synapses would completely fail
- Small, wandering cells that engulf cell debris and pathogens in the CNS are called
- microglia
- Voltage-gated channels are present
- in the membrane that covers axons
- In a(n) ________ synapse, current flows directly between cells.
- electrical
- the adult spinal cord extends only to
- the first or second lumbar vertebrae
- true or false: gray matter is primarily involved in relaying info to the brain
- FALSE
- a sensory region monitored by the dorsal rami of a single spinal segment is
- a dermatome
- the synapsing of several neurons on the same postsynaptic neuron is called
- convergence
- an example of a stretch reflex triggered by passive muscle movement is the
- patellar reflex
- the subarachnoid space contains
- CSF
- ascending tracts carry
- sensory info to the brain
- this site of CSF production is the
- choroid plexus
- this contains tracts that link the cerebellum with the brain stem
- the pons
- CSF is produced and secreted by what kind of cells
- ependymal cells