CHAPTER 7 Exam 1
potassium via potassium channels
*Repolarization* - return to the resting state (-70 mV) with the help of the sodium-potassium pump and outward flux of ____ via____
Relative refractory period
- greater than normal stimulus required to elicit action potential
Depolarization
- inside of cell becomes less negative relative to outside (> -70 mV)
Hyperpolarization
- inside of cell becomes more negative relative to outside (< -70 mV)
Graded potentials
- localized changes in membrane potential (either depolarization or hyperpolarization)
Action potentials
- rapid, substantial depolarization of the membrane (-70 mV to +30 mV to -70 mV all in 1 ms (1/1000 sec))
Axon
-Carries electrical impulse AWAY from cell body -May be covered by Schwann cells §Forms discontinuous myelin sheath along length of axon
§Central governor theory
-Central control center regulates exercise performance §Reduces motor output to exercising muscle -Protects against catastrophic disruptions of homeostasis
§Neurotransmitter
-Chemical messenger released from presynaptic membrane -Binds to receptor on postsynaptic membrane -Causes depolarization of postsynaptic membrane
Dendrites
-Conduct impulses TOWARDS cell body
Kinesthesia
-Conscious recognition of the position of body parts -Limb movement rates
Synapse
-Contact points between axon of one neuron and dendrite of another neuron
Cell body
-Contains the nucleus
Absolute refractory period
-During depolarization and early repolarization -Neuron unable to respond to another stimulus -Na+channels already open, can't open more -*Na+ channels become inactive*
Relative refractory period
-During mid-later stages of repolarization -Neuron responds only to very strong stimulus -K+channels open (Na+closed, could open again)
§Central fatigue
-Higher brain centers and/or motor neurons -Depletion of excitatory neurotransmitters in the motor cortex -Reduced motor output to muscle
§Proprioceptors
-Receptors that provide CNS with information about body position -Located in joints and muscles
Larger; faste; larger
-____ diameter neurons conduct nerve impulses _____ because ____ diameter neurons present less resistance to current flow (type II motor neurons are large).
tension
1. Golgi tendon organs detect _____ applied to a tendon 2. Sensory neurons conduct action potentials to the spinal cord 3. Sensory neurons synapse with inhibitory interneurons that synapse with aplha motor neurons 4. inhibition of alpha motor neuron causes muscle relaxation, relieving the tension applied to the tendon
withdrawal reflex
1. a sensory nerve sends a nerve impulse to the spinal cord 2. interneurons locates in the spinal cord are excited and stimulate the motor neurons 3. depolarization of specific motor neuron occurs due to the excited interneurons 4. while the flexor muscles contract, the antagonistic muscle group, that is, the extensors are inhibited by inhibitory postsynaptic potential, and they get relaxed without involvements of the brain, the muscles function during a reflex action
-70 mV
1. at rest the membrane potential is about
stretch
1. muscle spindles detect ___ of the muscle 2. sensory neurons conduct action potentials to the spinal cord 3. sensory neurons synapse with alpha motor neurons 4. stimulation of the alpha motor neurons causes the muscle to contact and resist being stretched
sodium; inward; depolarized
2. when the membrane reaches threshold (-55mV) ___ channels open, some _____ ions diffuse ___ and the membrane is ?
potassium; outwards; repolarized
3. when the ____ channels open, _____ channels diffuse ____ and the membrane is ______
sodium gates; into; depolarizing; nodes of Ranveer
ACTION POTENTIAL A neural message is generated when a stimulus is sufficient strength reaches the neuron membrane and open _____ which allows sodium ions to diffuse ____ the neuron making the inside of the cell more positive (____ the cell) when depolarization reaches a critical value called *threshold* more sodium gate open and an action potential or nerve impulses formed after an action potential has been generated a sequence of ionic exchanges occurs along the axon to propagate the nerve impulse this ionic exchange among the neuron occurs in a sequential fashion at the?
Repolarization; potassium; negative
ACTION POTENTIAL ____ occurs immediately FOLLOWING depolarization. Depolarization of the cell with a slight time delay causes a brief increase in membrane permeability to _____ as a result potassium leaves so rapidly making inside of the membrane more ____. Further after depolarization stimulus is removed the sodium gate within the cell membrane closes and sodium entry into the cell is slowed (there for a few positive charges are entering the cell) the combined results of these activities quickly restores the resting membrane potential to the original negative charge thus repolarizing the cell
gains in strength (Disinhibition of GTO reflexes)
Ability to voluntarily oppose GTO inhibition may be related to
Repolarization
Action Potential; 4. ___ return to the resting state (-70 mV) with the help of the sodium-potassium pump and outward flux of potassium via potassium channels
5 to 50
Action potential is ______ times faster in myelinated compared to unmyelinated axons. -Motor neurons are myelinated
pre; post ligand gated, non-selective cation channel Na+
Action potential; 1. Starts as a graded potential: -Neurotransmitter released from ____-synaptic neuron binds to receptor on ____-neuron -This receptor is a _______ -_____mostly, trickles into cell until threshold is reached
depolarization
Action potential; 2. Requires _____ that increases membrane potential greater than -60 to -50 mV (Threshold Potential)
threshold
Action potential; 3. Once _____ is met or exceeded, the all-or-none principle (if a nerve impulse is initiated the impulse will travel the entire length of the axon without a decrease in voltage-- the neural impulse is just as strong after traveling the length of the axon as it was at the initial point of stimulation) applies
)Parasympathetic Nervous System ("Housekeeping" or "Rest and Digest"
Actions oppose : 1.Decreases heart rate 2.Constricts coronary vessels - reduced blood supply to the heart 3.Constricts tissues in the lungs - reduced gas exchange between lungs and blood
2; in
Active Transport of Na+and K+ __K are pumped __
3; out
Active Transport of Na+and K+ __Na are pumped __
RMP in cells
Compared to the outside of the cell, more negatively charged (fixed) ions exist INSIDE the cell this results in a negative resting membrane potential (-70 mV). Both sodium and potassium can diffuse across the plasma membrane with potassium diffusing from the inside of the cell to the extracellular fluid whereas sodium diffuses into the cell from the extracellular fluid.
K+; Na+
Concentrations of Ions Across a Cell Membrane High concentration of ___ inside the neuron and ____ outside the neuron
central and peripheral factors
Current research suggests that fatigue is related to both
Irritability
Electrical Activity in Neurons -Ability to respond to a stimulus and convert it to a neural impulse
Conductivity
Electrical Activity in Neurons -Transmission of the impulse along the axon
positive; positively charged ions
Electrical Activity in Neurons Transmembrane potential; OUTSIDE membrane is slightly? -Due to slight excess of
negative; negatively charged ions and proteins
Electrical Activity in Neurons; Transmembrane potential; INSIDE membrane is slightly? -Due to slight excess of?
membrane permeability to various ions and active transport
Electrochemical Gradient Results from differences in?
closed; open; leave
Events During an Action Potential STEP 4 Repolarization; •Na+ channel _____ •K+ channel ____ allowing K+ to ____ cell •Return to the resting state with the help of the sodium-potassium pump
second
Events During an Action Potential which step does depolarization occur (increases Na+ permeability & opens Na+ channel, Na+ enters cell)
third
Events During an Action Potential which step involves the Propagation of an action potential
first
Events During an Action Potential which step is the resting state? (action of the Na+K+ pump)
sodium
Excitatory neurotransmitters increases neuronal permeability to ____ and results in excitatory postsynaptic potentials (EPSPs)
depolarization
Excitatory postsynaptic potentials (EPSP) Causes? -Temporal summation §Summing several EPSPs from one presynaptic neuron -Spatial summation §Summing from several different presynaptic neurons
Sympathetic Nervous System (Fight-or-flight)
Facilitates your motor response with increases in 1.Heart rate and strength of heart contraction 2.Blood pressure 3.Blood supply to the heart and active muscles 4.Metabolic rate and release of glucose by the liver 5.Rate of gas exchange between lungs and blood 6.Mental activity and quickness of response 7.Increase in adrenal hormones - catecholamines - epinephrine and norepinephrine
ligand gated, non-selective cation channels; Na+
GRADED POTENTIALS are due to opening of _______ but ____ is primary ion that flows in.
tension
Golgi Tendon Organ (GTO) Monitors ____ developed in muscle
Na+ influx = depolarization
Graded Potentials; Localized changes in membrane potential -Excitatory signal = _____= ?????
dendrites;
Graded Potentials; Localized changes in membrane potential -Generated by incoming signals from ?
K+ efflux = hyperpolarization
Graded Potentials; Localized changes in membrane potential -Inhibitory signal =____= ????
sodium
HIGHER CONCENTRATION OF ___ *OUTSIDE* THE CELL
potassium
HIGHER CONCENTRATION OF ____ *INSIDE* THE CELL
inhibitory postsynaptic potential (IPSP)
Inhibitory neurotransmitters cause the neuron to become more negative (hyperpolarized); This hyperpolarization of the membrane is called an
hyperpolarization
Inhibitory postsynaptic potentials (IPSP) Causes?
muscle length; stretch reflex; contraction force
Muscle Spindle Responds to changes in ___ and are responsible for ____ & Increased ______
repolarization
Na+ channels close K+ channels open allowing K+ to leave cell Return to the resting state with the help of the sodium-potassium pump
depolarization
Na+ channels open K+ channels closed
excitable
Neurons (functional unit of the nervous system) are an "_______ tissue"
afferent fibers
PNS the sensory division is responsible for transmission of neuron impulses from sense organs (receptors) to the CNS. These sensory nerve fibers which conduct information towards CNS are called
(1) the sensory portion (2) the motor portion
PNS can be further subdivided into 2 sections
150 in; 5 out
POTASSIUM (K+) intracellular fluid concentration is __mM and its extracellular fluid concentration is ___mM
Muscle Proprioceptors
Provide sensory feedback to nervous system -Tension development by muscle -Account of muscle length
neurons; motor neurons
Resting Membrane Potential Negative charge INSIDE cells at REST -Magnitude can be ~ -5 to -100 mv --40 to -75 mV in ______ -Typically ~-70 mV in ____
separation of charges across a membrane
Resting Membrane Potential (transmembrane potential of a cell at rest) -Caused by?
The Na+/K+ pump
Resting Membrane Potential is maintained by?
12 in; 145 out
SODIUM's (Na+) intracellular fluid concentration is __mM and its extracellular fluid concentration is ___mM
Golgi Tendon Organ (GTO)
Stimulation results in reflex relaxation of muscle Inhibitory neurons send IPSPs to agonist muscle fibers Causes reflexive contraction of antagonist muscle via EPSPs
True
T or F: Elevated levels of extracellular CO2 triggers increasing breathing rate in order to return CO2 lives back to normal, would be an example if negative feedback
False
T or F: Release of the inorganic phosphate molecule from the sodium-potassium pump causes it to release 3 sodium ions into the extracellular fluid
False
T or F: the sodium and potassium channels actively transports 3 Na+ out of the cell and 2 K+ into the cell and operate constantly to maintain or restore the resting membrane potential
False
T or F: when representing data on a graph, the variable manipulated by the researcher is the dependent variance and is found on the Y axis
-Potassium tends to diffuse out of cell, sodium in -Actively transports K+ (in) and Na+ (out) ions to maintain imbalance across membrane -2 K+ enter and 3 Na+ exit -Requires ATP and constitutes about 40% of resting metabolic rate.
The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?
Permeability of plasma membrane to ions & Difference in ion concentrations across membrane
The Resting Membrane Potential RMP (-70mV) in Cells is determined by?
active transport; out ; 2; into
The sodium potassium pump requires energy (ATP) and is therefore an _____ pump that moves ____ molecules of sodium ___ of the cell and returns __ molecules of potassium ___ the cell.
3 Na+
The sodium potassium pump steps; 1. Carrier has a shape that allows it to take up ?
ATP
The sodium potassium pump steps; 2. ___ is split and phosphate group attaches to carrier
outside
The sodium potassium pump steps; 3. Change in shape results and causes carrier to release 3 Na+ _____ of cell
2 K+
The sodium potassium pump steps; 4. Carrier has a shape that allows it to take up ?
Phosphate group
The sodium potassium pump steps; 5. _____ is released from carrier
inside
The sodium potassium pump steps; 6. Change in shape results ad causes carrier to release 2 K+ ____ the cell
B
Voltage-gated Na+ channels open upon reaching what state? A) resting potential B) threshold C) repolarization D) hyperpolarization
B
What does a ligand-gated channel require in order to open? A) increase in concentration of Na+ ions B) binding of a neurotransmitter C) increase in concentration of K+ ions D) depolarization of the membrane
A
What does a mechanically gated channel respond to? A) physical stimulus B) chemical stimulus C) increase in resistance D) decrease in resistance
A
What ion enters a neuron causing depolarization of the cell membrane? A) sodium B) chloride C) potassium D) phosphate
B
Which of the following is NOT a function of the body's intracellular control system? A) Protein breakdown and synthesis B) Replenish oxygen and cardon dioxyde C) Energy production D) Maintenance of stored nutrients E) all of the above are correct
E
Which of the following is false regarding the RESTING transmembrane potential of a neuron? A) there are neg charged proteins within the cytosol of the cell that contribute t the electrochemical gradient B) sodium ion is significantly higher outside the cell than inside the cell C) 2 K+ are actively transported into the cell, while 3 Na+ are actively transported out of the cell D) potassium tends to passively diffuse out of the cell E) none of the above are false
D
Which of the following is probably going to propagate an action potential fastest? A) a thin, unmyelinated axon B) a thin, myelinated axon C) a thick, unmyelinated axon D) a thick, myelinated axon
D
Which of the following voltages would most likely be measured during the relative refractory period? A) +30 mV B) 0 mV C) -45 mV D) -80 mv
stimulus; antagonistic muscles
Withdrawal Reflex Reciprocal inhibition -EPSPs to muscles to withdraw from ? -IPSPs to ?
sodium; enters
an action potential is produced by an increase in ___ conductance into the neuron. As ____ ____ the neuron, the charge becomes more and more POSITIVE and an action potential is generated
graded potential
an action potential starts as a?
rest
at ____ almost all the sodium channels are closed, whereas a few potassium channels are pome this means that there are ore potassium ions leaving the cell them odium ions "leaking" into the cell
voltage inactivation of Na channels.
during Absolute refractory period the action potential is not conducted due to?
Must depolarize to threshold mV; down axon; transmitted to next cell;
how strong must the graded potential be to form an action potential? -AP will be propagated ___ ____ -AP will be ____ ___ ____ ___
nervous system
in addition to integrating body activities and controlling voluntary movement the ______ is responsible for storing experiences (memory) and establishing patterns of response based in previous experience (learning)
Na+, K+, little bit of Cl-, and Ca++
ions that dictate RMP?
autonomic nervous system
is part of the peripheral nervous system. It controls some of the internal organs of the body which are not usually under voluntary control. It plays an important role in maintenance of homeostasis
Graded Potentials
localized changes in membrane potential
Juxtacrine
one cell sending a chemical message to its adjacent cell is considered what type of signaling?
inactivation gate
part of a voltage-gated Na+ channel that closes when the membrane potential reaches +30 mV
CNS
receptors capable of sensing touch, pain, temp changes, and chemical stimuli, send info to the ___ which responds to the stimuli in several ways. the response may be involuntary movement (e.g. rapid removal of hand from hot surface) or alteration in the rate of release of some hormone from the endocrine system.
Proprioceptors
receptors that provide the CNS with info about the body position (also called kinesthetic receptors)
synaptic cleft; synapse
synaptic transmission for a nerve impulse to continue from one neuron to another, it must cross the _____ at a ______
endocrine
the adrenal cortex secretes aldosterone into the blood, where it travels to the kidneys to bind to its receptors, which results in higher sodium retention. This is an example of which type of cell signaling mechanism???
synaptic vesicles, the synaptic cleft, and the postsynaptic membrane (receiving neuron)
the basic structure of the chemical synapse ; the terminal of the presynaptic axon (sending neuron) containing?
somatic; autonomic; efferent fibers
the motor portion of the PNS can be further subdivided into the _____ motor division (which innervates skeletal muscle) and _____ motor division (which innervates involuntary effector organs like smooth muscle muscle surrounding blood vessels, cardiac muscle, and glands) Motor nerve fibers which impulses away from the CNS are referred to as
1) higher permeability of the membrane for potassium than sodium 2) the concentration gradient for potassium promotes moment of potassium ions out of the cell
the negative membrane potential in a resting neuron is due promptly to the diffusion of potassium to of the cell caused by
Muscle spindles
these receptors act as length detectors those muscles that require finest degree of control have highest density of the receptor. They detect stretch of the muscle and send signals to the nervous system which respond and causes a muscle to contract. They are responsible for stretch reflex (or myotatic reflex). They help in the regulation of movement and to maintain posture
Golgi tendon organs
these receptors are located within the tendon. They constantly sense tension produced by muscle contraction. They help prevent excessive force during contractions. They send info to the spinal cord via sensory neurons. The spinal cord in turn, excites inhibitory neurons which prevent the motor neurons from firing, reduces the muscle force production, and thus protects the muscle from injury.
parasymphatic division
this division has antagonistic effects to that of the sympathetic division. It activates the digestive system, decreases blood pressure and slows down the heart rate. The cell bodies of this division are located within the brain stem and spinal cord
symphatic division
this division has stimulating effect on the target organs. It generally prepares the body for emergency situations. The stimulation from this division increases the heart rate, dilates the pupils, increases the blood glucose level, and stimulates muscles.
Muscle Spindles
what Consists of: -Intrafusal fibers --Run parallel to normal muscle fibers (extrafusal fibers) -Gamma motor neurons --Stimulate intrafusal fibers to contract with extrafusal fibers (by alpha motor neuron) Keeps spindles taut for greater responsiveness
sodium potassium and chloride
what ions play the most important roles in determining the resting membrane potential in cells due to their large ion concentration?
Refractory periods
what limit the maximum frequency of APs
Golgi tendon organs
what services as safety devices that help preempt excessive force during muscle contractions ?
repolarized
when K+ channels are open and Na+ channels are closed the action potential is being?
depolarized
when Na+ channels are open and K+ channels are closed the action potential is being?
withdrawal reflex
when the decor muscle on one side of the body is stimulated to contract via a ________, the extensor on the opposite side also contracts.
IPSP; EPSPs
while the _____ resist depolarization of the postsynaptic neuron,______ cause depolarization of the neuron to the threshold
E
you just exercised and induced muscular damage to your quads, drastically increasing the production of superoxide anion. This oxidative stressor causes phosphorylation of a transcriptional activator molecule. What happens next? A) tRNA delivers amino acids to the ribosome for formation of a peptide sequence B) mRNA taels to the ribosome for protein translation C) DNA is transcribed into mRNA D) The transcriptional activator stabilizes the damaged proteins for refolding E) none of the above
-Saltatoryconduction
§Action potential (impulse) traveling along a myelinatedfiber passing from one node of Ranvierto the next.
Multiple Sclerosis
§Neurological disease that destroys myelin sheaths of axons -Has genetic component -Due to immune attack on myelin §Results in progressive loss of nervous system function -Fatigue, muscle weakness, poor motor control, loss of balance, mental depression §Exercise can improve functional capacity -Leads to improved quality of life through "Immunomodulation" -Repairing of Schwann Cells
Transmembrane potential
—an unequal distribution of charge across a cell membrane
