EXAM 1 Study Guide Flashcards
Wide dark band of thick filaments in the center of the sarcomere
A-band
During the action potential, you won’t get another action potential no matter how strong a second stimulus is.
absolute refractory period
Acetylcholine is found is the (PNS/CNS/both)
both
Neurons that use acetylcholine are known as
cholinergic neurons
This chemical acts at muscarinic (G-protein coupled) receptors
Acetylcholine
This chemical acts at nicotinic (ion channels) receptors
Acetylcholine
Where are nicotinic receptors found?
at the neuromuscular junctions of skeletal muscules.
Where does the degradation of ACh occur?
synaptic cleft
What enzyme is responsible for the degradation of ACh?
acetylcholinesterase (AChE)
Degradation of ACh is as follows
Acetylcholine -> ______ + _______
acetate + choline
What inhibits acetylcholinesterase and what is the result of the inhibition?
Sarin (Nerve Gas); causes a buildup of ACh in the synaptic cleft.
Interconnected proteins that anchor actin thin filaments
Z=line
A cross-sectional view of a skeletal muscle fiber through the H zone reveal the presence of what?
Myosin, but no actin
formed by globular actin that is polymerized into a single stand called filamentous actin
Actin
Each actin has _______ binding sites
myosin
Why are myosin binding sites important on actin?
They are important in developing muscle contraction
A double helix of F-actin is called:
Actin strand
What are the two important regulatory molecules on actin filaments
Troponin and Tropomyosin
A long fibrous molecule that blocks the myosin binding sites
Tropomyosin
A complex of three different proteins that binds tropomyosin, actin, and Ca2+
Troponin
What three different proteins binds to troponin?
Actin, Tropomyosin, and Ca2+
What does Ca2+ binding to troponin do?
shifts tropomyosin away from the myosin binding sites
True or False
Action potentials are generally slow and may repeat at frequencies of several hundred per minute.
False
generally fast and may repeat at frequencies of several hundred per second
The ability to generate action potentials is known as:
excitability
A large change in membrane potential is known as
an action potential
Also known as an “all or none” response
action potential
In order to cause an action potential, a cell must utilize (at least one/ several) type(s) of ion channel(s).
several
What type of channels often serve as the initial stimulus for an action potential?
ligand-gated channels and mechanically gated channels
What type of channel gives the membrane the ability to undergo action potential by allowing the rapid depolarization and repolarization phases of the response?
Voltage gated channels
channels that conduct ions such as Na+, K+, Ca2+, or Cl- are referred to as:
voltage gated channels
Mechanisms of Neurotransmitter release:
What is the active zone?
the release region of the presynaptic membrane; SNARE proteins dock vesicles in this region
the release region of the presynaptic membrane; SNARE proteins dock vesicles in this region
Active zone
What three ways can muscle fiber form ATP?
- Creatine phosphate
- Anaerobic metabolism
- Aerobic metabolism
What supplies the energy for muscle contraction
ATP
Without ___ no contraction can take place
ATP
oxidative phosphorylation occurs through (aerobic/ anaerobic) metabolism
aerobic
Glycolysis occurs through (aerobic/ anaerobic) metabolism
anaerobic
(afferent/efferent/ Inter) neurons transmit information from peripheral system to CNS
afferent
(afferent/ efferent/ Inter) neurons cell body is often found in ganglion.
afferent
a collection of cell bodies is called a :
ganglion
(afferent/ efferent/ Inter) neurons are the most numerous type of neuron.
interneurons
(afferent/ efferent/ Inter) neurons are all located in the CNS
Interneurons
(afferent/ efferent/ Inter) neurons process afferent abd efferent signals.
interneurons
(afferent/ efferent/ Inter) neurons are key in reflexes
Interneurons
(afferent/ efferent/ Inter) neurons transmit information from the CNS to the peripheral system.
Efferent
(afferent/ efferent/ Inter) neurons transmit information from CNS to effector cells such as muscle or gland
efferent
(afferent/ efferent/ Inter) neurons cell body is located in the CNS
efferent
(afferent/ efferent/ Inter) neurons soma in CNS
efferent
Small interneurons in the brain that dampen activity within neural circuits
GABA neurons
Somatic efferent neurons are also known as:
motor neurons
What organic chemical is directly correlated with Alzheimer’s Disease?
Acetylcholine
The degradation of neurons associated with the ACh system:
Alzheimer’s Disease
Associated with a decreased amount of ACh in certain areas of the brain
Alzheimer’s disease
The loss of postsynaptic neurons that responded to ACh:
Alzheimer’s disease
Results in declining language and perceptual abilities, confusion, and memory loss:
Alzheimer’s disease
The sixth-leading cause of death in the US
Alzheimer’s disease
Astrocytes can be found in the (CNS/PNS)
CNS
This is most abundant in the Glial cell:
Astrocytes
Define primary active transport
The direct use of ATP in ion channels
What is an autocrine substance?
it acts on the same cell that secreted the substance
What is paracrine substance?
They target cells in close proximity to site of release of paracrine substance
Where are paracrine substances found
Local Cells
Where are autocrine substances found?
Local Cells
____ from many neurons are packaged together along with connective tissues to form a nerve
Axons
Structure of a Neuron:
Sends information away from the cell body by impulses called action potentials
Axon
Structure of a Neuron:
Connected to the soma at the axon hillock
Axon
Structure of a Neuron:
Connected to the soma at the initial segment
Axon
Structure of a Neuron:
Does not branch, may have collaterals
Axon
Structure of a Neuron:
has axon terminals
Axons
Structure of a Neuron:
Releases neurotransitter
Axon Terminal
This membrane transports glucose out of the cell
basolateral membranes
This membrane transports glucose into the cell
apical membrane
Interferes with SNARE proteins at excitatory synapses that activate muscles
Clostridium botulinum bacili toxin
________ is characterized by muscle paralysis
botulism
Used to treat facial wrinkles, severe sweating, and uncontrollable blinking
botulinum toxin (Botox)
Structure of a Neuron:
Receives information, direct information towards the cell body
Dendrites
Structure of a Neuron:
Short branching
Dendrites
Structure of a Neuron:
Axons can synapse here
Dendrites
Composed of the brain and the spinal cord
Central nervous system (CNS)
What glial cells are found in the CNS
- Astrocytes
- Ependymal cells
- Microglia
- Oligodendrocytes
This cells function in the CNS is to guide developing neurons into making the correct connections
Astrocytes
This cells function in the CNS is to modulate synaptic activity
astrocyte
This cells function in the CNS is to help maintain the proper electrolyte composition of the extracellular fluid
astrocyte
This cells function in the CNS is to protect against toxic substances by forming the Blood-Brain barrier
Astrocyte
This cells function in the CNS is to form an epithelia that lines portions of the ventricle system of the brain and the spinal cord
Ependymal Cells
This cells function in the CNS is to produce cerebral spinal fluid (CSF)
ependymal cells
This cell in the CNS is ciliated
ependymal cells
Why are ependymal cells ciliated?
to help in the movement of cerebral spinal fluid
This cell in the CNS is small and elongated with short irregular processes.
Microglia
This cells function in the CNS is to respond to infection
microglia
This cells function in the CNS is to protect the CNS by removing foreign material and the remains of dead or injured cells
microglia
This cells function in the CNS is to perform phagocytosis
microglia
This cells function in the CNS is to protect against oxidative stress
microglia
This cell in the CNS is a large cell body, thin-flat processes that wrap repeatedly abound the portions of the axon
oligodendrocytes
This cells function in the CNS is to produce a myelin sheath around the axons of neurons
oligodendrocytes
What is the purpose of myelination
allows for rapid transmission of action potentials (electrical signal within the neuron)
True or False
Each oligodendrocyte can myelinate multiple axons
True
True or False
Neuron outnumber glial cells 10 to 1 in the CNS
False
Glial cells outnumber neurons 10 to 1
Serotonin is a (CNS/PNS) neurotransmitter
CNS
Chemical synapses ar the most common in _______.
neurons
What are the different types of neuronal chemical synapses:
- Neuron to neuron
- Neuron to effector cell (neuromuscular junction)
- Neuron to non-neuron or non-muscle cell
__________ neurons rlease neurotransmitter from their axon terminals
Presynaptic
Anatomy of a chemical synapse:
has a high density of membrane potentials
postsynaptic density
Anatomy of a chemical synapse:
Has 10-20 nm extracellular space
synaptic cleft
Anatomy of a chemical synapse:
Prevents direct propagation of current
synaptic cleft
Anatomy of a chemical synapse:
a chemical messenger released from the presynaptic axon terminal
neurotransmitter
These cells connect, anchor, and support the structures of the body
Connective Tissue cells
A deadly arrowhead poison used by indigenous peoples of South America
Curare
This binds to ACh receptors. It does NOT open their ion channels and acetylcholinesterase does NOT destroy it
Curare
ACh cannot bind to receptor when occupied by this chemical
Curare
This chemical can cause death by asphyxiation
Curare
What are the four steps of cross-bridge cycling
- Attachment of a cross-bridge to a thin filament (Activated myosin head binds to actin, forming a cross-bridge)
- movement across the cross bridge
- Detachment of the cross bridge (Let it go)
- Energizing the cross bridge again so that it can attach to the thin filament
During the cross-bridge cycle, when is the myosin head in high energy form?
when the ATP that is attached to the myosin is hydrolyzed from ATP to ADP + Pi
The (high/low) energy form of myosin has a high affinity for actin
High
The (high/low) energy form of the myosin head has No ATP, ADP, or Pi bound to itself and remains bound to actin
low
What does the cross-bridge cycle rely on?
ATP hydrolysis
Explain the figure at each step of the cross-bridge cycle
- Cross-bridge binds to actin
- Cross-bridge moves
- ATP binds to myosin, causing cross-bridge to detach
- Hydrolysis of ATP energizes cross-bridge
Activation of Cross-bridge cycling is by
(Na+ / K+ / Ca2+)
Ca2+
What is the role of Ca2+ in cross-bridge cycling?
- Ca2+ binds to troponin
- Tropomyosin exposes the cross-bridge binding site on actin
- Cross-bridge binds to actin and generates force
Low cytosolic Ca2+ = (activated/relaxed) muscle
relaxed
High cytosolic Ca2+ = (activated/relaxed) muscle
activated
Mechanism of cytosolic increase in Ca2+
Where does the Ca2+ come from?
The sarcoplasmic reticulum within the muscle fiber
Once an action potential is triggered in the muscle, it travels along the __________ and into the __________
sarcolemma; T-tubules
Where are T-tubules located?
Between the terminal cisternae of the sarcoplasmic reticulum
A voltage-gated Ca2+ channel located inside a
t-tubular system
dihydropyridine receptors (DHPR)
DHPR directly contacts and opens these Ca2+ channels located on the sarcoplasmic reticulum
ryanodine receptors
What are considered the cargo trucks in axonal transport
Kinesin and dynein
What is considered the road in axonal transport
microtubules
(Kinesin/Dynein) transport is mainly retrograde (towards the cell body)
Dynein
(Kinesin/Dynein) transport is mainly anterograde
(from cell body towards axon terminal)
Kinesin
Which type of axonal transport moves processively (step by step)
Kinesin transport
What type of cargo is carried in kinesin transport
nutrients, neurotransmitter-filled vesicles
What type of cargo is carried in dyneintransport
recycled membrane vesicles, growth factors
creatine phosphate provides (slow/fast) energy production
fast
how long does the energy from creatine phosphate last?
10-15 seconds
What are the 3 major phases of muscle twitch?
- Latent period
- Contraction Phase
- Relaxation Phase
Name the major muscle phase:
The period of time from the action potential to the onset of contraction
Latent period
Name the major muscle phase:
The action potential sweeps across the sarcolemma
latent period
Name the major muscle phase:
Ca2+ ions are released from the sarcoplasmic reticulum
Latent Period
Name the major muscle phase:
Lasts about 2 seconds
Latent phase
Name the major muscle phase:
This is the time that tension is developing due to the cross-bridge cycling
Contraction Phase
Name the major muscle phase:
Ca2+ binds to troponin revealing binding sites for myosin on the actin filament
Contraction Phase
Name the major muscle phase:
Cross-bridges form
Contraction phase
How long does the contraction phase last?
10-100 msec
Name the major muscle phase:
This is the time the tension is decreasing
relaxation phase
Name the major muscle phase:
Ca2+ is actively transported back into the sarcoplasmic reticulum
Relaxation Phase
Name the major muscle phase:
Myosin binding sites are covered up by tropomyosin
Relaxation phase
How long does the relaxation phase last?
10-100msec
What’s the contraction time of fast twitch fibers?
~10 msec
What’s the contraction time of slow twitch fibers?
~100 msec or longer
Define Isometric twitch
Twitches that generate tension but do not shorten the muscle (constant length)
When the load is greater than the force generated by the muscle, an (isometric/isotonic) twitch occurs
isometric
Define Isotonic twitch
the muscle contracts with a greater force than resistance; causing the muscle to shorten.
Occurs when the load is greater than the tension
Isometric twitch
Trying to lift a car with your arms or maintaining posture is an example of:
Isometric twitch
occurs when the load is less than the tension
isotonic twitch
Name the twitch contraction:
Has a short latent period
Isometric twitch
Name the twitch contraction:
Has a long period of force generation
Isometric twitch
Name the twitch contraction:
Tension begins to increase as soon as the first cross-bridge attaches
isometric twitch
Name the twitch contraction:
Latent period is only due to the excitation-contraction coupling delay
isometric twitch
Name the twitch contraction:
Longer latent period
isotonic twitch
Name the twitch contraction:
Latent period includes both times for:
1) excitation-contraction coupling and
2) the extra time it takes to accumulate enough attached cross-bridges to lift the load off of the platform
Isotonic twitch
Name the twitch contraction:
The period of muscle shortening is shorter
Isotonic twitch
What are the characteristics of twitch dependent on?
- The type of contraction (isotonic or isometric)
- The magnitude of the load being lifted
The force generated by an individual muscle fiber depends on the number of active _______.
cross-bridges
The force generated by an individual muscle fiber depends on the number of active cross-bridges. The number of cross-bridges is influenced by:
- Frequency of stimulation
- Fiber diameter
- Length of fiber
The whole muscle contraction is dependent on the number of ______ stimulated.
fibers
A single action potential in a skeletal muscle fiber lasts ______ ms and the twitch lasts up to ______ ms.
1-2 ; 100
When a stimulus is applied before a fiber has completely relaxed from a twitch, it induces a contractile response with a peak tension greater than that produced in a single twitch, This is called:
Summation
The Tension vs Time graph below is an example of:
Summation
True or False:
Postsynaptic potential summation observes the effect if additional attached cross-bridges
False
Summation (Frequency- Tension Relation) observes the effect of additional attached cross-bridges.
True or False:
Postsynaptic potential summation involves additive voltage effects on the membrane
True
A maintained contraction in response to repetitive stimulation is known as a:
Tetanus (tetanic contraction)
The Tension vs Time graph below is an example of:
a tetanus (tetanic contraction)
What is the significance of muscle fiber diameter in a whole muscle contraction?
It influences the force-generating capacity of a fiber
The (smaller/larger) the fiber, the greater the force
larger
The force generated by a muscle contraction also depends on the length of the _______ within a muscle before contraction occurs
sarcomeres
