As acetylcholine binds at the motor-end plate, this depolarization is called an end-plate potential. It then spreads along the sarcolemma, creating
an action potential as voltage-dependent (voltage-gated) sodium channels
adjacent to the initial depolarization site open.
When ACh binds to receptors on the sarcolemma what happens?
As ACh binds at the motor end plate, this depolarization is called an end-plate potential. The depolarization then spreads along the sarcolemma, creating
an action potential as sodium channels
adjacent to the initial depolarization site sense the change in voltage and open.
What happens after acetylcholine binds to its receptors?
At the synapse of a motor neuron and striated muscle cell, binding of acetylcholine to nicotinic acetylcholine receptors triggers
a rapid increase in permeability of the membrane to both Na
+
and K
+
ions, leading to depolarization, an action potential, and then contraction
(see Figure 21-37).
When acetylcholine binds to receptors on the sarcolemma?
In vertebrates, motor neurons release acetylcholine (ACh), a small molecule neurotransmitter, which diffuses across the synaptic cleft and binds to nicotinic acetylcholine receptors (nAChRs) on the cell membrane of the muscle fiber, also known as the sarcolemma.
What happens when acetylcholine binds to its receptor quizlet?
Acetylcholine binds to its receptor
in the junctional folds of the sarcolemma
. … Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine. Cation channels open and sodium ions enter the axon terminal while potassium ions exit the axon terminal.
What is the function of ACh receptors?
The nicotinic acetylcholine receptor (nAChR), a key player in neuronal communication,
converts neurotransmitter binding into membrane electrical depolarization
. This protein combines binding sites for the neurotransmitter acetylcholine (ACh) and a cationic transmembrane ion channel.
What is the main role of acetylcholine?
Acetylcholine is the
chief neurotransmitter of the parasympathetic nervous system
, the part of the autonomic nervous system (a branch of the peripheral nervous system) that contracts smooth muscles, dilates blood vessels, increases bodily secretions, and slows heart rate.
What happens if acetylcholine is not released?
Specifically, without acetylcholine,
muscles cannot contract
. Symptoms of myasthenia gravis can range from mild to severe. They may include: weakness in the arms, legs, hands, fingers, or neck.
What happens if the acetylcholine receptors are blocked?
The acetylcholine receptor is an essential link between the brain and the muscles, so it is a sensitive location for attack. Many organisms make poisons that block the acetylcholine receptor,
causing paralysis
.
What triggers the release of acetylcholine from a synaptic terminal?
The release of acetylcholine occurs when an action potential is relayed and reaches the axon terminus in which depolarization
causes voltage-gated calcium channels to open and conduct an influx of calcium
, which will allow the vesicles containing acetylcholine for release into the synaptic cleft.
What happens to the muscle fiber when acetylcholine binds?
Acetylcholine Is Released and Binds to Receptors on the Muscle Membrane. …
Open channels allow an influx of sodium ions into the cytoplasm of the muscle fiber
. The sodium influx also sends a message within the muscle fiber to trigger the release of stored calcium ions. The calcium ions diffuse into the muscle fiber.
How does acetylcholine exerts its effect?
Acetylcholine exerts its effect by:
binding to receptors at the motor end plate
. Which is the neurotransmitter that causes the release of calcium ions from within the muscle cell and thereby initiates the steps of contraction? … enhanced stimulation of the muscle due to decreased Ach breakdown.
What type of receptor is acetylcholine?
The acetylcholine receptor (AChR) is
a membrane protein
that binds to the neurotransmitter acetylcholine (Ach). These receptors can be divided into two main types of distinct receptors, nicotinic and muscarinic.
What triggers the release of acetylcholine from a neuron quizlet?
Calcium enters
the presynaptic cell and causes the release of ACh. As a presynaptic action potential reaches the synaptic terminal, voltage-gated calcium channels open. The open calcium channels allow calcium to diffuse into the synaptic terminal.
Which condition is an autoimmune disorder in which acetylcholine receptors are blocked or destroyed quizlet?
In
myasthenia gravis
, antibodies (immune proteins produced by the body’s immune system) block, alter, or destroy the receptors for acetylcholine at the neuromuscular junction, which prevents the muscle from contracting.
How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal muscle?
How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal muscle?
It would cause flaccid paralysis
(muscles are relaxed and unable to contract).
