26 - Synapses and the neuromuscular junction

Question 1

Synapse

Answer 1

the junction where a neuron communicates with another cell across a narrow gap via a neurotransmitter of an electrical coupling

Question 2

Neurotransmitter

Answer 2

A molecule that is released from the synaptic terminal of a neuron at a chemical synapse, diffuses across the synaptic cleft, and binds to a postsynaptic cell, triggering a response

Question 3

Synaptic vesicle

Answer 3

is a small, membrane-bound sac found in nerve cells (neurons) that stores neurotransmitters, which are chemical messengers.

Question 4

Action potential

Answer 4

an electrical signal that propagates along the membrane of a neuron or other excitable cell as a nongraded (all or none) depolarization

Question 5

Synaptic cleft

Answer 5

is the small gap between two neurons at a synapse, where communication between the neurons occurs. It separates the axon terminal of the sending neuron from the dendrite or cell body of the receiving neuron.

Question 6

Ligand-gated ion channel

Answer 6

a transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule (ligand), allowing or blocking the flow of specific ions; also called an ionotropic receptor

Question 7

Threshold

Answer 7

The potential that an excitable cell membrane must reach for an action potential to be initiated

Question 8

Excitatory input

Answer 8

refers to signals that increase the likelihood that a neuron will fire an action potential, which is an electrical impulse.

Question 9

Inhibitory input

Answer 9

refers to signals that decrease the likelihood that a neuron will fire an action potential. This type of input involves neurotransmitters that bind to receptors on the receiving neuron and cause a negative change in the neuron’s membrane potential.

Question 10

Integration/summation

Answer 10

A phenomenon of a neural integration in which the membrane potential of the postsynaptic cell is determined by the combined effect of EPSOs or IPSPs produced in rapid succession at one synapse or simultaneously at different synapses

Question 11

Excitatory post synaptic potential (EPSP)

Answer 11

An electrical change (depolarization) in the membrane of a post synaptic cell caused by the binding of an excitatory neurotransmitter from a presynaptic cell to a postsynaptic receptor ; makes it more likely for a postsynaptic cell to generate an action potential

Question 12

Inhibitory post synaptic potential (IPSP)

Answer 12

An electrical change (usually hyperpolarization) in the membrane of a postsynaptic neuron caused by the binding of an inhibitory neurotransmitter from a presynaptic cell to a postsynaptic neuron to generate an action potential

Question 13

Neuromuscular junction

Answer 13

is the site where a motor neuron connects with a muscle fiber to transmit signals that control muscle contraction

Question 14

Sarcoplasmic reticulum

Answer 14

A specialized endoplasmic reticulum that regulates the calcium concentration in the cytosol of muscle cells

Question 15

Sacromere

Answer 15

is the basic structural and functional unit of a muscle fiber, responsible for muscle contraction. It is a segment within a myofibril, the thread-like structures that make up muscle cells

Question 16

Ca2+ channel

Answer 16

calcium channels help trigger the release of neurotransmitters at synapses, enabling communication between neurons.

Question 17

Ca2+ pump

Answer 17

is a type of transport protein found in the cell membrane that actively moves calcium ions (Ca²⁺) across the membrane, usually against their concentration gradient.

Question 18

Thin filament

Answer 18

A filament consisting of two strands of actin and two strands of regulatory protein coiled around one another; a component of myofibrils in muscle fibers

Question 19

Thick filament

Answer 19

a filament composed of staggered arrays of myosin molecules; a component of myofibrils in muscle fibers

Question 20

T Tubule

Answer 20

is an invagination of the cell membrane (sarcolemma) of muscle cells. These tubules extend into the interior of the cell and play a crucial role in the excitation-contraction coupling process of muscle fibers.

Question 21

Myosin