Week 2 Vocabulary

Question 1

Electron

Answer 1

A negatively charged subatomic particle

Question 2

Proton

Answer 2

A postively charged subatomic particle

Question 3

Ions

Answer 3

Atoms that do not have an equal number of protons and electrons. If an atom loses an electron, it will be positively charged, an example being potassium (K+). In an atom gains an electron, it will be negatively charged, an example being chloride (Cl-).

Question 4

Electrical Potential

Answer 4

The difference in voltage between the inside and outside of the cell.

Question 5

Volt

Answer 5

The unit of electrical potential. In neurons, voltage is always in millivolts (mV).

Question 6

Current

Answer 6

The flow of electrical charge. In neurons, current is carried by ions flowing across the cell membrane.

Question 7

Resistance

Answer 7

The impedance to current flow in a system. In neurons, the cell membrane creates resistance by preventing free ion flow, while open ion channels in the membrane reduce resistance by creating a path for ion flow.

Question 8

Insulator

Answer 8

A substance with a high resistance to current flow. Myelin acts as an insulator by wrapping axons and preventing ions from flowing out, forcing them to take the path of least resistance, which is down the axon towards the synaptic terminal.

Question 9

Cell/Plasma Membrane

Answer 9

A barrier of fat (lipids) surrounding all parts of the cell. The inside of the cell is known as intracellular, or cytoplasmic. The outside of the cell is known as the extracellular space. The integrity of the cell membrane is essential to maintaining resting membrane potential in neurons.

Question 10

Ion Channel

Answer 10

A protein complex within the cell membrane that allows ions to pass between the inside and outside of the cell.

Question 11

Resting Membrane Potential

Answer 11

The steady state voltage of the inside of the cell relative to the extracellular space, which is approximately -65 mV. This is maintained by three ions: potassium (K+), sodium (Na+), and chloride (Cl-). At rest, K+ is at a higher concentration inside the cell, while Na+ and Cl- are at a higher concentration outside the cell.

Question 12

Chemical Force

Answer 12

This refers to the chemical gradient between the inside and outside of the cell that causes molecules to move. Molecules want to move towards areas of lower concentration. For example, potassium is at a higher concentration inside the cell, so the chemical force pushes potassium out.

Question 13

Electrical Force

Answer 13

This refers to the electrical potential difference between the inside and outside of the cell that causes ions to move. Ions are attracted to the opposite charge. As the inside of the cell is more negative, electrical forces will push positively charged ions like potassium into the cell. At rest, the chemical and electrical forces working on potassium are perfectly opposed, resulting in zero net movement (this doesn’t mean no movement at all though!)

Question 14

Ground

Answer 14

This refers to the reference point of voltage (0 mV), which in the case of neurons is the extracellular space.

Question 15

Demyelinating Disease

Answer 15

A disease that is caused by a loss of myelin. These disease can affect central neurons, peripheral neurons, or both. Importantly, the symptoms are dependent on which type(s) of neurons are affected, and are often different between patients with the same disease.

Question 16

Diabetes

Answer 16

A disease in which patients can no longer control their blood sugar. High blood sugars in diabetic patients can lead to demyelination of sensory nerves in the peripheral nervous system.

Question 17

Multiple Sclerosis

Answer 17

A demyelinating disease of the central nervous system.

Question 18

Charcot-Marie-Tooth Disease

Answer 18

A demyelinating disease of the peripheral nervous system.

Question 19

Synaptic Cleft

Answer 19

The small space between the presynaptic and postsynaptic cell, across which neurotransmitters diffuse.

Question 20

Presynaptic Terminal

Answer 20

The site of release of neurotransmitters.

Question 21

Postsynaptic Terminal

Answer 21

The site of binding of neurotransmitters to receptors.

Question 22

Neuromuscular Junction

Answer 22

The synapse where a motoneuron contacts a muscle.

Question 23

Constitutive

Answer 23

Always active. In the synapse, constitutive release of neurotransmitters is suppressed.

Question 24

Organelle

Answer 24

A subunit within a cell that is surrounded by its own membrane.

Question 25

Vesicle

Answer 25

A small organelle that carries specific molecules, such as neurotransmitters.

Question 26

SNARE Pin Complex

Answer 26

Proteins that anchor neurotransmitter-containing vesicles to the cell membrane.

Question 27

Calcium (Ca++)

Answer 27

The ion that flows into the presynaptic terminal following the arrival of an action potential, leading to fusion of the vesicle and cell membranes, and thus release of neurotransmitters into the synaptic cleft.

Question 28

Clostridial Toxins

Answer 28

Proteins released by the Clostridium genus of bacteria. These include botulinum toxin, tetanus toxin, as well as others involved in serious gastrointestinal illness.

Question 29

Botox

Answer 29

The pharmaceutical name for botulinum toxin. It functions by cleaving the SNARE proteins, impairing release of acetylcholine at the neuromuscular junction, and thus paralyzing the muscle.

Question 30

Dopaminergic Neuron

Answer 30

A neuron that releases dopamine.

Question 31

Parkinson’s Disease

Answer 31

A neurodegenerative disease characterized by the death of some dopaminergic neurons, specifically in the substantia nigra pars compacta of the basal ganglia.

Question 32

Substrate

Answer 32

A building block used by a cell to create a product. For example, the substrate for dopamine can be given to Parkinson’s patients so the surviving dopaminergic neurons can produce enough dopamine to make up for the loss of other neurons.

Question 33

Focal dystonia

Answer 33

A condition where patients suffer from localized, involuntary and sustained muscle contractions.

Question 34

Diffusion

Answer 34

The natural spread of molecules from high concentration to low concentration. An important method of terminating the signal between two neurons.

Question 35

Reuptake

Answer 35

The transport of neurotransmitters from the synaptic cleft back into the presynaptic terminal, for signal termination and recycling.

Question 36

Acetylcholinesterase (AChE)

Answer 36

The enzyme responsible for breaking down acetylcholine (ACh) at the neuromuscular junction, the primary means of terminating ACh signaling.

Question 37

Receptor

Answer 37

The “ears” of the postsynaptic neuron. Neurotransmitter binds these to transmit a signal, often leading to the opening of an ion channel.

Question 38

Excitatory

Answer 38

A response to a stimulus that leads to the membrane potential becoming more positive. For example, an ion channel opening that allows sodium to flow into the cell.

Question 39

Glutamate

Answer 39

The most common excitatory neurotransmitter.

Question 40

Inhibitory

Answer 40

A response to a stimulus that leads to the membrane potential becoming more negative. For example, an ion channel opening that allows chloride to flow into the cell.

Question 41

GABA

Answer 41

The most common inhibitory neurotransmitter.

Question 42

Myasthenia Gravis

Answer 42

A disease where the patient’s immune system inappropriately destroys acetylcholine receptors at the neuromuscular junction, leading to weak and unsustainable muscle contraction. Treatment involves either inhibiting AChE to maintain a high concentration of acetylcholine in the synaptic cleft, and/or suppressing the patient’s immune system.