Chapter 12

Absolute refractory period causes

Action potential propagation to occur in one direction.

2. With a _____, the ligand-regulated channels begin closing as they release their bound ACh.

Decreasing cleft concentration of ACh. With a decreasing cleft concentration of ACh, the ligand-regulated channels begin closing as they release their bound ACh.

3. This results in membrane _____.

Depolarization. This results in membrane depolarization.

Repolarization of the neuron inner membrane is caused by

The opening of the potassium gates, and the diffusion of potassium ions out of the neuron.

Oligodendrocytes

Form the myelin sheath in the CNS.

True or false. During the transmission of an action potential along the neurilemma of a myelinated neuron, as one node is depolarizing, the next node is depolarizing.

Is true.

Arrange the following in the proper order in which they occur at the pre-synaptic side of a neuromuscular junction.

2,1,3. Macrophages ingest antigen. Helper T cells are activated. B cells differentiate into plasma cells and memory cells.

When a nerve fiber is cut the fiber distal the injury _____ survive.

Cannot. When a nerve fiber is cut the fiber distal the injury CANNOT survive.

The diffusional movement of sodium and potassium across the membrane is the membrane is driven at all times by the _____.

Electrochemical gradient. The diffusional movement of sodium and potassium across the membrane is driven at all times by the ELECTROCHEMICAL GRADIENT.

As the membrane potential is _____, the voltage-regulated sodium channels begin closing which in turn reduces the sodium movement to the ICF.

Increasing Towards Zero. As the membrane potential is INCREASING TOWARDS ZERO, the voltage-regulated sodium channels begin closing which in turn reduces the sodium movement to the ICF.

The sodium-potassium pump uses bulk transport to move the sodium and potassium ions.

Is false.

True or false. Receptors that bind the neurotransmitter at the post-synaptic cell membrane are voltage-gated.

Is false.

The ACh diffuses across the cleft and binds to the _____ channels.

Ligand-Regulated Sodium. The ACh diffuses across the cleft and binds to the LIGAND-REGULATED SODIUM channels.

Depolarization occurs because

More Na+ diffuse into the cell than K+ diffuse out of it.

During depolarization, which of the following statements about voltage gated ion channels is TRUE?

Na+ gates open before K+ gates.

In somatic neurons, an action potential arrives at the synapse causing synaptic vesicles to fuse with the _____ membrane.

Pre-synaptic. In somatic neurons, an action potential arrives at the synapse causing synaptic vesicles to fuse with the PRE-SYNAPTIC membrane.

Near the site of injury the basal lamina and the neurilemma term a _____ tube.

Regeneration. Near the site of injury the basal lamina and the neurilemma form a REGENERATION tube.

Depolarization of the neuron inner membrane is caused by the opening of the

Sodium gates, and the diffusion of sodium ions into the neuron.

Satellite Cells

Surrounding and insulating cells of the PNS that are found around the somas.

An action potential arriving at the presynaptic terminal causes voltage-gated calcium ion channels

To open, and calcium ions to diffuse into the cell.

2. An action potential at the _____ zone causes sodium to diffuse into the cell.

Trigger. An action potential at the TRIGGER zone causes sodium to diffuse into the cell.

Arrange the following in the proper order in which they occur at the post-synaptic side of a neuromuscular junction.

3,2,1. Sodium ions move into muscle cell. Depolarization of the post-synaptic membrane. Action potential is propagated over the muscle cell membrane.

During depolarization, which of they following statements about voltage-gated ion channels is True?

Na+ gates open before K+ gates.

In order to maintain the electrochemical gradients for sodium and potassium, ATPase pumps move these ions _____ their respective gradients.

Against. In order to maintain the electrochemical gradients for sodium and potassium, ATPase pumps move these ions against their respective gradients.

Schwann Cells

1. Form the myelin sheath in the PNS. 2. Function to insulate neurons and enhance the rate of transmission in the PNS.

Local Potentials

1. Ligand-regulated sodium channels. 2. Inhibitory post-synaptic potentials. 3. Decremental. 4. Occurs in the membrane of dendrites.

Structure or Events in stage two

1. Area associated with saltatory conduction. 2. Site of action potential propagation. 3. Structure might be ~1 meter long.

Nervous

1. Faster communication. 2. Electrical. 3. Cell to cell communication. 4. Basic life support (breathing regulation).

Endocrine

1. Slower communication. 2. Blood transport. 3. Growth. 4. Chemical only. 5. Utilizes hormones. 6. Gamete (sex cells) production.

True or false. The voltage-gated potassium channels close before the membrane potential is brought back to its resting level.

Is false.

As a result of question number one

Synaptic vessels migrate to the plasma membrane and release acetylcholine.

Astrocytes

1. Most abundant CNS glial cells. 2. Multi-functioning cells involved with neurogenesis, scar formation, BBB maintenance ect.

The movement of positive charges to the _____ causes the relative charge across the membrane to become positive on the inner surface.

ICF. The movement of positive charges to the ICF causes the relative charge across the membrane to become positive on the inner surface.

True or False. After the passage of the action potential, the sodium-potassium pump reestablishes the resting membrane potential.

Is true.

True or False. The nerve impulse is an electrical current that travels along dendrites or axons.

Is true.

True or false. If the post-synaptic membrane potential reaches threshold level, an action potential will be produced.

Is true.

True or false. Signal conduction on an unmyelinated neuron is a chain reaction occurring along the neural membrane.

Is true.

True or false. The area between the presynaptic nerve cell and the post-synaptic muscle cell is termed the synaptic cleft.

Is true.

With membrane potentials approaching +35 mV, the _____ channels become fully activated.

Voltage-Regulated Potassium. With membrane potentials approaching +35 mV, the VOLTAGE-REGULATED POTASSIUM channels become fully activated.

Decreasing resting membrane potential

1. ATP stores are declining through mitochondrial poison (arsenic). 2. Increased concentration of leaky sodium channels in the membrane. 3. Decreased concentration of leaky potassium channels in the membrane. 4. Increasing permeability of existing leaky potassium channels.

Peripheral Nervous System

1. Nerves located in the abdomen. 2. Ganglia and nerves.

Depolarization occurs because more Na+

Diffuse into the cell than K+ diffuse out of it.

With a larger duration of activation than sodium channels, the potassium channels allow for a greater movement of potassium to the ECF causing a short period of

Hyperpolarization.

Resting membrane potential is created as a result of a greater net flow of positive charges from the _____.

ICF to the ECF. Resting membrane potential is created s a result of a greater net flow of positive charges from the ICF to the ECF.

True or False. The sodium-potassium pump is involved in establishing the resting membrane potential.

Is True.

Acetylcholine has which effect on the post-synaptic neuron?

Ligand gated sodium ion channels open and sodium diffuse in.

Prior to the arrival of an action potential, the post-synaptic membrane is polar with a greater relative _____ charge to the ECF.

Positive. Prior to the arrival of an action potential, the post-synaptic membrane is polar with a greater relative POSITIVE charge to the ECF.

The electrical and chemical gradients for _____ are both high during resting membrane potential which results in a very high electrochemical gradient towards the inside of the cell.

Sodium. The electrical and chemical gradients for SODIUM are both high during resting membrane potential which results in a very high electrochemical gradient towards the inside of the cell.

As a result of question number

Synaptic vessels migrate to the plasma membrane and release acetylcholine.

Which of the following statements about the resting membrane potential is TRUE?

The exterior of the cell has a net positive charge and the interior has a net negative.

Hyperpolarization, or after potential occurs because

The increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.

An action potential causes

The inside of the neuron cell membrane to become positively charged in reference to the outside.

As a result

The sodium channels open and sodium ions pour into the intracellular fluid.

Microglia

1. Cells of the lymphatic system. 2. Macrophages of the CNS.

Motor

1. Efferent fibers.

An action potential arriving at the presynaptic terminal causes

Voltage-gated calcium ion channels to open, and calcium ions to diffuse into the cell.

Influences the ability of the cell to repolarize

1. Voltage-regulated potassium channels are blocked. 2. Acetylcholine esterase concentration is decreased.

4. As electrical charge is re-established back to -70 mV, the _____ return the ions to their initial position with sodium more highly concentrated in the ECF.

ATPase pumps. As electrical charge is re-established back to -70 mV, the ATPASE PUMPS return the ions to their initial position with sodium more highly concentrated in the ECF.

1. Neurotransmitter release from the presynaptic membrane is ceased and existing ACh in the cleft is broken down by _____.

Acetylcholine Esterase. Neurotransmitter release from the presynaptic membrane is ceased and existing ACh in the cleft is broken down by ACETYLCHOLINE ESTERASE.

The primary neurotransmitter at the neuromuscular junction is _____.

Acetylcholine. The primary neurotransmitter at the neuromuscular junction is ACETYLCHOLINE.

At resting membrane potential, which of the following statements about the voltage-gated sodium ion (Na+) channels is True?

Activation gated are closed and inactivation gates are open.

An action potential

Causes the inside of the neuron cell membrane to become positively charged in reference t the outside.

Upon arriving at the node of a myelinated neuron, the excitatory postsynaptic potential (EPSP)

Causes the neurons inner cell membrane to become more positively charged.

Repolarization occurs because potassium ions

Continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.

An action potential generates local currents that tend to _____ the membrane immediately adjacent to the action potential.

Depolarize. An action potential generates local currents that tend to DEPOLARIZE the membrane immediately adjacent to the action potential.

Depolarization occurs because more sodium ions

Diffuse into the cell than potassium ions diffuse out of it.

Activated (open) sodium channels allow a rapid _____ down their electrochemical gradient towards the ICF.

Diffusion of Sodium. Activated (open) sodium channels allow a rapid DIFFUSION OF SODIUM down their electrochemical gradient towards the ICF.

The pre-synaptic membrane releases (via exocytosis) acetylcholine (ACh) into the _____.

ECF of the synaptic cleft. The pre-synaptic membrane releases (via exocytosis) acetylcholine (ACh) into the ECF OF THE SYNAPTIC CLEFT.

True or False. The voltage-gated potassium channels close before the membrane potential is brought back to its resting level.

Is False.

True or false. Acetylcholine is actively transported from the presynaptic membrane to the post-synaptic membrane.

Is false.

True or false. Action potentials can travel in both directions on the axon.

Is false.

True or false. An action potential cannot occur until the inner membrane reaches resting membrane potential, at which point an action potential will be propagated.

Is false.

True or false. The inflow of sodium ions into the intracellular fluid causes depolarization of the neuron's inner cell membrane.

Is true.

True or false. The sodium-potassium pump is involved in establishing the resting membrane potential.

Is true.

True or false. Threshold is the minimum current required for the cell membrane to generate an action potential.

Is true.

3. Without continued sodium influx into the cell through the ligand-regulated channels, the constant _____ causes the membrane potential to return back to RMP.

Leak of Potassium to the ECF. Without continued sodium influx into the cell through the ligand-regulated channels, the constant LEAK OF POTASSIUM TO THE ECF causes the membrane potential to return back to RMP.

1. An unmyelinated fiber has voltage gated ion gates along its entire _____.

Length. An unmyelinated fiber has voltage gated ion gates along its entire LENGTH.

A damaged _____ nerve fiber may regenerate if its soma is intact and some neurilemma remains.

Peripheral. A damaged PERIPHERAL nerve fiber may regenerate if its soma is intact and some neurilemma remains.

Though potassium (+1) and sodium (+1) both leak through the membrane at rest, there is a greater diffusional flow or _____ at rest.

Potassium. Though potassium (+1) and sodium (+1) both leak through the membrane at rest, there is a greater diffusional flow or POTASSIUM at rest.

Through the activated channels, _____ now flows outwards causing the membrane to repolarize back towards RMP.

Potassium. Thought he activated channels, POTASSIUM now flows outwards causing the membrane to repolarize back towards RMP.

4. The depolarization causes a _____ that excites the entire membrane.

Repetition. The depolarization causes a REPETITION that excites the entire membrane.

5. This continues until the traveling _____ reaches the end of the axon.

Signal. This continues until the traveling SIGNAL reaches the end of the axon.

Which results in

Sodium ions diffusing through the intracellular fluid of the internode to the next node.

When contact is established the _____ shrinks and reinnervated muscle fibers regrow.

Soma. When contact is established the SOMA shrinks and reinnervated muscle fibers regrow.

Sensory

1. Afferent. 2. Pain fibers in the hand. 3. Functions to receive environmental information. 4. Responds to the environmental conditions.

Ependymal Cells

1. Ciliated cells resembling epithelium. 2. Function in the production and circulation of CSF.

Central Nervous System

1. Includes the brain. 2. Interneurons. 3. White matter. 4. Nuclei (gray matter).

Influences the ability of the cell to depolarize

1. Ligand-regulated sodium channels are blocked. 2. Hyperkalemia (high ICF potassium). 3. Neurotransmitter synthesis is compromised due to Golgi dysfunction in the pre-synaptic neuron. 4. Hyperhydration (high water concentration in ECF). 5. The size of the synaptic cleft is increased. 6. Neurotransmitter release is blocked. 7. Hyponatremia (low ECF sodium).

Structure or Events in stage three

1. Location of EPSPs (excitatory postsynaptic potential). 2. Location of IPSPs (inhibitory postsynaptic potential). 3. Postsynaptic membrane. 4. Structures involved with the reception of impulses. 5. Site of action potential origin. 6. Area of ligand binding. 7. Site of graded (local) potentials. 8. Site of temporal summation.

Structure or Events in stage one

1. Presynapaptic membrane. 2. Contains secretory vesicles containing acetylcholine. 3. Contains secretory vesicles containing glycine. 4. Information moving through section "B" is headed to which section next?

Both Actions Potentials and Local Potentials

1. Voltage-regulated potassium channels. 2. Sodium-potassium ATPase pumps work to re-establish RMP.

Action Potentials

1. Voltage-regulated sodium channels. 2. Important for transmission over long distances. 3. Rate of transmission is increased with myelination. 4.Require threshold.

The tube guides the growing sprout back to the original target cells reestablishing _____ contact.

Synaptic. The tube guides the growing sprout back to the original target calls reestablishing SYNAPTIC contact.