Chapter 11: Nervous System and Action Potentials

1. In this picture, which neuron is the presynaptic cell?

Blue

Green

The presynaptic cell is the neuron that sends signals to another neuron across a synapse. In the given picture, the blue neuron is positioned before the synapse, indicating that it is the presynaptic cell.

Explanation

The presynaptic cell is the neuron that sends signals to another neuron across a synapse. In the given picture, the blue neuron is positioned before the synapse, indicating that it is the presynaptic cell.

2. In this picture, which neuron is the postsynaptic cell?

Blue

Green

The postsynaptic cell is the neuron that receives signals from the presynaptic neuron. In this picture, the green neuron is the only one that has an arrow pointing towards it, indicating that it is receiving signals from another neuron. Therefore, the green neuron is the postsynaptic cell.

Explanation

The postsynaptic cell is the neuron that receives signals from the presynaptic neuron. In this picture, the green neuron is the only one that has an arrow pointing towards it, indicating that it is receiving signals from another neuron. Therefore, the green neuron is the postsynaptic cell.

3. Concerning concentration differences across the plasma membrane (at rest), there is

More K+ and Na+ outside the cell than inside

More K+ and Na+ inside the cell than outside

More K+ outside the cell than inside and more Na+ inside the cell than outside

More K+ inside the cell than outside and more Na+ outside the cell than inside.

Which side is more negative during resting membrane potential? Which one is more positive?

Explanation

Which side is more negative during resting membrane potential? Which one is more positive?

4. The autonomic nervous system is a two neuron system.

True

False

The autonomic nervous system is indeed a two neuron system. It consists of two types of neurons: preganglionic neurons and postganglionic neurons. Preganglionic neurons originate in the central nervous system and extend to ganglia located outside the spinal cord. From there, postganglionic neurons extend to target organs and tissues. This two-neuron pathway allows for the transmission of signals from the central nervous system to various organs and tissues, regulating involuntary bodily functions such as heart rate, digestion, and respiration.

Explanation

The autonomic nervous system is indeed a two neuron system. It consists of two types of neurons: preganglionic neurons and postganglionic neurons. Preganglionic neurons originate in the central nervous system and extend to ganglia located outside the spinal cord. From there, postganglionic neurons extend to target organs and tissues. This two-neuron pathway allows for the transmission of signals from the central nervous system to various organs and tissues, regulating involuntary bodily functions such as heart rate, digestion, and respiration.

5. Afferent means sending action potentials away from the CNS

True

False

The statement is false because afferent actually means sending action potentials towards the CNS, not away from it. Afferent neurons carry sensory information from the peripheral nervous system to the central nervous system, while efferent neurons carry motor signals from the central nervous system to the peripheral nervous system.

Explanation

The statement is false because afferent actually means sending action potentials towards the CNS, not away from it. Afferent neurons carry sensory information from the peripheral nervous system to the central nervous system, while efferent neurons carry motor signals from the central nervous system to the peripheral nervous system.

6. The central nervous system includes (select all that apply):

Brain

Spinal nerves

Motor neurons

Spinal cord

The central nervous system consists of the brain and spinal cord. The brain is the main control center of the body, responsible for processing and coordinating information from the senses, making decisions, and controlling body movements. The spinal cord is a long, thin bundle of nerves that extends from the base of the brain down the back. It acts as a pathway for signals between the brain and the rest of the body, allowing for communication and coordination of movement and sensory information. Spinal nerves and motor neurons are not part of the central nervous system, as they are peripheral nerves that connect the central nervous system to the muscles and sensory organs.

Explanation

The central nervous system consists of the brain and spinal cord. The brain is the main control center of the body, responsible for processing and coordinating information from the senses, making decisions, and controlling body movements. The spinal cord is a long, thin bundle of nerves that extends from the base of the brain down the back. It acts as a pathway for signals between the brain and the rest of the body, allowing for communication and coordination of movement and sensory information. Spinal nerves and motor neurons are not part of the central nervous system, as they are peripheral nerves that connect the central nervous system to the muscles and sensory organs.

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7. The absolute refractory period

Limits how many action potentials can be produced during a given period of time

Prevents an action potential from starting another action potential at the same point on the plasma membrane.

Is the period of time when a strong stimulus can initiate a second action potential.

Both a and b are correct

All of these are correct.

Both a and b are correct. The absolute refractory period refers to a period of time after an action potential where the neuron is unable to generate another action potential. This prevents an action potential from starting another action potential at the same point on the plasma membrane. Additionally, the absolute refractory period also limits how many action potentials can be produced during a given period of time. Therefore, both statements accurately describe the characteristics of the absolute refractory period.

Explanation

Both a and b are correct. The absolute refractory period refers to a period of time after an action potential where the neuron is unable to generate another action potential. This prevents an action potential from starting another action potential at the same point on the plasma membrane. Additionally, the absolute refractory period also limits how many action potentials can be produced during a given period of time. Therefore, both statements accurately describe the characteristics of the absolute refractory period.

8. Which of these are open on an undisturbed cell?

Sodium-gated channels

Potassium-gated channels

Potassium leak channels

Chloride-gated channels

Potassium leak channels are open on an undisturbed cell. These channels allow the passive movement of potassium ions out of the cell, helping to maintain the resting membrane potential. This leakage of potassium ions contributes to the negative charge inside the cell and the positive charge outside, creating an electrochemical gradient. This is essential for various cellular processes, including the transmission of nerve impulses and muscle contractions. Sodium-gated channels, potassium-gated channels, and chloride-gated channels are not open on an undisturbed cell.

Explanation

Potassium leak channels are open on an undisturbed cell. These channels allow the passive movement of potassium ions out of the cell, helping to maintain the resting membrane potential. This leakage of potassium ions contributes to the negative charge inside the cell and the positive charge outside, creating an electrochemical gradient. This is essential for various cellular processes, including the transmission of nerve impulses and muscle contractions. Sodium-gated channels, potassium-gated channels, and chloride-gated channels are not open on an undisturbed cell.

9. Hyperpolarization can happen when

The inside of the cell membrane becomes much more negative

The inside of the cell becomes much more positive

K+ gated channels are open

Na+ gated channels are open

A and C

B and D

What does increased membrane permeability allow K+ to do (where will it go)?

Explanation

What does increased membrane permeability allow K+ to do (where will it go)?

10. Summation

Is caused by combining two or more graded potentials

Can occur when two action potentials arrive from different dendrites

Results in an action potential if it reaches the threshold potential

Can occur when two action potentials arrive in close succession

All of these are correct.

What are the types of summation called?

Explanation

What are the types of summation called?

11. Which of the following is probably going to propagate an action potential fastest?

A thin, unmyelinated axon

A thin, myelinated axon

A thick, unmyelinated axon

A thick, myelinated axon

A thick, myelinated axon is probably going to propagate an action potential fastest because the myelin sheath acts as an insulating layer around the axon, preventing the leakage of ions and allowing for saltatory conduction. This means that the action potential "jumps" from one node of Ranvier to another, skipping the myelinated regions in between. This speeds up the conduction of the action potential along the axon.

Explanation

A thick, myelinated axon is probably going to propagate an action potential fastest because the myelin sheath acts as an insulating layer around the axon, preventing the leakage of ions and allowing for saltatory conduction. This means that the action potential "jumps" from one node of Ranvier to another, skipping the myelinated regions in between. This speeds up the conduction of the action potential along the axon.

12. _____ are the resident glial cells that help form the blood-brain barrier.

What is the blood-brain barrier and why is it important? What type of cell junction helps form it along with these glial cells?

Explanation

What is the blood-brain barrier and why is it important? What type of cell junction helps form it along with these glial cells?

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13. A _____-gated channel involves the binding of acetylcholine to a receptor.

A ligand-gated channel involves the binding of acetylcholine to a receptor. In this type of channel, the acetylcholine molecule acts as a ligand, binding to a specific receptor protein on the channel. This binding event triggers a conformational change in the channel protein, allowing ions to flow through the channel and altering the membrane potential of the cell. Ligand-gated channels are important for the transmission of signals in the nervous system and play a crucial role in processes such as synaptic transmission and muscle contraction.

Explanation

A ligand-gated channel involves the binding of acetylcholine to a receptor. In this type of channel, the acetylcholine molecule acts as a ligand, binding to a specific receptor protein on the channel. This binding event triggers a conformational change in the channel protein, allowing ions to flow through the channel and altering the membrane potential of the cell. Ligand-gated channels are important for the transmission of signals in the nervous system and play a crucial role in processes such as synaptic transmission and muscle contraction.

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14. Match the following Glial Cells

Astrocyte