ANPS 019 Lab #5

A: Central Nervous System (CNS) B: Peripheral Nervous System (PNS)

What are A AND B?

C: Sensory (afferent) division D: Motor (efferent) division

What are C AND D?

E: Somatic nervous system F: Autonomic nervous system

What are E AND F?

G: Sympathetic division H: Parasympathetic division

What are G AND H?

Collections of neuron cell bodies located outside the CNS

What are ganglia?

Muscles and glands

What are the "effector organs"? (2)

1. Interprets sensory input 2. Dictates motor output based on reflexes, current conditions, and past experiences

What are the 2 functions of the CNS?

Brain and spinal cord

What are the 2 parts of the CNS?

1. Sympathic Nervous System: "fight or flight" response; stress/emergency 2. Parasymathetic Nervous System: "rest and digest"; general housekeeping body functions

What are the 2 subdivisions of the ANS? What do they mean?

1. sensory/afferent: sensory nerves carry information TOWARDS the CNS 2. motor/efferent: motor nerves carry information AWAY FROM the CNS

What are the 2 subdivisions of the PNS? What do they mean?

1. Voluntary/somatic: Everything you're aware of/have voluntary control over (skeletal muscles, bones of skeleton) 2. Involuntary/autonomic: Everything you don't have much control over; involuntary actions of viscera (internal organs) are controlled by the 2 motor divisions of the ANS

What are the 2 subdivisions of the motor/efferent division of the PNS? What do they mean?

D) dendrites, cell body (soma), axon The three main parts of a neuron are the dendrites, the cell body or soma and the axon.

What are the three main structural components of neurons? A) dendrites, axons, synapses B) axons, nucleus, cell body (soma) C) synapses, axons, axon hillock D) dendrites, cell body (soma), axon

Going toward (the CNS)

What does the term afferent mean?

Going away (from the CNS)

What does the term efferent mean?

Anaxonic neuron

What is A?

Chromotaphilic (Nissl) substance

What is A?

Endoneurium

What is A?

Ependymal cells

What is A?

Neuron

What is A?

Receptive region

What is A?

Peripheral axon

What is A? Hint: The peripheral axon is on the left of the image and the central axon is on the right.

A) brain

What is A? A) brain B) cranial nerves C) ganglia D) spinal cord E) spinal nerves

Astrocytes

What is B?

Biosynthetic center and receptive region

What is B?

Bipolar neuron

What is B?

Dendrites

What is B?

Perineurium

What is B?

Processes

What is B?

Schwann cell

What is B? Hint: The peripheral axon is on the left of the image and the central axon is on the right.

D) spinal cord

What is B? A) brain B) cranial nerves C) ganglia D) spinal cord E) spinal nerves

Cell body

What is C?

End-feet

What is C?

Epineurium

What is C?

Impulse generating and conducting region

What is C?

Oligodendrocytes

What is C?

Pseudounipolar neuron

What is C?

Satellite cell

What is C? Hint: The peripheral axon is on the left of the image and the central axon is on the right.

B) cranial nerves

What is C? A) brain B) cranial nerves C) ganglia D) spinal cord E) spinal nerves

Astrocyte

What is D?

Axon

What is D?

Axon hillock region of axon

What is D?

Impulse direction

What is D?

Microglia

What is D?

Multipolar neuron

What is D?

Central axon

What is D? Hint: The peripheral axon is on the left of the image and the central axon is on the right.

C) ganglia

What is D? A) brain B) cranial nerves C) ganglia D) spinal cord E) spinal nerves

Myelin sheath

What is E?

Oligodendrocyte

What is E?

Satellite cells

What is E?

Schwann cell

What is E?

Secretory region

What is E?

Cell body

What is E? Hint: The peripheral axon is on the left of the image and the central axon is on the right.

E) spinal nerves

What is E? A) brain B) cranial nerves C) ganglia D) spinal cord E) spinal nerves

Fasicle

What is F?

Microglial cell

What is F?

Node of Ranvier

What is F?

Schwann cells

What is F?

Axon terminals

What is G?

Ependymal cell

What is G?

Fluid being secreted

What is H?

Cilia

What is I?

Capillary

What is J?

Carries information to and from the CNS (has both sensory and motor nerve fibers)

What is a mixed nerve?

D) dendrites and cell body (soma) Axon terminals from other neurons can form synapses on the dendrites and cell body (soma), so both of these regions are considered the receptive region of the neuron. These areas "receive" the incoming signals. These areas also integrate the incoming signals, so they can also be considered the "integrative" region. We will learn more about integration of incoming signals in a later lab exercise (Synaptic Potentials and Cellular Integration).

What is considered the receptive portion(s) of the neuron? A) axon terminal B) axon C) dendrites only D) dendrites and cell body (soma) Axon terminals from other neurons can form synapses on the dendrites and cell body (soma), so both of these regions are considered the receptive region of the neuron. These areas "receive" the incoming signals. These areas also integrate the incoming signals, so they can also be considered the "integrative" region. We will learn more about integration of incoming signals in a later lab exercise (Synaptic Potentials and Cellular Integration).

K+ The concentration of K+ is higher inside than outside the cell.

first (top) sentence

K+, Na+ The resting membrane potential is maintained by Na+-K+ pumps that actively transport K+ into and Na+ out of the cell.

fourth (bottom) sentence

C) potassium (K+)

At rest, a neuron's plasma membrane is most permeable to which of the following ions? A) sodium (Na+) B) chloride (Cl-) C) potassium (K+) D) protein anions (A-)

1. Top Blue: Positive charge along this surface 2. Bottom Blue: Negative charge along this surface

*Blue only* 1. Top Blue: 2. Bottom Blue:

1. Top Green: Measures membrane potential 2. Bottom Green: K+ leak channel

*Green only* 1. Top Green: 2. Bottom Green:

1. Top Pink: K+ (4 mM / Na+ (150 mM) 2. Bottom Pink: K+ (140 mM / Na+ (15 mM)

*Pink only* 1. Top Pink: 2. Bottom Pink:

1. Inside: Negative 2. Outside: Positive The separation of charges creates a voltage (electrical potential difference), which can be measured using a voltmeter. The resting membrane potential of a neuron averages -70mV (millivolts). All neural activities begin with a change in the resting membrane potential of a neuron.

1. Inside: Negative or Positive? 2. Outside: Negative or Positive?

B) become more negative

A K+ deficiency reduces extracellular K+ concentration from 4 mM to 2 mM. As a result, a neuron's resting membrane potential will __________. A) become less negative B) become more negative C) remain largely unchanged

1. (Top): K+ permeability: The primary determinant of the resting membrane potential 2. Membrane potential of −70 mV: The resting membrane potential of the cell 3. Na+ permeability: Although it plays a role, it is not a primary determinant of the resting membrane potential 4. Membrane potential of -90 mV: There is no net movement of K+ into or out of the cell because electrical gradient equals chemical gradient

From top to bottom, what are the answers? 1. ______: The primary determinant of the resting membrane potential 2. ______: The resting membrane potential of the cell 3. ______: Although it plays a role, it is not a primary determinant of the resting membrane potential 4. ______: There is no net movement of K+ into or out of the cell because electrical gradient equals chemical gradient

A) Na+/K+ pump

In order to ensure that Na+ concentration remains high outside a neuron, and that K+ concentration remains high inside, the neuron depends on the activity of the _______________. A) Na+/K+ pump B) K+ leak channels C) Na+ leak channels D) none of the above

A) Na+/K+ ATPase pump Because some K+ is always leaking out of the cell, and some Na+ is always leaking in, the concentration gradients would have a tendency to "run down", resulting in equal concentrations of Na+ and K+ inside and outside the cell. This does not happen because the Na+/K+ ATPase pump ejects 3 Na+ ions from the cell for every 2 K+ ions it transports back into the cell. This has the effect of maintaining the high ionic concentration gradients for K+ and Na+, which helps to stabilize the resting membrane potential.

In order to ensure that the Na+ concentration remains high outside a neuron, and the K+ concentration remains high inside, the neuron depends on the activity of the _________________________ to maintain the ionic concentration gradients. A) Na+/K+ ATPase pump B) Na+ leak channel C) resting membrane potential D) K+ leak channel

D The visceral motor division, also called autonomic nervous system (ANS), is responsible for maintaining homeostasis through control of the body's involuntary motor functions. Its neurons innervate cardiac muscle cells, smooth muscle cells, and the secretory cells of glands.

In the above image, the visceral motor division of the PNS is labeled _____. A B C D

A) Resting membrane potential (RMP) The resting membrane potential is the membrane potential that can be recorded across the plasma membrane of an excitable cell while it is at rest (prior to excitation).

Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference (voltage) across the membrane. What is the name given to this potential difference? A) Resting membrane potential (RMP) B) Action potential C) Positive membrane potential D) Threshold potential

1. Bundles of axons that extend from the brain and spinal cord 2. -Cranial Nerves: innervate structures in the head -Spinal Nerves: Innervate structures in the rest of the body; communication lines that link all parts of the body to the CNS

Nerves: 1. What are they? 2. What are the 2 classifications of nerves/Define them

1. The master controlling and communicating system of the body 2. -Gathers SENSORY INPUT from the environment -Processes/interprets that and decides what should be done, which is called INTEGRATION -Activates effector organs (muscles and glands) to cause a response called MOTOR OUTPUT

Nervous System: 1. What is it? 2. What are the 3 functions of it?

A) neurons, muscles, and glands. Neurons can form synapses on, and therefore communicate with, other neurons, muscle cells, and glands. Neurons can even form synapses with themselves at synapses called "autapses".

Neurons can communicate with (form synapses on) A) neurons, muscles, and glands. B) neurons and muscles. C) only other neurons. D) muscles and glands.

B) The inside surface of the plasma membrane is much more negatively charged than the outside surface. The inside surface of the plasma membrane accumulates more negative charge because of the presence of Na+ and K+ gradients and the selective permeability of the membrane to Na+ and K+.

On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you? A) There is no electrical potential difference between the inside and the outside surfaces of the plasma membrane. B) The inside surface of the plasma membrane is much more negatively charged than the outside surface. C) The outside surface of the plasma membrane is much more negatively charged than the inside surface. D) The inside surface of the plasma membrane is much more positively charged than the inside surface.

C) Use a voltmeter with two electrodes, one placed in the extracellular fluid and the other placed in the intracellular fluid.

Select the method that correctly represents how the membrane potential of a neuron is measured. A) Use a voltmeter with only one electrode placed in the intracellular fluid. B) Use a voltmeter with two electrodes, both placed in the extracellular fluid. C) Use a voltmeter with two electrodes, one placed in the extracellular fluid and the other placed in the intracellular fluid. D) Use a voltmeter with two electrodes, both placed in the intracellular fluid.

D) Leak channels Leak channels for Na+ and K+ are ubiquitous (in all cells), and they allow for the diffusion of these ions across plasma membranes and are responsible for generating the resting membrane potential. It is important to remember that leak channels are "open" all of the time. They are sometimes called "passive" or "non-gated" channels because they do not have a gate that opens and closes. We'll learn more about "gated" channels later.

Sodium and potassium ions can diffuse across the plasma membranes of all cells and generate a resting membrane potential because of the presence of what type of channel? A) Sodium-potassium ATPases B) Chemically-gated channels C) Voltage-gated channels D) Leak channels

B) are mixed nerves with both sensory and motor nerve fibers. Spinal nerves extend from the spinal cord to the periphery of the body. They are mixed nerves, which means that they contain axons from both motor neurons and sensory neurons. We'll learn more about motor neurons and sensory neurons later in the course.

Spinal nerves A) travel from the spinal cord to the brain. B) are mixed nerves with both sensory and motor nerve fibers. C) carry only sensory information. D) carry only motor information.

D) nerves and ganglia The PNS is the part of the nervous system that is outside the CNS. Since the CNS is made up of the brain and spinal cord, the PNS is the nerves that extend from the CNS into the periphery, and the ganglia that can be found along those nerves. Ganglia are clusters of neuron cell bodies, and we'll learn more about them in Lecture blocks 3 and 4. The peripheral nerves that extend from the brain and innervate structures in the head and a portion of the neck are called cranial nerves. The peripheral nerves that extend from the spinal cord and innervate structures in the rest of the body are called spinal nerves.

The Peripheral Nervous System or PNS is made up of __________________. A) brain and spinal cord B) spinal cord and skeletal muscles C) spinal cord and ganglia D) nerves and ganglia

C) Na+ and Cl- In a typical cell, the concentration of K+ is high inside the cell and the concentration of Na+ is high outside the cell. Extracellular and intracellular fluid environments are electrically neutral, so the high extracellular Na+ concentration is balanced by high Cl-, and the high K+ concentration inside the cell is electrically balanced by negatively charged protein anions (A-).

The concentrations of which two ions are highest outside the cell? A) K+ and Cl- B) Na+ and protein anions (A-) C) Na+ and Cl- D) K+ and protein anions (A-)

A) central nervous system and peripheral nervous systems. The two divisions of the nervous system are the central nervous system (CNS) and peripheral nervous system (PNS). The structural components of the CNS are the brain and the spinal cord while the structural components of the PNS are nerves and ganglia. The PNS can also be further divided functionally into the sensory and motor divisions. The sensory or afferent division conveys impulses to the CNS from sensory receptors throughout the body. The motor or efferent division transmits impulses from the CNS to effector organs, such as muscles and glands. These efferent signals are the commands that tell muscles to contract, and gland cells to secrete.

The divisions of the nervous system are the A) central nervous system and peripheral nervous systems. B) nerves and ganglia. C) muscle tissue and nervous tissue. D) brain and spinal cord.

D) There are many more K+ leak channels than Na+ leak channels in the plasma membrane. More leak channels translates into more leakiness. Thus the outward flux of K+ is greater than the inward flux of Na+.

The plasma membrane is much more permeable to K+ than to Na+. Why? A) There are many more voltage-gated K+ channels than voltage-gated Na+ channels. B) The Na+-K+ pumps transport more K+ into cells than Na+ out of cells. C) Chemically-gated cation channels favor a greater influx of Na+ than K+. D) There are many more K+ leak channels than Na+ leak channels in the plasma membrane.

B) The presence of concentration gradients and leak channels The concentration gradient and the large number of K+ leak channels allow for rather robust K+ diffusion out of a cell. In contrast, the concentration gradient and the relatively few Na+ leak channels allow for much less Na+ diffusion into a cell.

The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors. A) The presence of concentration gradients and Na+-K+ pumps B) The presence of concentration gradients and leak channels C) The presence of concentration gradients and voltage-gated channels D) The presence of a resting membrane potential and leak channels

B The somatic motor or efferent division is depicted in panel B. It is considered "somatic" because you have voluntary control of the action, and it is "motor or efferent" because the neurons are carrying a motor command from the CNS (spinal cord) to a skeletal muscle, in order to tell it to contract.

The somatic motor (efferent) division is indicated by which panel in the above image? A B C D

A The somatic sensory or afferent division is depicted in panel A. It is considered "somatic" because you are aware of it, and it is "sensory or afferent" because the neurons are collecting information from the periphery and sending it toward the CNS for analysis and integration.

The somatic sensory (afferent) division is indicated by which panel in the above image? A B C D

C) Schwann cell The Schwann cell is the cell in the peripheral nervous system that produces the myelin sheaths around some axons. (In the central nervous system, the oligodendrocyte makes myelin.) It takes many Schwann cells to insulate a single axon, because each Schwann cell wraps only a small portion of the axon. Neighboring Schwann cells do not touch each other, and the gaps between Schwann cells are called Nodes of Ranvier. In a later lab exercise, we will learn that these nodes have an important function during propagation of the action potential in myelinated axons.

What is the name of the cell that forms the myelin sheath in the peripheral nervous system? A) Axon B) Muscle cell C) Schwann cell D) Neuron

C) dendrite A indicates the dendrites of the neuron.

What is the structure at A? A) soma B) axon C) dendrite D) axon collateral

A) cell body or soma The term soma applies to the cell body, the area that includes the nucleus.

What is the structure at B? A) cell body or soma B) axon collateral C) dendrites D) axon

C) axon terminal This is the terminal portion of the axon which is called the axon terminal. This is where synaptic vesicles containing neurotransmitters are released, so it can also be called the synaptic terminal.

What is the structure at E? A) axon hillock B) dendrite C) axon terminal D) cell body or soma

D) Na+-K+ ATPase Also known as the Na+-K+ pump, or simply the pump, this transporter moves three Na+ out of the cell and two K+ into the cell for every ATP it hydrolyzes. This pumping action prevents the Na+ and K+ concentration gradients from running down as these ions passively move through leak channels.

What prevents the Na+ and K+ concentration gradients from dissipating (running down)? A) Na+ cotransporter B) H+-K+ ATPase C) Na+ and K+ leaks D) Na+-K+ ATPase

A) electrochemical

When the electrical charge of an ion as well as its concentration gradient favor movement of that ion into the cell, the ion is said to move down its ________ gradient. A) electrochemical B) K+ Resting C) Na+ Permeability D) active

1. Double the size of the cell, without adding channels 2. Double the number of closed channels for K+

Which are largely unchanged?

1. Double the number of K+ leak channels 2. Decrease the concentration of Na+ outside the cell by half

Which are more negative?

1. Double the concentration of K+ outside the cell 2. Triple the number of Na+ leak channels

Which are more positive?

A) potassium (K+)

Which cation is most concentrated inside the cell? A) potassium (K+) B) protein anions (A-) C) sodium (Na+) D) chloride (Cl-)

D The visceral motor (efferent) division, which is part of the involuntary or autonomic nervous system will send motor commands to the smooth muscles in the walls of the bronchioles of the lung.

Which division can tell the bronchioles (air passages) in your lungs to dilate? A B C D

C) Axon The axon is considered the conductive part of the neuron because this is where the action potential occurs and is propagated. The action potential actually starts at the axon hillock, the initial portion of the axon. We will learn more about this later.

Which is considered the conductive portion of the neuron? A) Cell body (soma) B) Dendrites C) Axon

A) different permeabilities of the membrane to Na+ and K+ ions

Which of the following factors is important in creating a resting membrane potential of -70 mV? A) different permeabilities of the membrane to Na+ and K+ ions B) size of the cell C) equal concentrations of K+ in the intracellular and extracellular fluids D) number of closed voltage-gated ion channels

C) increasing the number of K+ leak channels

Which of the following would increase a neuron's membrane permeability to (K+)? A) decreasing the number of K+ leak channels B) making the membrane potential more negative C) increasing the number of K+ leak channels D) allowing the membrane potential to stay at rest

B Kicking a soccer ball is a volitional movement - you can choose and control the action of the skeletal muscles in your lower extremity in order to perform the kick. This would be a motor (efferent) command from the somatic nervous system, which is depicted in panel B.

Which part of the nervous system can you use to kick a soccer ball? A B C D

K+ The membrane is more permeable to K+.

second sentence down

Na+ The concentration of Na+ is higher outside than inside the cell.

third sentence down