A&P Chapter 12
List 3 types of sensory receptors.
1. Special sensory receptors 2. Motor sensory receptors 3. Somatic sensory receptors
Compared with type C fibers, type A fibers have a larger diameter and can increase propagation __________ times faster.
120
CNS neurons cannot be replaced if lost to injury or disease. Why can't they be replaced?
CNS neurons cannot divide
Which ion triggers synaptic vesicles to discharge neurotransmitter into the synaptic cleft?
Calcium
Relative refractory period
Can only respond to larger than normal stimulus
Most neurons lack ________ and so are permanently blocked from undergoing cell division.
Centrioles
The ventricles of the brain and the central canal of the spinal cord are filled with __________.
Cerebrospinal fluid
At a(n) ________ synapse, a neurotransmitter is released to stimulate the postsynaptic membrane.
Chemical
In order to communicate with multiple cells at the same time, an axon may branch along its length, producing side branches called __________.
Collaterals
Which of the following is NOT one of the three classes of mechanisms by which neurotransmitters function?
Compounds that prevent inactivation of neurotransmitter at the synaptic cleft
During the initiation of an action potential in an area of excitable membrane, which of the following does NOT occur?
Potassium channels open to increase the level of depolarization attained by the membrane.
Which neurotransmitter is released at adrenergic receptors?
Norepinephrine
The myelin sheath that covers many CNS axons is formed by
Oligodendrocytes
Which of the following glial cells can form a myelin sheath around axon fibers in the central nervous system?
Oligodendrocytes
Multipolar neurons have __________.
One axon and several dendrites
The Autonomic Nervous System (ANS) is divided into two parts, the __________ Nervous System and the ________________ Nervous System.
Parasympathetic, sympathetic
Sensory receptors send sensory information to the Central Nervous System (CNS) using the ______________ division of the Peripheral Nervous System (PNS) while the _____________ division sends motor commands from the CNS to effectors in the PNS.
afferent, efferent
What are the small gaps located between internodes of myelinated axons called?
nodes
The Extracellular Fluid (ECF) contains high concentrations _____________ cations while the Intercellular Fluid (ICF) contains high concentrations of ____________ cations.
sodium & chloride, potassium
Which high energy compound is used to drive the active Na+/K+ exchange pumps?
sodium-potassium exchange pumps
A neuron that receives neurotransmitter from another neuron is called
the postsynaptic neuron
What is the resting potential of a typical neuron?
−70 mV
List and describe the function of 4 types of neuroglial cells found in the CNS.
- Astrocytes: maintain blood brain barrier, provide structural support, regulate ion, nutrient, and dissolved gas concentrations, absorb and recycle neurotransmitters, form scar tissue after injury - Ependymal cells: line ventricles (brain) and central canal (spinal cord), assist in producing, circulating, and monitoring cerebrospinal fluid. - Oligodendrocytes: myelinate CNS axons, provide structural framework - Microglia: remove cell debris, wastes, and pathogens by phagocytosis
List and describe the function of 2 types of neuroglial cells found in the PNS.
- Satellite cells: regulate the interstitial fluid around the neurons - Schwann cells: either form a thick myelin sheath or indented folds of plasma membrane around peripheral axons in in all parts of the PNS
Describe the anatomical difference between white and gray matter.
- White matter: regions in the CNS that are dominated by the myelinated axons - Gray matter: areas in the CNS that are dominated by neuron cell bodies, neuroglia, and unmyelinated axons
What is the resting membrane potential value (in mV) of a neuron?
-70 mV
Depolarization
A change in the membrane potential from a negative value toward 0 mV
Describe what a neurotransmitter is and explain its function.
A chemical compound released by one neuron to affect the membrane potential of another. They are important in cell-to-cell communication.
The decreased release of which neurotransmitter is the cause of Parkinson's disease?
Dopamine
Which neurotransmitter is released at cholinergic synapses?
Acetylcholine (ACh)
There are two major categories of ion channels: leak channels and __________.
Active channels
The ________ division of the peripheral nervous system brings sensory information to the central nervous system.
Afferent
The many functions of the astrocytes include which of the following?
All of the listed responses are correct.
Which of the following statements about resting potential is true?
All of the listed responses are correct.
Which of the following statements about facilitation is FALSE?
All of the listed responses are false; none is true.
Graded potentials __________.
Are found in many cell types
IPSPs (inhibitory postsynaptic potentials)
Are local hyperpolarizations
The largest and most numerous of the glial cells in the central nervous system are the
Astrocytes
When a person has a stroke, blood leaks into the brain tissue. Which type of neuroglia cells would make structural repairs to the damage?
Astrocytes
The axon emerges from the soma at a thickened region called the __________.
Axon hillock
The simplest level of information processing takes place at the __________.
Axon hillock
The site in the neuron where EPSPs and IPSPs are integrated is the
Axon hillock
The movement of materials from the soma to the synaptic terminal is called __________.
Axoplasmic transport
The central nervous system consists of the __________.
Brain and spinal cord
A shift of the resting transmembrane potential toward 0 mV is called
Depolarization
Opening of sodium channels in the axon membrane causes
Depolarization
The ________ division of the nervous system carries motor commands to muscles and glands.
Efferent
EPSPs (excitatory postsynaptic potentials) occur when
Extra sodium ions enter a cell.
Damage to ependymal cells would most likely affect the
Formation of cerebrospinal fluid
In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by
Forming a cellular cord that directs axonal regrowth.
The refractory period occurs __________.
From the time an action potential begins until the normal resting potential has stabilized
Which of the following is the most important excitatory neurotransmitter in the brain that is important in learning and memory?
Glutamine
Which of the following statements comparing action potentials and graded potentials is INCORRECT?
Graded potentials occur only in excitable membranes, whereas action potentials occur in most cell membranes.
Saltatory transmission __________.
Has all of the listed characteristics
Norepinephrine (NE)
Has an excitatory, depolarizing effect on the postsynaptic membrane
Dopamine
Has inhibitory effects which control precise movement and excitatory effects
A stimulus causes a neuron's membrane potential to rise to −60 mV. Which of the following is NOT going to occur?
Inhibition of action potential due to hyperpolarization
Presynaptic facilitation __________.
Is activity at an axoaxonal synapse that increases the amount of neurotransmitter released when an action potential arrives at the synaptic terminal
Gamma-aminobutyric acid (GABA)
It has inhibitory affects, in the CNS it appears to reduce anxiety.
Which type of ion channel is always open?
Leak
Small, wandering cells that engulf cell debris and pathogens in the CNS are called
Microglia
Which of the following statements about motor neurons is true?
Motor neurons form the efferent division of the PNS
Which neuron classification is the most common neuron found in the CNS?
Multipolar neurons
The presence of ________ dramatically increases the speed at which an action potential moves along an axon.
Myelin
What is the relationship between myelin and the propagation speed of an action potential?
Myelin greatly increases propagation speed
________ account for roughly half of the volume of the nervous system.
Neuroglia
Which of these neurotransmitters does NOT bind to a plasma membrane receptor?
Nitric oxide
The tiny gaps between adjacent Schwann cells are called
Nodes of Ranvier
What type of sensory neurons would Amy, a gymnast, use to inform her brain of the position of her skeletal muscles and joints?
Proprioceptors
Gated channels may be __________.
Regulated in any of the listed ways
The movement of substances from the synaptic terminal to the soma is called __________.
Retrograde flow
SAME principle
S = sensory A = afferent M = motor E = efferent
Which of the following glial cells surround cell bodies in the PNS and regulate levels of oxygen and carbon dioxide around ganglionic neurons?
Satellite cells
Which of the following are NOT glial cells of the CNS?
Schwann cells
Which neurotransmitter is affected by SSRI's such as Zoloft, Paxil and Prozac?
Seratonin
Which neurotransmitter has widespread effects on a person's attention and emotional state?
Serotonin
Summation that results from the cumulative effect of multiple synapses at multiple places on the neuron is designated
Spatial summation
Which of the following statements about synaptic transmission is INCORRECT?
Synaptic delay is greater at synapses of myelinated neurons than at those of unmyelinated neurons.
When you take a pain reliever, which of the following best describes, in general terms, how this affects the threshold of neurons?
Taking a pain reliever increases the threshold
Which of the following is NOT a neurotransmitter?
Testosterone
Which of the following statements about neural organization is INCORRECT?
The afferent division is also known as the visceral motor system.
Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons?
The axon would be unable to generate action potentials.
Which of the following statements about gated channels is INCORRECT?
The binding of ACh on the axon hillock triggers the opening of voltage-gated channels.
What is the implication of a mature neuron's having no centrioles?
The cell is not able to divide
Which of the following statements about electrical synapses is FALSE?
The connections between presynaptic and postsynaptic cells allow neurotransmitters such as ACh and dopamine to travel directly from one cell to another.
Which of the following statements about graded potentials is INCORRECT?
The effect of graded depolarization is spread actively as ATP is required to open channels.
Which of the following statements about the nervous system is FALSE?
The efferent division of the peripheral nervous system contains sensory and motor neurons
Absolute refractory period
The membrane cannot respond to further stimulus
Repolarization
The movement of the membrane potential away from a positive value and toward the resting potential
hyperpolarization
The movement of the membrane potential away from the normal resting potential and farther from 0 mV.
The speed at which an action potential is transmitted depends on __________.
The myelination and diameter of the axon
Describe the function of acetylcholinesterase.
The neurotransmitters effects on the postsynaptic membrane are temporary, because the synaptic cleft and the post synaptic membrane contain acetylcholinesterase.
Which of the following does NOT describe a synapse?
The point where neurotransmitters are assemble
Which of the following statements about neural function and information processing is INCORRECT?
The rate of action potential generation at a postsynaptic membrane is constant for each particular synapse.
Which one of the following statements about the transmembrane potential is correct?
The resting negative charge on the interior of the plasma membrane is due mainly to charges on proteins.
Which of the following statements about action potentials and their propagation is INCORRECT?
The smaller the diameter of an axon, the more rapidly it can conduct an action potential.
The transmembrane potential found in all living cells is maintained by __________.
The sodium-potassium pump
How does blocking retrograde axoplasmic transport in an axon affect the activity of a neuron?
The soma becomes unable to respond to changes in the distal end of the axon.
What is the major anatomical difference between an anaxonic neuron and all other classified neurons?
They have numerous dendrites and less obvious axons
Where are bipolar neurons located?
They occur in special sense organs and relay information about sight, smell, or hearing from receptor cells to other neurons.
The minimum stimulus required to trigger an action potential is known as the
Threshold
Deteriorating changes in the distal segment of an axon as a result of a break between it and the soma is called ________ degeneration.
Wallerian
What part of the neuron is clustered in masses called ganglion?
cell bodies of neurons in the PNS
Serotonin
inadequate amounts can have widespread effects on a person's attention and emotional states
Due to the concentrations of Na+ and K+ in their respective compartments (intercellular or extracellular), a passive chemical gradient occurs. What type of channel is involved in passive chemical gradients?
leak channels
Rapid impulse conduction from "node" to "node" is called
saltatory propagation
The site of intercellular communication between a neuron and another cell is the
synapse
Axons terminate in a series of fine extensions known as
telodendria