Chapter12 Study guide
Okay, here are the answers to the 14 questions based on the provided lectures:
Neuron Zones:
Receptive Segment (Dendrites and Cell Body):
Conduction Type: Graded potentials
Duration: Variable, short to long
Location: Dendrites and cell body
Function: Receives and integrates incoming signals.
Axon Hillock (Initial Segment):
Conduction Type: Action potentials
Duration: Brief (1-2 ms)
Location: Axon hillock
Function: Generates action potentials.
Transmissive Segment (Synaptic Knobs):
Conduction Type: Neurotransmitter release
Duration: Short (milliseconds)
Location: Synaptic knobs
Function: Releases neurotransmitters to communicate with other neurons or target cells.
Glial Cells Forming Myelin:
Oligodendrocytes (in the CNS)
Schwann cells (in the PNS)
Events of EPSP in Correct Order:
Excitatory neurotransmitter release from the presynaptic neuron.
Neurotransmitter diffuses across the synaptic cleft.
Neurotransmitter binds to receptors on the postsynaptic neuron.
Ion channels open, allowing influx of positive ions (e.g., Na^+, Ca^{2+}).
Depolarization of the postsynaptic membrane (EPSP).
Synaptic Cleft Definition:
The synaptic cleft is the narrow gap between the presynaptic neuron and the postsynaptic cell (another neuron, muscle cell, or gland cell), across which neurotransmitters diffuse to transmit signals.
Examples of E-factors (Likely referring to factors influencing reaction rate or efficiency):
This question is unclear without more context. E-factors typically relate to enzymatic reactions or metabolic efficiency. Examples might include:
Enzyme concentration
Substrate concentration
Temperature
pH
Presence of cofactors or inhibitors
Structural and Functional Classification of Nerves:
Structural Classification:
Cranial Nerves: Originate from the brain.
Spinal Nerves: Originate from the spinal cord.
Functional Classification:
Sensory (Afferent) Nerves: Transmit sensory information from receptors to the CNS.
Motor (Efferent) Nerves: Transmit motor commands from the CNS to effectors (muscles or glands).
Mixed Nerves: Contain both sensory and motor fibers.
Resting Potential Sub-Questions:
What makes the resting potential and what kind of charges are involved?
The resting potential is made by the distribution of ions (primarily K^+ and Na^+) across the cell membrane and the selective permeability of the membrane to these ions. The inside of the cell is negatively charged relative to the outside.
Which ion (sodium or potassium) has greater diffusion flow?
Potassium (K+) has a greater diffusion flow at rest due to more leaky potassium channels.
What is the electrochemical gradient?
The electrochemical gradient is the combination of the concentration gradient and the electrical gradient that affects the movement of ions across the membrane.
When is the electrochemical gradient for sodium high?
The electrochemical gradient for sodium is high at resting potential because there is a strong concentration gradient (more sodium outside) and a strong electrical gradient (negative inside).
What is the function of the sodium-potassium pump (specifically when the electrochemical gradient for sodium is high)?
The sodium-potassium pump maintains the resting potential by pumping 3 Na^+ ions out of the cell and 2 K^+ ions into the cell, against their electrochemical gradients. This is crucial when the electrochemical gradient for sodium is high to prevent excessive sodium influx.
Statements About Graded Potentials:
Graded potentials are:
Local changes in membrane potential.
Can be either depolarizing (EPSP) or hyperpolarizing (IPSP).
Amplitude varies with stimulus intensity.
Summate (add together).
Do not have a refractory period.
Temporal Summation Definition:
Temporal summation is the process where repeated stimuli at the same location occur in rapid succession, building upon each other to reach the threshold for an action potential.
Function of the Somatic Sensory Division:
The somatic sensory division transmits sensory information from the skin, muscles, and joints to the CNS, providing conscious awareness of sensations such as touch, temperature, pain, and proprioception.
Content from Slide 19:
Without the specific content of slide 19, it's difficult to answer. Generally, slide 19 would likely cover one of the introductory topics, such as the divisions of the nervous system or basic neuron structure.
Match Functions of Neuroglia to the Correct Cell and Location:
CNS:
Astrocytes: Support, blood-brain barrier formation, regulate the chemical environment.
Ependymal Cells: Line ventricles, produce cerebrospinal fluid.
Microglia: Phagocytosis, immune defense.
Oligodendrocytes: Myelination.
PNS:
Satellite Cells: Surround neuron cell bodies in ganglia, regulate the environment.
Schwann Cells: Myelination.
Hyperpolarization Definition:
Hyperpolarization is when the membrane potential becomes more negative than the resting membrane potential (e.g., more negative than -70mV), making the neuron less likely to fire an action potential.
Essay Question: Physiological Effects of a Non-Inactivating Voltage-Gated Sodium Channel:
If voltage-gated sodium channels do not inactivate due to a mutation, the following physiological effects on action potential would occur:
Prolonged Depolarization Phase: The sodium channels would remain open longer, leading to a prolonged influx of Na^+ and an extended depolarization phase.
Suppressed Repolarization: The extended influx of Na^+ would delay or prevent the opening of potassium channels, thus suppressing repolarization.
Extended Action Potential Duration: The overall duration of the action potential would be significantly prolonged.
Increased Refractory Period: The neuron may remain in a depolarized state for an extended period, leading to a prolonged refractory period. The neuron would be