BIO 360 - Exam 2 - Chapter 8 Summary Questions Flashcards
The ______ ______ is a complex network of neurons that form the rapid control system of the body.
nervous system
______ ______ of the nervous system include consciousness, intelligence, and emotion.
Emergent properties
The nervous system is divided into the ______ ______ ______, composed of the brain and spinal cord, and the ______ ______ ______.
central nervous system (CNS) / peripheral nervous system (PNS)
The peripheral nervous system has ______ (______) neurons that bring information into the CNS, and ______ neurons that carry information away from the CNS back to various parts of the body.
sensory (afferent) / efferent
The efferent neurons include ______ ______ neurons, which control skeletal muscles, and ______ neurons, which control smooth and cardiac muscles, glands, and some adipose tissue.
somatic motor / autonomic
Autonomic neurons are subdivided into ______ and ______ branches.
sympathetic / parasympathetic
Neurons have a ____ ____ with a nucleus and organelles to direct cellular activity, ______ to receive incoming signals, and an ______ to transmit electrical signals from the cell body to the ______ ______.
cell body / dendrites / axon / axon terminal
______ are neurons that lie entirely within the CNS.
Interneurons
Material is transported between the cell body and axon terminal by ______ ______.
axonal transport
The region where an axon terminal meets its target cell is called a ______.
The target cell is called the ______ ______.
The neuron that releases the chemical signal is known as the ______ ______.
The region between these two cells is the ______ ______.
synapse / postsynaptic cell / presynaptic cell / synaptic cleft
Developing neurons find their way to their targets by using ______ ______. The human CNS also contains electrical synapses that allow electrical current and chemical signals to pass between cells through gap junction channels. Communication at electrical synapses is bidirectional as well as faster than at chemical synapses. Electrical synapses allow multiple CNS neurons to coordinate and fire simultaneously.
chemical signals
______ ______ provide physical support and communicate with neurons.
______ ______ and ______ ______ are glial cells associated with the peripheral nervous system.
______, ______, ______, and ______ cells are glial cells found in the CNS.
______ are modified immune cells that act as scavengers.
Glial cells / Schwann cells / satellite cells / Oligodendrocytes, astrocytes, microglia, and ependymal cells / Microglia
Schwann cells and oligodendrocytes form insulating ______ ______ around neurons. The ______ ___ ______ are sections of uninsulated membrane occurring at intervals along the length of an axon.
myelin sheaths / nodes of Ranvier
______ ______ ______ that can develop into new neurons and glia are found in the ependymal layer as well as in other parts of the nervous system.
Neural stem cells
The ______ ______ describes the membrane potential of a cell that is permeable to only one ion.
Nernst equation
Membrane potential is influenced by what two things?
(1) the concentration gradients of ions across the membrane (2) the permeability of the membrane to those ions.
The Goldman-Hodgkin-Katz (GHK) equation predicts what two things?
(1) membrane potential based on ion concentration gradients
(2) membrane permeability for multiple ions.
The permeability of a cell to ions changes when?
Ion channels in the membrane open and close. Movement of only a few ions significantly changes the membrane potential.
Gated ion channels in neurons open or close in response to?
Channels also close through?
(1) chemical or mechanical signals
(2) in response to depolarization of the cell membrane.
inactivation.
Current flow (I) obeys what law?
______ to current flow comes primarily from the cell membrane, which is a good insulator, and from the cytoplasm. ______ is the reciprocal of resistance: ______.
Ohm’s law: I = voltage / resistance
Resistance / Conductance (G) / G = 1/R
______ ______ are depolarizations or hyperpolarizations whose strength is directly proportional to the strength of the triggering event.
______ ______ lose strength as they move through the cell.
Graded potentials in neurons are depolarizations or hyperpolarizations that occur in the dendrites and cell body or, less frequently, near the axon terminals.
Graded potentials
The wave of depolarization that moves through a cell is known as?
Current in biological systems is the net movement of ______ electrical charge.
Local current flow / positive
______ ______ are rapid electrical signals that travel undiminished in amplitude (strength) down the axon from the cell body to the axon terminals. Action potentials are very brief, large depolarizations that travel for long distances through a neuron without losing strength. Their function is rapid signaling over long distances, such as from your toe to your brain.
Action potentials
Action potentials begin in the ______ ______ if a single graded potential or the sum of multiple graded potentials exceeds the ________ voltage.
trigger zone / threshold
______ ______ ______ make a neuron more likely to fire an action potential.
______ ______ ______ make a neuron less likely to fire an action potential.
Depolarizing graded potentials / Hyperpolarizing
Action potentials are uniform, ______ depolarizations that can travel undiminished over long distances.
all-or-none
The rising phase of the action potential is due to increased ______ permeability. The falling phase of the action potential is due to increased ______ permeability.
Na+ / K+
The voltage-gated ______ channels of the axon have a fast ______ ______ and a slower ______ ______ .
Na+ / activation gate / inactivation gate
Very few ions cross the membrane during an action potential. The ____________ eventually restores ______ and ______ to their original compartments.
This exchange does not need to happen before the next action potential fires, however, because the ion concentration gradient was not significantly altered by one action potential.
Na+-K+-ATPase / Na+ / K+
Once an action potential has begun, there is a brief period of time known as the ______ ______ ______ during which a second action potential ______ ______ ______, no matter how large the stimulus. Because of this, action potentials cannot be summed.
absolute refractory period / cannot be triggered
During the ______ ______ ______ , a higher-than-normal graded potential is required to trigger an action potential.
relative refractory period
The myelin sheath around an axon speeds up conduction by what two things?
______ ______ ______ conduct action potentials faster than ______ ______ ______ do.
(1) increasing membrane resistance
(2) decreasing current leakage
Larger-diameter axons / smaller-diameter axons
The apparent jumping of action potentials from node to node is called?
saltatory conduction
Changes in blood ______ concentration affect what two things?
K+ / resting membrane potential and the conduction of action potentials.
In ______ ______, signal passes directly from the cytoplasm of one cell to another through gap junctions.
______ ______ use neurotransmitters to carry information from one cell to the next, with the neurotransmitters diffusing across the synaptic cleft to bind with receptors on target cells.
electrical synapses / Chemical synapses
Neurotransmitters come in a variety of forms.
______ neurons secrete ______ .
______ neurons secrete ______.
______, ______, ______, ______, and ______ are other major neurotransmitters.
Cholinergic / acetylcholine
Adrenergic / norepinephrine.
Glutamate, GABA, serotonin, adenosine, and nitric oxide
Neurotransmitter receptors are either one of which two receptors?
(1) Ligand-gated ion channels (ionotropic receptors)
or
(2) G protein-coupled receptors (metabotropic receptors).
Neurotransmitters are synthesized in the _____ _____ or the ______ ______ . They are stored in ______ ______ and are released by ______ when _______________________________.
cell body / axon terminal / synaptic vesicles / exocytosis / an action potential reaches the axon terminal.
Neurotransmitter action is rapidly terminated by what three things? RED
(1) Re-uptake into cells
(2) Enzymatic breakdown
(3) Diffusion away from the synapse
Information about the strength and duration of a stimulus is conveyed by the amount of ______ ______.
Increased frequency of action potentials releases more ______.
neurotransmitter released / neurotransmitter
What is divergence? Convergence?
When a presynaptic neuron synapses on a larger number of postsynaptic neurons, the pattern is known as divergence.
When several presynaptic neurons provide input to a smaller number of postsynaptic neurons, the pattern is known as convergence.
Synaptic transmission can be modified in response to activity at the synapse, a process known as ______ ______.
synaptic plasticity
G protein-coupled receptors either create ______ ______ ______ or modify ______ ______.
Ion channels create ______ ______ ______.
slow synaptic potentials / cell metabolism / fast synaptic potentials
What is spatial summation? Temporal summation?
The summation of simultaneous graded potentials from different neurons is known as spatial summation.
The summation of graded potentials that closely follow each other sequentially is called temporal summation.
______ ______ of an axon terminal allows selective modulation of collaterals and their targets.
______ ______ occurs when a modulatory neuron synapses on a postsynaptic cell body or dendrites.
Presynaptic modulation / Postsynapticmodulation
Long-term ______ and long-term ______ are mechanisms by which neurons change the strength of their synaptic connections.
potentiation / depression
