Biopsychology chapter 1
neuron
information processing and information transmitting cells of the nervous system
Nodes of Ranvier
interruptions in myelin sheeths
Potassium ions are mostly ____ (extra or intracellular)
intracellular
Cytoplasm
jelly-like substance that fills the cell
The speed of nerve impulse ranges from
less than 1 meter/second to 100 meters/seconds
membrane
lipid bilayer that defines the boundary of cell
multipolar neuron
most common neuron in the CNS
diffusion (aka concentration gradient)
movement of molecules from regions of high concentrations to regions of low concentrations
Once the threshold of excitation is reached, a subsequent _______ occurs (effect is for even more sodium/ Na+ to rush in)
nerve impulse
Depolarization
reduction of the membrane potential from its normal resting potential (move towards zero/ goes up/ less negative)
neuron cell membrane
semi-permeable: some, but not all, particles cna pass through it -proteins anchored in the membrane allow certain things to pass through
Fluid surrounding the outside of the cell
sodium and chloride
An unusually rapid series of action potentials can lead to a buildup of _____ within the axo which can be toxic (rare instances such as stroke for example)
sodium ions
Resting potential
state of a neuron prior to sending a nerve impulse (electron charge of a neuron)
CNS
the brain and spinal cord
Refractory periods
the neuron resists the production of another action potential after the first action potential
relative refractory period
the second part, right after neuron fires, in which is takes a stronger than usual stimulus to trigger an action potential (after this its difficult to start another action potential)
The brain is not set up to register small differences in the time of arrival of touch messages, except in the case of
vision (movements must be detected as accurately as possible. in some cases time matters with other senses, in others it doesnt)
Sodium and potassium channels' permeability depends upon the __________ across the membrane
voltage difference
Threshold of excitation
voltage level that triggers an action potential
The threshold of excitation occurs when the charge reaches about ______, although this can differ between neurons (the charge in 1 single neuron is always the same though)
-65mV
The resting potential inside a neuron is approximately
-70mV
Local neurons
Have short axons, exchange info with only close neighbors, and do not produce action potentials (special case)
What does an efferent axon do? a. it controls involuntary behavior. b. it controls voluntary behavior c. it carries output from a structure d. it brings information into a structure
It carries output from a structure
Does the nerve impulse travel directly down the axon?
No. It is regenerated at points along the axon so that it is not weakened (signal strength and speed maintained throughout the impulse)
When the neuron is at rest, the ____ (inside/ outside) of a neuron is more positively charged than the ______
Outside; inside (the neuron has more sodium ions outside than inside and sodium channels are closed)
Which of these can easily cross the blood-brain barrier by active transport? a. Oxygen, water, and fat-soluble molecules b.. Glucose and amino acids c. Proteins d.. Viruses
Oxygen, small uncharged molecules, psychoactive drugs, water and fat-soluble molecules
Sensory neuron
Specialized at one end to be highly sensitive to a particular type of stimulation such as light, sound, or touch.
Which of the following is a function of astrocytes? a. Conduct impulses over long distances b. Build myelin sheaths that surround and insulate axons c. Create the blood-brain barrier. d. Synchronize activity for a group of neurons.
Synchronize activity for a group of neurons
Saltatory conduction
The jumping of the action potential from node to node
polarization
The maintaining of a membrane's electrical gradient (a difference in electrical charge inside and outside the cell)
Which part of a neuron has its own genes, separate from those of the nucleus? a. The ribosomes b. The mitochondria c. The axon d. The dendrites
The mitochondria
presynaptic terminal
The swelling end of each axon branch (aka button or bulb)
What is most distinctive about neurons, compared to other cells? a. Their temperature b. Their shape c. Their internal components, such as ribosomes and mitochondria d. Their color
Their shape
Which of these do dendritic spines do? a. They synthesize proteins. b. They increase the surface area available for synapses c. Their internal components such as ribosomes and their mitochondria d. They metabolize fuels to provide energy for the rest of the neuron
They increase the surface area available for synapses
Interneuron (intrinsic neuron)
a cell's dendrites and axon are entirely contained within a single structure
Microelectrode
a very fine electrode that can be used to electrically stimulate or record from a neuron (placed in the soma and axon of a neuron)
What causes potassium ions to leave the axon just after the peak of the action potential? Select one: a. A continuing concentration gradient and the opening of the potassium gates b. Binding of potassium ions to proteins that leave at this time c. An increased tendency of the sodium-potassium pump to push potassium out d. An increase in the concentration gradient across the membrane
a. A continuing concentration gradient and the opening of the potassium gates
n efferent axon carries information away from a structure. Select one: a. True b. False
a. True
The major disadvantage of a blood-brain barrier is that ____. Select one: a. certain required chemicals must be actively transported b. so much glucose is required to maintain it c. many chemicals can easily diffuse into the brain d. viruses cannot escape
a. certain required chemicals must be actively transported
The tree-like branches of a neuron that receive information from other neurons are called _____. Select one: a. dendrites b. axons c. soma d. myelin
a. dendrites
During the relative refractory period, the ____. Select one: a. sodium gates are reverting to their usual state b. sodium gates are wide open c. potassium gates are firmly closed d. sodium gates are firmly closed
a. sodium gates are reverting to their usual state
After ______ occurs, sodium (Na+) channels are quickly closed
action potential
Presynaptic terminal
at the end points of an axon release chemicals to communicate with other neurons
What type of glia helps to synchronize the activity of axons? Select one: a. Radial glia b. Astrocytes c. Oligodendrocytes d. Schwann cells
b. Astrocytes
What term describes the difference in voltage that typically exists between the inside and the outside of a neuron? Select one: a. Generator potential b. Resting potential c. Shock gradient d. Concentration gradient
b. Resting potential
When the neuronal membrane is at rest, the potassium channels ____. Select one: a. prohibit any movement of potassium ions b. permit potassium ions to pass slowly c. permit potassium ions to pass quickly and easily d. help to open up the sodium channels
b. permit potassium ions to pass slowly
Afferent axon
brings info into a structure (sensory neuron)
Which type of glia builds myelin sheaths around axons in the periphery of the body? Select one: a. Radial glia b. Oligodendrocytes c. Schwann cells d. Astrocytes
c. Schwann cells
When the potential across a membrane reaches threshold, the sodium channels ____. Select one: a. open to let sodium exit the cell rapidly b. close to prevent sodium from exiting the cell c. open to let sodium enter the cell rapidly d. close to prevent sodium from entering the cell
c. open to let sodium enter the cell rapidly
When a neuron's membrane is at rest, the concentration gradient tends to move potassium ____ the cell and the electrical gradient tends to move it ____ the cell. Select one: a. out of; out of b. into; into c. out of; into d. into; out of
c. out of; into
Efferent axon
carries info away from a structure (motor neuron)
Potassium ions flow out due to the ____________ and take with them their positive charge
concentration gradient
Saltatory conduction
conserves energy for the cell (requires fewer Na+/K+) pumps -larger/ longer axons= greater conduction speed
bipolar neuron
conveys sensory info to CNS (esp changes in environment like temperature, movement, placement in environment)
unipolar neuron
conveys sensory info to CNS (esp relevant in sensation of touch)
Dr. Ruggs is giving a lecture about the all-or-none-law. What would she tell the class? Select one: a. That all neurons produce an action potential at the same time or none produce one. b. That all ion channels open at the same time or none at all. c. That all neurons are active at the same time or none at all. d. That after reaching threshold, the amplitude and velocity of the action potential is the same each time.
d. That after reaching threshold, the amplitude and velocity of the action potential is the same each time
What type of glial cells myelinate axons in the brain and spinal cord? Select one: a. Schwann cells b. astrocytes c. radial glia d. oligodendrocytes
d. oligodendrocytes
When sodium channels are opened and they rush in, this _____ (hyper or depolarizes?) the neuron
depolarizes (increases the charge)
A cell membrane's charge is produced by a balance between the forces of ____ and ______
diffusion; electrostatic pressure
Nerve impulse
electrical message transmitted down the axon of neuron
Chloride ions are mostly ____ (extra or intracellular)
extracellular
Sodium ions are mostly _____ (extra or intracellular)
extracellular
At each node of Ranvier, the axon is exposed to _______ and ____ from node to node
extracellular fluid; jumps
myelin sheath
fatty insulating substance that prevents messages from escaping the axon
action potential of a neuron
image of AP
Hyperpolarization
increase in the membrane potential relative to the normal resting potential (more negative, goes down)
Chemicals that are actively transported into the brain through the blood-brain barrier include
- glucose (the brain's main fuel) - amino acids (the building blocks of proteisn) - purines - choline - a fewvitamins - iron - hormones
radial glia
-Guide the migration of neurons and their axons and dendrites during embryonic development -after embryonic development, radial glia differentiate into neurons/ usually astrocytes/ oligodendrocytes sometimes
oligodendrocytes
-In the brain and spinal cord, build/produce myelin sheaths that surround and insulate certain vertebrate axons and supply axons with nutrients for functioning
Basic functions of Glia
-Provide physical and chemical buffers to isolate neurons (make sure only firing at targeted neurons) -surround neurons and hold them in place (not free-floating) -Control supply of chemicals to/ from neurons -Insulate neurons from each other so that neural signals dont get scrambled -Housekeepers: destroy and remove dead cells
Which ions come in and out of a neuron's protein channels/ membrane?
-Sodium (Na+) -Potassium (K+) -chloride (Cl-)
Why is the blood-brain barrier necessary in the brain?
-The immune system destroys damaged or infected cells throughout the body - neurons in the brain generally dont regenerate, so its important for the blood brain barrier to block harmful material from entering
sodium-potassium pump
-a protein complex embedded in the cell membrane - helps to maintain the electrical gradient -uses active transport (requires ATP)
microglia
-act as part of immune system -remove viruses and fungi and dead or damaged neurons and weakened synapses from the brain -smallest glia cells -protect the brain from microorganisms -inflammatory response when there is brain damage
Two forces that move ions
-diffusion -electrostatic pressure
Molecules reliant on active transport to get through the blood-brain barrier
-glucose -thiamine -amino acids -certain hormones
Blood-brain barrier
-mechanism that excludes most chemicals from the vertebrate brain
Cell body (soma)
-most of a neurons metabolic work occurs here -contains the nucleus, ribosomes, and mitochondria
Schwann Cells
-only in the periphery of the body - build myelin sheaths that surround and insulate a single vertebrate axon -can guide regrowth in case of axon damage
Organic anions
-only intracellular -too big to ass through membrane
The sodium-potassium pump continually pumps ____ sodium ions out of the cells while drawing ___ potassium ions into the neuron
3; 2
Dendrites
Branching fibers that get narrower near their ends and their surface is lined with specialized synaptic receptors that receive info from other neurons
Diffusion pushes ______ (which ion?) into the cell and electrostatic pressure pushes it out of the cell (it has no net movement at rest)
Chloride
What is the brain's main source of fuel? a. Glucose b. Glutamate c. Choline d. Proteins
Glucose
PNS
Has two divisions: -Somatic: sensory organs and skeletal muscles -Autonomic: Regulation of smooth and cardiac muscle and glands
Thiamine
Needed for the body/ brain to use glucose
Endoplasmic reticulum
Network of thin tubes that store or transport newly synthesized proteins to other locations through the cell
Does action potential travel both directions on a neuron?
No because it -starts at initial segment at the edge of the soma -has a refractory period for Na+ channels (which tend to close rapidly after opening)
Axoplasmic Transport
Process by which substances are transported up and down the axon (active process- requires energy/ ATP)
motor neuron
Receives excitation through its dendrites and conducts impulses along its axon to a muscle (soma in spinal cord)
The _____ prevents too many action potentials from firing at once
Refractory period
Which of the following is the function of the microglia? a. Remove dead cells and weak synapses b. Build myelin sheaths that surround and insulate axons c. Dilate blood vessels to increase blood supply to active brain areas d. synchronize activity for a group of neurons
Remove dead cells ad weak synapses
Dendritic spines
Short outgrowths that increase the surface area available for synapses
Diffusion pushes ______ (which ion?) into the cell and electrostatic pressure pushes it into the cell (It is ready for action and therefore has no net movement at rest- there are certain conditions where is rushes into the cell)
Sodium
Saltatory conduction
The myelin sheath of axons are interrupted by short, unmyelinated sections called nodes of Ranvier
Santiago Ramon y Cajal was responsible for which of these discoveries? a. the human cerebral cortex has many specializations to produce language b. The brain's left and right hemispheres control different functions. c. The nervous system is composed of separate cells. d. Neurons communicate at specialized junctions called synapses
The nervous system is composed of separate cells
PNS
The part of the nervous system outside of the brain and spinal cord including attached nerves
For the brain to use its main source of fuel, what does it also need? a. Steroid hormones b. Vitamin C c. Thiamine d. Acetylsalicyclic acid
Thiamine
Local neurons
When stimulated, produce membrane potentials that vary in magnitude and don't follow the all-or-none law -they depolarize and hyperpolarize in proportion to the stimulation
Does the action potential remain at equal strength throughout the transmission down the axon?
Yes. Behind each area of sodium entry, potassium ions exit, restoring the resting potential
As an action potential occurs at 1 point on the axon, enough sodium enters to depolarize the next point to its threshold, producing a __________ at that point
action potential
catabolic enzymes
aids with breakdown of different substances
metabolic enzymes
aids with synthesis of different substances
action potential
an abrupt depolarization (increase in charge) of the membrane that allows the neuron to communicate over long distances and last 2 ms (how the neuron sends a message)
There are two types of glial cells that produce myelin sheath. In the central nervous system, Schwann cells fulfill this role and, in the periphery, oligodendrocytes produce it. Select one: a. True b. False
b. False
When a neuron's membrane is at rest, the concentration gradient tends to move sodium ____ the cell and the electrical gradient tends to move it ____ the cell. Select one: a. out of; into b. into; into c. into; out of d. out of; out of
b. into; into
Gaps in the insulating material that surrounds axons are known as ____. Select one: a. myelin synapses b. nodes of Ranvier c. interpeduncular nuclei d. presynaptic terminals
b. nodes of Ranvier
Which type of glia release chemicals that modify the activity of neighboring neurons? Select one: a. Schwann cells b. Oligodendrocytes c. Astrocytes d. Radial glia
c. Astrocytes
Which type of glia remove waste material in the nervous system? Select one: a. Radial glia b. Oligodendrocytes c. Astrocytes d. Schwann cells
c. Astrocytes
Which action would depolarize a neuron? Select one: a. Decreasing membrane permeability to calcium b. Increasing membrane permeability to potassium c. Increasing membrane permeability to sodium d. Decreasing membrane permeability to sodium
c. Increasing membrane permeability to sodium
If all of a neuron's dendrites or axons were contained within the spinal cord, it would be considered a(n) ____ neuron. Select one: a. Purkinje b. efferent c. intrinsic d. afferent
c. intrinsic
The primary feature of a neuron that prevents the action potential from traveling back from where it just passed is the ____. Select one: a. concentration gradient b. phospholipid bilayer c. refractory period d. sodium potassium pump
c. refractory period
Axon
conducts/ transmitstHE an impulse toward other neurons, an organ, or a muscle
cytoskeleton
consists of microtubules which are strands of proteins linked together to give the cell shape
unipolar neuron
contains a single axon that leaves the soma and divides into 1 branch
Multipolar neuron
contains one axon and many dendritic trees branching from soma
bipolar neuron
contains one axon and one dendritic tree at opposite ends of the soma (2 axons in total)
What mechanism prevents or slows some chemicals from entering the brain, while allowing others to enter? Select one: a. An endoplasmic wall b. A threshold c. A differential-drug inhibitor d. A blood-brain barrier
d. A blood-brain barrier
Dr. O'Reilly is trying to produce hyperpolarization in the neurons in her laboratory. What should she do? Select one: a. Add a drug that will increase the membrane's permeability to sodium b. Add a drug that will decrease the membrane's permeability to potassium c. Use a microelectrode to apply a positive charge d. Use a microelectrode to apply a negative charge
d. Use a microelectrode to apply a negative charge
Many dendrites contain short outgrowths called spines that _____. Select one: a. eliminate cell waste products b. increase the speed of transmission c. increase the symmetry of the soma d. increase the surface area available for synapses
d. increase the surface area available for synapses
In order to produce an action potential, the collective amount of depolarization must exceed the _____ Select one: a. energy required to open the potassium channels b. resting membrane potential c. absolute refractory period d. threshold of excitation
d. threshold of excitation
Within the nervous system, a given neuron is ______ from one structure and ______ to another
efferent; afferent
_____ and _____ work to pull sodium ions into the neuron
electrical gradient; concentration gradient
The rate of entry and voltage of sodium into the neuron is ______ (slower/faster and higher/lower?) than the rate of exit of potassium from the neuron
faster and higher/ more positive voltage
intracellular fluid
fluid inside the neuron cell
extracellular fluid
fluid outside the neuron cell
Electrostatic pressure (:aka electrostatic gradient)
force of attraction/ repulsion between ions
terminal buttons
form synapses with other neurons
The only time an action potential travels backwards is when
its right at the starting point, it can back-propagate into the soma, which leads to some of the structural changes involved in learning
Oscilloscope
measures and shows voltage over time (good way for researchers to get info on neural threshold/ action potential)
Golgi apparatus
membrane that packages products to be secreted by the cell
In saltatory conduction along the axon, the action potential is regenerated by a chain of _________ pushed along by the previous segment
positively charged ions
Diffusion pushes ______ (which ion?) out of the cell and electrostatic pressure pushes it into the cell (it has no net movement at rest)
potassium
The neuron is returned to its resting state by the opening of _____ channels
potassium (K+)
The neuron has more _____ ions inside than outside, and _____ channels are partially closed (allowing for very slow passage)
potassium (K+) ions
The ions surrounding the inside of the Cytoplasm are
potassium ions and other organic anions
electrical gradient tends to pull ______ into the neuron also, even though they also slowly leak out, carrying a _____ charge with them
potassium; positive
Active Transport
protein-mediated process that expends energy to pump chemicals form the blood into the brain
Saltatory conduction
provides rapid conduction of impulses, which enables fast thinking/ response time
a touch on the ____ reaches the brain more quickly than a touch on the ____
shoulder; foot
The resting potential of a neuron remains stable until the neuron is _______
stimulated
Glia
support cells of the nervous system -support and protect neurons in the CNS -More limited role in the PNS
The greater the ___ of a dendrite, the more info it can recieve
surface area
All-or-none law
the amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it (an action potential, once triggered, is transmitted w/ out decreasing in size to the end of the neuron/ axon)
Absolute refractory period
the first part of the period in which the membrane cannot produce an action potential
Astrocytes
type of glia that shields synapses from chemicals circulating in the surroundings (make sure neurons firing where they should) -helps synchronize closely related neurons -dilate the blood vessels to bring more nutrients into brain areas that have heightened activity -aid in controlling extracellular chemical environment -maintain the blood-brain barrier
Enzymes
type of protein that controls a chemical rxn
Glucose
vertebrate neurons depend almost entirely on this
