BIOL 216 TOPIC 5

The central nervous system includes the brain, _______ cord, and _________, which integrate _______ and formulate _________.

Spinal, interneurons, information, responses

The peripheral nervous system includes ________ and _______ neurons.

Efferent, afferent

Afferent neurons are ______ neurons which pick up a stimulus through sensory __________ and transmit this information to ________ in the central nervous system.

Sensory, receptors, interneurons

Efferent neurons carry ________ signals to muscles and glands so the response coordinated by the _______ nervous system can be executed. Includes motor neurons, which send a signal to ________ muscles.

Response, central, skeletal

Afferent neurons have one ______ and two ________, a peripheral one which connects the cell body to the _______ and ends in a sensory _______, and a central one which connects the cell body to the ___________. Don’t have dendrites.

Axon, branches, periphery, receptor, spinal cord

Efferent neurons have one ______ and two _______, a peripheral one which connects to either a ______, ______, or other ________, and a central one which connects to the _____________.

Axon, branches, muscle, gland, neuron, spinal cord

Interneurons have ______ branches and dendrites. They are located in between ________ and ________ neurons.

Two, afferent, efferent

Nerve, fibers, electrochemical, blood vessels, connective, tracts

A _______ is a structure containing many axons, or ______, which provide a common pathway for _________ nerve impulses that are transmitted along each axon. Contain _________ and ________ tissues to protect the axons. In the central nervous system, nerves are called ______.

Triceps, forearm, skin, joints

The Radial nerve supplies the _______ of the arm and all 12 _________ muscles as well as the associated _____ and ________.

There are two kinds of matter in the nervous system. White matter is composed of _________ axons and _______ cells. Gray matter is composed of the cell bodies of ________.

Myelinated, glial, neurons

Neuronal, nutrition, support

A glial cell is a non-_________ cell which provide _________ and _________ to neurons.

Examples of glial cells include ____________ cells (produce cerebrospinal fluid), ________ (phagocytic cells which break down pathogens and waste in CNS), ________ (cover blood vessels, providing structural support and maintaining ion concentration in interstitial fluid in the CNS), ________ cells (very similar function in the PNS), _________ (form myelin sheaths in the CNS), and __________ cells (form myelin sheaths in the PNS).

Ependymal, microglia, astrocytes, satellite, oligodendrocytes, Schwann

A myelin sheath is a ________ structure along an axon which insulates an _________ impulse and has a high ______ content.

Protective, electrical, lipid

Nodes of Ranvier are ______ in the ______ sheath of axons which expose the axon ________ to ________ fluid, increases the rate of impulse _________ down an axon.

Gaps, myelin, membrane, extracellular, movement

The axon hillock is a part of a neuron which protrudes from the _______. It has a very ____ concentration of voltage activated ________ channels and is considered the spike initiation zone for APs. Multiple signals from the presynaptic neuron terminals are _________ here.

Soma, high, sodium, converged

A synapse is a _______ between the axon _______ of the ________ neuron and the receiving ______. _________ synapse is between axon & dendrite; __________ synapse is between axon & soma; _________ synapse is between two axons.

Junction, terminals, presynaptic, cell, axodendritic, axosomatic, axoaxonic

In an electrical synapse, _________ of the pre and postsynaptic cell, which are connected by ______, make contact and _______ flow through ______ junctions. Used in the pulp of tooth, heart muscle tissue, and some smooth muscle tissue when a uniform __________ response is needed.

Plasma membranes, connexons, ions, gap, contractile

In a chemical synapse, a _________ molecule is released in _________. It diffuses across the synaptic ______ and binds to a receptor on the postsynaptic cell’s _______. Once enough is bound, _______ channels open which generate an impulse.

Neurotransmitter, vesicles, cleft, membrane, ion

Electrical synapses are ________ than chemical synapses and create a better ________ response. However, chemical synapses are better __________.

Faster, synchronized, modulated

Membrane potential arises when there is a difference in _______ _______ on 2 sides of a membrane. The resting membrane potential for humans involves a _______ charged cell interior and a _______ charged cell exterior.

Electrical charge, negatively, positively

The negative resting membrane potential is largely caused by the Na+/K+ pump which pumps ___ Na+ out for every ___ K+ in. Additionally, K+ channels are _______, so K+ can diffuse _____ freely. Due to this net ______ motion of cations and due to negatively charged molecules in the cell, such as _________ and ________, the resting membrane potential is ______.

3, 2, leaky, out, outward, proteins, DNA, -70mV

________ channels in the cell are leaky, which means that the cations can somewhat move freely out of the cell. However, as the cations leak out, a _____ internal charge develops, and negatively charged molecules inside the cell, including ______ and ______, create electrical force which oppose the passive efflux.

Potassium, negative, proteins, DNA

The resting membrane potential is the equilibrium condition when there is _____ net flow of ions. The equilibrium membrane potential is the membrane potential at which the _______ and _________ gradients oppose, resulting in _____ net movement of an ion. The electrochemical gradient combines these two gradients and drives the _____ of any ion.

No, voltage, concentration, flow

The ______ equation is used to predict the equilibrium potential of any ion. The __________ equation predicts the resting membrane potential when the membrane is permeable to ________ ions.

Nernst, Goldman, multiple

Voltage gated ion channels open when the membrane potential achieves a specific ________. They are ______ membrane proteins, and they vary widely in terms of how quickly they _______ (for example, A-type currents inactivate very _____) and if they have multiple internal gates which respond to potential in different _______.

Charge, integral, inactivate, quickly, ways

Ligand gated ion channels open and allow for the passage of ions when a specific ________ binds to a specific ________.

Ligand, receptor

Mechanically gated ion channels need to be ________ pulled ______ to allow for the passage of ions. An example of this is in sensory receptors in the inner ear hair cells.

Physically, open

The rate of ionic flow through a channel is determined by ________ channel ________ and the ___________ driving force for that ion.

Maximum, conductance, electrochemical

An action potential is the ________ and _______ change in membrane ________ that occurs when a neuron conducts an electrical _______.

Abrupt, transient, potential, impulse

When an AP occurs, a _______ causes _______ to flow into a neuron, inducing ________. This happens slowly until the membrane reaches _________ and a sudden influx of _____ causes a rapid increase in membrane potential. Membrane potential then falls as _______ channels close and ________ channels open, which induces ________. Eventually the membrane potential returns to ______ as ______ channels close.

Stimulus, cations, depolarization, threshold, sodium, sodium, potassium, hyperpolarization, resting, potassium

Action potentials are ____ or _______ (once threshold is reached, the AP will fire equally regardless of the size of the stimulus), maintain their ______, and _______ (one AP can trigger another in a neighboring stretch of membrane).

All, nothing, size, propagate

The absolute refractory period is a time when an excitable membrane cannot generate any ____________ in response to a stimulus. Occurs when Na+ channels are ____ or ________. This phase can be overcome by _______ the membrane.

Action potentials, open, inactive, repolarizing

The relative refractory period is a time when the excitable membrane will only produce an action potential to stimuli of ______ strength than the typical _________.

Greater, threshold

Voltage gated ________ channels opening are the biggest contributor to the relative refractory period because some _____ can exit the cell while ______ cannot enter, creating ________ and making it harder to depolarize the membrane enough to reach ________. The length of this period is _______.

Potassium, potassium, sodium, hyperpolarization, threshold, variable

Stronger stimuli have a faster _______ of action potentials than weaker stimuli rather than a ________ action potential. This is because they can overcome the _________ refractory period by reaching threshold even through hyperpolarization.

Frequency, bigger, relative

________ nerve fibers are the largest and fastest axons. They carry information related to ___________.

A-alpha, proprioception

__________ nerve fibers are the second largest and second fastest axons. They carry information related to _____.

A-beta, touch

__________ nerve fibers are the second smallest and second slowest axons. They carry information related to _____ and ___________.

A-delta, pain, temperature

________ nerve fibers are the smallest and slowest axons because they are not _________. They carry information related to ____, _____________, and ____.

C, myelinated, pain, temperature, itch

The _______ the diameter, the ________ the conduction velocity because there is less internal ________.

Larger, greater, resistance

The flow of electricity through a neuron has been described by ________ theory, which treats an axon as a perfectly cylindrical, electrically passive transmission cable. Calculates the flow of a current along an axon, accounting for _________ and __________.

Cable, resistance, capacitances

A capacitance is ______ electrical ______/_______. In a neuronal fiber, they are due to ____________ forces which act through the phospholipid bilayer.

Stored, charge, energy, electrostatic

___________ in a neuronal fiber is due to the ________’s significant aversion to the movement of _________ charge.

Resistance, cytosol, electrical

The lambda length constant measures the _______ at which an action potential deteriorates to _____ of its original ______________. The equation square root of membrane resistance/internal resistance describes this because having a higher membrane resistance means the cytoplasm can _______ electrical charge better, but having a higher internal resistance makes it ________ for ______ to move across the axon.

Distance, 1/3, applied voltage, retain, harder, charge

Nodes of Ranvier harbor voltage gated _______ and _______ channels. When one node ________, excess cations cannot exit through the myelinated surface, so they travel to the next node, causing it to reach _______ and ________. This process continues. In a myelinated axon, APs can only be regenerated on these nodes.

Sodium, potassium, depolarizes, threshold, depolarize

Chemical synapses allow neurons to receive inputs from multiple ____________ at the same time, facilitating __________.

Axon terminals, modulation

In direct neurotransmission, the _________ binds to a _______ gated ion channel, causing the channel to open and allow for the passage of small ions. In indirect neurotransmission, it instead binds to ______ coupled receptor, activating the _________ ________ pathway and causing the channel to open. This process is ______.

Neurotransmitter, ligand, G protein, second messenger, slower

A G protein coupled receptor is a kind of _________ receptor, which is indirectly linked to the _______ of _____ channels.

Metabotropic, opening, ion

___________ is a neurotransmitter used in the muscles, in the brain (for memory, attention, and learning), and in the heart. Degeneration of neurons which release this causes ____________ disease.

Acetylcholine, Alzheimer’s

_______ and ________ are action potential inhibitors. They do this by opening Cl- channels on the postsynaptic cell membrane to combat depolarization.

GABA, glycine

________ is a neurotransmitter used in the brain for learning and memory.

Glutamate

_______________ and ____________ work both as neurotransmitters and hormones. They are involved in attention, mental focus, pleasure and reward, memory, and motor control. Can be excitatory or inhibitory, derived from tyrosine. Production increased by ADHD drugs.

Norepinephrine, epinephrine

____________ works both as a neurotransmitter and neurohormone and is important in behavior, cognition, voluntary movement, motivation and reward, sleep, mood, attention, learning, and inhibition of prolactin (lactation). Derived from tyrosine. Degeneration of neurons producing this causes Parkinson’s.

Dopamine

_________ is a neurotransmitter derived from tryptophan and it regulates intestinal movements and is involved in mood, appetite, and sleep.

Serotonin

Neuropeptides released during a pleasurable experience and reduce the perception of pain are ________ in the PNS and _____________ in the CNS.

Endorphins, enkephalins

_____________ is a neuropeptide released by the spinal cord to increase the perception of pain.

Substance P

Dissolved _________ is a neuropeptide which regulates the release of hormones from the hypothalamus.

Carbon monoxide

Dissolved __________ is a neuropeptide which is important during learning, muscle movement, and vasodilation.

Nitric oxide

Stimulatory neurotransmitters induce _______ channels to open, causing a change in membrane potential which pushes us closer to threshold (AKA _______). Inhibitory neurotransmitters induce _______ channels to open, causing a change in membrane potential which moves us farther from threshold (AKA _______).

Sodium, EPSP, potassium, IPSP

When an action potential has subsided, any leftover neurotransmitters in the _____________ either _______ away or are _______ or _______ in the presynaptic axon terminal.

Synaptic cleft, diffuse, stored, degraded

A graded potential is an increase or decrease in membrane potential that is _______ threshold, so it doesn’t trigger an _____________. IPSPs and EPSPs are a kind of graded potential.

Below, action potential

__________ summation is the summation of EPSPs produced by the firing of different presynaptic neurons. __________ summation is the summation of EPSPs produced by the same presynaptic neuron.

Spatial, temporal