Vocab 2 Temme

Question 1

voltage-gated ion channel

Answer 1

an ion channel in which the opening and closing of its “gate” is controlled by changes in membrane potential—the charge gradient across the membrane. (Typically, such channels open when the membrane is depolarized past some threshold, and closes when the membrane is re- or hyper polarization beyond that threshold).

Question 2

axon hillock

Answer 2

the region along a nerve cell where voltage-gated ion channels are first located and thus an action potential can begin. (It is also called the trigger zone; and its location designates where the sensory end of a neuron stops, and the signal conduction region begins.)

Question 3

interneuron

Answer 3

any neuron within a nervous pathway positioned in between sensory and motor neurons.

Question 4

transmission

Answer 4

when the firing of a presynaptic neuron has some means to directly influence whether the postsynaptic cell (be it neuron or muscle fiber) fires an action potential

Question 5

chemical (direct) transmission

Answer 5

when a presynaptic neuron influences whether a post-synaptic neuron will fire an action potential by releasing a chemical signal (a neurotransmitter) that binds to and opens an ion channel. The effect could either be positive (stimulatory) or negative (inhibitory), based on the type of ion channel opened.

Question 6

nicotinic ACh receptor

Answer 6

the ligand-gated ion channel, where acetylcholine is the ligand, found on postsynaptic muscle fibers at the neuromuscular junction (as well as some other locations). (The name comes from the fact that nicotine will also bind to and open these ion channels.)

Question 7

acetylcholinesterase

Answer 7

the enzyme (found on the postsynaptic cell in a neuromuscular junction) that catalyzes the breakdown of acetylcholine into acetate and choline, and thus plays a role in removing acetylcholine from the synapse.

Question 8

modulation

Answer 8

the binding of a chemical signal (typically released from a presynaptic neuron) to a receptor in someway alters the release of neurotransmitter from a presynaptic neuron and/or triggers changes in how a postsynaptic neuron responds to subsequent exposure to neurotransmitters.

Question 9

neuropeptide

Answer 9

– any of a variety of peptides released as signal molecules from neurons. They are often released from
the same axon terminals as neurotransmitters, and have been found to have a wide range of effects, including acting as a neuromodulator.

Question 10

learning

Answer 10

when an animal’s response changes with experience.

Question 11

long-term potentiation

Answer 11

a form of activity-dependent, synapse specific facilitation. That is, frequent use of a synapse triggers changes that enhance the connection strength between the presynaptic and postsynaptic neuron at that specific synapse. Furthermore, the change lasts for at least a while after whatever triggered the frequent activity has passed. muscle fiber – an elongated multinucleated single muscle cell that is formed by the fusion of more than one cell (called myoblasts). Each fiber, which can be centimeters in length, is densely packed with contractile proteins in an arrangement that leads to the fiber contracting (shortening) in only one dimension

Question 12

sarcomere

Answer 12

repeating structural unit of a myofibril, containing an arrangement of actin filaments (thin filaments) and myosin-containing filaments (thick filaments) that allows the structure to shorten (contract in one dimension). Overall, it is the smallest unit of contraction within a muscle fiber.

Question 13

T-tubules

Answer 13

invaginations of the outer membrane of muscle fibers that allow action potentials to spread past the sarcoplasmic reticulum surrounding every sarcomere within a muscle fiber.

Question 14

troponin

Answer 14

the protein associated with actin filaments that can bind to calcium ions, and in the process initiate muscle fiber contraction by moving another protein (tropomyosin) off the actin-mysosin binding sites

Question 15

motor unit

Answer 15

a single motor neuron and all of the muscle fibers (within a muscle) that it innervates

Question 16

MLCK

Answer 16

enzyme that catalyzes the phosphorylation of myosin in smooth muscles (which in turn initiates muscle contraction)

Question 17

gray matter

Answer 17

regions in the nervous system where nerve cell bodies, dendrites and axon terminals are located. In other words, the regions in the nervous system where synapses between neurons are found.

Question 18

neurulation

Answer 18

the process by which a region of dorsal ectoderm invaginates and eventually transform into a dorsal neural tube (which subsequently differentiates into the brain and spinal cord).

Question 19

neural crest

Answer 19

ells originally part of the dorsal ectoderm that break free during neurulation in vertebrates and subsequently give rise to sensory neurons of the body (along with postganglionic neurons and the adrenal medulla of the autonomic nervous systems), as well as with many features of the vertebrate head.

Question 20

myelin sheath

Answer 20

a covering that forms when a glial cell (Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system) wraps its membrane around a portion of the conducting region of a neuron. Myelin sheaths spaced periodically along an axon can increase an action potential’s speed.

Question 21

dorsal horn

Answer 21

the gray matter region on each side of the spinal cord where sensory neurons enter and typically form synapses.

Question 22

topographic organization

Answer 22

arrangement of neurons within the CNS reflects the spatial arrangement of incoming sensory neurons (within a receptor field) or the skeletal muscles to which outgoing (motor) neurons innervate.

Question 23

alpha motor neuron

Answer 23

a motor neuron that innervates extrafusal muscle fibers.

Question 24

muscle spindle

Answer 24

a stretch sensor located within skeletal muscles whose length can be constantly adjusted so that it can detect stretch across the full range of a muscle’s contraction

Question 25

intrafusal fibers

Answer 25

the muscle fibers found within a muscle spindle

Question 26

gamma motor neuron

Answer 26

gamma motor neuron a motor neuron that innervates the muscle fibers located within a muscle spindle (intrafusal muscle fibers).

Question 27

golgi tendon organ

Answer 27

sensors found at the junction of tendons and muscle fibers that respond to stretch and can trigger a reflex that acts to block continued muscle contractions once the force detected gets too large

Question 28

central pattern generator

Answer 28

networks of interneurons in the central nervous system (CNS) that generate and control certain rhythmic muscle movements.

Question 29

cortex

Answer 29

a thin layer of gray matter that forms in different regions of the brain when cell bodies migrate to the dorsal surface of the developing neural tube

Question 30

stimulus

Answer 30

the presence of some form of energy or chemical.

Question 31

sense

Answer 31

a form of stimulus that is detectable by an organism; (2) when an organism possesses the means to convert a particular form of stimulus into an action potential; or (3) a form of stimulus that can initiate the opening (or closing) of membrane ion channels

Question 32

specialized receptor cell

Answer 32

a cell that responds to a specific type of stimulus by changing the rate that it releases a chemical signal to a connecting nerve cell (commonly a sensory neuron). Examples: hair cells, rod and cone cells, taste buds.

Question 33

raphe nuclei

Answer 33

a cluster of nuclei within the brain stem that send axons to nearly all other parts of the central nervous system where they release serotonin.

Question 34

locus ceruleus

Answer 34

a brain stem nucleus that send axons to other parts of the central nervous system where they release norepinephrine.

Question 35

substantia nigra

Answer 35

a brain stem nucleus that send axons to other parts of the central nervous system where they release dopamine.

Question 36

ventral tegmental area

Answer 36

a brain stem area that send axons to other parts of the central nervous system where they release dopamine.

Question 37

reticular activating system

Answer 37

a set of nuclei within the reticular formation (a collection of nuclei located around the core of the brainstem) that send axons into higher brain regions, especially around the thalamus, which influence an individual’s wakefulness—that is, its overall degree of alertness and consciousness.

Question 38

amygdala

Answer 38

two brain regions (one on each side) that play an important role in coordinating reactions to dangerous situations (and in forming memories of dangerous situations).

Question 39

vestibular apparatus

Answer 39

a sense organ that is part of each inner ear, which detects both linear and angular (rotational) acceleration of the head. In other words, it keeps track of how an individual’s head is moving about in space.

Question 40

tectospinal tract

Answer 40

a descending tract that originates in the midbrain roof and terminates on interneurons in the cervical region of the spinal cord. It plays an important role in coordinated reflexive orientation of the head.

Question 41

corticospinal tract

Answer 41

a descending tract that originates mostly in the motor cortex region (of the cerebral cortex) and commonly directly innervates alpha and gamma motor neurons along different regions of the spinal cord. It provides an important pathway for forebrain control of limb movements, especially skilled hand movements.