ch. 37 neurons, synapses, & signals

The nervous system is the principal (1) _____ system in animals.

1) regulatory

Chapter 37 covers three major topics: (1) _____ structure, generating (2) _____ potentials, and (3) _____ transmission.

1) neuron; 2) action; 3) synaptic

The nervous system contains two major cell types. (1) _____ receive and send information, while (2) _____ support, protect, and regulate neurons.

1) Neurons; 2) glial cells

The major parts of a neuron include (1) _____, which receive incoming signals; the (2) _____, which contains the nucleus; the (3) _____, which carries signals away; and the axon (4) _____, where action potentials typically begin.

1) dendrites; 2) cell body; 3) axon; 4) hillock

The branched ends of (1) _____ transmit signals at junctions called (2) _____. The sending cell is the (3) _____ cell, and chemical signals called (4) _____ are released toward the receiving cell.

1) axons; 2) synapses; 3) presynaptic; 4) neurotransmitters

The nervous system processes information in three stages: (1) _____ input, (2) _____, and (3) _____ output.

1) sensory; 2) integration; 3) motor

There are three major types of neurons. (1) _____ neurons transmit information about stimuli, (2) _____ integrate information, and (3) _____ neurons transmit signals to muscles.

1) Sensory; 2) interneurons; 3) motor

The (1) _____ nervous system includes the brain and spinal cord and performs integration. The (2) _____ nervous system carries information into and out of the CNS through bundles of neurons called (3) _____.

1) central; 2) peripheral; 3) nerves

Neural signaling involves maintaining a (1) _____ potential, generating (2) _____ potentials, and transmitting signals through continuous or (3) _____ conduction.

1) resting; 2) action; 3) saltatory

Membrane potential is the difference in (1) _____ across the plasma membrane. At rest, the inside of a neuron is relatively (2) _____ compared with the outside. A typical resting potential is approximately (3) _____ mV.

1) charge (voltage); 2) negative; 3) −70

Membrane potential depends on differences in ion (1) _____ and selective membrane (2) _____. The concentration of K⁺ is higher (3) _____ the neuron, while Na⁺ concentration is higher (4) _____.

1) concentrations; 2) permeability; 3) inside; 4) outside

Resting potential forms partly because K⁺ diffuses (1) _____ of the neuron, making the inside more (2) _____. K⁺ movement alone would approach (3) _____ mV, but slight Na⁺ movement inward contributes to a resting potential of about (4) _____ mV.

1) out; 2) negative; 3) −90; 4) −70

The sodium-potassium pump maintains ion concentration (1) _____ by moving (2) _____ Na⁺ ions OUT of the neuron and (3) _____ K⁺ ions INTO the neuron. This movement occurs (4) _____ their concentration gradients.

1) gradients; 2) 3; 3) 2; 4) against

Neurons send electrical signals when there is a significant change in their (1) _____ membrane potential. This allows neurons to (2) _____ information.

1) resting; 2) transmit

Voltage-gated ion channels respond to changes in membrane (1) _____. Two important types are voltage-gated (2) _____ channels and voltage-gated (3) _____ channels.

1) potential (voltage); 2) Na⁺; 3) K⁺

During depolarization, membrane potential becomes (1) _____ negative because Na⁺ permeability (2) _____. During hyperpolarization, membrane potential becomes (3) _____ negative, often because K⁺ permeability (4) _____.

1) less; 2) increases; 3) more; 4) increases

A graded potential is a (1) _____ change in membrane potential. Unlike an action potential, a graded potential decreases in strength with (2) _____ and (3) _____ from its source.

1) local; 2) time; 3) distance

An action potential occurs when membrane depolarization reaches the (1) _____ of approximately (2) _____ mV. Action potentials are (3) _____-or-_____ responses that travel along the (4) _____.

1) threshold; 2) −55; 3) all-or-none; 4) axon

During the resting state, voltage-gated (1) _____ channels and voltage-gated (2) _____ channels are closed. However, ion (3) _____ channels remain open.

1) Na⁺; 2) K⁺; 3) leak

During initial depolarization, a stimulus causes voltage-gated (1) _____ channels to open, allowing (2) _____ to enter the neuron. Once the membrane reaches (3) _____, an action potential is triggered.

1) Na⁺; 2) Na⁺; 3) threshold

During the rising phase of an action potential, more voltage-gated (1) _____ channels open. These allow positive ions to move (2) _____ the neuron, causing further (3) _____. Voltage-gated K⁺ channels remain (4) _____.

1) Na⁺; 2) into; 3) depolarization; 4) closed

During repolarization, voltage-gated Na⁺ channels become (1) _____ while voltage-gated (2) _____ channels open. This allows K⁺ to move (3) _____ the neuron, making membrane potential more (4) _____.

1) inactivated; 2) K⁺; 3) out of; 4) negative

During the undershoot, also called (1) _____, the membrane becomes more (2) _____ than resting potential. Voltage-gated (3) _____ channels eventually close, allowing the neuron to return to its (4) _____ state.

1) hyperpolarization; 2) negative; 3) K⁺; 4) resting

The main stages of an action potential occur in this order: (1) _____ state, (2) _____, (3) _____ phase, (4) _____, and (5) _____ before returning to rest.

1) resting; 2) depolarization; 3) rising; 4) repolarization; 5) undershoot

An action potential is self-(1) _____, meaning a wave of (2) _____ travels along the length of the (3) _____.

1) propagating; 2) depolarization; 3) axon

During the (1) _____ refractory period, another action potential cannot occur. During the (2) _____ refractory period, another action potential is possible, but a (3) _____ stimulus is required.

1) absolute; 2) relative; 3) stronger

Continuous conduction occurs in (1) _____ axons. The electrical impulse travels progressively along the entire membrane. Increasing axon (2) _____ increases the (3) _____ of transmission.

1) unmyelinated; 2) diameter; 3) speed

Myelin acts as an electrical (1) _____ surrounding the axon. The gaps between myelin segments are called nodes of (2) _____. These gaps contain ion channels important for movement of (3) _____ and (4) _____.

1) insulator; 2) Ranvier; 3) Na⁺; 4) K⁺

Saltatory conduction occurs in (1) _____ axons. The action potential appears to jump between nodes of (2) _____. This type of conduction is (3) _____ and requires (4) _____ energy than continuous conduction.

1) myelinated; 2) Ranvier; 3) faster; 4) less

Multiple sclerosis (MS) is an (1) _____ disease affecting the (2) _____ nervous system. The immune system attacks (3) _____ sheaths, leading to inflammation and disrupted nerve (4) _____.

1) autoimmune; 2) central; 3) myelin; 4) signaling

There are two major types of synapses: (1) _____ synapses, which transmit signals through direct ion movement, and (2) _____ synapses, which transmit signals using (3) _____.

1) electrical; 2) chemical; 3) neurotransmitters

A synapse is a junction between two (1) _____ or between a neuron and an (2) _____, such as a muscle or gland. The (3) _____ cell sends the signal, while the (4) _____ cell receives it.

1) neurons; 2) effector; 3) presynaptic; 4) postsynaptic

In electrical synapses, neighboring cells are connected by protein channels called (1) _____ junctions. These allow (2) _____ to pass directly between cells, resulting in (3) _____ signal transmission.

1) gap; 2) ions; 3) rapid

Most synapses are (1) _____ synapses. The two cells are separated by a space called the synaptic (2) _____. Chemical messengers called (3) _____ are stored in synaptic (4) _____ before release.

1) chemical; 2) cleft; 3) neurotransmitters; 4) vesicles

During synaptic transmission, an (1) _____ potential reaches the presynaptic terminal. Voltage-gated (2) _____ channels open, allowing (3) _____ to enter. This causes synaptic (4) _____ to fuse with the membrane and release neurotransmitters.

1) action; 2) Ca²⁺; 3) Ca²⁺; 4) vesicles

After neurotransmitters are released, they bind to (1) _____ on the postsynaptic membrane. This causes ion channels to open or (2) _____, producing either (3) _____ or (4) _____ of the postsynaptic cell.

1) receptors; 2) close; 3) depolarization; 4) hyperpolarization

Neurotransmitters are signaling (1) _____ released by neurons. A single neurotransmitter can interact with many different (2) _____. Examples include (3) _____, which is listed among amino acid neurotransmitters, and (4) _____, which is listed among biogenic amines.

1) molecules; 2) receptors; 3) glutamate (or GABA/glycine); 4) dopamine (or serotonin/norepinephrine)