Chapter 11

Question 1

Nervous system

Answer 1

A system that rapidly communicates information throughout the body; composed of the brain, the spinal cord, nerves, and ganglia

Question 1

Ganglion

Answer 1

A mass of nerve cells in the peripheral nervous system that resembles a knot.

Question 2

Peripheral Nervous System

Answer 2

The parts of the nervous system outside of the brain and spinal cord; composed of nerves and ganglia.

Question 3

Central Nervous System

Answer 3

The brain and spinal cord.

Question 4

Electrical Potential

Answer 4

The brain and spinal cord.

Question 5

Current

Answer 5

A moving cluster of charged particles.

Question 6

Stress

Answer 6

A condition that upsets homeostasis and stimulates a physiological response.

Question 7

Alarm

Answer 7

This step is your body’s immediate reaction to stress and it prepares you to fight or escape danger caused by stress. The body consumes large quantities of stored glycogen to handle the physical symptoms of stress.

Question 8

Resistance

Answer 8

Longer stress stimuli (more than a few hours) deplete the body’s glycogen reserves, and the body must provide alternative and less efficient fuels, such as fat, for metabolism. Under sustained conditions, the body has trouble fighting off infections and maintaining hormone levels.

Question 9

Exhaustion

Answer 9

• After a longer time period (months) the body uses all its fat storage. When this store is depleted, homeostasis is upset and the body begins breaking down protein for energy, resulting in the depletion of muscle and overall weakness that can lead to heart or kidney failure and infections.

Question 10

The sensory division - PNS

Answer 10

transmits action potentials to the CNS.

Question 11

The motor division - PNS

Answer 11

carries action potentials away from the CNS.

Question 12

The somatic nervous system - Motor division - PNS

Answer 12

innervates skeletal muscle and is mostly under voluntary control.

Question 13

The autonomic nervous system (ANS) - Motor - PNS

Answer 13

innervates cardiac muscle, smooth muscle, and glands.

Question 14

The enteric nervous system

Answer 14

controls the digestive system.

Question 15

Glial cells - CNS

Answer 15

are supportive cells that support and aid the neurons of the CNS and PNS.

Question 16

Astrocytes - CNS

Answer 16

provide structural support for neurons and blood vessels. Astrocytes influence the functioning of the blood-brain barrier and process substances that pass through it. Astrocytes isolate damaged tissue and limit the spread of inflammation. Astrocytes also help maintain synaptic function.

Question 17

Ependymal cells - CNS

Answer 17

line the ventricles and the central canal of the spinal cord. Some are specialized to produce cerebrospinal fluid.

Question 18

Microglia - CNS

Answer 18

phagocytize microorganisms, foreign substances, and necrotic tissue.

Question 19

An oligodendrocyte - CNS

Answer 19

forms myelin sheaths around the axons of several CNS neurons.

Question 20

A Schwann cell - PNS

Answer 20

forms a myelin sheath around part of the axon of a PNS neuron.

Question 21

Satellite - PNS

Answer 21

cells support and nourish neuron cell bodies within ganglia.

Question 22

Myelinated axons

Answer 22

are wrapped by several layers of plasma membrane from Schwann cells (PNS) or oligodendrocytes (CNS). Spaces between the wrappings are the nodes of Ranvier. Myelinated axons conduct action potentials rapidly.

Question 23

Unmyelinated axons

Answer 23

rest in invaginations of Schwann cells (PNS) or oligodendrocytes (CNS). They conduct action potentials slowly.

Question 24

White matter

Answer 24

consists of myelinated axons; it propagates action potentials. forms nerve tracts in the CNS and nerves in the PNS.

Question 25

Gray matter

Answer 25

consists of collections of neuron cell bodies or unmyelinated axons. Axons synapse with neuron cell bodies, which are functionally the site of integration in the nervous system. forms cortex and nuclei in the CNS and ganglia in the PNS.

Question 26

Neuron communication can be described in three phases

Answer 26

Generation of action potential Propagation of action potential Communication with target cell at the synapse

Question 27

A graded potential

Answer 27

is a small change in the resting membrane potential that is confined to a small area of the plasma membrane. The term graded potential is used because a stronger stimulus produces a greater potential change than a weaker stimulus.

Question 28

The absolute refractory period

Answer 28

is the time during an action potential when a second stimulus, no matter how strong, cannot initiate another action potential.

Question 29

The relative refractory period

Answer 29

follows the absolute refractory period and is the time during which a stronger-than-threshold stimulus can evoke another action potential.

Question 30

A subthreshold stimulus

Answer 30

produces only a graded potential.

Question 31

A threshold stimulus

Answer 31

causes a graded potential that reaches threshold and results in a single action potential.

Question 32

A submaximal stimulus

Answer 32

is greater than a threshold stimulus and weaker than a maximal stimulus. The action potential frequency increases as the strength of the submaximal stimulus increases.

Question 33

A maximal or a supramaximal stimulus

Answer 33

produces a maximum frequency of action potentials.

Question 34

Electrical synapses

Answer 34

are gap junctions in which tubular proteins called connexons allow local currents to move between cells.

Question 35

The enlarged ends of the axon - Chemical synapse

Answer 35

are the presynaptic terminals containing synaptic vesicles.

Question 36

The postsynaptic membranes - Chemical synapse

Answer 36

contain receptors for the neurotransmitter.

Question 37

The synaptic cleft - chemical syanpse

Answer 37

is a space separating the presynaptic and postsynaptic membranes

Question 38

Convergent pathways

Answer 38

have many neurons synapsing with a few neurons.

Question 39

Divergent pathways

Answer 39

s have a few neurons synapsing with many neurons.

Question 40

Reverberating circuits

Answer 40

have collateral branches of postsynaptic neurons synapsing with presynaptic neurons.

Question 41

Parallel after-discharge circuits

Answer 41

have neurons that stimulate several neurons arranged in parallel that stimulate a common output.