Chapter 11 Nervous System

Question 1

nerve is resetting the Na+ and K levels to original concentrations during this period, not enough concentration gradient has been established, prevents neuron from generating an action potential (absolutely no action potential)

Answer 1

absolute refractory period

Question 2

almost all of the Na+ and K have been restored, a very strong stimuli could cause depolarization

Answer 2

relative refractory period

Question 3

-Axon diameter - the larger the diameter, the faster the impulse
-Presence of a myelin sheath - myelination dramatically increases impulse speed

Answer 3

rate of impulse propagation is determined by

Question 4

current passes through myelinated axon only at the nodes of Ranvier, voltage-gated Na+ channels are concentrated in these nodes, action potentials are triggered only at the nodes and jump from node to node, much faster than conduction along unmyelinated axons

Answer 4

saltatory conduction

Question 5

destruction of the myelin sheath on neurons in the CNS and its replacement by plaques of sclerotic (hard) tissue, can harm motor control

Answer 5

Multiple Sclerosis (MS)

Question 6

“voluntary” nervous system innervates skeletal muscle

Answer 6

somatic motor division

Question 7

“involuntary” nervous system: innervates cardiac muscle, smooth muscle, glands, broken down into sympathetic (speeds up) and parasympathetic (back to normal)

Answer 7

autonomic motor division

Question 8

Act as phagocytes, eating damaged cells and bacteria, and act as the brain’s immune system

Answer 8

microglia

Question 9

holds nucleus and nucleolus, focal point of outgrowth of neuronal processes

Answer 9

nerve cell body

Question 10

Branchlike parts of a neuron that are specialized to receive information, carry impulses toward the cell body

Answer 10

dendrites

Question 11

Carry impulses away from the cell body, surrounded by myelin sheaths, contacts nerves, muscles, and glands

Answer 11

axons

Question 12

outside wrap of Schwann cell containing the nucleus and organelles

Answer 12

neurilemma

Question 13

gaps in the myelin sheath between the adjacent Schwann cells

Answer 13

nodes of ranvier

Question 14

found in the brain and spinal cord, white is dense collection of myelinated fibers, and gray is mostly soma and unmyelinated fibers

Answer 14

white matter vs gray matter

Question 15

the state of the neuron when not firing a neural impulse, about -70mv

Answer 15

resting potential

Question 16

the change in electrical potential associated with the passage of an impulse along the membrane of a nerve cell, Na+ permeability increases

Answer 16

action potential

Question 17

inside of the cell becomes less negative, Na+ in, greater than -70mv

Answer 17

depolarization

Question 18

the membrane returns to its resting membrane potential, K out, inside of the cell becomes more negative, returns to -70mv

Answer 18

repolarization

Question 19

inside of cell becomes more negative than resting potential of -70mv, extra K out, nerve is now less likely to fire

Answer 19

hyperpolarization

Question 20

caused by frequency of impulse transmission

Answer 20

stimuli intesity

Question 21

a junction that mediates information transfer from one neuron to another, there is a gap that separates them which is why we need neurotransmitters, neurotransmitter also opens sodium potassium channel

Answer 21

synapses

Question 22

nerve impulse comes down axon terminal and opens Ca+ channels which releases neurotransmitter, Ca+ comes into the axon terminal to cause the release of neurotransmitters

Answer 22

function of Ca at axon terminal