Bio 2 Exam 2 Chap 44Nervous System

Front 1

What member of the animal phyla does not have nerve cells?

Back 1

sponges

Front 2

The CNS (Central Nervous System) includes what? What is the difference between a neuron and glial cell?

Back 2

includes brain and spinal cord; 90% GLIAL CELLS (support) and 10% NEURON (excitable cells that communicate via electrical and chemical messages)

Only 2% of brain is neurons

Front 3

What is included in the PNS (Peripheral Nervous System)? What is the difference between the somatic and autonomic nervous system?

Back 3

everything outside of CNS; includes the SOMATIC nervous system ( voluntary; controls skeletal muscle) and
AUTOMATIC nervous system (involuntary; regulates activity in smooth muscle, cardiac muscle, and glands of the body )

Front 4

What produces the nerve impulses?

Back 4

plasma membrane of neuron
produces electrical signals (electrical difference across a neuronal membrane measured as millivolts) that are nerve impulses

Front 5

What is the difference in AFFERENT and EFFERENT neurons?

Back 5

EFFERENT -transmit information from CNS to periphery effectors (muscles and glands)
Exiting (CNS): Efferent

AFFERENT-transmit information from periphery to CNS; sensory neurons
Approaching (CNS) :Afferent

Front 6

Interneurons are found where?

Back 6

association neurons; found only in CNS as complex interconnections between one neuron and another; complex reflexes, learning, and memory

Front 7

What are parts of a basic neuron? What is the functions of these parts? Where is the action potential generated?

Back 7

functional unit of nervous system; can produce electrical signals and action potentials where inside of cell becomes positively charged relative to outside of cell; made up of

DENDRITE (cytoplasmic portion that RECEIVES incoming information),
SOMA (cell body that CONTNAINS nucleus and most organelles),
AXON (long cellular extension which TRANSMITS action potentials/nerve impulses;
AXON HILLOCK is closest to the cell body and is responsible for GATHERING action potential)

Front 8

electrical signal travels from sensory neuron to interneuron in the CNS to motor neuron (no direct brain activity)

Back 8

reflex arc

Front 9

The "electrochemical gradient" that determines how a charged ion will move through a permeable membrane depends on the _______of electrical forces and ______across the membrane.

Back 9

The "electrochemical gradient" that determines how a charged ion will move through a permeable membrane depends on the COMBINED EFFECTS of electrical forces and CONCENTRATION DIFFERENCES across the membrane.

Front 10

only neurons and muscle cells are ____

Back 10

excitable

Front 11

Which glial cells produce myelinated axons and where?

Back 11

neuroglial cells
support cells...make up 90% of nervous system cells; include oligodendrocyte (produce myelin in CNS), and Schwann cells (produce myelin in PNS) and others (include astrocytes (metabolic support; stem cells), microglia (phagocytic removal cellular debris)

Front 12

What is the difference in white and gray matter?

Back 12

WHITE MATTER- myelinated axons in CNS
GRAY MATTER- dendrites/cell bodies in CNS

Front 13

What are nerves?

Back 13

bundled myelinated axons in the PNS

Front 14

What is myelin?

Back 14

layers of plasma membrane from oligodendrocytes (CNS) and Schwann cells (PNS) that FORM INSULATION around the axons of neurons thereby reducing a membrane's ion permeability and increasing the speed of action potential generation; in an unmyelinated axon, conduction velocity is primarily determined by diameter of the axon

Front 15

What is saltatory conduction and why is it fast?

Back 15

action potential conduction that occurs in myelinated axons where the action potentials jump from Node of Ranvier ( gap of exposed axon in the myelin sheath) to Node

Front 16

What is the resting membrane potential? What are the factors that influence this? On each cycle of the sodium/potassium pump, how many of each ion are pumped and in what direction? What is the average value of the resting membrane potential?

Back 16

- a potential difference (electrical in nature measured in millivolts) exists across cell's plasma membrane even if the nerve cells are not producing electrical responses;
- factors that influence this are concentration of INTRACELLULAR anions (e.g., proteins), sodium (Na+) and potassium (K+) and presence of sodium and potassium gated channels, potassium (K+) leakage channels, and sodium/potassium pump (2 K+ into cell and 3 Na+ out of cell);
- ELECTROCHEMICAL FORCES are acting for sodium ions to move into the cell and potassium ions to move out of the cell (resting membrane is more permeable to POTASSIUM than to sodium, so it moves OUT of cell due to electrochemical gradient);
- when neuron is not being stimulated, inside of the cell is more negative than the outside of the cell primarily because of passive leakage of K+ ions across the membrane and it AVG. as -70mV (millivolts)

Front 17

3 factors contributing to resting potential:
Na+/K+ -ATPase (sodium-potassium pump
-- Transports 3 Na+ out for every 2 K+ moved in
Ion specific channels allow passive movement of ions
--K+ channels open more frequently at resting potential
--Membrane more permeable to K+
Negatively charged molecules such as proteins more abundant inside cell

Back 17

resting membrane potential

Front 18

determines how a charged ion will move through a permeable membrane depends on the combined effects of electrical forces and concentration differences across the membrane

Back 18

electrochemical gradient

Front 19

How do ions flow and in what order during an actions potential? How is an action potential like the falling of dominoes?

Back 19

The rapid INWARD diffusion of Na+ followed by the OUTWARD diffusion of K+ producing a rapid change in the membrane potential towards the positive direction and exceeding threshold; action potentials are regenerated along an axon as one action potential serves as the depolarization stimulus for the next action potential

Front 20

What is the role of threshold in the all-or-none principle?

Back 20

in an excitable cell, the critical value (between -70mV and -55mV) of the membrane potential to which the cell (axon hillock) must depolarized in order to trigger an action potential; this follows the "all-or-none" law

Consider: Positive feedback occurs as the neuron is being depolarized and passes the threshold potential.

Front 21

cell membrane less polarized, less negative relative to surrounding solution, due to increasing the flow of Na+ ions into a neuron at rest

Back 21

depolarization

Front 22

Both opening of the K+ channel gate and closing of the Na+ channel inactivation gate stops the rapid depolarization that occurs as the "upsweep" of membrane potential peaks during the action potential.

Back 22

repolarization/hyperpolarization

Front 23

WHICH channel activation gate responds slightly more slowly to depolarization?

Back 23

The K+ channel activation gate responds slightly more slowly to depolarization than the Na+ channel activation gate to prevent canceling out each other's effects on membrane potential changes.

Front 24

The refractory period is what?

Back 24

period following an action potential during which a neuron CANNOT be stimulated to generate another action potential; ensures action potential does not move backward

Front 25

NAME 2 gated ion channels

Back 25

VOLTAGE gated - open close in response to voltage changes

LIGAND-gated - open and close in response to ligands or chemicals

Front 26

A graded potential is what and in which neurons does it have an important role?

Back 26

a neuron undergoes a change in membrane potential that is proportional to (i.e., varies depending on) the strength of the stimulus given to that neuron; important for CONVEYING STIMULUS intensity in SENSORY NEURON.

Front 27

Varies based on AXON diameter and/or myelination

Back 27

conduction speed

Front 28

What is the synapse?

Back 28

functional association (junction) of a neuron with another neuron or effector organ ( muscle or gland)...can be electrical or chemical; synaptic cleft is small gap between two successive neurons or between a neuron and an effector

Front 29

What is the difference in an electrical and a chemical synapse?

Back 29

ELECTRICAL-message (ions) travel between cells via GAP JUNCTION proteins; communication is bi-directional; synapses can be gated; DONOT utilize neurotransmitters

CHEMICAL-makes up most synapses in nervous system; communication is SLOWER than electrical; utilizes NEUROTRANSMITTERS; boundaries are the presynaptic neuron that releases neurotransmitters (chemicals stored in synaptic vesicles which when released via exocytosis must diffuse across the synaptic cleft and by binding to postsynaptic receptors (chemically regulated gates and ligand regulated gates), regenerate the action potential) and the postsynaptic neuron, which contains receptors; most neurotransmitters are synthesized in cytosol

Front 30

synaptic cleft

Back 30

junction where nerve terminal meets a neuron, muscle cell, or gland and into which NEUROTRANSMITTER ARE RELEASED

Front 31

What is the role of calcium in neurotransmitter release? What happens to the neurotransmitter after it is released?

Back 31

triggered by voltage-gated Calcium channels (these channels open in response to arrival of action potential at the axon terminal, allowing influx of calcium ions that cause FUSION OF NEUROTRANSMITTERS containing vesicles to membrane and exocytosis of neurotransmitter); voltage gated channels allow axon and axon terminal function; neurotransmitter diffuses across cleft to interact with receptors on ligand gated channels, triggering DEPOLARIZATION OF POST SYNAPTIC membrane

Front 32

postsynaptic cell membrane potential changes due to neurotransmitter binding

Back 32

Excitatory postsynaptic potential (EPSP) Brings membrane closer to threshold potential
 Inhibitory postsynaptic potential (IPSP) Takes membrane farther from threshold
potential (hyperpolarization)

Front 33

synaptic integration

Back 33

Refers to the summing of excitatory (EPSP) or inhibitory (IPSP) influences in a postsynaptic neuron

Front 34

vertebrate neuromuscular junction activity

Back 34

Action potentials are generated in the neuron, STIMULATION of the entry of Ca2+ into the neuron, release of ACETYLCHOLINE into the synapse, and muscle fiber membrane is DEPOLARIZED

Front 35

What happens to the neurotransmitter after the message has been delivered?

Back 35

neurotransmitter REMOVAL diffusion out of cleft, DEGRAGATION by enzymes (such as ACETYLCHOLINESTERASE), active REUPTAKE across the presynaptic membrane (after which they can be reused), and binding to the receptor (concentration of neurotransmitter primarily determines binding)

Front 36

Acetylcholine is found where and where is most abundant? What degrades it?

Back 36

released by cholinergic synapse in somatic motor neurons; found in PNS & CNS; most abundant neurotransmitter in PNS and is always an excitatory neurotransmitter; excess degraded by acetylcholinesterase into acetate and choline (which is transported back into the axon terminal to be resynthesized into active neurotransmitter)

Front 37

cocaine effects

Back 37

by blocking DOPAMINE REUPTAKE from synapses causing disruption of neural signaling and producing profound changes in MOOD AND BEHAVIOR

Front 38

Saltatory conduction is a term applied to conduction of action potentials
A. across electrical synapses.
B. along the postsynaptic membrane from dendrite to axon hillock.
C. in two directions at the same time.
D. from one neuron to another.
E. along myelinated axons.

Back 38

E. along myelinated axons.

Front 39

Which of the following are NOT important in chemical synapses?
A. gap junctions
B. neurotransmitters
C. specific neurotransmitter receptors
D. secretory vesicles
E. voltage-gated Ca2+ channels

Back 39

A. gap junctions

Front 40

Synaptic vesicles discharge their contents by exocytosis at the
A. dendrite.
B. axon hillock.
C. nodes of Ranvier.
D. postsynaptic membrane.
E. presynaptic membrane.

Back 40

E. presynaptic membrane.