Intro to NS 1

Description:	Intro to nervous system 1 - Borges
Category:	Physiology
Created by:	P1StudyStack on 2009-01-15

Question	Answer
Functional units of the nervous system are ___________.	Neurons
Axons are unbranched except _______.	at their ends
Most cells in the brain are ______ cells.	glial
___________ provide structural and metabolic support, and participate in the blood brain barrier.	Astrocytes
Myelin forming cells in the CNS are _________.	Oligodendrytes
Myelin forming cells in the PNS are _________.	Schwann cells
Disease during which the myelin sheaths are gradually degraded by the immune system.	Multiple Sclerosis
Macrophages in the brain	Microglia
Form tracks for migrating neurons during development.	Radial Glia
The resting potential arises from uneven distribution of ions across the membrane. Outside is mainly ____.	Na+
The resting potential arises from uneven distribution of ions across the membrane. Inside is mainly ____.	K+
The sodium-potassium pump helps maintain the concentration gradient. Ion movement by the sodium-potassium pump moves how many, and which ion from the inside to the outside.	3 Na+
The sodium-potassium pump helps maintain the concentration gradient. Ion movement by the sodium-potassium pump moves how many, and which ion from the outside to the inside.	2 K+
When Na+ leaks down its concentration gradient, in which direction does it move?	Outside to inside
When K+ leaks down its concentration gradient, in which direction does it move?	Inside to outside
When a cell becomes depolarized, which side is more positive?	outside
How can a cell become depolarized?	Open Na channels, Na enters the cell; Open Ca channels, Ca enters the cell; Close K channels
When a cell is hyperpolarized, which side is more positive?	The outside
When a cell is hyperpolarized, which side is more negative?	The inside
When a cell becomes depolarized, which side is more negative?	The inside
How can a cell become hyperpolarized?	Open K channels and K exits the cell; open Cl channel and Cl enters the cell
_________ is the sudden reversal of the membrane potential and is an all or none response.	Action potential
What is the threshold potential voltage?	The voltage at which gated Na+ channels open and reverse the MP to about +50 mV
________ is the period during which no action potentials can be initiated and all sodium channels are inactivated.	Absolute refractory period.
_______ is the period during which some sodium channels are inactivated by not all.	Relative refractory period
Why is there one-way movement of the neuronal signal?	The refractory period does not allow an action potential to occur.
The _______ the diameter, the faster the conduction of a nerve.	Larger
The larger the diameter, the _____ the conduction of a nerve.	conduction
The action potential jumps from node to node in myelinated nerves. This is called ________.	Saltatory conduction
Which is faster, myelinated nerves or nonmyelinated nerves?	Myelinated nerves
Which cells make myelin in the CNS?	Oligodendrytes
Which cells make myelin in the PNS?	Schwann cells
What two types of junctions are there between neurons?	Electrical synapses and chemical synapses
The cytoplasm of 2 cells is connected by _______ through which ions can travel from cell to cell.	gap junctions
Neurotransmitter receptors are located on the __________ membrane. (presynaptic / postsynaptic)	Postsynaptic
How are neurotransmitters removed from the synaptic cleft	Re-uptake or enzymatic breakdown
What breaks down acetylcholine into acetate and choline?	Acetylcholinesterase
What kind of receptors bind norepinephrine?	Adrenergic receptors
How is norepinephrine degraded?	Mono-aminoxidase (MAO) or taken back up into synaptic vessels in the presynaptic cleft
This is also known as excitatory postsynaptic potential (EPSP).	Depolarization
What kind of neurotransmitters open cation channels leading to Na+ influx and depolarization?	Glutamate and acetylcholine
the current associated with EPSP is called ________.	Excitatory postsynaptic current (EPSC)
The voltage-gated Na+ channel threshold potential is about _________.	-40 mV
Axon potentials are triggered at the ___________.	Axon hillock
Hyperpolarization is called _________________.	Inhibitory postsynaptic potential (IPSP)
What does neurotransmitters such as GABA do?	Open Cl- channels that hyperpolarize the postsynaptic membrane which decrease the tendency of the receiving cell to develop action potentials.
Which way does chloride usually flow?	inwards