Exam #4 chapter 11 Flashcards
with graded potentials when channels close what happens?
the ions diffuse away and the membrane returns to the resting membrane potential
what will ions do with graded potentials?
flow through an open channel and make the membrane more polarized (hyperpolarized) or less polarized (depolarized)
what is the structure of a dendrite?
branched, short and tapering processes
what are glial cells of the CNS?
supporting cells
what is the cation, potassium level ?
intracellular: 148 and extracellular: 5
what is the structure of an axon?
usually unbranched, long and do NOT taper
what does the ANS do?
sends commands to the smooth and cardiac muscles and glands (involuntary)
what do axons do?
branch and form enlarged presynaptic (axon) terminals
why is the plasma membrane selectively permeable? (2) (PC)
1) proteins are too large to pass through
2) charged ions cannot pass through the membrane but they can pass through ion channels in the membrane
what does ependymal cells do?
produce, monitor and circulate CSF
what are the characteristics of bipolar neurons? (3) (HHS)
1) has one dendrite
2) has one axon
3) small sensory neurons
what is the functional classification of sensory (afferent) neurons?
they conduct action potential to the CNS
where is the enteric nervous system located?
part of the ANS in the wall of the GI tract that controls the GI tract.
what are some types of glial cells of the CNS? (4) (AEMO)
1) astrocytes
2) ependymal cells
3) microglia cells
4) oligodendrocytes
what can be done with graded potentials?
they can be summed or added together
what are unlyelinated axons in the PNS enclosed by?
schwann cells
what do schwann cells do?
wrap a portion of one axon and form a myelin sheath
what is the similarity and difference between the extracellular fluid and intracellular fluid?
they have the same amount of cations and anions but differ the concentrations of different ions
what does the sympathetic division do?
functions in stressful situation (or exercise)
with graded potentials what is the change at a distance from the site of ion flow?
smaller
what are the characteristics of leak channels? (3) (AAP)
1) always open
2) allow certain ions to pass through the membrane continuously
3) put in the membrane by the cell
what does the PNS consist of?
the nervous tissues outside the CNS
what does the motor (efferent) division consist of?
1) the somatic nervous system (SNS)
2) the autonomic nervous system (ANS)
why does the resting membrane potential exist?
because of an unequal distribution of ions
how are astrocytes shaped and where are they located?
they are star-shaped in the CNS
what are the characteristics of pseudo-unipolar (unipolar) neurons? (2) (SC)
1) has short dendrites attached to a long axon
2) cell body off axon- sensory
what are graded potentials?
electrical signals that do not travel far
what does astrocytes regulate?
the chemical enviornment around neurons
when is the membrane potential termed hyperpoloraization?
a change away from 0mV
what is the functional classification of motor (efferent) neurons?
they conduct action potentials from the CNS
what does the cytoskeleton of astrocytes provide?
structure in nervous tissue
what do myelin sheaths do?
increase the speed of an action potential considerably
if calcium channels open what happens?
calcium ions will flow into the cell (depolarization)
what are sensory receptors?
ends of neurons, or separate specialized cells that detect temperature, touch, pain, pressure etc.
what are ligand-gated channels opened by?
the binding of specific chemical, a ligand-
if sodium channels open what happens?
sodium ions will flow into the cell (depoloarization)
what are the causes of the resting potential? (3) (MIS)
1) more potassium leaves the cell than sodium enter the cell
2) the inability of most anions to leave the cell since they are large
3) the sodium- potassium exchange pump pumps 3 sodium out and 2 potassium in
what type of ligand opens ligand-gated channels?
sodium channels in the the neuromuscular junction
what does grey matter in the nervous system consist of? (4) (NDUG)
1) neuron cell bodies
2) dendrites
3) unlyelinated axons
4) ganglia in the PNS and nuclei in the CNS