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48 Cards in this Set

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Generally thee Plasma membrane is not permeable to?
Proteins, nucleic acids, or other Large molecules ( it is permeable to ions, nutrients, and wastes)
Simple Diffusion
no membrane protein involved- movement of molecules through bilayer from high concentration to low concentration
Facilitated Diffusion
involves integral membrane proteins, including channels and carriers. causes some sort of conformational change to allow something through the bilayer
Active Transport
Requires integral membrane proteins (carriers and pumps) Moving molecules across the membrane but against the gradient. REQUIRES THE INPUT OF ENERGY!!
Osmosis
Simple diffusion of water
Diffusion through Phospholipid bilayer
-pure phospholipid bilayers are selectively permeable
 -small or nonpolar molecules move across phospholipid bilayers quickly
 -charged or larger polar molecules cross slowly, if at all
-pure phospholipid bilayers are selectively permeable
-small or nonpolar molecules move across phospholipid bilayers quickly
-charged or larger polar molecules cross slowly, if at all
What and Why Diffusion?
If a membrane is permeable to solute, net diffusion occurs sown a concentration gradient. If molecule is charged electrochemical gradient.
What and Why Osmosis?
If a molecule is impermeable to the membrane then osmosis causes water to move toward the area of higher solute. (remember water will move to make sure that the amount of solute per volume is equal)
Channel Protein
Channels facilitate diffusion (still moves things from high to low concentration). Always Passive. Most are gated (can be opened or closed in response to some signal)
Carrier Protein
Carriers bind to molecules that are being transported. Causes a conformational change to transport to inside of cell. Still Passive!
Primary Active Transport
the sodium-potassium pump (Na/K)- this pump uses energy from ATP to pump ions against their electrochemical gradient. directly uses energy to transport molecules across a membrane
Secondary Active Transport
In contrast to primary active transport, there is no direct coupling of ATP; instead, the electrochemical potential difference created by pumping ions out of the cell is used.
Antiport
two ions or other solutes are pumped in opposite directions across a membrane.One of these species is allowed to flow from high to low concentration which yields the entropic energy to drive the transport of the other solute from a low concentration region to a high one.
Symport
Symport uses the downhill movement of one solute species from high to low concentration to move another molecule uphill from low concentration to high concentration (against its electrochemical gradient). The two species move in the same direction across the membrane.
The two subdivisons of the Nervous system
Central Nervous System and Peripheral Nervous System
Central Nervous System (Structures)
Brain and Spinal Cord
Peripheral Nervous System( Structures)
Everything else besides the Brain and spinal cord including cranial and spinal nerves
The Nervous system consists of 2 kinds of cells
Neurons and Glial cells
Neurons gather,process and transmit information by:
responding to stimuli, producing and carrying electrochemical impulses and releaseing chemical messages
Neuron Structure
Cell Body- contains nucleus
Dendrites- recieve information from other cells
Axon- conduct impulses away from cell body
Sensory/ Afferent neurons
-neurons conduct implulses INTO CNS
Motor/ Efferent-
neurons carry impulses OUT OF CNS
Interneuron
integrate nervous system activity . located entirely inside CNS
Neuron Classifications(Functional)
Neuron Classifications (Structural)
Pseudounipolar Neurons (Structure)
the cell body sits along side of single process
many sensory neurons have this structure
Bipolar Neurons (Structure)
the dendrite and axon arise from opposite ends of cell body
found in retinal neurons
Multipolar Neurons (Structure)
have many dendrites and one axon
motor neurons and many other types are multipolar
Glial Cells in CNS
Oligodendrocytes, Microglia, Astrocytes, Ependymal
Glial Cells In PNS
Schwann Cells and Satellite Cells
Schwann Cells
Myelinate PNS axons
Oligodendrocyte
Myelinates several CNS axons
Ependymal Cells
Neural Stem Cells
Myelination
this process electronically insulates the axon. Myelination enables nerve cells to transmit information faster and allows for more complex brain processes.
Resting Membrane Potential
unequal distribution of ions across the PM. Internal area has negative charge relative to external. Th Na/K pump causing electrochemical gradient, very limited permeability of Na(sodium), Relatively high permeability of K(potassium). -70mV is typical
Astrocytes
most common glial cell in CNS. Involved in:
buffering potassium levels, recycling neurotransmitters, regulating adult neurogenesis, releasing transmitters that regulate neuronal activity.
Action Potential
an action potential is a wave of membrane potential change that sweeps along the axon from cell body to synapse
this wave is formed by rapid depolarization of the membrane  by Na+ influx, followed by rapid repolarization by K+ efflux
an action potential is a wave of membrane potential change that sweeps along the axon from cell body to synapse
this wave is formed by rapid depolarization of the membrane by Na+ influx, followed by rapid repolarization by K+ efflux
Depolarization
Occurs when the membrane potential becomes LESS
negative than resting potential
Hyperpolarization
Occurs when the membrane potential becomes MORE
negative than resting potential
Action Potential (Mechanisms)
-depolarization and repolarization both occur via diffusion of ions down their electrochemical gradients
-the action potential itself does not require active transport
-the Na+/K+ pump maintains the ion gradients by using energy from ATP hydrolysis to pump out Na+ and pump in K+
Action Potentials Are All-or-None
when the membrane potential reaches threshold, an AP is irreversibly fired the amplitude of the action potential is a property of the membrane and its embedded voltage-gated channels; the intensity of the stimulus is irrelevant as long as it is sufficient to cause the membrane to reach threshold
Refractory period
the amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following an excitation
Absolute refractory period
interval during which a second action potential absolutely cannot be initiated, no matter how large a stimulus is applied. Na+ channels are inactivated
Relative refractory period
interval immediately following during which initiation of a second action potential is inhibited but not impossible. another action potential is more difficult to initiate because voltage-gated K+ channels are still open
Action Potential Speed
action potential travels faster along an axon with a greater diameter and myelinated
Synapse
is a functional connection between a neuron(presynaptic) and another cell (postsynaptic)
Chemical (Large majority) and Electrical (rare among neurons)
Chemical synapses
-the two cells are separated by a small space called the synaptic cleft. neurotransmitters are stored in synaptic vesicles in the axon terminus of the presynaptic neuron.
-when an action potential reaches the axon terminus, the vesicles fuse with the pre
-the two cells are separated by a small space called the synaptic cleft. neurotransmitters are stored in synaptic vesicles in the axon terminus of the presynaptic neuron.
-when an action potential reaches the axon terminus, the vesicles fuse with the presynaptic membrane neurotransmitters are released by exocytosis
-amount of neurotransmitter released depends on the frequency of action potentials
postsynaptic potentials
graded potentials – they are not all-or-none, they vary in intensity, they decease with time and with distance along the cell body and dendrites