Chapter 2 Flashcards
Name the different types of cells in the brain **
- neurons
- glia cells
- unipolar: 1 axon, NO dendrites
- multipolar: 1 axon, many dendrites
- bipolar: 1 axon, 1 dendrite
Name the parts of the neurons **
- soma
- dendrites
- axon (myelin sheath and node of ranvier)
- terminal buttons
When electrical and chemical signals are used by neurons **
- electrical signals: intracellular communication (info flows WITHIN the neuron; through axon)
- chemical signals: intercellular communication (information flows BETWEEN neurons; terminal buttons to dendrites)
The different “pressures” that control a neuron’s resting potential **
- diffusion
- electrostatic pressure
Na+ role in the brain **
- positive charge
- enter cell
- depolarization
K+ role in the brain **
- positive charge
- hair cells rich in K+
- leaves cell
- hyperpolarization
Cl- role in the brain **
- negative charge
- enter the cell
- hyperpolarization
Ca++ role in the brain **
- positive charge
- attached to the vesicles so they can diffuse into the membrane and allow fro neurotransmitter release
Mg++ role in the brain **
-kicked out of NMDA receptors die to activation and depolarization of AMPA receptors
how neurons create action potentials: At rest? depolarization? steps?
**
AT REST: more Na+ and Cl- outside the cell / more K+ inside the cell, but K+ can pass freely (membrane selectively permeable to K+)
DEPOLARIZATION: neuron must be exposed to a depolarizing stimulus (makes the inside less negative and more likely to fire)
- the membrane is depolarized to a threshold of -40mV; Na+ channels open, and Na+ goes inside (due to diffusion and electrostatic pressure)
- K+ channels open, K+ beings to leave cell
- Na+ ion channels lead to sodium influx causing membrane to reach the equilibrium potential for Na+ (+40). Na+ channels then close and inactivate (no more Na+ enters cell)
- inside of cell is now positive, so K+ channels open and cause an even greater outflow of K+
- outflow of K+ causes the membrane to return to rest
- sodium potassium pump re-establishes resting membrane potential : K+ channels close, Na+ channels reset, extra K+ outside diffuses away
how action potentials are passed down the axon **
- regenerated along the length of the axon (recreating AP at every new node of ranvier)
- myelin prevents K+ leakage out, channeling the depolarization down the axon interior
- depolarization travels one direction down the neuron very rapidly
- propagation
the role of myelin in communicating action potentials **
speed up action potentials
-allows the electrical impulse to travel a bit longer
how action potentials lead to neurotransmitter being released into the synapse **
- AP reachers the terminal = Ca++ channels open
- opens fusion pore
- fusion pore widens and incoming Ca++ ions attach to the receptors of the vesicles of the neurotransmitter
- causing molecules to bend to the membrane and neurotransmitter to leave terminal button into the synaptic cleft
metabotropic receptors and their characteristics **
- receptors once a chemical is bond to it
- cause a change in reaction in the postsynaptic neuron
- they G coupled proteins
inotropic receptors and their characteristics **
-open an ion channel and allow certain ions in once bon day neurotransmitter
Soma
- the cell body of a neuron
- contains nucleus
Dendrites
- “tree” branches off the soma
- receive information from the terminal buttons of other neurons
Axon
-conveys information from soma to terminal buttons
Terminal Buttons
- the bud at the end of a branch of an axon
- sends information to other neurons
Neurons
- cells that transmit information
- 3 shapes: multipolar, bipolar, unipolar
glial cells
- support cells
- 4 types: astrocytes, microglia, oligodendrocytes, schwann cells
sensory neurons *
cells gather information from the external world
interneurons *
processes information
motor neurons*
generates movements in response to the external world
action potentials
- nerve impulses are brief but large changes in membrane potential which communicate info within the cell
- all or nothing
- patterns of action potentials carry information to target cells
hyper polarization in action potentials
due to efflux of K+ = makes outside more positive ; influx of Cl- also can produce HP
-makes the inside of the cell more negative and less likely to fire
depolarization in action potentials
due to an influx of Na+ through normally closed Na+ channels
-makes the inside of the cell less negative and more likely to fire
Excitatory post-synaptic potentials (EPSP) **
- DEPOLARIZATION, EXCITATORY
- often result from Na+ or Ca++ going into the cell
Inhibitory post-synaptic potentials (IPSP)
- HYPERPOLARIZATION, INHIBITION
- results from Cl- going into the cell or K+ going out
How can Na+ remain with greatly concentrated in the extracellular fluid if both forces are pushing Na+ into the cell?
- at rest membrane is not very permeable to Na+
- so the Na+ ions that do enter the cell are removed by the sodium potassium pump (pushes 3 Na+ out and 2 K+ in)
