Download Unit 2A Neurophysiology

Human Physiology 2A:
Neurophysiology
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Paige Stieneke
BIOL 256
Dr. Karri Haen
February 10, 2013
Basic Types of Cell Signaling
Matching. Select the best option for the following statements:
1.
2.
3.
4.
5.
___ Diffuses to nearby target cell (neighbors)
___ Secretion of hormone into the blood, goes into circulatory system
___ Via cytoplasm via gap junctions
___ Signal substance affects secretory cell (itself)
___ Neuron’s axon terminal secretes neurotransmitter
Neurophysiology
Nodes of Ranvier
Nucleus
Oligodendrocytes
Axon
Myelin Sheath
a.
b.
c.
d.
e.
Cell-to-cell
Paracrine
Autocrine
Synaptic
Endocrine
Neurons
 Neurons transmit nerve impulses
as ____________________ (two words)
 Information always travels from
(dendrite, axon) to (dendrite, axon)
Glial Cells: support neurons
a. _________________ are cells that
produce the myelin sheath of the (CNS,
PNS) and is known as “white matter”
b. _________________ produce the
myelin sheath of the (CNS, PNS)
c. _________________ = insulation
to conduct action potentials!
Cell Membrane Potentials
Voltage across a membrane due to differential concentration and charges of ions inside/outside the cell
 Two types of signals:
a. ___________________: Small changes in membrane potential, leads to action potential
b. ___________________: Neuron sends an impulse, an all-or-none response
Graded Potential
Magnitude varies directly with the strength of the stimulus
a. ____________ Summation: Summed up over time
b. ____________ Summation: Summed over multiple inputs
Resting Membrane Potential
 What is the charge of a neuron at rest?
(always the charge INSIDE the cell!)
 AT REST: There is more K+ (inside, outside) the cell, and Na+ (inside, outside) the cell
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
Action Potential
Stage
Charge
(mV)
Function
Resting
Depolarization
Repolarization
Hyperpolarization
Steps of the Action Potential
1. _________________ (ligand) binds to ligand-gated channel
2. Binding of the ligand causes a _____________________
3. If graded potential strong enough, then the
___________________ is initiated at the axon hillock! It will
start to occur when the threshold inside of the cell is -55 mV (a charge in mV)
4.
: Voltage-gated Na+ channels open, and Na+ rushes (into, outside) the
cell. In other words, the cell becomes more (positive, negative) and the charge goes from
________ to _________.
 Voltage-gated K+ channels (open, close) allowing K+ to flow (into, outside) the cell
 Voltage-gated Na+ channels (open, close) at the peak of the action potential (+30 mV)
5.
: Starts due to halted influx of Na+. Voltage-gated K+ channels also
start to (open, close). In other words, the charge changes from +30 mV back to -70 mV. However,
the resting potential is overshot to _______.
6.
: The resting potential is overshot to ________. So how does the cell
return to its resting potential?
 ______________ pumps _________ out for every ________ in to return to the resting potential
Refractory Period
 How does the cell maintain the all-or-none response of an action potential?
 ______________________________: Enforces one-way of a nerve transmission to prevent a
2nd action potential from occurring too soon
 ______________________________: Follows the absolute refractory period, occurs during
repolarization and will allow a new action potential to occur when the threshold level is reached
(approx. -70 mV)
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu