Biology Ch. 4 Flashcards
What is the equilibrium potential of potassium
-90mV
The resting potential of a cell is similar to the potential of (Na+/K+) because ____
K+. because the cell is slightly more permeable to potassium
Explain the movement of ions with the sodium potassium pump
Potassium in, sodium out
Describe the events of an incoming stimulus on the membrane potential
1) stimulus causes graded potential and ligand gated cation channels open
2) graded potential reaches threshold and voltage gated sodium channels open to allow sodium in
3) membrane is depolarized; voltage gated potassium channels start opening and voltage gated sodium channels close
4) repolarization; voltage gates sodium channels closed and potassium channels open so potassium leaves cell
5) voltage gated potassium channels closing
6) hyperpolarization; all potassium leak channels are open and some voltage gated potassium channels are open
7) all voltage gated potassium channels are closed
During hyperpolarization, all ___ channels are open and some ___ channels are open and some are closed
K+ leak channels are open, some voltage gated potassium channels are open and some closed
Define temporal summation
Multiple signals are integrated during a brief time period
Define spatial summation
additive effects are based on number and location of incoming signals (i.e. many firing on the hillock versus many [or few] signals firing on dendrites)
Define absolute refractory period
no amount of stimulation can cause an action potential
Define relative refractory period
must be greater than normal stimulation to cause action potential as membrane is starting from potential that is more negative than its resting value
How does axon length impact action potential speed?
Longer axon = higher resistance and slower conduction
How does cross section impact action potential speed?
Greater cross section = decreased resistance and faster propagation
Action potential speed is determined by both ___ and ___, though ___ has a greater effect
cross section and length, cross section has greater effect
Define effector
A postsynaptic cell on a gland or muscle that receives neuron signals
When an action potential reaches the nerve terminal, voltage-gated ___ channels open, allowing ___ to flow into the cell
Calcium
What ways are neurotransmitters regulated at the synaptic cleft?
1) broken down by enzymatic reactions
2) brought back via reuptake
3) diffuse out of synaptic cleft
What neurotransmitter(s) are regulated by being broken down by enzymatic reactions? what are they broken down by?
Ach by AchE
What neurotransmitter(s) are regulated by being brought back into the synaptic cleft via reuptake?
Serotonin by 5-HT
Dopamine
NE
What neurotransmitter(s) are regulated by diffusing out of the synaptic cleft?
NO
Define supraspinal circuits
reflexes that require input from the brain or brain stem
List the 4 divisions of the spinal cord
1) cervical
2) thoracic
3) lumbar
4) sacral
____ protects the spinal cord and transmits nerves between adjacent vertebrae
Vertebral column
The dorsal horn/root receives ___ information
sensory
the ventral horn/root receives ___ information
motor
Axons of motor and sensory neurons are found in the ____
spinal cord
Sensory cell bodies are found in the ____ of the spinal cord
dorsal root ganglia
Sensory neurons enter the spinal cord ____
dorsally
Motor neurons exit the spinal cord _____
ventrally
How to motor neurons go from the spinal cord to the muscle?
Directly, without synapsing
The peripheral component of the autonomic nervous system has _ neurons to transmit information
2
List the two neurons of the ANS
1) preganglionic
2) postganglionic
The soma of preganglionic neurons of the ANS is located ____
in the CNS
The axon of the preganglionic neurons of the ANS is located ____
in the PNS
Preganglionic neurons of the ANS snapes onto ____
the cell bodies of post ganglionic neurons
Postganglionic neurons of the ANS stimulate ___ to release ___ for the ___ system
Postganglionic neurons of the ANS stimulate target tissue to release NE for the sympathetic nervous system
List the two types of reflex arcs
1) monosynaptic
2) polysynaptic
Define monosynaptic reflex arc
single synapse between sensory neuron that receives stimulus and motor neuron that responds
Define polysynaptic reflex arc
at least 1 interneuron between sensory and motor neurons; Interneurons in spinal cord provide connections from incoming sensory information to motor neurons of supporting limb
The knee-jerk (patellar) reflex goes along the _____ reflex arc
monosynaptic
The withdrawal reflex uses a ____ reflex arc
polysynaptic
