ch 12 nervous system pt 2 Flashcards
Regeneration is possible if:
Neuron cell body is intact and enough neurilemma remains
After a traumatic injury pns axons can…
Regenerate
CNS axon regeneration is
extremely limited
What are pumps?
Active transport, needs energy, sodium-potassium pumps
What are channels?
More proteins
What are leak channels?
Always open
What are chemically gated channels?
Closed unless when neurotransmitters bind
What are voltage gated channels
Closed unless membrane charge changes (neg charge)
Three states of voltage gated Na+ channels
resting, activation, inactivation state
What is resting state gates?
Activation gate closed, inactivation gate open
What is the Na+ movement in resting state?
Can’t go through
What is activation state gates
Activation and inactivation gates open
What is the Na+ movement in activation state?
Can move through channel
What is inactivation state gates
Activation gate closed, inactivation gate open
What is the Na+ movement in activation state?
Can’t go through
What are mechanically gated channels?
Closed unless open in response to a stimulus
What is in an entire plasma membrane of a neuron?
Leak channels, Na+ and K+ pumps, resting potential
What is in the receptive segment?
Dendrites and cell body
What gate is in the receptive segment?
Chemically gated channels Cl-
What gate is in the initial segment?
voltage-gated Na+ and K+ channels
What is in the initial segment?
Axon hillock
What is in the conductive segment?
Axon and its branches
What is gate is in the conductive segment?
Voltage-gated Na+ and K+ channels
What is in the transmissive segment?
Synaptic knobs
What gate is in the transmissive segment?
Voltage-gated Ca2+ channels and pumps
What is voltage energy (potential energy)
Inside and outside cell; concertation gradient
What is electrical energy?
Movement of ions
What is resistance energy?
Opposition to movement of ions such as membrane
What is current energy?
When channels open
What is Ohms law?
current = voltage/resistance
How is voltage energy exist?
Exists across the membrane due to unequal distribution of ions
How is current energy generated?
Generated when ions diffuse through channels
RMP =
-70mv
How does resistance energy change?
due to the actions of gated channels
What is the most important factor in setting RMP?
K+ diffusion
Influx is what polarization?
Depolarization
What triggers the RMP to raise from -90mv to -70mv?
Sodium
Efflux is what polarization?
Repolarization
What is the role of Na+/K+ pumps
Pushing 3 positive charges out and pushing only 2 in
What is graded potential?
Are small, short-lived changes in the RMP
Graded potentials in a postsynaptic neuron =
Postsynaptic potentials
EPSP
Depolar, Na+ influx
IPSP
Hyperpolar, Cl- Influx, K+ Efflux
Glial cells and their functions in CNS
Astrocytes; Maintaining the blood-brain barrier, regulate tissue fluid, form structural support, providing nutrients to neurons
Glial cells and their functions in PNS
Neurolemmocytes (Schwann cells); Form the myelin sheath around the neurons, supply nutrients to individual axons.
Structure for CNS
Brain and spinal cord
Structure for PNS
Nerves
Clusters of cell bodies are called what in CNS
Nuclei
Clusters of cell bodies are called what in PNS
Ganglion
Bundles of neuron processes are called what in CNS
Tract
Bundles of neuron processes are called what in PNS
Nerves
Order of the nervous system
stimulus -> sensory receptors -> sensory neuron -> CNS -> motor neuron -> effector
What is considered the thermoreceptor?
Sensory receptors and sensory neurons
What does the PNS do in the beginning?
Collects info and afferent
What does the PNS do at the end?
Output and efferent
What does the CNS do?
Integrate
What are the 4 types of effectors?
Skeletal muscle, smooth muscle, cardiac muscle, glands
What is somatic sensory system?
Hearing, vision, touching
What is visceral sensory system?
Smooth muscle, cardiac muscle, glands
What is somatic motor system?
Sends voluntary signals to skeletal muscles
What is autonomic motor system?
Sends involuntary commands to heart, smooth muscle, and glands
What is sympathetic?
Fight or flight and stressor occurring
What is parasympathetic?
Rest and digest and controls homeostasis
Come from
Visceral
Go to
Motor
All or none law
If we get to -55mv we will have an action potential
Threshold mv
-55mv
Na+ become inactive at what mv
+30mv
What is depolarization?
Gain a positive charge as Na+ enters through voltage gated Na+ channels
What is hyperpolarization?
Return to negative potential as K+ exits through voltage gated K+ channels
Steps to return to RMP
Na+ and K+ leak channels and Na+/K+ pumps
What is absolute refractory period?
Absolutely cannot have another action potential; Na+ channels open then inactivated
What is relative refractory period?
Another action potential is possible just hard to get
When is the absolute refractory period?
Right before and after action potential; Na+ channels have reset and K+ channels close slowly
What is continuous conduction?
Occurs on unmyelinated axons and impulse has to go through each channel
What is saltatory conduction?
Occurs on myelinated axons and impulse can past nodes
Activity at the synaptic knob
Action potential opens voltage-gated Ca 2+ channels and diffuse into knob and binds to proteins associated with synaptic vesicles and triggers exocytosis
What is action potential?
Propagated without any loss in intensity along the axon
What is graded potential?
Local changes in the membrane potential found in the cell body and dendrites
What does myelination do?
Speeds up an action potential
What is nerve fiber?
An axon and its myelin sheath
What is group A
Large diameter, myelinated fibers
