Chapter 13 and 14 course packet Flashcards
What gives us our physiological distention as humans?
The nervous system and the senses
What are the 4 areas we need to know for the exam?
- The structure and function of the nerve cell
- The overview of the nervous system, with three different levels of organization
- The brain, with a specific list of things to know
- Six specific senses: Somatic, taste, smell, hearing, balance, and vision
What are the two kind of cells in the nervous system?
- Neurons
2. Neuroglia
What is the neurons percent of nervous system volume?
Less than or equal to 50%
What is the neuroglias percent of nervous system volume?
Greater than or equal to 50%
What is the neurons percent of nervous system cells
≈10%
What is the neuroglia percent of nervous system cells?
≈90%
What is the overall function of the neurons?
They conduct the nerve impulses
What is the overall function of the neuroglias?
They support neuron function
What is the input zone of a neuron?
The dendrites and cell body
What is the conducting zone of a neuron?
The axon
What is the the trigger zone of a neuron?
The axon hillock
What is the output zone of a neuron?
The axon endings
Describe a neuron at rest?
The resting membrane potential is ≈ -70 mV. The lipid bilayer of the neuron’s membrane is impervious to charged particles (ions)
What is floating within the lipid bilayer of a neuron?
Various kinds of proteins that serve as three kinds of ion (sodium or Na+, potassium or K+) channels
What are sodium-potassium pump proteins?
They are proteins that continuously and actively transport Na+ out of and K+ into the neuron?
Some sodium Na+ and potassium K+ diffuse (leak) through all the time
Permanently open channel proteins
What are gated channel proteins?
They are voltage sensitive gates that open with a nerve stimulus
What is the action potential?
Literally refers to an abrupt, brief reversal “depolarization” in the resting membrane potential across the neural plasma membrane. It moves like a wave down to the axon to the axon endings, this is called the “nerve impulse”
At the base of the axon hillock, or trigger zone, the stimulus must reach a specific threshold level in order to generate an action potential. At the threshold, a positive feedback loop of Na+ influx will initiate
Threshold level
What is all or nothing according to the threshold?
If the threshold is reached, a short (≈millisecond) sharp spike of the action potential results, and all action potentials will be identical
What is the action potential propagation with the neurons?
Once triggered, they spread by themselves (self-propagating) and in only ONE direction: away from the trigger zone. They also do not diminish in magnitude. After ≈millisecond, the gated Na+ channels close, and the resting membrane potential returns “depolarized”
What is the effect of myelin?
Schwann cells in the peripheral nervous system (PNS), and oligodendrocytes in the central nervous system (CNS)
The axon ending (of the presynaptic neuron) has many?
Synaptic vesicles filled with neurotransmitter (acetylcholine, serotonin, norepinephrine, dopamine, GABA)
They synaptic vesicles fuse with what and what happens?
The plasma membrane, releasing their contents into the synaptic cleft by exocytosis
The neurotransmitters cross the synaptic cleft and find what?
Receptor sites on the postsynaptic neuron or effector (muscle or gland cell)
When the neurotransmitter binds to postsynaptic receptor it can what effect?
Either an excitatory or inhibitory effect
Describe the synaptic integration process
In a multiple synaptic environment like the brain, both excitatory (EPSP’s) and inhibitory (IPSP’s) can coverage on the postsynaptic neuron and cancel each other out
What happens once the postsynaptic neuron fires it’s action potential?
The body must rid the synaptic cleft of neurotransmitter in a rapid and controlled fashion
How is the rapid and controlled fashion done?
Usually done via: 1) diffusion out of the cleft 2) enzymes released within the cleft break down the neurotransmitter and 3) membrane transport proteins actively pump the neurotransmitter back into the presynaptic neuron or neuroglial cell
Overview of the nervous system
1) the nervous system divides into the central nervous system (CNS) and the peripheral nervous system (PNS)
2) the PNS then divides into somatic and autonomic
3) the autonomic then divides into sympathetic and parasympathetic
What does the CNS include?
The brain and spinal cord
What does the PNS include?
Everything else that conducts nerve impulses outside of the brain and spinal cord
What is the somatic subdivision within the PNS?
It deals with things of which you are conscious
What is the autonomic subdivision within the PNS?
It deals with things of which you are not conscious of
What is the function related to somatic subdivision?
“Conscious” sensory and motor functions
What are the organs innervated for somatic subdivision?
Sensory: skin, skeletal muscle and tendons
Motor: skeletal muscle
What is the location of the nerve cell bodies for somatic subdivision?
Entirely within the CNS (axons reach all the way to and from organs
What is the function related to autonomic subdivision?
“Unconscious” sensory and motor functions
What are the organs innervated for autonomic subdivision?
Smooth and cardiac muscle, glands and viscera
What is the location of nerve cell bodies for autonomic subdivision?
The neurons that have cell bodies in the CNS are preganglionic neurons, they synapse with postganglionic neurons in the autonomic system ganglia in the PNS
Sympathetic autonomic nerves deals with what type of responses?
Fight or flight responses
The parasympathetic autonomic nerves deals with what responses?
Ease and feast responses
The typical overall response for sympathetic nerves?
Fight or flight