Nervous System Flashcards
What is a reflex arc +example
A reflex arc is a neural pathway controlling reflexes. In order to create a quicker response the sensory neurons synapse in the spinal cord.
Stimuli (somatic nerve receptors)-> Sensory (afferent) neuron innervation carry signal to posterior horn-> synapse to inter-neuron (integrating center) -> synapse to motor (efferent) neuron which carry signal from anterior horn -> appropriate response (effector muscle).
What is the layout and placement of a sensory neuron?
A sensory neuron contains receptor cells which are innervated by stimuli to fire action potentials along the axon of the cell’s peripheral branch, towards the cell body (located in dorsal -root ganglion), which then continues to propagate the action potential along the axon of the central branch, towards the axon terminals.
How is the nervous system broken up into catergories?
It contains the central nervous system and peripheral nervous system.
What forms the central nervous system?
The brain and spinal cord.
What forms the peripheral nervous system?
All nerves and ganglia outside of the brain and spinal cord.
What categories form the peripheral nervous system?
Autonomic and Somatic Nervous system.
What is the autonomic nervous system?
Regulates bodily processes on an involuntary basis. Controls things smooth muscle innervation and things like heart rate, digestion, breathing, etc.
What is the somatic nervous system?
Voluntary control of the efferent nerves which innervate the skeletal muscle, and afferent innervation of our skin, joints, and muscles.
How do cholinergic receptors work?
Acetylcholine is then stored in pre-synaptic neuronal vesicles by vesicular acetylcholine transporter, and stored there until an action potential signals its release into the synaptic cleft. Once in the synapse, the acetylcholine moves to the post-synaptic neuron, and binds to a receptor found on ligand-gated Na+ channels. As a result, the binding causes a conformational change which allows the Na+ channel to open, and an influx of sodium to cause a depolarization and resulting action potential to be fired in the next neuron.
In the PNS, Ach is released into the neuromuscular junction between a muscle and motor neuron terminus, when an action potential signals. It binds with receptors on the post-synaptic membrane, which results in a conformational change of the Na+ channels the receptor is located on. This allows positive Na+ to enter the muscular end plate, and if sufficient, will initiate muscle contraction.
How is acetylcholine formed?
Ach is formed in cholinergic neurons by the enzyme choline acetyltransferase, using acetyl coenzyme-A, which is produced in the breakdown of glucose during the Krebs’ cycle (glycolysis), and choline.
How is acetylcholine used?
A neurotransmitter of Somatic NS (neuromuscular junctions), and is used in the para/sympathetic nervous system of the Autonomic NS. In the CNS, Ach acts as a neurotransmitter and neuromodulator. Ach has excitatory and inhibitory capabilities.
