Autonomic NS and Somatic Motor Control (PNS) Flashcards
Division of the nervous system
Central Nervous System
- Brain & Spinal Cord
Peripheral Nervous System
- Autonomic NS
- Sympathetic NS
- Parasympathetic NS
- Somatic NS (skeletal muscle)Afferent vs efferent neurons
Afferent neurons are sensory neurons that take in information from the environment and send it to the CNS interneurons for processing. They tell us how the environment AFFECTS us.
Efferent neurons receive information from the CNS internneurons to do some kind of motor output. They are how we EFFECT our environment.
How do efferent and afferent neurons relate to the CNS and PNS?
These neurons span the CNS and PNS though are largely thought of as “belonging” to the PNS. They are the major actors of the PNS. They are involved in both autonomic and somatic branches of the PNS.
How is the autonomic NS related to homeostasis and the endocrine system?
Together with the endocrine system, the autonomic NS monitors important homeostatic and behavior state processes including temperature control, water balance, eating behavior, bladder control, secondary respiratory control, etc.
Which parts of the brain initiate autonomic, endocrine, and behavioral responses?
Hypothalamus, pons, and medulla
Antagonistic control of organ systems
Represents the balance of parasympathetic and sympathetic control.
Two neuron relay for autonomic pathways
Two neurons connect the CNS to the target tissue. The first is the preganglionic neuron. It synapses with the postganglionic neuron at the autonomic ganglion. The postganglionic neuron signals to the target tissue. The ganglion is a cluster of nerves in the PNS>
Types of cholinergic receptors
Nicotinic and muscarinic
Preganglionic neurons release which neurotransmitter?
ACh - this is both sympathetic and parasympathetic preganglionic neurons
Sympathetic post-ganglionic neurons release which neurotransmitter
Norepinephrine which is received by an adrenergic receptor (subtypes include alpha 1 & 2, beta 1, 2…) on the target tissue
Parasympathetic post-ganglionic neurons release which neurotransmitter
ACh which is received by a muscarinic receptor on the target tissue
Where to find nicotinic ACh receptors
Postsynaptic membrane of:
- all autonomic ganglia
- all neuromuscular junctions
- some CNS pathways
What are nicotinic ACh receptors
Ligand-gated channels that cause depolarization and thus neuron excitation only
What are muscarinic ACh receptors
GPCRs that produce parasympathetic nerve effects in the heart, smooth muscles, and glands. Can cause hyperpolarization or depolarization by opening or closing K+ channels which allows for both inhibition and excitation.
Inhibition ex is a slower heart rate
Autonomic neuron axon terminals/synapses
Varicosities - vesicles that contain NT and spread out the signal across target cells/tissue. Function the same as an axon terminals where vesicles are brought to the membrane and NT is released via exocytosis. The NT diffuses to the receptors on the target cell instead of having one axon for each cell.
