Week 8 - Chapter 15: The ANS
How does the somatic nervous system differ from the autonomic nervous system (ANS) in terms of control?
The somatic nervous system is under conscious control, while the ANS usually operates without conscious control.
What types of sensory input does the somatic nervous system receive?
From somatic senses and special senses
How do motor pathways differ between the somatic nervous system and the ANS?
Somatic motor neurons directly synapse with effectors, while ANS motor pathways involve two neurons: a preganglionic neuron and a postganglionic neuron.
What are the two major divisions of the ANS?
Sympathetic and Parasympathetic
Division of the ANS which usually excites
Sympathetic
The division of the ANS which usually inhibits
Parasympathetic
Somatic nervous system effectors are:
Skeletal muscles
ANS effectors include:
Cardiac muscle, smooth muscle, and glands
What is a preganglionic neuron?
A preganglionic neuron is the first neuron in an autonomic motor pathway that synapses with a postganglionic neuron in an autonomic ganglion.
Where are the cell bodies of sympathetic preganglionic neurons located?
In the thoracic and lumbar spinal cord
Where are the cell bodies of parasympathetic preganglionic neurons located?
In certain cranial nerve nuclei and sacral spinal cord.
What are the two major groups of autonomic ganglia?
Sympathetic ganglia (sympathetic trunk and prevertebral ganglia) and parasympathetic ganglia (near or inside visceral effectors)
What neurotransmitter do cholinergic neurons release?
Cholinergic neurons release acetylcholine, which binds to cholinergic receptors
What do adrenergic neurons release, and what do they bind to?
Adrenergic neurons release norepinephrine, which binds to adrenergic receptors like alpha and beta receptors
What is the difference between an agonist and an antagonist?
An agonist activates a receptor, mimicking natural effects, while an antagonist blocks a receptor, preventing those effects
What does the sympathetic division of the ANS do?
It supports physical activity and rapid energy production (fight-or-flight response)
How do the effects of sympathetic stimulation compare to parasympathetic stimulation?
Sympathetic stimulation effects are longer lasting and more widespread than those of parasympathetic stimulation
What is an autonomic reflex?
An autonomic reflex adjusts the activities of smooth muscle, cardiac muscle, and glands, involving a reflex arc
What is the major control center of the ANS?
The hypothalamus is the main control and integration center for the ANS, connected to both divisions
Where are ganglia located?
Near or within target organs
Sensory input mainly comes from _______
Interoreceptors
The ANS has a ____ neuron pathway:
2 Neuron pathway;
- Preganglionic neuron synapses with postganglion neuron before reaching target oragn
The primary transmitters in the ANS:
Acetylcholine and norepinephrine
Sympathetic response:
Fight or flight response, prepares body for emergency situations
Parasympathetic response:
Rest and digest response, promotes relaxation and recovery
Preganglionic sympathetic fibers synapse with cells in the _____ medulla, triggering release of adrenaline into bloodstream
Adrenal
The ANS regulates the:
Heart, smooth muscles, and glands
The ____ nerve carries a lot of parasympathetic signals that reach chest/abdomen
Vagus (X) nerve
Key Ganglia:
Ciliary (eye), pterygopalatine (nasal/palate), submandibular (salivary glands), and otic (parotid glands)
_______ tone is controlled by the hypothalamus and helps balance the sympathetic/parasympathetic activities
Autonomic
What structures ONLY get singnals from the sympathetic divsion of the ANS:
Sweat glands, kidneys, and blood vessels
During stress, the sympathetic divsion is active/inactive?
Active
The effects of the sympathetic response:
Dilation of pupils
Increased heart rate
Wide airways
Increased blood flow
Effects of the parasympathetic response:
Digestion
Narrow pupils
SLUUD responses
Decreased heart rate
Neurons in the ANS are either:
Adrenergic (release norepinephrine)
Cholinergic (release acetycholine ACh)
Preganglionic neurons in the thoracic and lumbar segments of spinal cord form the:
Throacolumbar outflow
Preganglionic neurons in cranial nerves and sacral segments form the:
Cranial Outflow
Preganglionic neurons are myelinated/unmyelinated
Myelinated
Postganglionic neurons are myelinated/unmyelinated
Unmyelinated
The two main types of adrenergic receptors:
Alpha and beta receptors