Lecture 16 Flashcards
What are the four forms of nervous system input (afferent division)?
- endocrine
- somatic sensory
- visceral sensory
- special sensory
What are the three forms of nervous system output (efferent division)?
- somatic motor
- autonomic motor (sympathetic, parasympathetic, and enteric)
- endocrine
TRUE or FALSE - most of somatic motor control is conscious
FALSE - most of it unconscious and is controlled automatically
What levels of the spinal cord are sympathetic system output?
Thoracic to lumbar
What levels of the spinal cord are parasympathetic output?
Cervical and sacral regions. Mostly, the 10th cranial nerve (vagus)
What does the vagus nerve control?
multiple elements within the viscera
TRUE or FALSE - many organs have dual intervention of both sympathetic and parasympathetic NS
TRUE
Where does viscera efferent enter?
The dorsal root
What systems act together in the gut?
for sympathetic, parasympathetic and enteric NS
What is role of the parasympathetic system?
rest, digest and propagate
What is the role of the sympathetic system?
fight or flight
TRUE or FALSE - only one system is active as a time
FALSE - both systems are always active
What are the target organs of the sympathetic nervous system?
It is widely distributed to salivary glands, eyes, skin, viscera and muscles
What is the structure of the sympathetic nervous system?
First synapse in the paravertebral and prevertebral ganglia, post-ganglionic fibres innervate organs.
What are the neurotransmitters used in the sympathetic nervous system?
Ach onto post synaptic neuron, norepinephrine onto target tissue
What does the adrenal medulla do?
release E and EN into circulation and NOT onto target tissue
What target tissue is the exception to being transmitted NE?
Sweat glands, they are transmitted Ach
What are the target organs of the parasympathetic nervous system?
It is distributed less widely, and mainly to the viscera, salivary glands, and eyes.
What is the structure of the parasympathetic NS?
The first synapse is in or near the target organ. it has long pre-ganglionic fibres, and short post ganglionic fibres.
What neurotransmitter is used in the parasympathetic NS?
Ach
What type of receptors does Ach bind to?
in the somatic NS, sympathetic NS and post ganglionic fiber in the parasympathetic NS - a nicotinic AchR.
in parasympathetic target organs, it is muscarinic AchR
What type of receptors do NE and E bind to?
several types of alpha and beta adrenergic receptors
What is the enteric nervous system?
It is the multi-layered ‘brain’ in the gut.
What are the characteristics of the ENS?
- contains about as many neurons as the spinal cord throughout the GI tract
- responds to local chemical and mechanical stimulation
- regulates motility, secretion, and endocrine singling through local reflexes
TRUE or FALSE - is ENS activity completely independent ?
False - it is autonomous, but it heavily influenced by para- and sympathetic NS inputs
What neurotransmitter inhibits smooth muscle contraction in the ENS
VIP
Are there inhibitory motor neurons in all muscles?
No, this is unique to the gut.
What does a local excitatory reflex induce in the gut?
Contraction (oral)
What does a local inhibitory reflex induce in the gut?
relaxation (anal)
