Chapter 11 - Nervous System Flashcards
Three types of neurons
1) Afferent: lead into the brain/spinal cord
2) Efferent: lead from the brain/spinal cord to
effector
3) Interneuron (association): contained within
the CNS
Nerve structure (char)
-large collection of neurons
-axon, myelin sheath
-fascicle: bundle of neurons
-perineurism: connective tissue around the
fascicle
-epineurium: surrounds nerve
-nerves can be composed of only efferent,
only afferent, or mixed neurons
Draw structure of NS
see notes
Characteristics of PNS
- 43 pairs of nerves: 12 cranial and 31 spinal
- Efferent and Afferent
- Vagus Nerve (CN10) “wondering nerve”
Characteristics of Somatic Nervous System
-cell bodies lie within the CNS
-direct connection to skeletal muscle (long
axons, A-alpha neurons)
- Ach released at neuromuscular junction
onto nicotinic receptor
-always excitatory
Mechanism of Neuromuscular junction
p. 17
Reciprocal Innervation
-between antagonistic muscle groups, one
receives AP, one does not
-processed in CNS, mixed neurons
Characteristics of the Autonomic Nervous System
-innervates all tissue except skeletal muscle
-two neurons between CNS and effector
-first neurons soma within CNS
(preganglionic)
-NT at first synapse always Ach onto
nicotinic receptors
-Either excitatory or inhibitory (on effector)
Components of ANS
1) Sympathetic: ganglia lie close to CNS
-utilize NE at postganglionic synapse
-Adrenergic receptor at postganglionic
synapse
2) Parasympathetic: ganglia close to
innervated tissue
-utilize Ach at postganglionic synapse
-muscarinic receptors at postganglionic
synapse
Dual Innervation (def)
many tissues affected by both sympathetic and parasympathetic NS
Tissue—Sym—Parasym
Tissue Sympathetic Parasympathetic
heart b1 - inc. rate M - dec. rate
heart b1 - inc. strength
bronchial a1,2 - relax M - contract
The adrenal gland also acts as
part of the sympathetic response due to neural activation resulting in Epi release
Adrenal gland pathway
p. 26-27
Synapses in the Autonomic Neurons (char)
-many autonomic neurons lack traditional
bouton endings at a synapse
-Instead, swellings called varicosities
influence effector cells
-AP initiates NT released into ECF
-NT impact a larger area (not limited to cleft
region)
-Effector response is slower acting but for
longer duration
Synapses in the Autonomic Neurons Mechanism
p. 29
Difference between para and sym
p. 30
Receptors and effect on Second Messengers
p. 31
Where do parasympathetic and sympathetic nerves originate from?
- Parasym: craniosacral region
- Sym: thoracolumbar region
