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
