chapter 11 Flashcards
(25 cards)
three types of neurons
-afferent neurons: lead to the brain and spinal cord
-efferent neurons: lead from the brain and spinal cord to the effector organ
-interneuron: contained within the CNS
nerve
collection of neurons
neuron
individual nerve cell, typically wrapped in myelin
fascicle
bundle of nerves t
perineurium
CT covering around fascicle, also contains blood vessels and lymphatics
epineurium
surrounds nerve, encloses a bundle of fascicles
describe the divisions of the nervous system
- CNS
-brain
-spinal cord - peripheral nervous system
-efferent
– autonomic: parasympathetic and sympathetic
– sympathetic
-afferent:
–visceral sensory
– somatic sensory
briefly describe the spinal cord
nerve tissue that runs between the vertebrae
-dorsal roots: sensory fibers (afferent). have ganglia before the rootletts
-ventral roots: motor (efferent fibers). cell bodies are inside the white matter
-grey matter: unmylelinated nerve cell bodies and dendrites
-white bodies: myelinated interconnecting fiber tract systems
how many pairs of nerves are in the PNS
43 pairs
PNS
afferent (sensory) division:
has general somatic sensory and visceral sensory
PNS
efferent (motor) system
somatic motor
- cell bodies lie within the CNS
- directly connects to skeletal muscles
- long axon
- releases Ach at neuromuscular junction into a nicotinic receptor. ( opens a Na+ channel= excitatory)
-always excitatory, also a type of graded response
-large and fast: a- alpha neurons
PNS
efferent motor system
ANS
-has two subdivisions
-innervates all tissue except skeletal muscle
-2 neurons are involved between the CNS and the effector organ= creates two synapses
-1st neuron: preganglionic; located in the CNS, always excitatory
-1st synapse: preganglionic; NT is always Ach onto a nicotinic receptor which excites the 2nd neuron.
-2nd neuron: post ganglionic; ganglia outside of the CNS. can be excitatory or inhibitory
-2nd synapse: post ganglionic; releases excitatory or inhibitory NT
PNS
efferent motor system
ANS
sympathetic
sympathetic: ganglia lie close to the CNS
-utilizes: nor-epi at post-ganglionic synpase and binds to adrenergic receptors on effector muscle or gland
-1st neuron: short; releases Ach onto nicotinic receptor
-2nd neuron: long: releases nor-epi onto adrenergic receptors
PNS
efferent motor system
ANS
parasympathetic
parasympathetic: ganglia close to innervated tissue.
-utilize Ach at postganglionic synapse onto muscarinic receptor (G protein 2nd messenger system) on target tissue.
-1st neuron: long, releases Ach onto nicotinic receptor
-2nd neuron: short; releases Ach onto muscarinic receptor on target tissue.
homeostasis is
a dynamic balance between autonomic branches
-when one is active, the other is inactive
dual innervation
many tissues are affected by both sympathetic and parasympathetic NS
describe the dual innervation present in the heart
- sympathetic
-beta 1 adrenergic: increases heart rate
1.parasympathetic:
-Muscarinic receptor: decreases heart rate - sympathetic
-beta 1 adrenergic: increases strength
describe the dual innervation present in the bronchial
- sympathetic
-beta 2 adrenergic: relaxes - parasympathetic
-muscarinic: contracts
asthma
symptoms: constricts bronchioles, airway gets small
-treatment: activating sympathetic NS will relax airways.
-administering with epi: fixed issue but also activated all other NS, heart rate increased more than it already was
-inhalers with albeuterol: binds to beta 2 adrenergic receptor on bronchioles, relaxes bronchi, does not bind to beta 1 on the heart.
adrenal medulla
modified sympathetic ganglion
-included in sympathetic response
-releases epi and nor-epi, they are activated by the medulla
-2nd neuron is buried in the medulla
varicosities
swellings that influence other cells. in ANS
-location: post ganglion synpapse
-process: AP initiates NT release into the ECF, so the NT impacts a larger area. The AP also depolarizes the next varicosity.
-result: effector response is slower acting but lasts a longer duration
explain why the signals in ANS are slower but last longer
-slow: not a true synaptic cleft
-lasts longer: lack of degrading enzymes
where do the parasympathetic nerves originate from
craniosacral region
where do the sympathetic nerves originate from
originates from the thoracolumbar region
