ANS - Lecture 1 Flashcards
The autonomous carries out it’s functions
involuntarily
What are the 3 functions of the autonomic system
- maintains homeostasis
- controls fight or flight system
- rest/digest
the 2 anatomical divisions of the nervous system
CNS and PNS
The peripheral nervous system is found outside of the
central nervous system
What are the 2 divisions of the PNS
- afferent/sensory
- efferent/motor
what does each of the following correspond to?
- somatosensory
- visceral sensory
- special sensory
- touch, pain, temperature
- internal organs
- special sense organs (visual, olfactory, auditory)
Two subdivisions of the efferent/motor division
- somatic nervous system
- autonomic nervous system
somatic motor nerves controls
voluntary movements of muscles and involuntary reflexes
autonomic motor nerves control
involuntary movements of the smooth muscle, cardiac muscle and glands
the autonomic system is composed of: (3)
- parasympathetic division
- sympathetic division
- enteric nervous system
what is smooth muscle
muscle tissue found in hollow organs e.g GI tract, bladder, uterus, blood vessels
a nerve is
a group of nerve fibers travelling together in the PNS; contains both efferent and afferent axons/fibers
a neuron is a
nerve cell
the 12 cranial nerves emerge
directly from the brain, including the brainstem, do not emerge from the spinal cord
Cranial nerve important for the parasympathetic division
Vagus nerve or nerve 10
Organization of the spinal cord
cervical nerves (neck region),
thoracic nerves (chest region),
lumbar, sacral, coccygeal (lower abdominal/pelvic)
How many and what kind of neurons are involved in ANS transmission
2 neurons
preganglionic and postganglionic neurons
Cell body/axon location of first neuron of the ANS chain (preganglionic)
cell body in the CNS; axon extends from the CNS to the ganglia
where does the preganglionic neuron synapse with the postganglionic neuron
the ganglia; a cluster of neuronal cell bodies OUTSIDE the CNS
cell body/axon loaction of the second neuron in the ANS chain (postganglionic)
cell bodies found outside the CNS in ganglia; axon leaves ganglia and travels to target tissue
myelination of pre and postganglionic neurons
pregnaglionic: lightly myelinated
postganglionic: unmylelinated
Length of the axons of the preganglionic and postganglionic fibers differ between the
SNS and PSNS
in the PSNS the ganglion is located
very close or within walls of target organ
Axons of pre and post ganglionic neurons in PSNS
- pre: long - long distance between the spinal cord and the ganglion
- post: short - short distance from the ganglion to reach organ
in the SNS the ganglion is located
close to the spinal cord
what is the sympathetic trunk/chain (paravertebral ganglion)
paired chains of interconnected sympathetic ganglia that lie on either side of the vertebral column
length of axon of the pre and postganglionic neurons in the SNS
- pre: short - allows branching and mass discharge
- post: very long - located further away from target
where is the cell body of the preganglionic neurons
CNS - brain or spinal cord
In the SNS, the cell bodies of the first neuron are found
in the thoracic and lumbar regions of the spinal cord
In the PSNS, cell bodies are found
in brain stem and sacral region of the spinal cord
The sympathetic ganglia is
a chain of ganglia running parallel to the spinal cord on each side
The 3 collateral (pre-vertebral) ganglia are
- celiac ganglion
- superior mesenteric ganglion
- inferior mesenteric
where are the collateral ganglia located
in front of the vertebral column in the SNS
axon of sympathetic preganglionic fibers leave the spinal cord by the
ventral roots
when a dorsal root and ventral root combine it is called
a spinal nerve
3 pathways a sympathetic preganglionic fiber can take when it leaves the spinal cord
- synapse with a postganglionic neuron in sympathetic ganglion
- travel up/down the chain and synapse in ganglia at other levels
- pass through chain, travel to collateral ganglion as splanchnic nerve
branch that leads into the ganglion from the spinal nerve carrying a myelinated preganglionic fiber
the white ramus communicans
branch that goes back into the spinal nerve from ganglion carrying an unmyelinated postganglionic fiber
the grey ramus communicans
Two main locations and types of ganglia in the sympathetic system:
Chain ganglia (para-vertibroganglia): both sides of spinal cord
Collateral ganglia (pre-vertibroganglia): in front of/before vertebral column
the adrenal medulla only receives ________ innervation
sympathetic
sweat glands only recieve _______ innervation
sympathetic
functions of the sympathetic system dominate during the
fight or flight response
where are the adrenal glands found
just above each of the kidneys
the adrenal medulla contains
an outer cortex and an inner medulla
the adrenal medulla is innervated by sympathetic _________ neurons
preganglionic
The adrenal medulla itself acts like a modified sympathetic
postganglionic neuron
adrenal medulla releases the horomones: _______ (80%) and ________ (20%) into the ________
- epinephrine
- norepinephrine
- blood
actions caused by norepinephrine and epinephrine will stop when
they are broken down in the liver
norepinephrine and epinephrine produce responses by
travelling through the blood to various target organs
