Lecture #19 Chapter 11 (ANS and Plexuses) Flashcards
CNS contains what?
Brain and spinal cord
PNS contains what?
Cranial and spinal nerves
Two divisions of the nervous system?
PNS and CNS
Two divisions of PNS?
Sensory and Motor divisions
Two divisions of motor division?
Somatic and autonomic
Two divisions of autonomic division?
Sympathetic and parasympathetic
What does the somatic division control?
Skeletal muscle
What does the autonomic division control?
Smooth muscle, cardiac muscle, and glands
Each spinal root splits into a ____ and a ____ ____ inside the vertebral column?
Dorsal… ventral root
What is the function of a dorsal/posterior root?
Sensory root
What is a dorsal root ganglion?
A collection of cell bodies of the sensory neurons whose axons conduct impulses from periphery body parts into the spinal cord
What type of root is the ventral/anterior root?
Motor root
What is a spinal nerve?
The union of the ventral and dorsal roots
____ + ____ = mixed nerve
Ventral … dorsal
What are the four branches of spinal nerves outside the spinal cord?
-Meningeal branch
-Dorsal branch/ramus
-Ventral branch/ramus
-Visceral branch (only in thoracic and lumbar)
What is a nerve plexus?
A complex network formed by ventral rami of spinal nerves
Plexus comes for the greek work ____?
Braided
There is no plexus for ____-____; for these spinal nerves, the rami become ____ nerves?
T2-T12… intercostal
Fibers of various spinal nerves are ____ and ____, so all fibers heading to the same peripheral body part reach it in the ____ ____?
Sorted and recombined… same nerve
What are the three nerve plexuses?
-Cervical C1-C4
Brachial C5-T1
Lumbosacral L1-S4
The brachial plexus is formed by ____ ____ ____-____ and lies deep within the ____?
Ventral branches C5-T1… shoulders
What are the five branches of the brachial plexus?
-Musculocutaneous
-Ulnar
-Median
-Radial
-Axillary
Musculocutaneous nerve do?
Muscles of anterior arms and skin of forearms
Ulnar and median nerves do?
Muscles of forearms, and skin and muscles of the hands
Radial nerve do?
Posterior muscles of arms, and skin of the hands and forearms
Axillary nerve do?
Muscles and skin of anterior, lateral, and posterior arms
What is the lumbosacral plexus formed by?
Anterior branches of L1-S4
The lumbosacral plexus extends from the ____ ____ into the ____ ____?
Lumbar region… pelvic cavity
What are the three branches of the lumbosacral plexus?
-Obturator nerve
-Femoral nerve
-Sciatic nerve
Obturator nerve do?
Supplies motor impulses to the adductors of the thigh
Femoral nerve do?
Supplies motor impulses to muscles of anterior thigh and sensory impulses from skin and legs
Sciatic nerve do?
Supplies muscles and skin of thighs, legs, and feet; largest and longest nerve in the body
ANS?
Autonomic nervous system
The ANS is a branch of the ____ which is ____ controlled?
PNS… involunatarily
What are the five functions of the ANS?
-Controls visceral activities
-Regulates smooth muscles, cardiac muscles, and glands
-Helps maintain homeostasis
-Helps the body respond to stress
-Prepares the body for intense physical activity
What are the two divisions of the ANS?
Sympathetic division and the parasympathetic division
When is the sympathetic division most active?
Under energy-requiring, stressful situations
When is the parasympathetic division most active?
Under resting, non-stressful conditions
Two functions of sympathetic division?
-Fight or flight
-Speeds body up
Two functions of parasympathetic division?
-Rest and digest
-Slows body down
Most ___ receive input from both the ____ and ____ division?
Organ… sympathetic and parasympathetic
All of the autonomic nerve fibers are ____/____?
Motor/efferent
ANS conduction uses a total of ____ neurons in a ____ ____?
Four… reflex arc
Preganglionic fibers?
Neuron cell bodies are in the CNS
Postganglionic fibers?
Neuron cell bodies are in the ganglia; extends to the visceral effector
The sympathetic division of the ANS is the ____ ____?
Thoracolumbar division (T1-L2)
Four facts about preganglionic fibers?
-Originate in the spinal cord
-leave via ventral roots
-Leave spinal nerves through white rami
-Enter sympathetic chain (paravertebral) ganglia
Sympathetic chain ganglia?
AKA paravertebral ganglia, form chains along the vertebral column
Sympathetic trunks?
Sympathetic chain ganglia + the fibers that connect them
Preganglionic fibers synapse with a ____ ____ in ____ ____. Continue through the paravertebral ganglion and synapse at another ____ ___. Then pass through to ____ ____ to ____ there?
Postganglionic neuron… paravertebral ganglion… sympathetic ganglion… collateral ganglia…. synapse
Postganglionic fibers extend from ____ ____ to ____ ____ ____?
Sympathetic ganglia… visceral effector organs
Postganglionic fibers that originate at ____ ____ usually pass through ____ ___ and return to a ____ ____ before proceeding to an ____?
Paravertebral ganglia… gray rami… spinal nerve… effector
What is the exception when preganglionic fibers pass through the sympathetic ganglia?
When they go to the adrenal medulla (adrenal medulla)
The parasympathetic division is also known as the ____ ____?
Craniosacral division
Preganglionic fibers in the parasympathetic division originate in the ____ and ____-____ spinal levels.
Brainstem and S2-S4
Preganglionic fibers of the head include ___, ___, and ___?
Oculomotor III, facial VII, and glossopharyngeal IX
Preganglionic fibers of the thorax and abdomen are parts of ____ ____, which contains ____ of all parasympathetic fibers?
Vagus (X) nerves… 75%
Preganglionic fibers of the sacral (S2-S4) region of the spinal cord carry impulses to ____ ____?
Pelvic viscera
What do cholinergic neurons release?
Acetylcholine
What are cholinergic nerurons?
-All preganglionic sympathetic and parasympathetic fibers
-Postganglionic parasympathetic fibers
What do adrenergic neurons release?
Norepinephrine (noradrenaline)
What are adrenergic neurons?
Postganglionic sympathetic fibers
What does monoamine oxidase (MAO) do?
Clears norepinephrine from the the synapse
The parasympathetic division contains ____ postganglionic fibers and ____ preganglionic fibers?
Short… long
The sympathetic division contains ____ postganglionic fibers and ____ preganglionic fibers?
Long… short
What are the four types of autonomic neurotransmitter receptors?
Cholinergic receptors
-Muscarinic receptors (excitatory, slow)
-Nicotinic receptors (excitatory, rapid)
Adrenergic receptors
-alpha receptors
-beta receptors
The autonomic nervous system is controlled mostly by the ____ via involuntary processes?
Hypothalamus
What does the medulla oblongata regulate?
Cardiac, vasomotor, and respiratory activities
Overtime the brain shrinks by ____?
10%
Overtime more ____ ____ than ____ ____?
Gray matter… white matter
By age ____, the frontal cortex has lost ____ its neurons?
90…. half
Over time, a decrease in ____ occurs and ____ ____ slow?
Neurotransmitter and action potentials
As people age the result is?
Fading memory, slowed responses and reflexes, and increased risk of fainting/falling
Lifespan changes in the nervous system?
-Over your lifetime, the brain shrinks by 10%
-More gray matter is lost than white matter
-By age 90, the frontal cortex has lost half its neurons
-Decrease in levels of neurotransmitters
-Action potential rates decline
-Results in: fading memory, slowed responses & reflexes, increased risk of fainting/falling
