Chapter 16 & 17 - Nerve Tracts & Autonomic Nervous System Flashcards
Types of sensory & motor pathways?
Ascending and decsending.
What does the ascending pathway conduct?
Sensory impulses to brain.
What does the descending pathway conduct?
Motor impulses from brain.
Divisions of sensory and motor pathways based on complexity?
Sensory, somatic motor, and autonomic motor pathways.
Divisions of sensory pathway?
First order neuron, second order, and third order.
First order neuron function?
Sensory info to CNS.
Second order function?
Receives impulse from first; spinal cord or brain stem.
Third order function?
Carries signal from thalamus to cerebral cortex.
Divisions of somatic motor pathway?
Upper motor neuron and lower motor neuron.
Upper motor neuron location?
In CNS.
Lower motor neuron location?
From CNS to effector.
Divisions of autonomic pathways?
Upper motor neuron, preganglionic neuron, and postganglionic neuron.
Upper motor neuron location?
In CNS.
Preganglionic neuron location?
From CNS to peripheral ganglion.
Postganglionic neuron location?
From ganglion to effector.
What are the ascending pathways?
Posterior column pathway, spinothalamic pathway, and spinocerebellar pathway.
Where do the posterior column pathways cross?
In medulla.
Functions of posterior column pathway?
Receive sensory impulses from skin, muscles, tendons & ligaments.
What does the posterior column pathway detect?
Fine touch, pressure & body position.
Where do the spinothalamic pathways cross?
In spinal cord.
What are the tracts of the spinothalamic pathway?
Lateral tract and anterior tract.
Lateral tract senses?
Pain & pressure.
Anterior tract senses?
Crude touch & pressure.
What are the tracts of the spinocerebellar pathway?
Anterior tract and posterior tract.
Where does the anterior tract cross?
In spinal cord.
Where does the posterior tract cross?
IT DOES NOT CROSS.
What is the function of the spinocerebellar pathways?
Propriorception for fine coordination.
Do the spinocerebellar pathways synapse in thalamus?
No.
Spinocerebellar pathway characteristics?
Never make it to cortex and subconscious processing.
What are the descending pathways?
Corticospinal pathway, medial pathway, and lateral pathway.
What does the corticospinal pathway do?
Controls voluntary movements.
What do corticospinal pathways generally direct?
Upper motor neurons synapse onto lower motor neurons.
What are the tracts of the corticospinal pathway?
Corticobulbar tract, lateral corticospinal tracts, and anterior corticospinal tracts?
Is the corticobulbar tract motor cranial or motor spinal nerves?
Motor cranial nerves.
Is the corticospinal tract motor cranial or motor spinal nerves?
Motor spinal nerves.
Is the anterior corticospinal tract motor cranial or spinal nerves?
Motor spinal nerves.
Where does the lateral corticospinal tract cross?
In medulla.
Where does the anterior corticospinal tract cross?
IT DOES NOT CROSS.
Medial pathway function?
Stimulat & inhibit same lower motor neurons as corticospinal.
Medial pathway tracts?
Vestibulospinal tract, tectospinal tract, reticulospinal tract.
Vestibulospinal tract function?
Postion & movement of head.
Tectospinal tract function?
Reflexive head movements.
Reticulospinal tract function?
Gross movements & muscle tone of trunk an proximal limb.
Lateral pathway function?
Muscle tone & precise movements of distal upper limb and stimulate & inhibit same lower neurons as corticospinal.
Lateral pathway tract?
Rubrospinal tract.
Where does the rubrospinal tract start?
Starts in red nucleus.
Where does the rubrospinal tract extend to ?
To cervical region of spinal cord.
What is the function of the rubrospinal tract?
Skeletal muscles of distal upper limb.
ANS general characteristics?
Functions continuously & independently, no conscious effort needed, and controls visceral activities (HR, BP, breathing rate, body temp, and response to stress).
How is the ANS different than the somatic nervous system?
The pathway usually consists of 2 neurons, which may result in additional synapse or ganglia.
What are the autonomic nerve fibers?
Preganglionic and postganglionic.
Preganglionic characteristics?
Soma in CNS and axon leaves CNS & synapse in autonomic ganglia.
Postganglionic characteristics?
Soma in autonomic ganglia and axon goes to visceral effector.
What are the 2 divisions of the ANS?
Sympathetic and parasympathetic.
What is the sympathetic division for?
Stressful situations.
What is the parasympathetic division for?
Restores body to restful state.
Do the divisions work together or separate?
The work together and antagonistically.
Sympathetic division vertebrae?
T1 - L2 and soma is in the CNS.
Preganglionic fibers of sympathetic division characteristics?
Exit CNS, join ventral root, travel with motor neurons in spinal nerve, leave spinal nerve, and enter sympathetic ganglia.
What are the sympathetic ganglia made of?
Made of the soma of the postganglionic neurons.
What are the types of sympathetic ganglia?
Chain ganglia and collateral ganglia.
Where are chain ganglia?
A sequence of ganglia running parallel to spinal column on either side.
Where are collateral ganglia?
In other areas of body.
Sympathetic chain vertebra associations?
3 cervical, 12 thoracic, 2-5 lumbar, 4-5 sacral and 1 coccygeal.
What presynaptic fibers innervate the ganglion chain?
T1 - L2 ONLY.
Is there a cervical input in the chain ganglia?
No.
Is there nerve input below L2?
No.
What ganglia do the thoracic nerves innervate?
Cervical ganglia and thoracic ganglia.
What ganglia do T12, L1, & L2 nerves innervate?
Lumbar and sacral ganglia.
How do preganglionic fibers enter the chain?
Via the white ramus.
What are the paths a preganglionic fiber can take?
Synapse with ganglia where they enter, travel through the chain and synapse with another ganglion in chain, and pass through directly to collateral ganglia or gland.
Postganglionic fibers exit the chain via?
Gray ramus to spinal nerve to effector or sympathetic nerve to effector.
How are collateral ganglia formed?
Presynaptic fibers go straight through chain ganglion without synapsing and synapse with postganglionc fibers in collateral ganglia.
Where do the postganglionic fibers go?
Usually to abdominal viscera.
What are the major collateral ganglia?
Celiac, superior mesenteric, and inferior mesenteric.
What do collateral ganglia mostly deal with?
Digestive processes.
What is an example of a modified collateral ganglia?
Adrenal (suprarenal) medullae.
Preganglionic fibers of adrenal medullae do what?
Go through both the chain and collateral ganglia and straight into the medulla of the adrenal gland.
Postganglionic fibers of the adrenal medullae are what?
They have been modified into glandular cells know as chromaffin cells.
What does the adrenal medullae stimulate?
Epinephrine and norepiniphrine.
Sympathetic activation?
CNS stimulates preganglionic neurons which relase Ach on to a nicotinic receptor stimulating postganglionic neuron or adrenal medullae. Postganglionic neurons then release NE on to an adrenergic receptor which stimulates target tissue.
What are the effects of the sympathetic division?
Increase alertness, energy & euphoria, excites cardiovascular & respiratory centers, increased muscle tone, and mobilization of energy.
Summary of the sympathetic division.
- Preganglionic fiber is short, postganglionic fiber is long.
- Synaping occurs in sympathetic chain or collateral ganglia.
- Preganglionic fiber releases Ach.
- Postganglionic fiber releases Ne.
- Prepares body for emergencies.
- Effects are widespread & persistent.
Parasympathetic division originates from where?
Neurons in midbrain, pons, medulla, and sacral region of spinal cord.
How does the parasympthetic division exit the CNS? (what nerves)
VIa cranial nerves 3, 7, 9, and 10 and sacral nerves 2 - 4.
Where do the preganglionic fibers of parasympathetic division go?
Cranial nerve 3, 7, and 9 go to ganglia near target organs (eyes, and facial glands) and cranial nerve 10 and sacral nerves 2 - 4 converge in a large autonomic plexus and then go to target organ. (heart, lungs, GI tract, urinary tract, and sexual organs)
Postganglionic fibers of parasympathetic division characteristics?
Usually very short, close to ore even within target organs, effects of parasympathetic system is more localized.
Functions of parasympathetic division?
Constrict pupils, stimulate secretion of digestive glands, secretion of hormones promoting nutrient absorption, increase motility of digestive tract, stimulate defecation, contraction of urinary bladder, constriction of respiratory passages, reduce HR & force of contraction, and sexual arousal.
Parasympathetic activation?
CNS stimulate preganglionic neurons which always release Ach onto nicotinic receptor stimulating postganglionic neurons. Postganglionic neurons release Ach onto a muscarinic receptor stimulating target tissue.
Parasympathetic activation details?
All neurons (pre and postganglionic) release Ach, quickle cleaned up aafter release of AChE, and short lived effects that are localized.
Summery of parasympathetic?
- Presynaptic neurons are long & secrete Ach.
- Postsynaptic neurons are short, produce Ach, either excitatory or inhibitory.
- Innervate organs in head & abdominal pelvic region.
- All ganglia in or near targets.
What is dual innervation?
When organ receives innervation from sympathetic and parasympathetic divisions.
Cranial area dual innervation?
Sympathetic reaches via chain ganglia and parasympathetic reaches via cranial ganglia.
Thoracic & abdominal region dual innervation?
Sympathetic & parasympathetic mingle at plexuses.
Examples of thoracic and abdominal dual innervation plexuses?
Cardiac plexus and esophageal plexus.
Visceral reflexes characteristics?
Simple functional units of ANS, provide an autonomic motor response, and common for digestive system.
What are the 2 types of visceral reflexes?
Long reflexes and short reflexes.
What are long reflexes?
Go to the CNS for processing.
What are short reflexes?
Are processed in the autonomic ganglion.
Control of autonomic activity?
Many control centers in medulla, hypothalamus regulates body temperature, and limbic system & cerebral cortex control ANS when person is stressed.
