Ch. 9: Autonomic Nervous System Flashcards
What does the autonomic system regulate?
Controls visceral organs, blood vessels, some endocrine organs & some exocrine organs
Where does the Sympathetic Division leave the spinal cord?
What is this outflow called?
T1 - L2
Thoracolumbar Outflow
What does the Sympathetic Division mediate?
What is its energy consumption?
- Mediates fight or flight response
- Uses energy - short periods of time before recharge needed
Where does the Parasympathetic Division leave the spinal cord?
What is this outflow called?
Cranial nerves and sacrum
Craniosacral outflow
What does the Parasympathetic Division mediate?
What is its energy consumption?
- Mediates: Rest & digest or feed and breath
- Energy storing system - predominates at rest. Prep for next time you need to fight or flee
What do Mechanoreceptors sense?
Pressure & Stretch
What do Chemoreceptors sense?
Chemical environment
What do Nociceptors sense?
Stretch & ischemia
What do Thermoreceptors sense?
Hypothalamic & cutaneous
(detect blood temp)
In the Afferent Pathways, what are the 2 ways to get info into the central system?
- Spinal nerves (anterolateral columns)
- autonomic afferent components to every peripheral and spinal nerve
- Cranial Nerves (VII, IX, X)
- important for autonomic afferent
Where are the Control Areas/Vital Centers located in the brain?
- Medulla
- Pons
Direct control → tell peripheral neurons exactly what messages to send
Where are the Modulatory Areas located in the brain?
Emotional & Autonomic systems above brainstem:
- Hypothalamus - homeostasis controller
- Thalamus
- Limbic System
Does not directly control → influences environment
What are the Multiple Connections of Visceral Afferents in Spinal Nerves?
-
brainstem, hypothalamus and thalamus via anterolateral columns…(contributes to autonomic response to pain). - to visceral controls centers and modulators -> message it is under attack
- Spinolimbic system
- homeostasis
-
somatosensory nociceptive afferents…(contributes to referred pain). - tries to go to consciousness -> but generates referred pain (since appendix has never hurt before)
- Spinothalamic
- location
Spinal level reflexes (doesn’t go up, goes to spinal cord and right back out):
-
Visceral efferents…(inhibits peristalsis of intestines). Visceral afferent to visceral efferent in spinal cord
- Pain message shuts off appendix
- Shut off
-
Somatic efferents…(produces muscle “guarding” in segmentally related muscles). Visceral afferent and somatic efferent (skeletal muscle)
- Protection (Muscle guarding)
Efferent Pathways are a 4 neuron system. What does this mean?
- 2 central, 2 peripheral
- Two systems
- Sympathetic
- Parasympathetic
- Two Neurons (in each pathway) peripheral efferent neurons
- Preganglionic
- Before synapse; start in spinal cord and goes to peripheral synapse
- Post-ganglionic
- After synapse; start at peripheral synapse and goes to visceral
- Preganglionic
What is the difference between Somatic Motor Efferent vs. Autonomic Efferent:
Peripheral pathway?
- Somatic: 1 neuorn
- Autonomic: 2 neurons
What is the difference between Somatic Motor Efferent vs. Autonomic Efferent:
Termination?
Efferent outputs
- Somatic: skeletal muscle fibers
- Autonominc: everything else (viscera, blood vessels and skin)
What is the difference between Somatic Motor Efferent vs. Autonomic Efferent:
Control?
- Somatic: conscious control
- Autonomic: largely unconscious control
What is the difference between Somatic Motor Efferent vs. Autonomic Efferent:
Mylination?
- Somatic = ALL are mylinated
- Autonomic = only preganglionic are mylinated
What is the difference between Somatic Motor Efferent vs. Autonomic Efferent:
Influence of nervous system?
- Somatic = Muscles will not function without nervous system input.
- Autonomic = Some organs will function without nervous system input.
What neurons release Cholinergic (acetylcholine)?
- All Preganglionic autonomic
- neurotransmitter of peripheral synapse
- Postganglionic parasympathetic
- neurotransmitter of visceral organs for the PNS! (makes contact
What neurons release Adrenergic (norepinephrine & epinephrine)?
[aka adrenaline & noradrenaline]
- Postganglionic sympathetic (norepinephrine)
- neurotransmitter of visceral organs (heart, blood vessels & bronchi
- Adrenal medulla (epinephrine)
- autonomic neurotransmitter released in blood stream
- Affects heart, blood vessels & stomach
- Effects metabolism of every cell
- autonomic neurotransmitter released in blood stream
In the Sympathetic Nervous System:
Where are the cell bodies located?
In Pons and Medulla
(entirely within CNS)
Where do Axons of Sympathetic “control” neurons descend spinal cord?
lateral columns
(located in vital centers of pons & medulla - axons go caudal in the lateral column of the spinal cord
Where are the cell bodies of the sympathetic PREganglionic neurons located?
In the lateral horn of the spinal cord from T1-T12
[synapse from lateral column to dorsal horn
Efferent leave spinal cord from ventral root (in front)]
Where are the cell bodies of the sympathetic POSTganglionic neurons located?
One of 3 places
- Paravertebral ganglia (limbs, face, body wall, heart, lungs
- next to nerve where peripheral & sympathetic synapse
- “White” rami communicates - mylinated
- from spinal cord to synapse
- “gray” rami communicates - unmylinated axon
- ganglion back to spinal nerve
- “Outlying” ganglia (abdominal and pelvic organs).
What is the primary role of the SNS?
Prepare the body for action (fight or flight)
What are the primary functions of the SNS?
- Regulate body temperature (metabolism, “shunting” (redirect), sweating)
- Regulate blood flow to muscles (“capacitance”, “shunting”)
- Capacitance: constricts venules -> store blood
- Shunting: shunts arterial blood away from muscles
- Regulate vision (dilate pupil, raise eyelid…improve far vision)
- Produce thick saliva (“dry mouth”)
- Increase heart rate and contractility)
- Dilate bronchial tree
- Dec activity of GI tract, bowel and bladder
- Inc metabolism
In the Parasympathetic Nervous System:
Where are the cell bodies located?
Pons and Medulla
(same as SNS)
What do the axons of parasympathetic “control” that serve?
sacral segments of the spinal cord descend in lateral column of spinal cord.
In the PNS, where are the cell bodies of PREganglionic neurons located?
Lateral horn - go out ventral horn
- Nuclei of cranial nerves III, VII, IX, X. - cranial part
- Axons go outside the brain stem through the cranial nerves
- Lateral horn of the spinal cord from S2 to S4. - sacral part
- Axons go outside the brain stem through the cranial nerves
In the PNS, where are the cell bodies of POSTganglionic neurons located?
- Peripheral ganglia near the organs they innervate.
- Synapse occurs close to visceral organ
What is the functions of the PNS?
- Primary: Prepares you at rest for activity
- Slow rate of the heart beat (no effect on contractility)
- Bronchoconstriction
- Produce thin saliva
- Increase peristalsis, glycogen (stored packaged energy) synthesis and glandular secretions
- Constrict the pupil, increase convexity of the lens (improve near vision)
- Empty bowel and bladder
- Produce erection of sexual organs
What are the synergistic effects of the SNS ans PNS
- Heart rate
- Bowel and bladder activity
What are the unopposed effects of the SNS ans PNS?
- SNS
- blood vessles
- sweat glands
- PNS
- lens of eye
- external genitalia
