Chapter 9 Flashcards
Autonomic nervous system
In charge of our viscera (controls circulation, respiration, digestion, metabolism, secretions, body temp, and reproduction).
Efferent is a 4 neuron chain of command.
Sympathetic system
Fight or flight (mobilizes energy to either fight or flee) makes decision.
Thoracolumbar outflow- peripheral autonomic neurons of sympathetic poke our from T1 and L2 (uses energy)
Thoracolumbar outflow
Peripheral autonomic neurons of sympathetic poke out from T1 to L2
Parasympathetic system
Rest and digest system (feed and breed system).
Craniosacral outflow- peripheral parasympathetic neurons poke out of brainstem and poke out of S2, S3, and S4.
Stores energy (while resting it is packing glycogen for storage that can be used when needed).
Mechanoreceptors
- Pressure and Stretch
- Sinus at carotid artery, when it gets stretched it sends more blood vessels into the brain to restore homeostasis
Chemoreceptors
- Chemical environment
- Sample blood and composition of blood to ensure homeostasis is being maintained.
Nociceptors
- Stretch, Ischemia, Chemicals
- Nerve endings that respond to extreme inputs (pain) will signal too much stretch, ischemia, chemicals
Thermoreceptors
- Hypothalamic and Cutaneous
- Can adjust blood vessels and sweat glands to restore thermal homeostasis
Afferent Pathways
Afferent messages travel , through cranial nerves 7, 9, and 10 (cranial nerves provide input)
-for the rest of the body, the signals get in through the peripheral nerves and spinal cord.
Central Regulation
- 4 neuron control pathway Modulatory (central) Modulatory (central) Control (central) Pre-ganglionic (peripheral)
Modulatory (central)
Neurons are part of our efferent system, cell bodies up in the limbic lobe (emotion system) or in the hypothalamus- influence the activity of the autonomic system broadly. Set a general direction and relay information to reticular formation (control)
in the head
Control (central)
Neurons with cell bodies in the reticular formation (core of pons and medulla is a long cluster of cells, they send autonomic control signals down to the spinal cord).
In brainstem
I control the tv remote, I send signals on TV remote, Wife modulates the channel by telling me what channel to turn to
Pre-ganglionic (peripheral)
Starts in the spinal cord and goes out into the periphery. Before the synapse, starts in the spinal cord and it ends at the synapse (ganglion)
-has cell bodies in spinal cord (cell bodies in lateral horn) leaves from ventral root and heads to peripheral synapse
Thoracolumbar, sacral
Anterior Insula, Amygdala, Thalamus, and Hypothalamus
Limbic and autonomic structures at base of brain that are modulatory in terms of autonomic nervous system.
Parasympathetic central regulation
Two central neurons (Modulatory and control)
and two peripheral neurons (pre-ganglionic and post-ganglionic)
Central regulation (afferent and efferent pathway)
If some sort of visceral distress (appendix is inflamed) sensory neurons bring signal through a peripheral nerve (that pain signal diverges into 4 neurons)
- one route is to the brainstem control centers plus the thalamus, hypothalamus, and emotion/motivation system. (synapses in dorsal horn and sends messages to visceral control centers (medulla, hypothalamus, and limbic lobe)
- 2nd route is to cortical (conscious) sensory areas which may be interpreted as referred pain. (synapses in dorsal horn and goes up to somatosensory areas of the brain. tells the brain it hurts to alert us about what is hurting).
- 3rd route loops back and terminates on the injured organ. The distress on the visceral organ initiates a reflex that shuts down that organ (if it is hurt the body doesn’t want to use it to protect it)
- 4th route is a divergent branch to motor cell bodies of the muscles of the abdominal wall right over the top of the organ (somatic body responds by splinting/contracting- trying to build a wall so nothing else can hurt the organ)
4 ways body responds to visceral stress
1) signals homeostasis controllers of our brain (initiates a body wide reaction to maintain homeostasis)
2) Alerts conscious brain so that we can focus on what is hurting us
3) Use reflex loop to shut down what is hurting
4) Locally, contracts muscles around whatever is hurting to protect it from further injury while brain figures out what is goin on.
All to maintain homeostasis
Post-ganglionic
After the synapse, starts at the ganglion (synapse) and ends at the visceral organ that is the target.
Synapse occurs in the periphery.
At the ganglion there is a synaptic connection between neurons
Differences between somatic and autonomic
-Control (regulation)
Somatic=conscious
Autonomic= nonconscious
-Organs function without neural input
Somatic=no
Autonomic=yes
-Peripheral nerve pathway
Somatic=one
Autonomic=usually two (with synapse) pre-ganglionic and post-ganglionic
Acetylcholine
occurs at two categories of synapses in the autonomic nervous system
1) the Peripheral synapse/ganglion (when pre and post interact with each other) Pre-ganglionic releases acetylcholine and post-ganglionic binds it.
- acts fast and creates action potentials fast
- Both sympathetic and parasympathetic (global neurotransmitter of autonomic NS at the ganglia)
- at the visceral organs it is only present in the parasympathetic nervous system (post-ganglionic neurons)
- viscera have muscarinic receptors (slow acting/long lasting receptors/G protein butler
Adrenergic (norepinephrine)
sympathetic, the neurotransmitter at the viscera in the sympathetic system (post-ganglionic release norepinephrine at viscera (Slow/long lasting response)
-effect on viscera through a local connection
Adrenergic (epinephrine)
Pre-ganglionic termination at the adrenal medulla turns on epinephrine (produces by short post-ganglionic), post-ganglionic produce and dump epinephrine into bloodstream.
-Has effect on viscera through a body wide blood supply
Peripheral synapses
Paravertebral ganglia (next to the vertebrae) -Rami communicantes= take pre-ganglionic out to paravertebral ganglia and brings post-ganglionic neurons back to go out to target.
At spinal nerve (motor, sensory, and pre-ganglionic are all together) post-ganglionic end up in peripheral nerves.
String of pearls
Some neurons that poke out of T1 and L2 rise up to cervical area or some leave the spinal cord and turn down to the paravertebral ganglia to the lumbar and sacral area.
Blood to skeletal muscle
- Venule- 5 liters of blood in body
- May only need 3 liters during simple tasks (typing) the venules on backside of muscle capillary beds are stretchy. When sitting, the venules on capillary beds swell out and pool some of the blood. Park 2 liters of blood outside of circulation. Right before we stand up ( body knows we need all 5 to stand so the venule squeezes so that all the blood is back in circulation.
Capacitance
At rest the venules hold blood out of circulation that is not needed.
Blood to skeletal muscles -Shunting
can affect the sphincters of arterials on muscles. Tones down blood supply to each muscle (just a little) so that whatever muscles are active and need more blood flow can open up its sphincters more and get all the blood that they need.
Muscles we end up needing to use get all the blood they need.
Some receptors constrict arterioles and some dilate arterioles
Sympathetic NS effect in the head
Dilate pupil
Elevate upper eyelid
Thick saliva
SNS effect on Heart
Increase rate
Increase contractility
SNS effect on Bronchial tree
Dilation of airways
Drugs for specific organs
Beta 1 receptors in heart
Beta 2 receptors in the airways
Create medications for specific beta receptors that are selective and that only bind to either Beta 1 or Beta 2 receptors.
SNS and GI tract
Decrease blood flow Decrease peristalsis Decrease secretions Inhibits contraction bladder Inhibits contraction bowel
SNS and metabolism
calls of adrenal medulla increase function and metabolism of every cell in the body
Parasympathetic NS
Craniosacral outflow- some cell bodies are in the brainstem and others have cell bodies in sacral spinal cord.
Cell bodies of para peripheral system are in lateral horn in S1, S2, S3, and S4
PNS and heart
Slow heart rate
PNS and Bronchial Tree
Constriction of airways- to maintain air pressure even when volume falls at rest
PNS and control in the head
Thin saliva- saliva takes dry food and creates a predigested much that you can continue to swallow and digest in intestines.
Constricts pupils- don’t need as much light to see things that are close
Increase curvature of lens- further better our near vision
PNS and GI tract
Increase secretions
Increase peristalsis
Glycogen synthesis
Emptying bladder/bowel
Synergistic control of organs by both PNS and SNS
Heart- Synergistic (rate) Bowel and Bladder- synergistic Blood vessels- SNS (only gas) Sweat glands-SNS (only gas) Lens of eye- PNS (only active or passive External genitalia- PNS
Horner’s syndrome
Damage to one of the sympathetic ganglia that is headed to your head, the stellate ganglion (in neck) a lot of people who have neck surgery damage their Stellate ganglion because it is hard to see. (unintentional damage)
autonomic loss to one part of the body
SNS not there to keep eyelids raised, pupil is constricted (SNS cant dilate it), redness of skin cause cant control sphincters of blood vessels, wont sweat on left side
Droopy dry pin point eye=Horner’s syndrome
Peripheral region
Musculocutaneous nerve- sympathetic NS neurons present
PNS only covers core
Peripheral vascular damage
nerves are dependent on a rich vascular supply sensory and motor changes start to die, also autonomic nerve damage.
