peripheral nervous system (pns) 1. nervous system classification-1 somatic nervous system –motor...
TRANSCRIPT
Peripheral Nervous System (PNS)
1
Nervous System Classification-1
• Somatic Nervous System– Motor nerves to skeletal muscle (somatic motor neurons)
• Upper and lower motor neurons– Skeletal Muscle Reflexes
• Sensory, interneurons, lower motor neurons
– Visceral (organ) Reflexes– Sensory nerves (somatosensory neurons)
• Autonomic Nervous System– Motor nerves to smooth and cardiac muscle (visceral motor
neurons)• Sympathetic• Parasympathetic
2
Today’s lectures are the red topics
Nervous System Classification-2
• Efferent Nervous System• Somatic Nervous System• Upper and lower motor neurons to skeletal muscle
(somatic motor neurons)• Visceral (Autonomic) Nervous System– Motor nerves to smooth and cardiac muscle (visceral
motor neurons)• Sympathetic• Parasympathetic
• Afferent Nervous System• Sensory nerves (somatosensory neurons)
• Reflexes 3
I did not organize the lectures by this method of classification
VISCERAL (“organ”) NERVES
• A visceral nerve innervates involuntary effectors (smooth muscles in organs). This is part of the ANS.
• A somatic motor nerve innervates voluntary effectors (skeletal muscle). It is not part of the ANS.– (don’t confuse this with a somatic sensory nerve for
the sense of touch; sensory nerves are not part of the ANS either)
4
VISCERAL (“organ”) SENSES
• Internal organs also have sensory nerves that tell you when you have eaten enough or your bladder is full. These are not part of the ANS because they are sensory.
• Not all organs have sensory nerves, for instance, you can’t feel when you have high blood pressure.
• You can also have visceral reflexes, which trigger the parasympathetic system to contract the bladder when full, etc.
• Reflexes are hard to localize. 5
Somatosensory Neurons
• The somatosensory system is made up of a number of different receptors, including thermoreceptors (action potential is triggered by heat or cold), photoreceptors (triggered by light), mechanoreceptors (triggered by movement) and chemoreceptors (triggered by chemicals).
• Each somatosensory neuron specializes in conducting one type of sensation, such as proprioception, mechanoreception (touch), thermoception (temperature), and nociception (pain).
• The sensory receptors cover the skin and epithelia, skeletal muscles, bones and joints, internal organs, and the cardiovascular system.
6
Somatic Senses
• Pain
• Haptic perception– Deep Pressure– Light Touch
• Vibration
• Thermoception (Hot/Cold)
• Two-point discrimination
• Proprioception
• Special senses7
These are routinely tested by doctors in a physical exam, especially for people with diabetes and lupus.
Sense of Touch
• Touch includes mechanoreception (deep pressure, light touch, vibration and proprioception), pain (nociception) and heat (thermoception).
8
Sense of Pain
• A nociceptor is a receptor of a sensory neuron (nerve cell) that responds to potentially damaging stimuli by sending signals to the spinal cord and brain.
• This process, called nociception, usually causes the perception of pain.
• They travel in the dorsal column pathway in the spinal cord, ascend to the thalamus in the brain, and go to the cerebral cortex.
9
Referred Pain
• Pain in an organ may not be where the organ is. • Heart pain usually manifests in the left side of
chest, the left shoulder, arm, but not the heart. • This is REFERRED PAIN. • Pain in the lungs usually shows up as neck pain.• These areas of referred pain are important to
know, but not for this class.
10
A Map of Referred Pain
11
Complex regional pain syndrome (CRPS)
• Formerly called Reflex Sympathetic Dystrophy (RSD)• Chronic progressive disease characterized by severe pain, swelling,
and changes in the skin. • It often affects an arm or a leg and may spread to another part of
the body and is associated with dysregulation of the autonomic nervous system resulting in multiple functional loss, impairment, and disability.
• Symptoms include burning and shooting pains and edema that occur more often during times of stress.
• Treatment is often unsatisfactory. Early multimodal therapy can cause dramatic improvement or remission of the syndrome in some patients.
• http://losangeles.cbslocal.com/video/9805202-theres-no-cure-for-complex-regional-pain-syndrome-but-doctors-say-treatment-offers-hope/
12
Treatment for Pain
• Somatosensory Rehabilitation of Pain is a method whose aim is to treat conditions of a reduced sense of touch or sensation (hypoesthesia) in order to decrease neuropathic pain.
• Neuropathic pain, with a prevalence of 6.9% of the general population, represents an important public health problem.
13
Treatment for Pain• Examples of pain syndromes include:
• Carpal Tunnel Syndrome (CTS) concerns 2.7% of the general population.
• Complex Regional Pain Syndrome (CRPS) concerns 26/100,000.
• Patients with chronic pain might use transcutaneous electrical nerve stimulation (TENS unit) and other physical therapy modalities, which bring substantial pain relief to large numbers of people. 14
Haptic perception(Sense of Touch)
–Deep Pressure
–Light Touch
15
• While touch (also called tactile perception) is considered one of the five traditional senses, the impression of touch is formed from several modalities including pressure, skin stretch, vibration and temperature.
• There are separate neurons for each of those sensations, and each group of neurons must be evaluated during a physical exam.
• In medicine, the colloquial term "touch" is usually replaced with "somatic senses" to better reflect the variety of mechanisms involved.
16
Haptic perception
• Haptic perception is the process of recognizing objects through touch. It involves a combination of somatosensory perception of patterns on the skin surface (e.g., edges, curvature, and texture) and proprioception of hand position and conformation (what position do my finger go into while tracing the surface of the object?).
17
Haptic perception
• People can rapidly and accurately identify three-dimensional objects by touch.They do so through the use of exploratory procedures, such as moving the fingers over the outer surface of the object or holding the entire object in the hand.
18
• Haptic perception is active exploration, whether with a body part or a tool, such as feeling the contours of something by using a stick to touch it.
• Haptic perception allows the creation of "virtual", illusory haptic shapes with different perceived qualities.
• Loss of the sense of touch is a catastrophic deficit that can impair walking and other skilled actions such as holding objects or using tools.
19
Disorder of Sense of Touch
• One disorder of the sense of touch:
• Allochiria
20
Allochiria• Allochiria (from the Greek meaning "other hand") is a neurological
disorder in which the patient responds to stimuli presented to one side of their body as if the stimuli had been presented at the opposite side.
• It is associated with spatial transpositions, usually symmetrical, of stimuli from one side of the body (or of the space) to the opposite one. Thus a touch to the left arm will be reported as a touch to the right arm
• If the auditory or visual senses are affected, sounds (a person's voice for instance) will be reported as being heard on the opposite side to that on which they occur and objects presented visually will be reported as having been presented on the opposite side.
• Commonly from damage to the right parietal lobe.
21
Allochiria
Allochiria can also occur to other senses.•Motor Allochiria•Reflex Allochiria•Audio Allochiria•Visual Allochiria•Gustatory Allochiria
22
Sense of Vibration
• Pallesthesia refers to the sensation of mechanical vibration on or near the body.
• Vibration sense may be lost as a result of a number of lesions to the nervous system, often in conjunction with other deficits.
• The word "pallesthesia" is derived from the Greek pallein, meaning "to shake."
• Pallesthesia may be tested for using a vibrating mechanical tuning fork, placed on a bony prominence.
23
Thermoception(Sense of Hot/Cold)
• Thermoception is the sense of heat and the absence of heat (cold) by the skin.
• There are specialized receptors for cold (declining temperature) and for heat.
• Cold receptors help an animal’s sense of smell, telling wind direction. Heat receptors help animals that can use radiation to detect prey, such as snakes.
• The information travels up the spinothalamic tract in the spinal cord and ascends to the thalamus.
• The thermoceptors in the skin are quite different from the homeostatic thermoceptors in the brain (hypothalamus), which provide feedback on internal body temperature.
24
Two-point discrimination
• Two-point discrimination is the ability to discern that two nearby objects touching the skin are truly two distinct points, not one. It is often tested with two sharp points during a neurological examination and is assumed to reflect how finely innervated an area of skin is and diagnosing tactile agnosia (don’t know what is touching me).
25
Two-point discrimination
• The therapist randomly alternates between touching the patient with one point or with two points on the area being tested (e.g. finger, arm, leg, toe).
• The patient is asked to report whether one or two points was felt. The smallest distance between two points that still results in the perception of two distinct stimuli is recorded as the patient's two-point threshold.
26
Two-point discrimination
• Performance on the two extremities can be compared for discrepancies.
27
PROPRIOCEPTION• There are sensors within the muscles and joints that measure
the amount of force, movement, and position. • Proprioception neurons travel up the spinocerebellar tract.
The brain can then interpret whether you are off balance, then send a command to the muscles to contract and straighten yourself up so you don’t fall.
• Note that this sense of balance is NOT the same as the sense of balance from equilibrium in the ears. Proprioception neurons are located within the muscles and joints.
• During a physical exam, a doctor will test the patient’s proprioception ability by telling them to close their eyes and place their finger on their nose. This may indicate a lesion in the cerebellum. Who else may ask you to do this test? Alcohol disrupts the cerebellum.
28
Muscle spindles• Muscle spindles are sensory receptors
within the belly of a muscle that primarily detect changes in the length of this muscle. The brain can then determine the position of body parts.
• Muscle spindle responses also play an important role in regulating the contraction of muscles, by activating motor neurons via the stretch reflex to resist muscle stretch.
29
Proprioceptors•Sensory receptors that report on internal events in your muscles and joints.
•They report on muscle stretch and joint position.
•They generate electrical impulses that will travel up neurons to the CNS.
•A muscle spindle is one type of proprioceptor.
30
Proprioception Disorders
• Not enough vitamin B1 (memory problems)• Too much vitamin B6 (balance problems)
– Damage to proprioceptors can occur from consuming excess vitamin B6 (pyridoxine).
– Patients cannot tell where their body parts are unless they look at them.
– They have difficulty with all motor tasks including walking, eating, dressing, etc.
– They must use their vision to watch each body part to make it move in the right direction.
31
PROPRIOCEPTORS
• Proprioception is often tested by having the patient close their eyes and saying if their fingers are up or down.
• Proprioceptors send information to the cerebellum. That’s how you know your legs are crossed before you stand up.
• Somatic senses and proprioception are NOT considered special senses.
32
Special senses• The special senses are those that have
specialized organs devoted to them:
• vision (the eye)
• hearing and balance (the ear)
• smell (the nose)
• taste (the tongue)
33
These will be discussed in a separate lecture.
• Somatic sense information goes into the spinal cord, travels up a tract and into the primary somatosensory area in the parietal lobe of the cerebral cortex.
• The mapping of the body surfaces in the brain is called a homunculus and plays a fundamental role in the creation of body image.
34
This brain-surface ("cortical") map is not immutable, however. Dramatic shifts can occur in response to stroke or injury.
SENSORY CUTANEOUS NERVES
• These come out of the spinal cord and go to specific regions of skin on the body.
• For example, nerve C4 innervates the skin region C4 of the DERMATOME MAP.
• It’s important to know these dermatome map regions (not for this class), especially physical therapists and nurses.
35
Dermatome Map
36
• If a patient has a shooting pain down the anterior shin, what nerve is pinched? L5.
• Numbness in pinky and ring finger is what nerve? C8.
• If a workman’s comp patient comes in saying his whole hand is numb, no other symptoms, you know he’s lying because the nerves don’t run that way.
DAMAGE TO THE NERVOUS SYSTEM
• If a person has a spinal cord injury in their cervical region, they could have quadriplegia (arms and legs paralyzed).
• If a person has a spinal cord injury in their thoracic region, they could have paraplegia (just legs are paralyzed).
37
Disruption of Blood Supply
• When a body part “falls asleep”, the region has become ischemic (lack of blood flow), impairing the action potential of the nerves.
• Unlike the CNS, when blood is restored to the PNS, the nerves recover.
• Damage to the CNS tends to be permanent, but damage to the PNS tends to heal.
38
Cut nerves
• If a small nerve is cut, it will regenerate because where are the cell bodies? In the posterior root ganglion (sensory) or anterior horn (motor).
• Since the cell body is about a meter away, axons can regrow.
• Large nerves are harder to regrow, but you can still stitch the ends together at the epineurium and perineurium, and you may get healing.
39
Doctors trying to fix damaged nerves•
http://www.foxnews.com/health/2012/11/13/doctors-trying-to-fix-damaged-nerves/ • Nerve disease and injuries are tough to treat, largely
because there's no way to regenerate many damaged nerve cells. Neurologist Joseph Corey is trying to change that.
• Corey and a team of scientists used tiny polymer fibers as a scaffold. They coaxed an oligodendrocyte to form a myelin sheath around the fiber. The artificial fiber mimicked an axon.
• Myelin provides the pathways along which some nerve cells regenerate after an injury. When a person has MS or cerebral palsy, the oligodendrocytes are damaged and don't function properly and the myelin sheaths start to break down.
40
Rat Brain in a Dish Flies Plane• An electrode grid was
placed at the bottom of a glass dish and then covered with rat neurons that gradually formed a neural network -- a brain.
• They then used the brain to control an F-22 fighter jet flight simulator.
• The research could lead to tiny, brain-controlled prosthetic devices and unmanned airplanes flown by living computers.
41
Exoskeleton Helps Paralyzed Patients Walk
• Exoskeletons have been designed for military use and boosting strength. But the same technology that makes people able to lift heavier loads might also one day allow those with spinal injuries to walk.
• Ekso Bionics, a California company, developed the Human Universal Load Carrier, or HULC for the military, and another one called the Ekso, for people who need either physical therapy or rehabilitation.
42
Tens unit
• Transcutaneous electrical nerve stimulation
43
TENS is usually applied at high frequency with an intensity below motor contraction. It just blocks pain impulses.
This is a different machine than a muscle stimulator, but they look the same.
TENS is available without a Rx.
Corydalis powder for pain• http://www.prevention.com/health/health-concerns/chinese-remedy-corydalis-pain
44
Put ½ teaspoon into one cup of hot fluid (tea, etc) and drink it.
Alleviates chronic pain in about 20 minutes!
Pinched nerves
• When a nerve gets pinched (e.g. herniated disc), it damages the nerve by interfering with its action potential, causing weakness, pain, or paralysis.
45
Spinal Nerves Posterior View
46
SOME CLINICALLY IMPORTANT PERIPHERAL NERVES:
• Note: an epidural nerve block during child birth will numb the mother from her navel to her knees.
• PUDENDAL NERVE: this is the nerve that can be anesthetized during childbirth as an alternative to an epidural (a pudendal nerve block is also called a saddle block because the numb areas are where you would be touching a saddle).
• PHRENIC NERVE: allows the diaphragm to contract. If it gets severed, the person can no longer breathe without assistance. 47
Nerve Plexus
A PLEXUS is a network of nerves that primarily serves the limbs. There are four major plexi: cervical, brachial, lumbar, and sacral.
1. CERVICAL PLEXUS comes out of the neck and are cutaneous nerves (sensory input of the skin) of the neck and back of the head. The phrenic nerve (supplies the diaphragm) is also in this plexus.
48
Cervical Plexus
49
BRACHIAL PLEXUS
2. BRACHIAL PLEXUS• This is the major group of nerves that supply the
upper limbs. It runs through the axilla. • If a person leans their armpits on their crutches,
they can damage this plexus and lose the use of their arms.
• The nerves in the brachial plexus change names as they go to different regions in the arm.
50
The Brachial Plexus
51
Major Nerves of the Upper
Extremity
Axillary
Musculocutaneus
52
Axillary Nerve
• Deltoid
53
Musculocutaneus Nerve
• Supplies anterior muscles of the arm
54
Median Nerve
• Supplies no muscles of the arm
• Supplies anterior forearm (except flexor carpi ulnaris)
• Damage can cause– Hand of benediction– Ape Hand– Carpal Tunnel Syndrome
Patient trying to make a fist
55
MEDIAN NERVE: Ape Hand
• This is the nerve that gets cut when people try to slit their wrists.
• The arteries are so small in the wrist; people rarely die from this type of suicide attempt.
• However, they live with a lot of tissue damage. • They are not able to move the thumb towards
the little finger, so it is hard to pick up small objects.
• This is called “ape hand”.
56
57
Carpel Tunnel Syndrome
58
Median Nerve:Carpel Tunnel Syndrome
• The median nerve travels under the transverse carpal ligament.
• The nerve is pinched in carpal tunnel syndrome.
59
Carpel Tunnel Syndrome
60
Patient Case
• George has been a computer programmer for 20 years. He has numbness in his right hand on the thumb, index finger, and middle finger.
• Tapping on the carpal tunnel causes parathesias (tingling) in the median nerve distribution (positive Tinel’s sign).
• Placing his wrist in sustain flexion for one minute also causes the parathesias (positive Phalen’s test).
61
Patient Case• Treatment began with splinting the wrist in
neutral position and patient education for proper ergonomics (use a wrist pad while typing).
62
Trigger Finger• Trigger finger is one example of the
disability that can be created when repetitive trauma to a flexor tendon results in the formation of nodules on the tendon. Finger flexion may be prevented completely, or the finger may be unable to re-extend.
63
Ulnar Nerve
• Supplies flexor carpi ulnaris
• “Funny Bone”
• Damage can cause claw hand; cannot adduct or abduct fingers
64
Radial Nerve• Supplies muscles on the posterior arm and
forearm– Triceps brachii– Extensor carpi radialis– Extensor digitorum communis
• Damage can cause wrist drop
• Also called “waiter’s hand”
65
Carpel Tunnel Syndrome
Ape Hand
66
Axillary, Musculocutaneus,
Ulnar, Median, Radial, Nerves
Figure 14.467
Brachial Plexus
• Damage to Brachial Plexus– Congenital (brachial plexus damaged during birth)
• Klumpke’s paralysis– Acquired Brachial Plexus injuries
• Crutch paralysis (total upper extremity paralysis)• Claw Hand • Carpal Tunnel Syndrome, Ape hand, Hand of
benediction • Wrist Drop (Waiter’s Hand)
68
LUMBAR PLEXUS
3. LUMBAR PLEXUS
• FEMORAL NERVE is the main nerve to the anterior thigh.
69
Lumbo-Sacral Plexus
• Lumbar: – Femoral nerve
• Sacral: – Sciatic nerve
70
The Lumbar Plexus
Figure 14.1571
Sacral Plexus4. SACRAL PLEXUS are spinal nerves from L4-S5• Some of the fibers from the lumbar plexus mix with the
sacral plexus, so these are often referred to together as the lumbosacral plexus.
• SCIATIC NERVE is the largest branch of the sacral plexus and the largest nerve in the body; it is about the size of your pinky finger. It leaves the pelvis through the greater sciatic notch.
• A short, thick muscle (Piriformis muscle) covers the greater sciatic notch, and when it contracts, it can pinch the sciatic nerve, causing a type of sciatica (sciatic nerve irritation) known as piriformis syndrome.
• This can be alleviated by stretching exercises (lay on back and move knee to opposite shoulder). However, sciatica can also be caused if there is a herniated lumbar disc, in which case stretching exercises make it worse.
72
The Sacral Plexus
Figure 14.16a, c73
74
• Sciatica tremors video
75
Spinal steroid shots may have little effect on sciatica
• http://www.foxnews.com/health/2012/11/13/spinal-steroid-shots-may-have-little-effect-on-sciatica/
• For the back pain component of sciatica, the researchers found that the injections didn't seem to make a difference over short or long periods of time.
• When it came to leg pain, there was no difference a year or so after the injection, but there was a statistically significant drop in pain scores over the short term - about 2 weeks to 3 months.
76
77
Nerves of the Lower
ExtremityFemoral
Obturator
The sciatic nerve supplies the back of the thigh, then branches out into the TIBIAL and FIBULAR (peroneal) nerves, which supply the leg and foot.The fibular nerve branches into superficial and deep.
78
Lower Extremity NervesObturator Nerve
Supplies adductor musclesFemoral Nerve
Supplies anterior ThighSciatic Nerve
Supplies back of thighTibial Nerve
Supplies posterior leg and footCommon Fibular Nerve
Superficial branch Supplies lateral side of leg
Deep branchSupplies anterior leg Injury causes “Foot Drop”
79
Tibial Nerve
• Sometimes a small branch of the tibial nerve in the foot gets pinched between the metatarsal heads, and the irritation causes nerve swelling and pain.
• It is called a neuroma (“nerve tumor”) and manifests as pain in the ball of the foot, made worse with high heels.
80
81
Nervous System Classification-1
• Somatic Nervous System– Motor nerves to skeletal muscle (somatic motor neurons)
• Upper and lower motor neurons– Skeletal Muscle Reflexes
• Sensory, interneurons, lower motor neurons
– Visceral (organ) Reflexes– Sensory nerves (somatosensory neurons)
• Autonomic Nervous System– Motor nerves to smooth and cardiac muscle (visceral motor
neurons)• Sympathetic• Parasympathetic
82
Efferent Nervous System
Somatic Division
Visceral (Autonomic) Division
Parasympathetic
Sympathetic
Adrenal Gland
Skeletal muscle
Blood vessel Smooth muscle, cardiac muscle, and glands
AUTONOMIC NERVOUS SYSTEM
• We don’t have voluntary control over these nerves.
• They are involved digestion, blood flow, urination, defecation, glandular secretion.
• Therefore, the ANS supplies the glands, smooth muscle, and cardiac muscle, but NOT the skeletal muscle.
• For this reason, the ANS is also called the general visceral motor system.
84
Sympathetic Division of the ANS
85
ANS
• All of the neurons of the ANS are motor neurons (there are no sensory neurons in the ANS).
• The ANS motor neurons differ from the somatic motor neurons (for skeletal muscle) because the ANS has two lower motor neurons in the periphery (the cell body of one is in the spinal cord and the cell body of the other is in the periphery), whereas the somatic motor neurons have one lower motor neuron, and its cell body is within the spinal cord, not in the periphery.
86
ANS has TWO lower motor neurons
Preganglionic neuron
Post-ganglionic neuron
Ganglion (where the cell bodies of the post-
ganglionic neurons are)
Somatic system has just one lower motor neuron
87
ANS
• The ANS lower motor neuron comes from the spinal cord and synapses on the cell body of another neuron, which then synapses on the target (gland, blood vessel or organ).
88
Ganglia• The area where the two neurons come together is the
AUTONOMIC GANGLIA.• The first neuron is the PRE-GANGLIONIC NEURON. • The second neuron is the POST-GANGLIONIC NEURON.
89
ANS• The ANS motor unit is characterized by
having more than one lower motor neuron, the axons may be myelinated or unmyelinated (tend to not be myelinated since they are only going to organs), conduction is slow, and the axons are thin (which also slows conduction like a freeway with only one lane).
• The ANS has two divisions: sympathetic and parasympathetic.
90
SYMPATHETIC DIVISION(has nothing to do with sympathy!)
• ↑heart rate and blood pressure,
• ↑metabolic activity (increased blood glucose),
• decreased peristalsis (decreased food digestion)
• dilation of bronchioles
• constricts blood flow to the skin
• sweating 91
Sympathetic Division• E.g. when running, ↑heart rate =
sympathetic. • When hot sweat = sympathetic. • The term “Fight or Flight” is inaccurate; it
refers to the ↑ heart rate, etc, but the sympathetic division is also active when relaxing on a nice beach with a cool drink on a hot day, because whenever you’re sweating, that’s the sympathetic division.
• Sympathetic and sympathy are opposites. They should call it the ANTI-sympathetic system.
92
93
ANATOMY OF THE SYMPATHETIC DIVISION
• The sympathetic neurons exit the spinal cord at the thorax and lumbar regions.
• The axons of most pre-ganglionic neurons in the sympathetic division are fairly short, and they synapse quickly on a ganglia.
• All these ganglia are lined up along the vertebral column and are called the SYMPATHETIC TRUNK (CHAIN) GANGLIA.
• Therefore, the postganglionic cell bodies of the sympathetic nervous system are in the chain ganglia.
• There are also nerves that connect the ganglia to each other.
94
Sympathetic Trunk Ganglia
95
Sympathetic Division
In Sympathetic division, preganglionic axons are SHORT because they terminate in ganglia that are close to the spinal cord
That means the post-ganglionic axons are LONG, because they have to reach all the way to the target muscle. 96
Sympathetic Division
• The axons of POST-GANGLIONIC NERVES are very long, and go to the target organs.
• Some pre-ganglionic neurons go into to the abdomen.
• They create a group of ganglia in the abdomen called the SOLAR PLEXUS (“sun”).
• When you get punched in the abdomen, you are punched in the solar plexus, and get the wind knocked out of you. It causes the diaphragm to go into spasm.
97
PARASYMPATHETIC DIVISION
• Unlike the sympathetic division, the axons of the preganglionic neurons of the parasympathetic division are long, and the axons of the postganglionic neurons are short.
• The nerve cell bodies (peripheral ganglia) of the parasympathetic division are closer to the organs being innervated than in the sympathetic division.
• In fact, the cell bodies are either next to or inside of the target organs. Therefore, they have short post-ganglionic fibers.
98
Parasympathetic Division
In the Parasympathetic division, preganglionic axons are LONG because they terminate in ganglia that are close to the target organ
That means the post-ganglionic axons are SHORT
99
PARASYMPATHETIC DIVISION
• “Rest and Digest”• Involved in vegetative activities, such as
digestion, voluntary urination and defecation• Has postganglionic cell bodies in terminal
ganglia, located either near or within target organs
• Has both preganglionic and postganglionic neurons that secrete acetylcholine
• Has preganglionic cell bodies located in the cervical (Vagus nerve) and sacral areas.
100
Parasympathetic Division
• The function of this division is often antagonistic (opposite) of the sympathetic, but actually, they work together.
• The parasympathetic division inhibits cardiac contraction, so there is: ↓heart rate, constricts bronchioles, activates digestive system, and causes salivation, urination, and defecation.
• When you are lounging on the beach, the heart rate decreases (parasympathetic), but the sweat increases (sympathetic).
101
Vagus Nerve
• The parasympathetic neurons come out of either the brain or the sacral region of the spinal cord.
• The majority of the parasympathetic outflow from the head is by the vagus nerve.
102
Vasovagal Syncope (Fainting)
• The most common type of fainting.• After a stressful trigger, the parasympathetic nervous
system is enhanced by the Vagus nerve.• The heart rate speeds up, then suddenly drops. • Then the blood pressure drops.• Unconsciousness results.• Treatment: elevate the legs above the heart for a few
minutes, and make sure the airway remains open.• A cold, wet cloth on the forehead and back of the neck
may make the person feel better as they recover.
103
Path of the Vagus Nerve
104
Reynaud's Phenomenon
• Autonomic nervous system (sympathetic division) is hyperactive in the ANS neurons that innervate the walls of blood vessels.
• It causes spasms of peripheral blood vessels, cuts off some blood supply, and causes the fingers and toes to be white or blue.
• Emotional stress and being cold tend to trigger the discoloration.
105
Caffeine
• With frequent use, tolerance to many of the effects of caffeine will develop. Caffeine causes vasoconstriction. In doses of 600 milligrams (about six cups of coffee) or more daily, caffeine can cause nervousness, sweating, tenseness, upset stomach, anxiety, and insomnia. It can also prevent clear thinking and increase the side effects of certain medications. This level of caffeine intake represents a significant health risk.
106
Caffeine
• Caffeine can be mildly addictive. Even when moderate amounts of caffeine are withdrawn for 18 to 24 hours, one may feel symptoms such as headache, fatigue, irritability, depression, and poor concentration. The symptoms peak within 24 to 48 hours and progressively decrease over the course of a week. To minimize withdrawal symptoms, experts recommend reducing caffeine intake gradually.
107
Caffeine• At levels over 200 milligrams per day, caffeine may delay
conception and doubles the risk of miscarriages and low birth weight babies.
• Caffeine and tannin in tea decreases iron and protein absorption, and is especially dangerous during pregnancy. Black tea during pregnancy causes birth defects.
• Caffeine taken during pregnancy is thought to increase the probability of a child contracting diabetes.
• Because children have developing nervous systems, it is important to moderate their caffeine consumption.
108
Caffeine, per cup• Ammo: 1140 mg• Redline Power Rush: 946 mg• Expresso: 500 mg• Jolt Energy: 300 mg• Coffee: 100 mg• Red Bull: 80 mg• Mountain Dew: 60 mg• Green tea: 50 mg• Tea: 50 mg• Coke: 37 mg• Dark Chocolate (1.5 oz): 20 mg• Milk Chocolate (1.5 oz): 9 mg• Hot Chocolate: 5 mg• Root Beer, Ginger ale, Lemon-Lime: 0 mg
109
The Ammo and Redline manufacturers recommend users dilute the concentrated energy drink prior to consumption. They also claim that drinkers should not just drink the shot straight out of the bottle due to the extreme potency!
Symptoms of Excess Caffeine
• nervousness headache increased heart rate• anxiety upset stomach irregular heartbeat• irritability GI irritation elevated BP• agitation heartburn increased cholesterol• tremors diarrhea nutritional deficiencies• insomnia fatigue poor concentration• depression dizziness bed wetting
110
Caffeine Withdrawal Symptoms
• headache constipation runny nose• craving anxiety nausea• irritability nervousness vomiting• insomnia shakiness cramps• fatigue dizziness ears ringing• depression drowsiness hot and cold• apathy inability to concentrate
111