The Autonomic Nervous System Flashcards
What is the foundation of our conscious personalities and behavior?
The nervous system
What are the two systems of the nervous system?
Nervous system
Endocrine system
What does the endocrine system do?
Send chemical signals (hormones) through blood
What does the two systems do? (Endocrine and nervous)
Detect changes in an organ and modify the activity of other organs
How does the nervous system carry out actions
Receive info about changes in the body and external environment
Process this info and determine the appropriate response
Issue commands to cells that carry out the response
How does the nervous system perceive and respond to environments?
Neurons (nerve cells)
What are the properties of the neurons?
Excitability, conductivity, secretion
Excitability
Respond to environmental changes (stimuli) at receptors
Conductivity
Responds to stimuli by electrical signals (impulses)
Secretion
At the end of the synapse or receptor
Neurons will secrete neurotransmitters that cross the gap and stimulates the next neuron
Exteroceptors
Respond to stimuli that originate from outside the body affecting skin, mucous membranes, or sense organs by touch, pressure or sound
Interoceptors (visceroceptors)
Respond to stimuli originating from within the body
Related to the function of internal organs
Proprioceptors
Sensory receptor that receives stimuli from within the body
Especially one that responds to position and movement
Central Nervous system
Brain and spinal cord
Peripheral Nervous System
Nerves that connect the CNS to different organs
1. Cranial nerves: 12 pairs
2. Spinal nerves: 36 pairs
Sensory Nerves
Afferent
Takes information to the CNS
Motor nerves
Efferent
Takes orders from the CNS to the structures
Spinal nerve
Formed by a ventral (motor) and dorsal (sensory)root
Ventral root
Cell bodies of motor nerves (pure efferent)
Dorsal Root
Cell bodies of sensory nerves (pure afferent)
How is the PNS divided?
Somatic and Visceral (autonomic) nervous system
Somatic Nervous System
Structures we have control over
Skin, bone, joints, skeletal muscles
Somatic sensory and somatic motor nerves make up one nerve wrapped around each other
Visceral/ Autonomic Nervous System
Regulates motor acts (not essential)
Structures we have no control over (Organs)
Efferent nerves are 2 nerves connecting @ ganglion
How is the Autonomic system divided?
Parasympathetic and Sympathetic
Parasympathetic
Acting all the time and doesn’t run everywhere (rest and digest)
Originates from cranio-sacral (brain/ SC segments1-3)
Synapse @ wall of target effector organ
How many cranial nerves have parasympathetic fibers?
4/12
Oculomotor (C3)
Facial (C7)
Glossopharyngeal (C9)
Vagus (C10)
Sympathetic
Emergency system for quick rigorous actions (fight, fright or flight)
Runs everywhere
Cardiac m., glands, smooth m.
Synapse @ paravertebral or prevertebral ganglion
Sympathetic trunk
Extra spinal tract that carries sympathetic nerves
Nuclei (Nucleus)
Collection of cell bodies within the CNS
Ganglion
Collection of cell bodies outside the CNS
Communication taking place between the 1st and 2nd nerve
Where synapse takes place
How do post synaptic autonomic nerves run?
- Head, abdomen, pelvis: with arteries
- Abdominal wall, body cavities, neck and limbs: with spinal nerves
- Thorax: runs by itself
Paravertebral
Ganglion close to the vertebral column
Cervicothoracic, sympathetic trunk, middle cervical and cranial cervical
Prevertebral
Ganglion away from the vertebral column
Left celiac, cranial mesenteric and caudal mesenteric
Sympathetic preganglionic/ synaptic nerves
Sitting and waiting for the synapse @ prevertebral or paravertebral gang
NT: ACH
Sympathetic post ganglionic/ synaptic nerves
Neuronal cell bodies sitting on the autonomic ganglia
Synapse @ target organ/ tissue
NT: norepinephrine
Where are all cell bodies of sympathetic nerves located?
At the thoracolumbar region
Rami comunicants
Sympathetic nerves that leave the thoracolumbar region and run with the ventral root to the trunk
Gray- postsynaptic, unmyelinated
White- presynaptic, myelinated
Ansa Subclavia
All nerves coming out of the thorax come out here
Takes pre and post synpatic nerves
Pathway to the head
- Ventral root
- Spinal nerve
- White rami communicants
- Sympathetic trunk
- Bypass the cerival sympathetic trunk and ansa subclavia
- Synapse @ cranial cervical ganglion
- Post ganglionic fibers run with internal carotid artery
What happens after the synapse at the cranial cervical ganglion
The sympathetic fibers will join to form the vertebral nerve
Now known as post synaptic nerves/ fibers
Pathway to the neck
- Ventral root
- Spinal nerve
- White rami communicants
- Sympathetic trunk
- Synapse @cervicothoracic ganglion
6.Vertebral Nerve - Gray rami communicants
- Spinal nerve
- Targets organs (smooth muscles and skin)
Pathway to the thorax
- Ventral root
- Spinal nerve
- White rami communicants
- Sympathetic trunk
- Synapse @ middle cervical ganglion or cervicothoracic ganglion
- Post syn. path: cardiosympathetic nerves from ansa subcavia
7.Post syn. nerves run by itself
Pathway of the limbs/ body wall
- Ventral root
- Spinal nerve
- White rami communicants
- Synaptic trunk
- Synapse @ sympathetic trunk ganglia
- Gray rami communicants
- Spinal nerve (ventral or dorsal)
- skin and smooth muscles
Pathway of the abdomen
- Ventral root
- Spinal nerve
- White rami communicants
- Sympathetic trunk
- Splanchnic n.
- Synapse @ celiacomesenteric gang (prevertebral)
- Post syn runs with arteries (nerve plexus on abdominal arteries supplying organs)
Pathway of the pelvis
- Ventral root
- Spinal nerve
- White rami communicants
- Sympathetic trunk
- Down the lumbar splanchnic nerve
- Synapse @ caudal mesenteric gang
- Post syn. will run to right or left hypogastric nerve, pelvic plexus branches to pelvic viscera
How many sympathetic spinal nerves are there?
- Cervical spinal nerves: 8
- thoracic spinal nerves: 13
What is the visceral motor efferent influenced by?
Spinal cord
Brain stem
Hypothalamus
What portions of the nervous system controls visceral functions of the body?
Blood pressure
Cardiac function
GIT
Urinary bladder
Sweating, etc.
What does the sympathetic system supply?
- Glands and smooth muscles of the skin
- Thoracic, abdominal and pelvic viscera
- Head structures: salivary glands and iris (smooth)
- Smooth muscles of blood vessels
- Cells of adrenal medulla
How does ANS differ from the rest of the PNS?
By having a second neuron interposed between the CNS and the innervated structure
What will happen if the somatic nerves to the skeletal mm are served?
Its nonfunctional in the absence of innervation
What does the sympathetic stimulation result in?
Increased HR and blood glucose
Decreased bowl motility
Dilation of the iris
Parasympathetic long preganglionic fibers
Ganglia at target organ
Short postgang fibers
NT: at both synapses is ACH
What does the parasympathetic stimulation result in?
Maintenance Response:
Decreased HR
Increase secretion of glands of GIT
Constriction of pupil
T/F: Distribution of parasym. system is more limited than the sym. system
True
T/F Parasympathetic fibers supply the skin, sweat glands, pilorector m or cutaneous blood vessels
False
Parasym. fibers don’t supply any of those structures
What is the exception to what parasym. fibers suppy?
Penile arteries
Adrenal Medulla
Modified sympathetic ganglion
When stimulated it secreted epinephrine
Vagus Nerve (C10)
Supplies thoracic and abdominal viscera
Goes from the vagosympathetic trunk to thorax
Where does the vagus nerve split
At the middle cervical ganglion to split off and run by itself
When does the vagus turn into the laryngeal nerves?
- Left laryngeal nerve leaves around the aortic arch
- Right recurrent laryngeal nerve leave around the right subclavian artery
Parasympathetic Path
Presynpatic path: Vertebral branch of S1 -S3
Synapse @ pelvic ganglia at pelvic plexus
Cholinergic fibers
Fibers that secrete Ach
Include pregang of symp and para symp and postgang of parasym
Adrenergic fibers
Fibers the secrete norepinephrine
Include symp post gang
Sympathomimetic drugs
Drugs that stimulate the symp. system at the neuroeffector junction
Parasympathomimetic drugs
Drugs that stimulate the parasympathetic system at the neuroeffector junction
Have a “muscarinic effect”
What do drugs that have a “nicotinic effect” stimulate?
The 2nd neurons of both symp. and parasymp systems at the autonomic ganglia
What drugs act on alpha and beta receptors?
Sympathetic drugs
How do effectors with alpha receptors respond?
By contraction of smooth muscles “increase BP”
How do effectors with beta receptors respond?
By relaxation of smooth muscles of blood vessels that supply the heart
Pathway to dilator mm of iris
- Pre gang: neuronal cell bodies located at T1-T13
- Rami communicants
- Thoracic symp. trunk
- Cervial- symp trunk
- Cr. cervical gang
- Post gang fibers: with internal coratid artery to dialtor iris mm.
What happens if the pathway to dialtor mm of iris is interupted?
Horner’s syndrome
In healthy animals, what does the symp. trunk from the cranial cervical ganglion do?
Supply orbital muscle (eyeball protruded) and dilator of pupil
Keep 3rd eyelid retracted
Keep palpebral fissue open
How is the dilatation of pupil initiated?
Fear, excitement or pain (atropin)
What are the signs of Horner’s syndrome?
C6-T2 (brachial plexus) avulsion can happen
Leads to loss of symp. innervation of the eye
What are the results of Horner’s syndrome?
Enopthalmus (sunken globe of the eye)
Profusion of the 3rd eyelid
Miosis (constriction of the pupil)
Ptosis (small droopy eye opening)
Sciatic Nerve
Going into the hamstring
Motor because it has more motor fibers than sensory
