ANS Flashcards
What is the autonomic nervous system ?
Nervous system that controls many involuntary functions of the body
Is the autonomic nervous system a part of the CNS or PNS?
PNS
True or false
ANS effects organs which are under voluntary control
False
Involuntary control
True or false
The ANS is important for maintaining homeostasis
True
Because it controls organs that participate in homeostatic control
What are the usual effectors of ANS?
Cardiac muscle
Smooth muscle
Glands
True or false
Skeletal muscles are effectors of the ANS
False
What is the difference between the somatic motor reflex and the autonomic motor reflex ?
In the efferent pathway:
Somatic reflex has ONE set of neurons
Autonomic reflex has TWO sets of neurons (pre + post)
Also autonomic reflex consists of an autonomic ganglion !!
Divisions of the ANS
Sympathetic division (thoracolumbar)
Parasympathetic division (craniosacral)
The thoracolumbar division of the ANS is also called
Sympathetic division
The craniosacral division of the ANS is also called
Parasympathetic division
In the sympathetic division, cell bodies of the preganglionic neurons are from ________________ + _____________
THORACIC spinal cord + LUMBAR spinal cord
In the parasympathetic division, cell bodies of the preganglionic neurons are from ________________ + _____________
BRAIN + SACRAL spinal cord
What is sympathetic chain and what is its importance ? (Picture is important for understanding)
Preganglionic neurons synapse at the sympathetic chain ganglia with postganglionic neuron
NOTE:⚠️
- Splanchnic nerves: preganglionic neurons enters and leaves the sympathetic chain ganglion WITHOUT synapsing in it. It synapses at different ganglions with postganglionic neurons.
- Adrenal medulla are innervated directly by PREganglionic fibers of the sympathetic nervous system
Which is supplied directly by preganglionic fibers?
A. Adrenal cortex
B. Liver
C. Spleen
D. Adrenal medulla
D. Adrenal medulla
Most important nerve in parasympathetic nervous system?
Vagus nerve (cranial nerve 10)
Vagus nerve runs with ____________ artery and branches everywhere.
Carotid
Difference between sympathetic and parasympathetic : where do the preganglionic and postganglionic fibers synapse ?
Sympathetic: synapse occurs outside of organ
- preganglionic : OUTSIDE of organ
- postganglionic: OUTSIDE of organ
Parasympathetic: synapse occurs at organ
- preganglionic : OUTSIDE of organ
- postganglionic: INSIDE of organ
what do you understand from this picture
1- Adrenal medulla is responsible for making epinephrine and norepinephrine (adrenaline and noradrenaline) , which both play a role in the body’s fight or flight.
2- Adrenal medulla is innervated DIRECTLY from PREganglionic fibers
True or false
Every organ is innervated by BOTH sympathetic and parasympathetic systems
False
What are some of the organs that are innervated by BOTH sympathetic and parasympathetic systems
Heart
Digestive tract
Pupil of eye
Salivary glands
What are some of the organs that are innervated by ONLY sympathetic innervation
Adrenal medulla
Sweat glands
Most blood vessels
Which ANS system prepares the body for Fight/Flight (activity)
Sympathetic system
Excitation of sympathetic centers will cause :
Excitation of parasympathetic centers will cause :
PNS or SNS
SNS
PNS or SNS
PNS
ANS can have both positive and negative effects on its effector organs. Why?
Because both PNS and SNS continuously transmit action potentials (signals) at low rate through their nerve fibers
Explain this image
Blood vessels are normally kept at a certain diameter due to LOW rate firing from the sympathetic fibers = normal blood flow
However, if the rate increases and now we have a HIGHER firing rate from the sympathetic fibers, the diameter of the blood vessels decreases = VASOCONSTRICTION = REDUCED blood flow
If we STOP the firing from the sympathies fibers, the diameter of blood vessels increase = VASODILATION = increases blood flow to organ
Which causes vasodilation?
A. High firing rate of SNS
B. Low firing rate of SNS
C. No firing of SNS
C. No firing of SNS
Examples of sympathetic system in action
Blood flow to muscle in exercise
- vasoconstriction of blood vessels of all organs except heart and brain
Liver
- stimulates glycogenolysis (glycogen to glucose), releasing glucose into the blood to provide muscles with energy
Examples of parasympathetic system in action
GI tract
- causes increased blood flow, motility and secretion of GI tract
Heart and lungs
- reduces heart rate and contracts air tubes (bronchioles) in lung