Comparison between tract and nerve

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  Comparison between tract and nerve Nerve Nerve contain bundle of axons (nerve fibers) in the peripheral nervous system (PNS) that transmits signals between the central nervous system (CNS) and other parts of the body. It is the most important part of peripheral nervous system Location: Peripheral nervous system. Structure: Made of axons, connective tissue layers (endoneurium: axon is surrounded by it , perineurium: bundle of axons are surrounded by it, epineurium: whole nerve trunk is surrounded by it), and blood vessels. It gets myelination by Schwann cell   Function: Carries sensory signals to the CNS (afferent) from peripheral part of body or motor signals carry from from the CNS (efferent) to target organs like skeletal muscle, cardiac muscle, smooth muscle or glands Example: Sciatic nerve, median nerve, except optic nerve (though optic nerve is technically part of CNS in develop...
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Difference between sympathetic and parasympathetic nervous system

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Topics
Sympathetic nervous system
Parasympathetic nervous system
Out flow
it is also known as thoraco lumbar outflow T1 to L 2
It is also known as cranio sacral outflow
Following Cranial nerves are involve   3,7,9 & 10
Sacral : S2,3,4
Pre ganglionic fibres
Short
Longer
Post ganglionic fibres
Longer
Shorter
Ganglia
Para vertebral sympathetic ganglia it is away from the target organ
Small ganglia close to viscera Ex: ciliary ganglia
Location of pre-ganglionic neuron
•       Lateral horn cells of all thoracic segments and upper two or three lumbar segments of spinal cord

•       Neurons are located in the brain stem and connected with the 3, 7, 9, 10 cranial nerves and 2,3,4 sacral segments of spinal cord

Location of post-ganglionic neuron
•       Lateral: sympathetic trunk
•       Collateral : coeliac, superior mesenteric ganglia
•       Terminal ganglia: supra-renal medulla
•       Ciliary ganglion
•       Pterygopalatine ganglion
•       Otic
•       Submandibular


This system activate during emergency and works during stress and strain for fight or flight
This system activate during relax period ( it is the nerve of tranquility )

Liberates non adrenaline at postganglionic ending except eccrine type of sweat glands and most of the blood vessels of skeletal muscle
Liberates acetylcholine at post ganglionic endings

This system is not essential for to life
This system is essential for life
Urinary bladder
It is the nerve of filling
It contract (close) urethral sphincter and relax detrusor muscles
It is the nerve of emptying
It relax(open)  urethral sphincter and contract  detrusor muscles
Heart
Cardiac muscles cells : increase force of contraction
Coronary vessels :  vasodilator ( so supply of nutrition and oxygen increase in cardiac muscle cells  )
Cardiac muscles cells : decrease force of contraction
Coronary vessels :  vasomotor / vasoconstriction  ( so supply of nutrition and oxygen decrease in cardiac muscle cells  )
Lung:
Bronchodilator / Trachealis muscles relax so diameter of trachea increase
Decrease secretion of tracheal glands
Broncho-constriction : Trachealis muscles contract so diameter of trachea decrease
increase secretion of tracheal glands
Stomach
Gastric musculature (smooth muscle cells ) is relax  but smooth muscle cells at the pyloric sphincter is contract (closer of pyloric sphincter )
Gastric musculature (smooth muscle cells ) is contract  but smooth muscle cells at the pyloric sphincter is relax  (opening  of pyloric sphincter )
Small gut
Inhibit peristalsis
Vasoconstriction (vaso motor)
stimulate peristalsis
relax ileocolic sphincter
increase secretion of gland (secretomotor)
Vasodilatation (vaso motor)
Summary : effect
•       Produce mass reaction
•       Cutaneous blood vessels undergo vasoconstriction but, skeletal and coronary vessels are dilated thus supplying more blood to the muscles, heart, brain. Heart rate is increased, blood pressure and blood sugar are elevated , pupil and bronchi are dilated. Intestinal peristalsis is suppressed and the sphincters of gut are closed.

Produces locatised and isolated effects
The heart rate is diminished, the blood pressure falls, the pupils are constricted, the peristalsis and glandular secretions of the alimentary tract are promoted to help absorption of the nutrients, and the urinary bladder and rectum are evacuated.
Eye
Pupil dilates
Pupil constricts: accommodation of lens
*Uterus
Uterine contraction
Vasoconstriction
Vasodilatation
Salivary glands
_
secretomotor
Pancreas
_
secretomotor
Gastric glands
_
secretomotor
Adrenal glands
secretomotor
_
Vessels of Skeletal muscle
Vasodilatation
…
Sweat gland
secretomotor
_
Afferents
Convey most of the visceral pain except pelvic organ

Convey  visceral pain from  pelvic organ
Cells of origin of afferents fibres
Dorsal root ganglia of T 1 to L1/L2
Cranial part ganglia of 9th cranial nerve and inferior ganglia of 10th cranial nerve
Sacral part : dorsal root ganglia of S2-S4
Central control
Posterior part of hypothalamus
Anterior part of hypothalamus

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