Articles & News Stories

A.N.S

Description
Biology
Published
of 2
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Related Documents
Share
Transcript
  A A N N S S  D D r r .. O O s s a a m m a a  A A b b o o  E E l l  N N a a s s r r  0 0 1 1 2 2 5 5 0 0 2 2 4 4 7 7 4 4 5 5   (1) DDii f  f  f  f eer r eennc c eess bbeet t  w  w eeeenn ssoommaat t iic c  && aauut t oonnoommiic c  r r ee f  f llee x  x  aar r c c    Autonomic reflex arc Somatic reflex arc 1.Receptor In the viscus or internal organ In the skin   2.Afferent Pass via a dorsal root or cranial nerve & has its cell body in the dorsal root ganglia The same   3.Center Lateral horn cells (LHCs)   Anterior horn cells   4.Efferent Composed of 2 neurons: preganglionic & postganglionic in between the 2 autonomic ganglia Composed of 1 neuron only 5.Effector Organ Smooth muscle, cardiac muscle or gland Skeletal muscle 6.Velocity of Conduction Slow due to thin nerve fiber   Fast due to thick nerve fiber Autonomic ganglia act as distribution center: -Each preganglionic axon diverges to an average of 8-9 postganglionic neurons   diffuse autonomic output. -In sympathetic system: preganglionic fiber synapse & activate many postganglionic neurons   generalizing sympathetic effects. -In parasympathetic system: preganglionic fiber synapse & activate only few postganglionic neurons    localized parasympathetic effects. *Function of Sympathetic system at rest: -The sympathetic system is continuously active. -The basal rate of activity is called sympathetic tone . -The sympathetic tone is mainly to maintain arterial pressure & help in distribution of blood to the various tissues.  A A N N S S  D D r r .. O O s s a a m m a a  A A b b o o  E E l l  N N a a s s r r  0 0 1 1 2 2 5 5 0 0 2 2 4 4 7 7 4 4 5 5   (2) Function of Sympathetic system in emergency (Alarm response 'stress response'): 1.Eye: dilatation of the pupil more light into the eye. 2.Heart:  increase heart rate &force of contraction & increase blood pressure   better perfusion of the vital organs & muscle. 3.Lung: bronchodilatation to ensure better ventilation & more O 2 . 4.Liver:  increase glycogenolysis elevating blood glucose level 5.Spleen: Contraction of Splenic capsule & squeezing of blood rich RBC s into the circulation. 6.Adrenal medulla: secretion of adrenaline & noradrenaline in the blood potentiating sympathetic activity. 7.Skin: -Vasoconstriction of blood flow limiting bleeding if wound. -Sweat glands: secretion of sweat increasing heat loss from the body. 8.Musle: Orbelli phenomenon : Better contraction, delayed fatigue & early recovery of skeletal muscle after fatigue. 9.Blood vessel: the blood flow is shifted from peripheral & unimportant organs as skin & splanchnic areas to important areas as CNS & muscle. 10.Metabolism: increase glucose &free fatty acids level supplying more energy. 11.CNS:- increase mental activity. -activation or reticular formation: reinforcing the alert &   arousal state.   -Types of cholinesterase: *True cholinesterase: -Present in the cell membranes of cholinergic nerve terminals. *Pseudocholinesterase: -present in the fluid surrounding the cholinergic nerve terminals as small amount of ACh diffuse to the surrounding fluids. -Value of cholinesterase: -It's value is to keep action of ACH localized in the site of liberation, otherwise it may diffuse to the blood giving generalized effect 6.Role of adrenal medulla in function of sympathetic system: -The organs are actually stimulated by 2 ways at the same time: *Directly by sympathetic nerves. *Indirectly   by medullary hormones adrenaline & noradrenaline. -Total loss of 2 adrenal medulla has a little effect on the sympathetic actions because the direct pathway can still perform all necessary functions.

O MQTT_ 5 Steps

Jan 24, 2019
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks