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Lecture 4:

AUTONOMIC

• Red : important • Pink : in girls slides only • Blue : in male slides only • Green : notes, Extra Objectives

At the end of the lecture, students should be able to:

❖ Define the . ❖ Describe the structure of autonomic nervous system ❖ Trace the preganglionic & postganglionic in both sympathetic & parasympathetic nervous system. ❖ Enumerate in brief the main effects of sympathetic & parasympathetic system Autonomic Nervous System

The autonomic nervous system is concerned with the Autonomic nervous system: Nerve cells innervation and control of Involuntary structures such as located in both central & visceral organs, smooth muscles, cardiac muscles and glands. peripheral nervous system

Skeletal muscles are controlled by somatic motor Difference between somatic and visceral motor: ● Somatic motor ● Function: Maintaining the homeostasis Fibers from Anterior horn cell —-> to target

of the internal environment along with ● Visceral motor Regulation: (Controlled) the endocrine system. 1-Brain: from nuclei by the Hypothalamus 2- spinal cord: lateral horn cell Note: Hypothalamus controls ﺗﻌدي ﻋﻠﻰ . ﻗﺑل ﺗوﺻل ﻟﻠـ Location: and Target ● both of Autonomic system + peripheral nervous system Endocrine system. Autonomic Nervous System

Unlike the somatic nervous system, the Efferent pathway

of the autonomic nervous system is made up of Preganglionic two neurons called as:

Preganglionic Postganglionic

The cell bodies are The cell bodies are Postganglionic Neuron located in the brain located in the and spinal cord autonomic ganglia (inside CNS ). (outside CNS). Preganglionic with the postganglionic neurons

Note: before the fibers reach the target, it should first pass by the autonomic ganglion and synapse ( interconnection). Synapse: a junction between two nerve cells Based on the anatomical, physiological and pharmacological characteristics, the autonomic nervous system is divided into:

Sympathetic Parasympathetic VS Activated during Concerned with exercise, excitement, conserving energy. and emergencies.

“fight, flight, or fright” “rest and digest”

Both divisions operate in conjunction with one another (have antagonistic control over the viscera) to maintain a stable internal environment For more understanding click here

Sympathetic Parasympathetic

Preganglionic neuron is in the Preganglionic neuron is in CNS. the CNS.

The Preganglionic fiber() The Preganglionic is shorter fiber(axon) is longer

The Postganglionic neuron is The Postganglionic neuron is in the PNS and far from the in the PNS and close to the target target

The Postganglionic The Postganglionic fiber(axon) is longer fiber(axon) is shorter Target organ Target organ

Note438: The cause of preganglionic (White) and postganglionic (Grey) fibers having different colors is the sheath that the preganglionic fibers (white) are sheeted with. Myelin helps isolate preganglionic (ﺗﺧﻠﯾﮫ ﻣﻌزول اﻛﺛر وﯾوﺻل اﺳرع) .fibers for faster transportation Sympathetic Nervous System

Postganglionic fiber

Preganglionic fiber

L2 Sympathetic Division

1- Preganglionic Neurons: 2- Postganglionic ganglia: Located nearer the central nervous system as: located in the lateral gray horn of

T1-L2 segments of spinal cord Prevertebral is the celiac and mesenteric (ThoracoLumbar outflow) In front of vertebral column

Paravertebral forming sympathetic chain

Next to,Parallel IMPORTANT NOTE(438): Sympathetic neurons only found in spinal cord NOTE: as their preganglionic neurons are short, their ganglia (POSTGANGLIONIC NEURONS) are located near to the CNS (spinal cord). NOTE: Outflow means the passage of impulses outwardly from the central nervous system. Postganglionic ganglia Paravertebral Ganglia

They are interconnected to form 2 sympathetic chains, one on each side of vertebral column.

3 in Cervical part of chain

Number of ganglia: 11-12 in Thoracic part

4 in Lumbar & Sacral parts each

The chains end into a common “” in front of coccyx. Preganglionic Fibers Within the sympathetic chain, these fibers may:

● Run in the ventral roots of 1- ascend : to move upward. 4- leave the sympathetic chain the spinal nerve. 2- descend : to move (without synapse) to reach downward. coeliac & mesenteric ganglia ● Travel through the spinal nerve, and then join the 3- remain at the same level Preganglionic fibers sympathetic chain via the to synapse with neurons surrounded by (around White Rami Communicans. (postganglionic) of branches of abdominal aorta) (WRC). paravertebral ganglia located to synapse with their neurons *Between nerve and ganglion in sympathetic chain. (postganglionic). *white ramus Preganglionic fibers = before rely Postganglionic fibers

1-Fibers from the sympathetic chain: Enter again into the spinal nerve through (Grey Rami Communicants), to supply structure in head, + blood vessels and sweat glands.

2- Fibers from the cells of coeliac, mesenteric(superior & inferior): supply abdominal and pelvic viscera Parasympathetic division

Cranial flow Sacral flow

Preganglionic Nuclei of the 3rd, 7th, 9th & 10th The lateral gray horn of cranial nerves, in the brain stem S2-S4 segments of (Cranial outflow) cord (Sacral outflow)

carried by 3rd, 7th, 9th & 10th Are carried by pelvic Preganglionic cranial nerves and terminate in to ciliary, pterygopalatine, peripheral ganglia in fiber (axon) submandibular, otic & peripheral where they synapse. ganglia

ciliary pterygopalatine, peripheral ganglia in pelvis Postganglionic Postganglionic submandibular, otic & peripheral ganglia. neuron

Postganglionic axons innervate innervate organs of the Postganglionic (supply) organs of the: fiber(axon) pelvis and lower head, , thorax, and abdomen fiber (axon) Structure Sympathetic effect Parasympathetic effect

pupil Constricts pupil (ﺗﺗوﺳﻊ) Iris of the eye(pupils) Dilates

Ciliary muscle of the eye Relaxes Contracts

Salivary glands Reduces secretion Increases secretion

Reduces secretion Increases secretion (اﻟﻐده اﻟدﻣﻌﯾﺔ) Lacrimal gland

Heart Increases rate and force of contraction Decreases rate and force of contraction

Dilates Constricts (اﻟﺷﻌب اﻟﮭواﺋﯾﺔ) Bronchi

Gastrointestinal tract Decreases motility Increases motility

Sweat glands Increases secretion ------

Erector pili muscles (attached to hair follicles) Contracts ------

MCQs

Q1) Preganglionic fibers of the sacral outflow are carried by: A) B) C) D) Peripheral ganglion

Q2) Post ganglionic neurons syanpse with: A) Preganglionic neuron B) Target organs C) Postganglionic fibers D) Preganglionic fibers

Q3) The cell bodies of preganglionic neurons are located in A) Spinal cord B) Brain C) Peripheral nervous system. D) A and B

Q4) Autonomic nervous system is requlated by: A) Pineal gland B) Diencephalon C) Hypothalamus D) Thymus gland

Q5) The parasympathetic division is activated during: A) Exercise B) Fear C) Conserving energy. D) Excitement

Q6) Which of the following is a parasympathetic effect: A)Decreased secretion of lacrimal gland B) Constriction of the ciliary muscle of the eye

C) Dilated iris of the eye D) Dilated bronchi

1-C 2-B 3-D 4-C 5-C 6-B 5-C 4-C 3-D 2-B 1-C Team members:

Team leaders:

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