Powerpoint 7 – Autonomic Nervous System (ANS)

1. Autonomic Nervous System (ANS)a. The ANS Innervates…

i. Internal organsii. Sweat glands

iii. Endocrine glandsiv. Smooth muscles of blood vessels

1. Control blood pressureb. Made of two parts

i. Sympathetic system1. Originates from the spinal cord, from T1 to L2 or L3 called thoraco-lumbar.

ii. Parasympathetic system1. Originates from two parts…

a. (1) Brain stem - the nuclei for cranial nerves (CN) 3, 7, 9, and 10b. (2) Spinal cord - S2 to S4 of spinal cord (sacral portion of spinal cord)

called the cranio-sacral. (Some sources say from S1-S3)

2. Functions of the ANSa. Sympathetic

i. Active when your body is active (running, swim, hiking, dancing, fear)1. Heart rate increases2. Respiratory rate increaess3. Sweat glands are active4. Sphincters close5. Relaxation of smooth muscle in bronchi in respiratory system6. Dilation of pupils7. Contraction of blood vessels (blood vessel wall constricts)

a. Increase blood supply to different tissue cells b. Increases blood pressure

b. Parasympathetici. Active when your body rests (sleeping) conserves and stores energy

1. Heart rate decreases decreases contractivity of myocardium2. Decreases nerve conductivity3. Body relaxes4. Sphincters open5. Constriction of pupils6. Increases peristalsis wavelike muscle contraction that pushes food through

digestive tract7. GI tract is more active

a. Increased digestion and absorption of nutrientsb. Digestion and absorption controlled by parasympathetic system

c. Increases GI tract secretion of endocrine hormones

3. Organization of ANSa. Sympathetic and parasympathetic have two fibers

i. Preganglionic fibersii. Postganglionic fibers

b. Each fiber for each system releases specific neurotransmittersi. Sympathetic system

1. Preganglionic neurotransmitters Ach2. Postganglionic neurotransmitters Noradrenaline (norepinephrine - NE)

ii. Parasympathetic system1. Preganglionic neurotransmitters Ach2. Postganglionic neurotransmitters Ach

c. Each neurotransmitter has specific receptorsi. Ach receptor called cholinergic receptor

1. 2 types of cholinergic receptorsa. Nicotinicb. Muscarinic

ii. NE receptor called adrenergic receptor1. 4 types of adrenergic receptors

a. Alpha 1 (α - 1)b. Alpha 2 (α - 2)c. Beta 1 (β - 1)d. Beta 2 (β - 2)

d. Most important: For ANS, effect of neurotransmitter depends on two important thingsi. Type of receptorii. Location of receptors

4. Sympathetic System Organizationa. Preganglionic fibers of sympathetic system are located from T2 to L2 or L3 in spinal cordb. Dorsal part of spinal cord (toward back) for sensory systemc. Ventral part of spinal cord (toward front) for motor systemd. Lateral part (lateral horn) of spinal cord is for autonomic nervous system (center for ANS)e. There is a chain of sympathetic ganglia which is close to the spinal cord and runs lateral and parallel

to spinal cord.f. Abdominal cavity (contains stomach) has 3 extra ganglia which are only located in abdominal

cavity.g. Innervation of Internal Organs in Thoracic Cavity

i. Preganglionic fibers from lateral horn of spinal cord travel to sympathetic ganglion which runs alongside the spinal cord and they synapse to the postganglionic fibers in sympathetic ganglia tract.

ii. Preganglionic fibers releases Ach which binds to the nicotinic type of cholinergic receptor on the postganglionic fiber. This stimulate postganglionic fibers.

iii. Postganglionic fibers take information to internal organs by stimulating them with norepinephrine/noradrenaline (NE).

iv. NE from postganglionic fibers has alpha 1, alpha 2, beta 1, and beta 2 receptors inside internal organs such as heart and stomach.

h. Innervation of Internal Organs in Abdominal Cavityi. In abdominal cavity, the lumbar region, the preganglionic fibers travel toward the

sympathetic chain.ii. They pass through sympathetic chain without synapsing and synapse instead with the 3

extra postganglionic fibers.iii. Preganglionic fibers stimulate postganglionic fibers by releasing Ach.iv. Postganglionic fibers travel to internal organs in abdominal cavity and stimulate with

norepinephrine (NE).i. Exception to Innervation in Abdominal Cavity Adrenal Medulla – center part of adrenal gland

(located on top of kidneys)i. Innervation of adrenal medulla is just by preganglionic fiber. ii. Preganglionic fibers releases Ach and activate adrenal medulla for secretion of adrenaline

and noradrenaline (NE) hormones.

5. Effect of NE on Alpha 1 Receptorsa. Alpha 1 receptors located…

i. Smooth muscle of blood vesselsii. Wall of GI tract

iii. Sweat glandsiv. Sphincter or urinary bladderv. Muscle of iris

b. Mechanism of action of norepinephrine (NE) on alpha 1 adrenergic receptorsi. NE binds to alpha 1 receptor on target cellii. This activates proteins in the cytoplasm called G protein

iii. G protein has subunits alpha, beta, and gamma. We need alphaiv. Alpha has two subunits…

1. S subunit stimulatory2. I subunit inhibitory

v. For this case, NE binds to alpha 1vi. This activates G protein Alpha-S (stimulatory)vii. This activates phospholipase C enzyme

viii. This activates Enzyme IP3

ix. This activates SR which releases more calcium in cytoplasm. Calcium binds and activates microfilaments like myosin leading to muscle contraction.

c. Physiological reaction of smooth muscle to NE vasoconstrictioni. NE causes smooth muscle to contract of squeeze blood vessels which increases blood

pressure. ii. If target cell is sphincter or urinary bladder closure of sphincter.

6. Effect of NE on Alpha 2 Receptorsa. Alpha 2 receptor locations…

i. GI tractii. Fat cells

iii. Presynaptic nerve terminalsb. Mechanism of action of NE on Alpha 2 receptors

i. NE binds to alpha 2 receptorsii. This activates G protein alpha-I (inhibitory)

iii. This inhibits AC (adenylate cyclase) prevents activation of ACiv. This decreases cAMP which means it decreases cellular energyv. This means no contraction but instead relaxation and dilation.

c. Physiological reaction of NE on Alpha 2 receptorsi. Relaxation of smooth musclesii. Dilation of sphincter in urinary bladder

7. Effect of NE on Beta 1 Receptora. Location of beta 1 receptor

i. Mostly located in heart, specifically in…1. SA node sinoatrial node2. AV node atrioventricular node3. Myocardium muscle

ii. Mechanism1. When NE binds to beta I receptor2. This activates G protein alpha-S (stimulatory)3. Activates AC adenylate cyclase4. Increases intracellular energy cAMP.

iii. Physiological reaction of NE on Beta 1 receptors1. Increase heart rate2. Increases contractility of myocardium3. Increase conduction velocity in neurons

iv. Example: 25 year old female has increase in NE1. Symptoms

a. Heart palpitationb. Heart disease

2. Treatmenta. You need a beta receptor blocker to block NE affect. b. Beta I blocker is Propranolol.c. When patient has heart problem, such as ??? cardium, and has asthma, you

cannot use propranolol because it blocks beta I and beta II receptors (in smooth muscle in bronchi).

i. Instead of propranolol, you can use Atenolol which only recognizes and blocks beta I but not beta II.

8. NE effect on Beta II Receptora. Location of Beta II receptor

i. Smooth muscle of bronchi in respiratory systemb. Mechanism

i. NE binds to beta IIii. This stimulates G protein alpha-S (stimulatory)

iii. This stimulates ACiv. This increase intracellular energy cAMPv. This relaxes smooth muscle

c. Asthma treatmenti. We have to relax smooth muscle in bronchi by stimulating Beta II receptors. ii. Albuterol acts like NE on Beta II receptors and relaxes bronchi.

9. Parasympathetic System Organization

a. Has a cranial and sacral portionb. Origin is called cranio-sacral.c. No ganglionic tract. d. Innervation of Internal Organs by this system

i. Preganglionic fibers travel directly to internal organs and synapse with post ganglionic fibers on inner wall of internal organs.

ii. Synapses occur in internal wall of internal organ. iii. Preganglionic and postganglionic fibers both release Ach and have cholinergic receptors.

1. Nicotinic receptors in…a. Neuromuscular junctionb. Adrenal medulla

2. Muscarinic receptors in…a. GI tractb. Heart

e. Example: What is effect of Ach on heart?i. Decreases heart rate (Ach decreases, NE increases)

f. Nerves for Parasympathetic systemi. Cranial portion is formed of 4 nuclei of cranial nerves

1. Nerve 3 Oculomotor2. Nerve 7 Facial3. Nerve 9 Glossopharyngeal4. Nerve 10 Vagus

a. Vagus nerve has 3 nuclei in brain stemi. 1st nucleus is for motorii. 2nd nucleus is for sensory

iii. 3rd nucleus is for autonomic nervous system parasympatheticb. Vagus nerve is main nerve of parasympathetic which innervates all internal

organs in thoracic, abdominal, and pelvic cavities.c. Vagus nerve releases Ach

i. Positive affect on GI tract1. Increases motility2. Increases secretion of hormones

ii. Negative affect on heart1. Decreases heart rate by decreasing contraction of

myocardium

10. Brain stem has three partsa. Midbrain

i. Contains renal system center (micturition center)b. Pons

i. Center for part of respiratory system (pneumotaxic center)c. Medulla oblongata

i. Medulla contains important centers…1. Cardiovascular center (vasomotor center)2. Respiratory center3. Vomiting, swallowing, coughing

d. Hypothalamusi. Contains emotional behaviorii. Sexual behavior

iii. Appetiteiv. Learningv. Memory

vi. Endocrine systemvii. Sleep

viii. Body temperature

11. Adrenergic receptorsa. Alpha I – Postsynapticb. Alpha 2 – Presynapticc. Beta 1 – Heartd. Beta 2 – Smooth muscle of bronchi, GI tract, liver

12. Heat (really important)a. Sympathetic everything increases in heart

i. Chronotropic means heart rate. ii. Dromotropic means conduction velocity and conductivity of myocardium.

iii. Chronotropic and dromotropic increases in sympathetic. iv. Dilates coronary artery

b. Parasympathetic decreases everything in hearti. Beta 1 adrenergic ii. Vasoconstriction of coronary arteries

iii. Decrease heart rate (-ve chronotropic)iv. Decrease conduction speed (-ve dromotropic)

13. Lunga. Sympathetic

i. Beta 2 important ii. Decreases mucus secretion

iii. Constricts blood vesselsiv. Dilates bronchi

b. Parasympathetici. Increases mucus secretion in glandsii. Dilates blood vessels

iii. Constricts bronchi

14. Parasympathetic neurotransmitter is Ach, sympathetic is NEa. Ach effect on glands increases mucus secretion

15. GI tracta. Mostly controlled by parasympatheticb. Main neurotransmitter – Achc. Vagus nerve is most important and controls everything in thoracic, abdominal, and pelvic cavityd. Active in Gi tracte. Sympathetic

i. Beta 2 receptors relax peristalsisii. Alpha receptors constrict sphincters

iii. Decreases gland secretionf. Parasympathetic

i. Activates peristalsisii. Relaxes sphincters

iii. Increases gland secretion

16. Livera. Sympathetic

i. Controls gluconeogenesis by beta 2 receptorb. Parasympathetic

i. Glycogenesis

17. Gall bladdera. Sympathetic relaxes by beta 2 receptorb. Parasympathetic constricts (sphincter)

18. Pancreasa. Parasympathetic

i. Controls insulin secretion ii. Increases secretion of pancreatic enzymes

b. Sympathetici. Inhibits secretion of pancreatic enzymes by alpha 2 receptorsii. Beta receptors activate insulin secretion

19. Adrenal medullaa. Innervation by preganglionic fiber of sympathetic system

i. Neurotransmitter of sympathetic Ach b. Parasympathetic has no effect

20. Urinary bladdera. Sympathetic

i. Controls filling of urinary bladder with urine by alpha 1 and beta 2 receptorsb. Parasympathetic

i. Controls emptying of urinary bladder by muscarinic receptor.

21. Uterusa. Pregnant females

i. Contraction by alpha I receptor of sympatheticb. Nonpregnant female

i. Relaxation of uterus by beta 2 receptor

22. Genitalsa. Emission means circulation of siemens in vas deferens

i. Controlled by sympathetic

b. Erection controlled by parasympathetic (vasodilation)c. Ejaculation is controlled by both parasympathetic and sympathetic because during ejaculation

erection also exists.