2. Autonomic Nervous System
Introduction
Chapter 61,pg773,Guyton 13th edition

4. Autonomic Nervous System
Visceral functions
Heart
GIT
Urinary Bladder
Rapidity & Intensity

5. Autonomic Nervous System
Higher control:
Spinal cord
Brain Stem
Hypothalamus
portions of the cerebral cortex,esp. limbic cortex, can transmit signals to the lower centers & can influence autonomic control.

6. ANS also operates through visceral reflexes i. e
ANS also operates through visceral reflexes i.e. subconscious sensory signals from visceral organs autonomic ganglia, the brain stem, or the hypothalamus return subconscious reflex responses directly back to the visceral organs to control their activities.

7. Visceral Reflexes

8. Efferent autonomic signals are transmitted to the various organs of the body through two major subdivisions
Sympathetic nervous system
Parasympathetic nervous system

12. In the central nervous system, a collection of neuron cell bodies is called a nucleus. In the peripheral nervous system, a collection of neuron cell bodies is called a ganglion.

13. Sympathetic system is also referred to
fear flight n fight response.
It extends between T1-L2, also called thoraco-lumber division.

14. Physiological Anatomy of the Sympathetic Nervous System
(1) one of the two paravertebral sympathetic chains of ganglia that are interconnected with the spinal nerves on the side of the vertebral column.
(2) prevertebral ganglia(the celiac, superior mesenteric,aortico-renal, inferior mesenteric,and hypogastric).
(3) nerves extending from the ganglia to the different internal organs

15. postganglionic neuron
Each sympathetic pathway from the cord to the stimulated tissue is composed of two neurons,
preganglionic neuron
postganglionic neuron
in contrast to only a single neuron in the skeletal motor pathway
The cell body of each preganglionic neuron lies in the intermediolateral horn of the spinal cord; its fiber passes through a ventral root of the cord into the corre-sponding spinal nerve.

16. After the spinal nerve leaves the spinal canal, the preganglionic sympathetic fibers leave the spinal nerve and pass through a white ramus into one of the ganglia of the sympathetic chain.

18. The fibers then can take one of the following three courses:
(1) they can synapse with postganglionic sympathetic neurons in the ganglion that they enter;
(2) they can pass upward or downward in the chain and synapse in one of the other ganglia of the chain; or

19. (3) they can pass for variable distances through the chain and then through one of the sympathetic nerves radiating outward from the chain, finally synapsing in a peripheral sympathetic ganglion.

20. Sympathetic Nerve Fibers in the Skeletal Nerve
Some of the postganglionic fibers pass back from the sympathetic chain into the spinal nerves through gray ramiat all levels of the cord.
These sympathetic fibers are all very small type C fibers, and they extend to all parts of the body by way of the skeletal nerves.

22. They control the blood vessels, sweat glands, and piloerector muscles of the hairs.
About 8 percent of the fibers in the average skeletal nerve are sympathetic fibers.

25. Segmental Distribution of the Sympathetic Nerve Fibers.
The sympathetic pathways that originate in the dif-ferent segments of the spinal cord are not necessarily dis-tributed to the same part of the body as the somatic spinal
nerve fibers from the same segments. Instead, the

26. Sympathetic fibers from cord segment
(1) T1 generally pass up the sympathetic chain to terminate in the head;
(2) from T2 to terminate in the neck;
(3) from T3, T4, T5, and T6 into the thorax;
(4) from T7, T8, T9, T10, and T11 into the abdomen;
(5) from T12, L1, and L2 into the legs.
This distribution is only approximate and overlaps greatly.

27. The distribution of sympathetic nerves to each organ is determined partly by the locus in the embryo from which the organ originated.
For instance, the heart receives many sympathetic nerve fibers from the neck portion of the sym-pathetic chain because the heart originated in the neck of the embryo before translocating into the thorax.

28. Special Nature of the Sympathetic Nerve Endings in the Adrenal Medullae.
Preganglionic sympathetic nerve fibers pass, without synapsing,all the way from the intermediolateral horn cells of the spinal cord, through the sympathetic chains, then through the splanchnic nerves, and finally into the two adrenal medullae.

29. There they end directly on modified neuronal cells that secrete epinephrine and norepinephrine into the blood stream

31. Physiological Anatomy of the Parasympathetic Nervous System
Parasympathetic fibers leave the central nervous system through cranial nerves III, VII, IX, and X.
Additional parasympathetic fibers leave the lowermost part of the spinal cord through the 2nd and 3rd sacral spinal nerves and occasionally the S1 and S4 nerves.

32. About 75 percent of all parasympa-thetic nerve fibers are in the vagus nerves(cranial nerve X), passing to the entire thoracic and abdominal regions of the body.

34. Parasympathetic fibers in the III cranial nerve go to the pupillary sphincter and ciliary muscle of the eye.
Fibers from VII cranial nerve pass to the lacrimal, nasal, and submandibular glands, and
Fibers from the IX cranial nerve go to the parotid gland.

35. The sacral parasympathetic fibers are in the pelvic nerves,which pass through the spinal nerve sacral plexus on each side of the cord at the S2 and S3 levels.
These fibers then distribute to the descending colon, rectum, urinary bladder, and lower portions of the ureters.

39. Basic Characteristics
Cholinergic & Adrenergic Fibers

40. Sweat Glands, Piloerecror Muscle,
Sympathetic
Parasympathetic
Cholinergic
Cholinergic
Cholinergic
Sweat Glands, Piloerecror Muscle,
A few Blood Vessels
Cholinergic
Adrenergic

43. Metabolism of Neurotransmitters
Norepinephrine
Synthesis
From Tyrosine
In axoplasm of nerve endings
Removal
Reuptake
Diffusion into body fluid n into Blood
Enzymes
MAO(in nerve endings)
catechol-O-methyl transferase(in tissues)
Acetylcholine
Synthesis
From Choline
In terminal nerve endings
Destruction
Acetylcholinesterase

45. Norepinephrine and epinephrine secreted into the blood by the adrenal medullae remain active until they diffuse into some tissue, where they can be destroyed by catechol-O-methyl transferase; this action occurs mainly in the liver.

46. Circulation of neurotransmitters
Acetylcholine:
Local
Noradrenalin/ Norepinephrine:
Blood
Adrenalin/ Epinephrine
Hormone

47. Synthesis & Release of Acetylcholine

48. Other Neurotransmitters
Dopamine
GnRH (Gonadotrophin Releasing Hormone)
Co-transmitters
VIP
ATP
Neuropeptide Y

49. Release of autonomic neurotransmitters in Smooth Muscle

50. Autonomic receptors

51. Muscarinic receptors, use G proteins as their signaling mechanism, are found on all effector cells that are stimulated by the postganglionic cholinergic neurons of either the parasympathetic nervous system or the sympathetic system.
Nicotinic receptors are ligand-gated ion channels found in autonomic ganglia at the synapses between the preganglionic and postganglionic neurons of both the sympathetic and parasympathetic systems.

52. Two major types of alpha receptors, alpha1and alpha2 which are linked to different G proteins.
The beta receptors are divided into beta1,beta2 and beta3 receptors because certain chemicals affect only certain beta receptors. The beta receptors also use G proteins for signaling.

56. Adrenergic
Receptors

58. Function of the autonomic nerves is determined by the type of receptor

59. Mainly act on alpha receptors to a lesser extent on beta receptors.
Norepinephrine
Epinephrine
Mainly act on alpha receptors to a lesser extent on beta receptors.
Strong constriction of blood vessels in muscles.
Increases peripheral resistance, increases arterial pressure.
Increases cardiac output to a lesser extent.
Acts equally on both the receptors.
Weak constrictor of blood vessels.
Increases arterial pressure to a lesser extent.
Greater affect on cardiac stimulation, greater increase in cardiac output
5 to 10 times greater metabolic affect

60. Sympathetic and Parasympathetic Tone
It allows a single nervous system both to increase and decrease the activity of a stimulated organ.
Intrinsic compensation

61. Autonomic Reflexes Cardiovascular Autonomic Reflexes.
Gastrointestinal Autonomic Reflexes.
Other Autonomic Reflexes.

62. ALARM OR STRESS RESPONSE
Mass discharge
Increased Arterial pressure
Increased blood flow to active muscle
Increased cellular metabolism
Increased blood glucose concentration
Increased glycolysis in liver and muscle
Increased muscle strength
Increased mental activity

63. Sympathetic functions

64. Parasympathetic functions

65. Autonomic functions Organ Parasympathetic Sympathetic EYE HEART
Miosis
Near Accommodation
Mydriasis
Opposite
HEART
↓ Heart rate
↓ force of contraction
↓ Conduction of velocity
(ß-1 receptors)
BLOOD VESSELS
Dilation ?
Alpha receptors: Constriction
ß-2 receptors : Dilatation e.g. Coronary arteries, skeletal muscles

66. Organ
Parasympathetic
Sympathetic
Lungs
Muscle contraction
↑ secretion
Opposite(ß-2)
GIT
Stomach, Intestine
↑ Motility
↑ Secretions
Sphincters relaxed
Gall Bladder/Ducts:
Contraction
Opposite
URINARY BLADDER
Muscle Contraction
Sphincter relaxed
MTABOLISM
Anabolism
Catabolism (ß receptors)
↑ glycogenolysis
↑ lipolysis
↑ BMR

67. Organ
Parasympathetic
Sympathetic
Kidney
Nil
↑ Renin
Mental activity ↑
Skeletal Muscle
↑ Glycogenolysis
↑ Stretch

68. Autonomic functions

69. Autonomic Functions Opposite Parasympathetic: Sympathetic:
Excitatory/Inhibitory
Parasympathetic:
Localized
Sympathetic:
Diffuse

70. The topic will be repeated in All Systems
Thank You
The topic will be repeated in All Systems