1	The Autonomic Nervous System
2	Objectives Describe the A & P of the ANS Compare the SNS and PNS Explain the function of the SNS List the four adrenergic receptors and explain the effect of each one on body organs Explain the function of the PNS
3	Nervous System Organization
4	Central Nervous System (CNS) Consist solely of : Brain Spinal Cord
5	Peripheral Nervous System (PNS) Composed of the cranial nerves and the peripheral nerves. Can be further divided into: Somatic Nervous System (SNS) Autonomic Nervous System (ANS)
6	Somatic Nervous Systems AKA Voluntary Nervous System Controls voluntary motor functions such as movement
7	Autonomic Nervous System AKA Autonomic Nervous System Controls involuntary autonomic functions such as digestion and pupil dilation and constriction Can further be divided into: Sympathetic Nervous System Parasympathetic Nervous System
8	Autonomic Nervous System Located mostly outside the CNS It does arise from the CNS and subsequently enter the autonomic ganglia Nerve fibers that leave the CNS and terminate in the autonomic ganglia are called preganglionic nerves. Nerves that leave the autonomic ganglia and terminate at the target tissue are called postganglionic nerves.
9	Autonomic Nervous System No physical contact exist between nerve cells or neuron and target organ. Instead a synapse and neuroeffector junction exist respectively. Neurotransmitters are thus used to conduct the nerve impulses between the presynaptic neuron and travel to postsynaptic neuron
10	Autonomic Nervous System Neurotransmitters of the ANS are Acetylcholine (Ach) Preganglionic – SNS Preganglionic and postganglionic – PNS Cholinergic synapses Norepinephrine Preganglionic and postganglionic – SNS Agrenergic synapses
11	Sympathetic Nervous System Arises from the thoracic and lumbar region of the spinal cord. Preganglionic nerves leave the spinal cord through spinal nerves and ends in the sympathetic ganglia. Two types of sympathetic ganglia: Sympathetic chain ganglia Collateral ganglia
12	Sympathetic Nervous System Sympathetic Chain Ganglia Postganglionic nerves leave the SNS and target several tissues. When stimulated Stimulate secretion by sweat glands Constriction of blood vessels in the skin Increase in blood flow to skeletal muscles Bronchodilation Stimulation of energy production
13	Sympathetic Nervous System Collateral ganglia Located in the abdominal cavity When stimulated Blood flow to the ABD is decreased Decreased digestive activity Relaxation of smooth muscles in the wall of the urinary bladder Release of glucose stores from the liver
14	Sympathetic Nervous System The SNS directly stimulates the adrenal medulla to release the following 2 hormones: Epinephrine (adrenalin) - 80% Norepinephrine (noradrenalin) – 20% Figure 6-3
15	Sympathetic Nervous System Adrenergic Receptors Four types of adrenergic receptors: Alpha₁ (a₁) – peripheral vasoconstriction Alpha₂ (a₂) - inhibitory Beta₁ (b₁) – increase HR and contraction Beta₂ (b₂) – vasodilation and bronchodilation Dopaminergic receptors – cause dilation of the renal, coronary, and cerebral arteries. Table 6-2
16	Parasympathetic Nervous System The PNS arises from the brain stem and the sacral segments of the spinal cord. Very long preganglionic neurons. Located very close to the target tissues Impulse travels from one of the 4 cranial nerves III, VII, IX, X and from sacral spinal serves. (fig 6-5)
17	Parasympathetic Nervous System Stimulation of the PNS results in the following: Pupillary constriction Secretion by digestive glands Increased smooth muscle activity along the digestive tract Bronchoconstriction Reduction in heart rate and contractile force
18	Parasympathetic Nervous System Uses acetycholine as a neurotransmitter ACh is quickly broken down into acetic acid and choline by acetylcholinesterase and reabsorbed by the presynaptic neuron. (fig 6-6) ACh is also used as a neurotransmitter of the somatic nervous system. 2 main types of ACh receptors in PNS Nicotinic Muscarinic (Table 6-3)
19	Key Word Review
20	Questions???