Autonomic Nervous System

Sympathetic Effects tend to last longer than parasympathetic effects

-ACh released by parasympathetics is broken down quickly at synapse -NE by sympathetics is reabsorbed by nerve, diffuses to adjacent tissues and passes into bloodstream

Unique roles of sympathetic division

-Thermoregulatory responses to heat -RElease of renin from kidneys -Increases metabolic rates of cells -Raises blood glucose levels -Mobilizes fats for use as fuel

Explain how the two divisions of the ANS differ in general function

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Describe the different classes of receptors in the ANS and how they relate to autonomic responses

Ach has two types of receptors 1) Muscarinic receptors which are on all cardiac muscle, smooth muscle and gland cells. They can be excitatory or inhibitory 2) nicotinic receptors which are on all ANS postganlionic neurons, in the adrenal medulla and at neuromuscular junctions of skeletal muscles -They are excitatory when ACh binding occurs

Atropine

Blocks muscarinic ACh receptors -Used to prevent salivation during surgery

Explain how the ANS controls many target organs through dual innervations, and how control is exerted in the absence of dual innervations

Dual Innervation: All visceral organs are served by both divisions (sympathetic and parasympathetic) but cause opposite effect. The dynamic antagonism between two divisions is what maintains homeostasis Antagonistic: oppose each other Coopertive effect: two divisions act on different effectors to produce a unified overal effect Without dual innervation nothing would be in control. Controls blood pressure and blood flow routes

Sympathetic innervation

Effectors in body wall are innervated by sympathetic fibers in spinal nerves Effectors in head and thoracic cavity are innervated by fibers in sympathetic nerves Effectors in abdominal cavity are innervated by sympathetic fibers in splanchnic nerves

Denervation Hypersensitivity

Exaggerated response of cardiac and smooth muscle if autonomic nerves are severed

Neostigmine

Inhibits acetylcholinesterase that breaks down ACh

Parasympathetic (craniosacral) division

Long preganglionic fibers from brain stem and sacrum -Exend from CNS almost to target organs -Synapse with postganglionic neurons in terminal ganglia close to target ogans - Short postganglionic fibers synapse with effectors

Enteric Nervous System

Neurons controlling the digestive tract. -Does not arise from brainstep or spinal cord -DOES innervate smooth muscle and glands -no components in CNS -Has own reflex arc

Adrenal Glands

On superior poles of the kidneys -Each is two glands with different functions -Adrenal cortex (outer) secretes steroid hormones -Adrenal medulla (inner) is a sympathetic ganglion that secretes a mixture of epinephrine and norepinephrine

Compare and contrast the specific anatomical and physiological roles of the sympathetic and parasympathetic nervous systems.

Parasympathetic: Promotes maintenance activities and conserves body energy REST & DIGEST Sympathetic: Mobilizes body during activity FIGHT OR FLIGHT -Arises in thoracic & lumbar regions of spine -Short preganglionic and long post -Take one of three routes 1) Spinal: sweat glands, blood vessels of skin & skeletal muscles 2) Sympathetic: lungs, espphagus and thoracic blood vessels 3) Splanchnic

Distinguish between preganglionic and postganglionic fibers of the autonomic nervous system

Preganglionic (in CNS): has thin, lightly myelinated preganglionic axon. -Preganglionic fibers release ACh Postganglionic : nonmyelinated postganglionic axon that extends to effector organ -Postganglionic fibers release norepinephrine or ACh at effectors

Name the neurotransmitters used at different synapses of the ANS

Preganglionic fibers release ACh Post release norepinephrine or ACh

Explain how the autonomic and somatic nervous system differ in form and function

Somatic controls all voluntary muscular systems within the body and the process of involuntary reflex arcs involving skeletal muscle -Effectors are skeletal muscles -Cell body in CNS, thick, myelinated muscle extends in spinal nerve to skeletal muscle The ANS consists of motor neurons that innervate smooth and cardiac muscle, and glands. Operates via subconscious control. The ANS is also called the involuntary nervous system. -Effectors are cardiac, smooth muscle and glands. -ANS uses two-neuron chain of pre and post ganglionic neurons

Compare and contrast the locations of sympathetic and parasympathetic neuron cell bodies, dendrites and axons

Somatic: Cell bodies are in CNS which extends in spinal or cranial nerve to skeletal muscle ANS: two neuron chain of pre and post gangionic neurons

Autonomic dysreflexia

Uncontrolled activation of autonomic neurons in quadriplegics and those with spinal cord injuries above T6 Blood pressure skyrockets Life-threatening