CHAPTER FOURTEEN: AUTONOMIC NERVOUS SYSTEM Flashcards
COMPARE THE SOMATIC AND AUTONOMIC NERVOUS SYSTEM WITH RESPECT TO EFFECTORS, EFFERENT PATHWAYS, AND NEUROTRANSMITTERS RELEASED
→ somatic: effectors are skeletal muscles, efferent pathway is a motor myelinated single nerve, and neurotransmitters used is acetylcholine that is always excitatory
→ autonomic: effectors are smooth muscle, cardiac muscle, and glands, neurotransmitters are acetylcholine and norepinephrine. Efferent pathway is a 2 neuron system
→ preganglionic: cell body is located in the CNS and has an axon extending to the ganglia
→ postganglionic: ganglion synapses with the effector
COMPARE AND CONTRAST SYMPATHETIC AND PARASYMPATHETIC FIBERS IN REGARDS TO ITS DOMINANCE IN CERTAIN AREAS, GANGLION ORIGIN, LENGTH OF PREGANGLIONIC AND POSTGANGLIONIC FIBERS, EFFECTOR ORGANS, NEUROTRANSMITTER AND NEUROTRANSMITTER RECEPTOR
→ parasympathetic fibers
Dominance: dominates during resting and digesting, essentially the body in its low energy state. GI tract activity is high, blood pressure, heart and respiratory rate are low.
Origins: origins are craniosacral, meaning the origins of the fibers are in the brain and sacral region of the spinal cord.
Length: has long preganglionic fibers and short postganglionic fibers
Effector organs: GI tract (smooth muscle), heart, and glands
Neurotransmitter info: both preganglionic and postganglionic release acetylcholine, however at preganglionic it has nicotinic receptors and at postganglionic it is muscarinic
→ sympathetic fibers
Dominance: dominates during the fight or flight response, essentially the body in high energy
Origins: originates in the thoracolumbar regions of the spine, meaning the thoracic and lumbar regions of the spine
Length: has short preganglionic and long postganglionic fibers. Fibers form the lateral horns of the spinal cord and pass through the rami communicans and sympathetic trunk.
Effector organs: the heart, lungs, sweat glands, and digestive organs
Neurotransmitter info: at the preganglionic fibers, acetylcholine and nicotinic receptors are found, at the postganglionic fibers norepinephrine and adrenergic receptors are found.
STATE THE EFFECTS OF SYMPATHETIC AND PARASYMPATHETIC FIBERS HAVE ON THE HEART, BLOOD VESSELS, GI TRACT, LUNGS, ADRENAL MEDULLA, URINARY BLADDER, AND EXTERNAL GENITALIA
→ parasympathetic: will lower heart rate, increase blood flow to GI tract, increase activity in GI tract. Decrease activity in the lungs, will not affect adrenal medulla, will lessen respiratory activity, promote usage of urinary bladder, and may promote arousal in genitalia
→ sympathetic: will increase heart rate, will increase blood flow in blood vessels to the heart and less to the GI tract, inhibit GI tract activity, increase lung capacity, cause norepinephrine release from the adrenal medulla to the blood, inhibit release of urine from bladder, and can allow for arousal of external genitalia
EXPLAIN HOW THE ADRENAL MEDULLA CAN AFFECT RECEPTORS ON VARIOUS ORGANS DESPITE THE FACT THAT IT’S CELLS HAVE NO AXONS. EXPLAIN THE STATEMENT “THE ADRENAL MEDULLA IS A MODIFIED SYMPATHETIC GANGLION”.
The adrenal medulla can affect receptors on other organs because it will release epinephrine or norepinephrine into the bloodstream. While this does produce a less intense response, it still gets the signal across to effector organs anyhow. It is referred to as a modified sympathetic ganglion because its actions are directly influenced by a preganglionic fiber, when it is stimulated it will release epinephrine or norepinephrine into the bloodstream. Because it is stimulated by a preganglionic fiber, it almost makes it a modified postganglionic fiber.
BRIEFLY OUTLINE THE LEVELS OF CONTROL OF AUTONOMIC NERVOUS SYSTEM FUNCTION
The autonomic nervous system does work through the brain stem, spinal cord, hypothalamus and the cerebral cortex.
→ brainstem: pupil size, heart rate, blood pressure, airflow, etc.
→ spinal cord: urinary functions, ejaculation, erections
→ hypothalamus: is the “boss” of the autonomic nervous system and is the main integration center
→ cerebral cortex: can subconsciously modify the autonomic nervous system, it also works through the limbic system
