Autonomic Nervous System ANS (Test 4)

24. Which fibers of the ANS are cholinergic? Which are adrenergic?

-all preganglionic axons are cholinergic -all postsynaptic parasympathetic fibers synapse with effectors are cholinergic -most sympatheric postganglionic fibers are adrenergic

8. Which of the above neurons (#7) releases neurotransmitter at a synapse within a ganglion? at the neuroeffector synapse?

- Preganglionic neurons release NT at a synapse within a ganglion - Postganglionic neurons release NT at the neuroeffector synapse

17. What are the three things that can happen to a preganglionic fiber in a paravertebral ganglion?

1. synapse with postganglionic neuron in paravertebral ganglion at same level 2. ascend/descend and synapse with another chain ganglion 3. through sympathetic trunk and synapse in collateral ganglion anterior to vertebral column

11. Which body regions and organs are served by parasympathetic preganglionic fibers originating with CNs III, VII, and IX?

CN III - eye CN VII - nasal, lacrimal, salivary glands CN IX - salivary glands

23. What is a cholinergic fiber? an adrenergic fiber?

cholinergic - release ACh adrenergic - release NE

22. Name and describe the synaptic terminals of sympathetic postganglionic fibers.

NT released from varicosities - branched endings with swellings

31. Describe the physiologic effects of parasympathetic activation.

SLUDD salivation lacrimation urination digestion defecation

38. Identify the main components of the ANS hierarchy of control. Describe the role played by each component.

hypothalamus - heart rate, blood pressure, body tempurature, water balance, endocrine activity brain stem - pupil size, heart, blood pressure, airflow, salivation, vagus nerve spinal cord - urination, defecation, erection, ejaculation

32. What is meant by the term agonist? antagonist?

agonist - initiates physiological response when combined with a receptor antagonist - inhibits physiological action

26. Identify the classes and subclasses of adrenergic receptors.

alpha - alpha 1 & alpha 2 beta - beta 1 & beta 2 & beta 3

21. Explain why the epinephrine- and norepinephrine-secreting cells of the adrenal medulla are correctly classified as modified sympathetic postganglionic neurons.

arise from the same embryologic tissue, lack nerve processes but secrete hormones

10. What are the CNS origins of the parasympathetic division?

brainstem and sacral region of the spinal cord

27. When activated, which of the receptor subclasses (#26) generally produce excitation of the target cell? which generally cause inhibition?

excitation alpha 1 beta 1 beta 3 (?) inhibition alpha 2 beta 2

30. Describe the physiologic effects of sympathetic activation.

fight or flight - skin vessel constriction - increased HR and force of contraction - errector pilli and sweat gland activation - blood to muscles away from viscera - lipolysis for epi - pupil and respitory dilation

1. Describe the sensory arm of the ANS, noting the general types of receptors supplying input.

from interoceptors in wall of organs chemioreceptors - monitor blood O2, pH, CO2 mechanoreceptors - changes in stretch

18. Which is more numerous -white rami communicantes or gray rami communicantes? Explain your answer.

grey rami communicans are more numerous because they issue from every ganglion from C to S

37. What part of the CNS performs overall integration of ANS activity?

hypothalamus

34. Explain why the heart at rest is said to exhibit parasympathetic (vagal) tone.

it is slowed by the parasympathetic nervous system

25. Identify the two types of cholinergic receptors. What is the general effect of activation (by ACh binding) of each receptor type.

nicotinic - always stimulatory/excites neuron or effector cell muscarinic - effect depends on the type of ion channel opened or closes

12. Which body regions and organs are served by parasympathetic preganglionic fibers originating with CN X?

organs in the abdominal and thoracic cavities - liver, gallbladder, stomach, small intestines, pancreas, proximal large intestine

4. Compare and contrast the motor pathways of the somatic nervous system (SNS) and the autonomic nervous system (ANS).

outputs begin in CNS SNS - lower motor neuron, myelinated, effector is skeletal MT, neurotransmitter is ACh ANS - preganglionic neuron, synapses with in ganglion with postsynaptic ganglion, postganglionic neuron to effector, pre-myelinated post-unmyelinated

35. Which ANS division, parasympathetic or sympathetic, produces a more diffuse response when activated? Which produces a more localized effect when activated?

parasympathetic - local sympathetic - diffuse

28. Explain why sympathetic activation vs. parasympathetic produces effects that are longer lasting and more widespread throughout the body.

parasympathetic - short because ACh is destroyed locally by ACh-ase sympathetic - highly branched, because NE and epi are released into the blood and act as hormones for a longer period of time

14. Which body regions and organs are served by sacral parasympathetic outflow?

pelvic organs -distal large intestine, bladder, ureters, reproductive organs

13. Name the nerves that carry parasympathetic preganglionic fibers originating at the S2-S4 level of the spinal cord.

pelvic splanchnic nerves

5. What is a preganglionic neuron? a postganglionic neuron?

preganglionic - first neuron in ANS pathway postganglionic - synapses within autonomic ganglion, second neuron, goes to effector

2. Identify and describe the 5 components of the visceral reflex arc.

receptor - sensory receptor in viscera sensory neuron - first order visceral sensory neuron integrations center - preganglionic neuron motor output - autonomic pathway with 2 neurons, pre ganglion and ganglion effector - smooth muscle, cardiac, gland

29. Many visceral organs have both parasympathetic and sympathetic innervation. However, there are 3 structures in the body that have only sympathetic innervation. What are they?

skin - sweat glands and errector pili kidneys blood vessels adrenal medulla ** there are 4 here??**

19. What organs of the head and neck are innervated by sympathetic postganglionic fibers? What is the effect of increased sympathetic outflow on these organs?

skin and blood vessels dilator iris muscles inhibit nasal and salivary glands lift smooth upper eyelid muscle heart, aorta, lungs espohogus, thyroid gland skin glands and erector pilli

3. What effectors can be activated by a visceral reflex arc?

smooth MT cardiac MT glands

20. Describe the pathway of the sympathetic preganglionic fibers that synapse with catecholamine-secreting cells in the adrenal medulla.

spinal cord thru ganglia (no synapse) to adrenal gland and synapse with adrenal medulla causes epi and norepi secretion

36. Explain why sympathetic activation produces longer-lasting effects than does parasympathetic activation.

sympathetic activates NE and epi from adrenal medulla that act as hormones circulating in blood parasympathetic releases ACh locally that is broken down in the synapse by ACh-ase

7. Contrast the sympathetic and parasympathetic motor pathways, noting differences in origin, length of preganglionic and postganglionic fibers, location of ganglia, and neurotransmitter profiles.

sympathetic- origin in T1-L2 lateral horns, long postganglion fibers, chain ganglion, NE neurotransmitter parasympathetic - origin in brainstem and sacral regions, pre = long, post = very short, ganglia close to effector, ACh neurotransmitter

33. Explain why blood vessels are said to exhibit sympathetic (vasomotor) tone.

they are in a state of partial constriction continually

6. Which division of the ANS is sometimes called the thoracolumbar division? the craniosacral? Explain these designations.

thoracolumbar = sympathetic, cell bodies in ventral roots of T1-L2 craniosacral = parasympathetic, cell bodies in brainstem and sacral regions of spinal cord

16. Trace the pathway of sympathetic preganglionic fibers from the spinal cord to a paravertebral ganglion.

ventral roots - ventral ramus - white ramus communicans - paravertebral ganglion at same level of cord

15. Where specifically does the sympathetic division arise?

ventral roots of spinal nerves T1-L2