Ch61_The Autonomic Nervous System & the Adrenal Medulla

Flashcards covering the autonomic nervous system and adrenal medulla.

1. Where is the Autonomic Nervous System primarily activated?

2. What does it operate in which two ways?

1. Centers in the spinal cord, brain stem, and hypothalamus.

2. Visceral reflexes (involuntary) and with efferent signals (sympathetics and parasympathetics)

Sympathetics can travel down 2 paravertebral sympathetic chains, what are they?

Prevertebral ganglia - celiac and hypogastric

Nerves extending from ganglia to organs

1. What type of neurons does each sympathetic pathway from the cord have?

2. What is the pathway?

1. Preganglionic and postganglionic neurons.

2. cell body of preganglionic neuron is in the intermediolateral horn and exits the anterior root into the spinal nerve.

   1. Then passes through white ramus into one of the ganglia of sympathetic chain.

   2. Then synapses with postganglionic neuron to effector organ

What do preganglionic sympathetic nerve fibers terminate on in the adrenal medulla?

Modified neuronal cells (postganglionic neurons) that secrete EPI and NOREPI.

• preganglionic sympathetic fibers pass without synapsing from the intermediolateral horn (the exception)

Where do parasympathetic fibers leave from?

Cranial nerves III, VII (7), IX (9), X (10)and the sacral area.

Each parasympathetic pathway from the cord has a preganglionic and postganglionic neuron. Except in a few cases, postganglionic neurons run uninterrupted to _____

The organ wall/organ

1. What do Cholinergic fibers secrete?

2. What do Adrenergic fibers secrete?

3. all preganglionic neurons are ______ in both divisions

4. In general, what neurotransmitters do postganglionic neurons secrete?

1. Acetylcholine.

2. Norepinephrine.

3. cholinergic

4. Parasympathetic – cholinergic (ACH), Sympathetic – adrenergic (NE).

What is the enlargement called where the nerve fibers of the SNS and PNS come into contact with the cells of the effector organ?

A varicosity.

• neurotransmitters are synthesized and stored, house mito and produce ATP, fiber is depolarized, calcium diffuses into the nerve terminal or into the varicosity causing secretion of neurotransmitters.

1. how is Acetylcholin synthesized?

2. What is Acetylcholine broken down into?

1. syntheized and stored in the varicosity of cholinergic nerve fiber: acetyl-CoA + choline

2. Acetylcholine = acetate + choline (catalyzed by acetylcholinesterase).

   1. choline is then transported back to varicosity to be used again

1. How is NE synthesized?

2. How is Norepinephrine destroyed?

1. synthesis starts at the terminal nerve ending of adrenergic nerve fiber:

   1. tyrosine > DOPA > Dopamine (transported into the varicosity)

   2. In the varicosity: Dopamine > NE

   3. In the adrenal medulla: NE >EPI

2. Reuptake into the adrenergic nerve ending, diffusion from the nerve endings, and destruction by tissue enzymes.

Define the second messenger

NE binds to adernergic receptor and causes confirmational of cAMP in cell and it will initiate cellular reactions

What are the two types of Ach receptors?

Muscarinic - on all effector cells and stimulated by PNS/SNS postganglionic cholinergic neurons

Nicotinic - in autonomic ganglia at syapses between pre and postgagnlionic neurons of both SNS and PNS and neuromuscular junction

Name the types of Adrenergic Receptors?

Alpha: NE primarily; Epi

• Alpha 1, Alpha 2,

Beta - Epi

• Beta 1, Beta 2, Beta 3.

***What are the effects of SNS and PNS on the heart, systemic blood vessels, and blood pressure?

Heart: SNS increases activity, PNS decreases activity. Systemic blood vessels: SNS induces vasoconstriction, PNS has almost no effect. Blood pressure: SNS increases BP, PNS decreases BP.

Stimulation of the adrenal medualla via sympathetic nerves results in secretion of EPI and NE.

What effects does NE induce?

Vasoconstriction, GI tract inhibition, pupil dilation, increased heart activity.

What is tone?

Why is it important?

When does intrinsic tone occur?

Defined as the basal rate of nervous system activity - sympathetic tone and parasympathetic tone

It allows a single nervous system both to increase and decrease the activity of a stimulated organ

When SNS and PNS are removed

Int

What cardiovascular reflex helps control arterial blood pressure and heart rate?

Baroreceptor reflex.

During the SNS stress response, what factors in the body increase?

Arterial pressure, blood flow to active muscles, cellular metabolic rate, blood glucose concentration, liver/muscle glycolysis, muscle strength, mental activity, and rate of blood coagulation increase.

• isolated activation may occur during thermoregulation, locaalized reflexes, and GI function

Is PNS discharge more specific or more general?

More specific creating a more Localized response.