Exam 2

Where does the ANS (autonomic nervous system) originate from?

CNS

What does the CNS consist of?

Brain and spinal cord

What are the two divisions of the ANS, based on the type of efferent nerves?

Sympathetic and Parasympathetic

What do efferent nerves do?

They help carry signals away from the CNS to muscles, glands, & organs

What is the saying for the sympathetic division?

Fight or flight

What is the saying for the parasympathetic division?

Rest & digest

Where do the sympathetic fibers originate from?

The first thoracic to the second/third lumbar segments of the spinal cord

Where do the parasympathetic fibers originate from?

The midbrain, medulla oblongata, & the sacral part of the spinal cord

What is autonomic ganglia?

Relay stations where one neuron communicates w/ another neuron outside the CNS

What do autonomic ganglia contain and where is it located?

Contains axodendritic synpases between preganglionic and postganglionic neurons.

Constricts pupil (division)

ParasympatheticS

Stimulates salivation (division)

Parasympathetic

Inhibits heart (division)

Parasympathetic

Constricts bronchi (division)

Parasympathetic

Stimulates digestive activity (division)

Parasympathetic

Stimulates gallbladder (division)

Parasympathetic

Contracts bladder (division)

Parasympathetic

Relaxes rectum (division)

Parasympathetic

Dilates pupil (division)

Sympathetic

Inhibits salivation (division)

Sympathetic

Relaxes bronchi (division)

Sympathetic

Accelerates heart (division)

Sympathetic

Inhibits digestive activity (division)

Sympathetic

Stimulates glucose release by liver (division)

Sympathetic

Secretion of epinephrine and nonepinephrine from kidney (division)

Sympathetic

Relaxes bladder (division)

Sympathetic

Contracts rectum (division)

Sympathetic

Pathway of how neurotransmitters are received from the CNS

CNS → Preganglionic neuron → Autonomic ganglion → Postganglionic neuron → Target organ

Where do preganglionic parasympathetic and sympathetic fibers originate in?

Cerebrum, brain stem, & spinal cord

In the ANS (Autonomic nervous system), the sympathetic nervous system has what kind of pre and post ganglionic fibers?

Short preganglionic and long postganglionic fibers

What kind of preganglionic fibers does the PNS (Parasympathetic Nervous system) have?

Long preganglionic fibers

What does the cholinergic neuron do?

Releases acetylcholine (ACh)

What does the noradrenergic neuron do?

Releases norepinephrine (NE), aka noradrenaline

What neurotransmitters does the SNS use along its pathway?

Preganglionic neuron is cholinergic but postganglionic neuron is noradrenergic

Pathway of SNS and its neurotransmitters

Spinal cord → ACh releases → Autonomic ganglion → NE releases → Target organ

Norepinephrine being released into the heart increases ?

Heart rate and contractility

T/F: Sympathetic nerves supplying most sweat glands release NE instead of ACh.

False (adrenal medulla is a special case)

What neurotransmitters does the PNS use along its pathway?

Pre and postganglionic neurons are both cholinergic, both release ACh

Pathway of PNS and its neurotransmitters

Brainstem/Sacral spinal cord → ACh → Autonomic ganglion → ACh → Target organ

Acetylcholine being released into the heart causes?

Decreased heart rate

Which receptor is found on the postganglionic neuron in an autonomic ganglion?

Nicotinic

What type of receptor is at the target organ in SNS?

Adrenergic (a or B)

What type of receptor is at the target organ in PNS?

Muscarinic

Nerve impulses travel down axon fibers as electrical signals called?

Action Potentials

Which receptor does norepinephrine typically activate in the heart?

B1

Which receptor does parasympathetic ACh activate in the heart?

M2

The autonomic ganglia is a collection of?

Postganglionic neuron cell bodies and synapses in the PNS

How can neurotransmission terminate?

Diffuse, broken down by enzumes, or reuptake (pumped back)

Once the neurotransmitters go back into the presynaptic terminal they may be repackaged into?

Synaptic vesicles

Neurotransmitters may be pumped back into the presynaptic terminal and could be broken down by?

Enzymes in the presynaptic terminal (MAO or COMT)

Types of Neurotransmitters

Ach & NE

NE belongs to a group of endogenous chemicals called?

Catecholamines (Includes dopamine & epinephrine)

How is NE action terminated?

By uptake by the pre-synaptic fiber or breakdown by MAO & COMT

Synthesis of catecholamines

Tyrosine → L-DOPA → Dopamine → Norepinephrine (NE) → Epinephrine (Epi)

What do presynaptic a2 receptors do

Inhibits NE release through negative feedback

Which receptor typically mediates the parasympathetic effect on the heart

M2

A1 receptors are present in? What does its activation lead to?

Arteriolar smooth muscles, vasoconstriction

A2 receptors are found in? What does its activation lead to?

Pre-ganglionically & in CNS, decerase in sympathetic flow from CNS

B1 receptors are found in? Activation leads to?

Heart & kidney, increased HR & force of contraction & release of renin from kidney

B2 receptors are found in? Activation/Stimulation leads to?

Blood vessels & bronchi, vasodilation & bonchodilation w/ breakdown of glycogen to glucose