The Autonomic Nervous System (ANS)

Synaptic terminal:

a bulb at the end of the axon in which neurotransmitter molecules are stored and from which they are released

Neurotransmitter:

a molecule that is releases from the synaptic terminal of a neuron at a chemical synapse, which is then diffused across the synapse and binds to the postsynaptic cell, causing a response

Pre ganglion neurons are always releasing

acetylcholine

What is the natural ligand nicotinic receptors?

acetylcholine (natural agonist)

ANS:Parasympathetic

acetylcholine --> nicotinic receptor (Nn) --> postganglionic neurons --> acetylcholine --> muscarinic receptor NOTE: two neurons

ANS: Sympathetic innervation of adrenal medulla

acetylcholine --> nicotinic receptor (Nn)--> adrenal medulla --> epinephrine & norepinephrine released into the blood --> adrenergic receptor NOTE: only one neuron

ANS: Sympathetic

acetylcholine --> nicotinic receptor (Nn)--> postganglionic neurons --> norepinephrine (noradrenaline) --> adrenergic receptor NOTE: two neurons

In the sympathetic nervous system...

acetylcholine and another neurotransmitter are present (e.g., epinephrine and/or norepinephrine) acting on adrenergic receptor

The neurotransmission in a cholinergic neuron is acting on

acetylcholine receptors

efferent neurons

away from the nervous system

After being released into the synapse, acetylcholine can

be broken down (hydrolyzed) back to choline and acetate by the enzyme AchE (acetylcholinesterase) in the synaptic cleft

Dendrites:

branched extensions that receive signals from other neurons

The neurotransmission in a cholinergic neuron:

choline transported into neuron --> acetyl CoA in the neuron binds with choline to make acetylcholine --> acetylcholine is moved into a storage vesicle --> whenever the neuron receives a signal it will release the stored acetylcholine (neurotransmitter) by fusing the presynaptic neuron with the storage vesicle --> the release acetylcholine to the synapse which will bind to receptors (Nm, Nn, Musclarinic)

Cell body:

contains most of the neurons organelles

Antagonist

counters the effects of the sympathetic system

Which nerves constitute the parasympathetic nervous system?

cranial & sacral

What are the five types of nerves originating from different sections of the spinal cord, from top to bottom?

cranial, cervical, thoracic, lumbar, & sacral

When the sympathetic is inactive:

decrease of renin and epinephrine

What is the difference between efferent and afferent neurons?

efferent: away from the nervous system afferent: towards the nervous system

The SANS is also known as:

fight or flight

What are the effector organs?

heart, skin, etc.

Is the Autonomic Nervous System (ANS) voluntary or involuntary?

involuntary

When the sympathetic is active:

it causes the release of renin and epinephrine

What makes up the central nervous system?

nerves in the brain and spinal cord

What makes up the peripheral nervous system?

nerves outside the CNS - autonomic - somatic nervous system (skeletal muscle)

somatic nervous system: skeletal muscle

no ganglia--> acetylcholine--> nicotinic receptor (Nm) --> skeletal muscle ***no ganglia, only one neuron*** from the CNS, where this nerve is originating, the same nerve is transmitting the signal directly from CNS to end site which is the skeletal muscle

automatic nervous system is

not voluntary

Do sympathetic and parasympathetic systems have similar or opposing effects?

opposing

Effects on ANS: Activity of adrenal medulla ***ONLY AFFECTED BY PANS***

release of epinephrine by adrenal medulla --> ↑ in BP

Effects on ANS: Renin release by kidneys ***ONLY AFFECTED BY PANS***

release of renin by the kidneys --> ↑ in BP

The PANS is also known as:

rest and digest

Agonist

stimulates the effects of the sympathetic system

What are the three types of peripheral nervous systems?

sympathetic, parasympathetic, somatic

Postsynaptic cell:

the cell receiving the signal

Presynaptic cell:

the cell transmitting the signal

Synapse:

the junction between two nerve cells

What is the anatomical difference between SANS & PANS?

the length of the neurons: - SANS first neuron is short, second neuron is longer -PANS first neuron is long and close to end organ, second neuron is short

Which nerves constitute the sympathetic nervous system?

thoracic & lumbar

afferent neurons

towards the nervous system

Axon:

transmits the signal to other cells

The Autonomic Nervous System is a...

two neuron system -the signal from spinal cord is carried by 2 neurons

somatic nervous system is

voluntary

If you block, AchE (acetylcholinesterase)

you increase in acetylcholine, which affects muscarinic and nicotinic receptors

What are the major parts of a neuron?

- dendrites, axon, cell body - presynaptic cell, synapse, synaptic terminal, postsynaptic cell, neurotransmitter

Effects on ANS: Bronchioles

SANS: dilate PANS: constrict

Effects on ANS: Pupils

SANS: dilate (mydriasis) PANS: constrict (miosis)

Effects on ANS: BP

SANS: ↑ PANS: ↓

Effects on ANS: Blood flow to skeletal muscles

SANS: ↑ PANS: ↓

Effects on ANS: Blood glucose levels (source of energy)

SANS: ↑ PANS: ↓

Effects on ANS: Heart

SANS: ↑ PANS: ↓

Effects on ANS: Activity of gastric organs

SANS: ↓ PANS: ↑

Effects on ANS: Activity of sexual organs

SANS: ↓ PANS: ↑

Effects on ANS: Activity of urinary bladder

SANS: ↓ PANS: ↑

Effects on ANS: Blood flow to skin and GI organs

SANS: ↓ PANS: ↑

What is the Autonomic Nervous System (ANS) comprised of?

Sympathetic Nervous System (SANS) and Parasympathetic Nervous System (PANS)