Autonomic Nervous System

Functions of the Autonomic Nervous System (ANS)

Regulates involuntary bodily functions such as heart rate, digestion, respiratory rate, and salivation.

• innervates smooth muscle, cardiac muscle and glands

Somatic

• 1 motor neuron chain

• Thick + more myelinated

• Ach always excitatory

Autonomic

• 2 motor neuron chain (pre and post ganglionic neuron/ fiber)

• Uses a ganglion to hold cell bodies

Preganglionic neuron is always going to release (always excitatory) BLANK

Ach

Postganglionic neuron will release BLANK

Ach or Norepinephrine (NE)

Sympathetic nervous system

• Thoracic + Lumbar nerves

• Preganglionic fibers are short

• Postganglionic fibers are long

Sympathetic Division

fight or flight

Parasympathetic Division

rest and digest

Parasympathetic nervous system

• Brain/ Sacral nerves

• Preganglionic are long

• Postganglionic are short

Ach

• All preganglionic neurons release

• All parasympathetic postganglionic release

• Some sympathetic postganglionic release (sweat glands, blood vessels in skeletal muscle and external genitilia)

NE

Most sympathetic postganglionic release

What are the 2 Types of fibers?

Cholinergic & Adrenergic fibers

Cholinergic fibers

release Ach

aka all preganglionic fibers are these

Adrenergic fibers

release NE

What are the 2 types of Cholinergic receptors?

Nicotinic & Muscarinic receptors

Cholinergic receptor

Bind to Ach (post ganglionic)

Nicotinic receptors

On all post ganglionic neurons/ fibers, on adrenal medulla, on receptors of motor end plate

• Ach is always excitatory

Muscarinic receptor

On all parasympathetic target organs, eccrine sweat glands, some blood vessels of skeletal muscles can be excitatory or inhibitory

Adrenergic Receptor

Binds to NE

Alpha receptors

usually excitatory

Beta receptors

usually inhibitory

What are the two types of adrenergic receptors?

Alpha and beta receptors

Sympathetic NS

• NE is slowly absorbed into varicosities

• NE 2nd messengers (indirect, uses a G-protein)

• NE —> Adrenal medulla —> Epinephrine —> Blood vessels (acts as a hormone)

Parasympathetic NS

• Ach

• Direct

Reticular formation

controls Heart rate, respiratory rate when aroused/ awake

Hypothalamus

modifier/ regulator

Cerebral Cortex

memories

Spinal cord

until potty trained, dedication + urination are autonomic reflexes

Hypertension

• ANS disorder

• Overactive sympathetic N.S

• Vasoconstriction of blood vessels (decrease diameter, increase blood pressure, damaging blood vessels causing cardiac/ renal problems, also leads to loss of vision affecting retina)

Raynaud’s disease

• ANS disorder

• Overactive sympathetic N.S

• Stimulus = cold temp.

• Leads to vasoconstriction of blood vessels, fingers + toes get a loss of blood flow to them turning white, can lead to Gangere/ Frostbite