PNS Efferent divisions

chapter 7.1

The involuntary branch of the nervous system is called the…

Autonomic nervous system

What organs recieve input from the autonomic nervous system?

cardiac muscle, smooth muscle, most exocrine glands,some endocrine glands, and adipose tissue

What does the efferent pathway of the autonomic system consist of?

2 neuron chain

cluster of neuronal cells in the PNS is…

ganglion

what are the two subdivisions of the ANS?

sympathetic and parasympathetic

The ?-ganglionic fiber has its cell body in the CNS, but its axon terminal in the ganglion within the PNS

preganglionic

Where do sympathetic preganglionic nerve fibers originate?

thoracic and lumbar region of spinal cord

sympathetic preganglionic fibers (lengthwise) are ___

short

what are the two sympathetic ganglion cell bodies called?

-sympathetic ganglion chain

-collateral ganglia

which sympathetic ganglion cell body has longer preganglionic fibers that synapse closer to the effector organ?

colateral ganglia

where do parasympathetic preganglionic nerve fibers originate?

cranial and sacral regions of the CNS

parasympathetic preganglionic fibers (lengthwise) are …

longer

what are the ganglia in the parasympathetic efferent pathway called?

ternimal ganglia

why are parasympathetic preganglionic nerve fibers so long?

the place where they synapse (terminal ganglia) is very close to the effector… this makes the postganglionic nerve fibers of this system very short.

all preganglionic nerve fibers release… that bind to … receptors on the postganglionic cells

Acetylcholine (ACh)…. Nicotinic

nicotinic receptors, once ACh is binded to it, opens __________________________

chemically gated ion channels

sympathetic postganglionic fibers release….

norepinephrine

norepinephrine from sympathetic postganglionic cells bind to__ and/or___ receptors

-alpha

-beta

alpha and beta receptors that norepinephrine binds to are all

metabotropic; G protein Coupled Receptors

Most sympathetic postganglionic fibers release norepinephrine (NE), which binds to
alpha and/or beta receptors (all metabotropic, GPCRs), except those that synapse on the ———— and release ACh.

sweat glands

postganglionic parasympathetic fibers release…

Acetylcholine

postganglionic parasympathetic fibers release ACh that binds to … receptors on the effector

muscarinic

an ionotropic receptor forms an___ _______ itself

ion channel

metabotropic receptors do not have ion channel as part of their structure. Instead binding of a neurotransmitter (NE) activates a G-protein, which initiates a _________ _______

signaling cascade

Are nicotininc receptors excitatory or inhibitory?

always excitatory

where are muscarinic receptors located?

Cardiac muscle, smooth muscle, and glands

Alpha and beta receptors bind norepineprine or epinephrine. T or F

true

Where are alpha 1 receptors found? Are they inhibitory or excitatory?

Found on most traget tissues and are excitatory

Where are Alpha 2 receptors found? Are they inhibitory or excitatory?

Found on digestive tract and are inhibitory

Where are beta 1 receptors found? Are they excitatory or inhibitory?

Found on the heart and always excitatory

Where are beta 2 receptors found? Are they excitatory or inhibitory?

Found on arterioles and bronchioles and are inhibitory

Alpha receptros have a higher affinity for…

norepinephrine

What receptor on the sympatheic efferent pathway has equal affinity fro NE and epinephrine?

Beta 1

What receptor only binds to epinephrine?

Beta 2

What is dual innervation?

dual innervation is where the organ is both innervated by the sympathetc and parasympathetic systems

Why is dual innervation helpful?

Allows for precise control over an organs activity

When is there sympathetic dominance?

-emergency situations

-stressful situations

-fight or flight

preparing body for strenuous activity

When is the parasympathetic nervous system donimant?

in quiet and relaxed situations; “rest and digest”

The ________ _______ is modified sympathetic ganglion but does not give rise to postganglionic fibers

Adrenal Medulla

What percent of epineprine and norepinephrine are released by the adrenal medulla?

Norepinephrine (20%) Epinephrine (80%)

What branch of the PNS is under voluntary control?

Somatic nervous system

Is there an intermidiate fiber in the somatic efferent pathway?

No. CNS to skeletal muscle.