Physio I Exam 4

What are the two divisions of the peripheral nervous system?

Somatic and autonomic

What are the two divisions of the autonomic nervous system?

Sympathetic and parasympathetic

Which nervous system controls voluntary muscles and is based on external stimuli?

Somatic nervous system

Which nervous system controls visceral bodily functions and is based on internal stimuli?

Autonomic nervous system

Which nervous system is known as the fight or flight system?

Sympathetic nervous system

Which nervous system is known as the rest and digest system?

Parasympathetic nervous system

Describe myelination in the pre and post ganglionic nerves in both divisions of the autonomic system

Preganglionic fibers are myelinated while postganglionic fibers are unmyelinated in both

Describe the length of pre and post ganglionic fibers in the sympathetic division

Pre - short

Post - long

Describe the length of pre and post ganglionic fibers in the parasympathetic division

Pre - long

Post - short

T/F Both symp and parasymp divisions release ach from the preganglionic fiber into nicotinic receptors

True

What is released from the postganglionic fibers in the sympathetic division?

Norepinephrine

What is released from the postganglionic fibers in the parasympathetic division?

Ach

What is released when ach is released into the adrenal medulla, and where?

Norepinephrine and epinephrine into the blood vessels

What kind of neuron is the preganglionic neuron in the sympathetic pathway? Parasympathetic pathway?

Both are cholinergic (releases ach)

What kind of receptor is the postganglionic neuron in the sympathetic pathway? Parasympathetic pathway?

Both are nicotinic receptors

What kind of neuron is the postganglionic neuron in the sympathetic pathway? Parasympathetic pathway?

Sympathetic - adrenergic neuron

Parasympathetic - cholinergic neuron

What is released by the postganglionic neuron in the sympathetic pathway? Parasympathetic pathway?

Sympathetic - norepinephrine

Parasympathetic - ach

What kind of receptor is in the target tissue in the sympathetic pathway? Parasympathetic pathway?

Sympathetic - adrenergic receptor

Parasympathetic - cholinergic receptor (muscarinic)

What is divergence?

When there are more postganglionic fibers than preganglionic fibers or when there is one stimuli and many responses

T/F Tracks in the CNS are the same as nerves in the PNS

True

What are afferent nerves? Efferent nerves?

Afferent nerves - conduct signals from sensory neurons to the CNS

Efferent nerves - conduct signals from CNS to motor neurons

What is a cluster of soma and dendritic structures bundled and connected together?

A ganglia

Name the sections of the spinal cord (31)

Cervical (8)

Thoracic (12)

Lumbar (5)

Sacral (5)

Coccygeal (1)

What does posterior or dorsal mean?

Towards the back

What does anterior or ventral mean?

Towards the front

Where are the cell bodies of each preganglionic neuron going to be located?

In the intermediolateral horn of the grey matter

What is another name for the sympathetic division and why?

Thoracolumbar division, connections are made in the thoracic and lumbar sections of the spinal cord

What is another name for the parasympathetic division and why?

Craniosacral division, connections are made in the cranial and sacral sections of the spinal cord

What are ganglia located close to in the sympathetic division?

Spinal cord

What are ganglia located close to in the parasympathetic division?

Target organs (aka intraneural ganglia)

What cranial nerves are a part of the parasympathetic division?

Cranial nerves 3, 7, 9, and 10

What are the three locations for ganglionic neurons of the sympathetic division?

1. Sympathetic chain ganglia

2. Collateral ganglia

3. Adrenal medulla

What is another name for the sympathetic chain ganglia and where are they located?

Paravertebral ganglia

Located very close to the spinal cord, on both sides

What does the sympathetic chain ganglia innervate?

The head and limbs

What is another name for the collateral ganglia and where are they located?

Prevertebral ganglia

Located close to spinal cord, more anterior

What does the collateral ganglia innervate?

Mostly abdominopelvic tissues and organs

What is another name for the adrenal medulla and where are they located?

Suprarenal medulla

Located near kidney

What is special about the preganglionic fibers that go to the adrenal medulla?

They bypass the intermediolateral horn in spinal cord and ganglia and go straight for the adrenal medulla

The postganglionic fibers from the adrenal medulla are short or long?

Very short

What is the effect of adrenal medulla receiving stimuli?

NE and E are released into bloodstream and act as hormones

Why are NE and E described to be acting as hormones?

Because they enter the bloodstream and affect target cells throughout the body

Preganglionic fibers travel through what structure after the intermediolateral horn to get to the ganglion?

The ventral root

Which cranial nerve accounts for ~80% of parasympathetic nerve cell connections?

Cranial nerve x (vagus)

What are the sacral connections of the parasympathetic division mainly for?

Sexual reflexes and bladder

Cholinergic fibers secrete what?

Ach

Adrenergic fibers secrete what?

NE

Which ganglionic neurons would be excited by Ach or Ach-like drugs?

Both symp. and parasymp. postganglionic neurons bc those are the parts that have receptors

Almost all of the postganglionic neurons of the parasym. system are cholinergic except in the?

Genitals (they secrete nitric oxide)

Why are sweat glands an exception?

Because they are controlled by sympathetic division but have the anatomy of parasympathetic division

Pregang = ach nicotinic receptors

Postgang = ach muscarinic receptors

Most of the postganglionic neurons of the parasym. system are? Sympathetic system? What is the exception?

Para = cholinergic

Symp = adrenergic

Exception - sweat glands

How do ach and NE from postganglionic nerve ending get secreted to the target organs?

By varicosities that synthesize and store NTs

How are varicosities able to synthesize and store so much NTs?

Because they have a lot of mitochondria that make a lot of ATP

Describe the process of NT release starting from stimulation.

1. Stimuli

2. Membrane depolarization

3. Calcium enters

4. Varicosities empty NTs

5. NTs react with receptors

6. NTs get reabsorbed or degraded

Are most NTs reabsorbed or degraded?

Reabsorbed to varicosities (50-80%)

How are NTs degraded?

By MAO or COMT enzymes

Why do NTs that are released in the blood last longer, and which NTs would this be?

NE and E, and because the breakdown enzymes have to follow them to the target to break them down

Answer for cholinergic neurons

NT released: _______

Synthesized from: ___________

Duration of action: ____________

Removed by: _________

NT released: Acetylcholine

Synthesized from: Acetyl CoA + Choline

Duration of action: Few seconds

Removed by: Acetylcholinesterase degradation into Acetate + Choline

Answer for adrenergic neurons

NT released: _______

Synthesized from: ___________

Duration of action: ____________

Removed by: _________

NT released: Norepinephrine

Synthesized from: Dopamine

Duration of action: Few seconds - 1 min

Removed by: Neuronal uptake, diffusion into blood to tissue, or degradation by MAO and COMT

What amino acid is NE derived from, and what enzyme converts dopamine to NE?

Tyrosine

Dopamine beta-hydroxylase

What enzyme converts NE to E, and where does this happen?

PNMT (Phenylethanolamine-N-methyltransferase), in the adrenal medulla

What is a plexus?

Interconnected ganglia; a branching network of nerves or vessels

What is the name, type, and function for cranial nerve III?

Name: Oculomotor

Type: Motor

Function: Moves exterior eye muscles

What is the name, type, and function for cranial nerve VII?

Name: Facial

Type: Mixed sensory and motor

Function: Facial muscles, taste, saliva secretion

What is the name, type, and function for cranial nerve IX?

Name: Glossopharyngeal

Type: Mixed sensory and motor

Function: Taste, gag reflex, swallowing, salivation

What is the name, type, and function for cranial nerve X?

Name: Vagus

Type: Mixed sensory and motor

Function: Swallowing, outer ear sensation, cardiac activity

What kind of receptors are ion channels?

Ionotropic receptors

What kind of receptors are GPCR?

Metabotropic receptors

Describe the process of ionotropic receptors

1. NT binds to binding site

2. Conformational change happens

3. Ions come through

Describe the process of metabotropic receptors

1. NT stim receptor

2. G-protein activates

3. Adenylate cyclase is activated with ATP to form cAMP (2nd messenger)

4. Enzymes that change cell metab are activated

Acetylcholine receptors are also called?

Cholinergic receptors

What are the types of cholinergic receptors? How are they different?

Muscarinic (M) is activated by muscarin and Nicotinic (N) is activated by nicotine

What kind of receptors are muscarinic receptors? And where are they found and stimulated by?

Metabotropic receptors

Found in all effector cells and stimulated by postganglionic neurons in either symp or parasymp (except sweat glands)

What kind of receptors are nicotinic receptors? And where are they found and stimulated by?

Ionotropic receptors

Found in autonomic ganglia at synapses of both symp and parasymp

What does M1 receptor innervate?

Neural, CNS, gastric mucosa

What does M2 receptor innervate?

Cardiac, inhibitory action on heart

What does M3 receptor innervate?

Glands and smooth muscles, secretions

What does M4 and M5 receptors innervate?

Unknown

What is N1 or Nm receptors and where is it found?

Muscle type receptors and found in motor end plate of neuromuscular junctions

What is N2 or Nn receptors?

Ganglion type

What are receptors for NE and E called? What kind of receptors are they?

Adrenoreceptors or adrenoceptors

GPCR metabotropic receptors but act thru different G-proteins

What is the most common metabotropic receptor, and what does it innervate?

Alpha-1, excites smooth muscle

What does alpha-2 metabotropic receptor innervate?

Inhibits GI

What does beta-1 metabotropic receptor innervate?

Stimulates heart (ex. heart rate)

What does beta-2 metabotropic receptor innervate?

Inhibits smooth muscle, causes smooth muscle relaxation

What does beta-3 metabotropic receptor innervate?

Lipolysis in adipocytes

Which NT affects both alpha and beta metabotropic receptors? Which NT affects one type more, and which one?

Epinephrine affects both

Norepinephrine affects alpha receptors more

What receptors are targeted by asthma medications, and why?

Beta-2 receptors to dilate the lung bronchi

Stimulation of which adrenoreceptor causes the following?

• Smooth muscle contraction

• GI smooth muscle relaxation

• Pupil dilation

• Saliva secretion

• Pilomotor hair erection

• Bladder sphincter contraction

• Worsened asthma symptoms

Alpha-1 receptors

Stimulation of which adrenoreceptor causes the following?

• Inhibition of NT release in presynaptic terminals

• Inhibition of lipolysis in adipocytes

Alpha-2 receptors

Stimulation of which adrenoreceptor causes the following?

• Increased heart rate and force of contraction

Beta-1 receptors

Stimulation of which adrenoreceptor causes the following?

• Inhibition/relaxation of vascular smooth muscle

• Inhibition/relaxation of bronchial smooth muscle

• Glycogenolysis in liver and skeletal muscle

Beta-2 receptors

Stimulation of which adrenoreceptor causes the following?

• Lipolysis stimulation in adipocytes

Beta-3 receptors

What is dual innervation?

When an organ is innervated by both the sympathetic and parasympathetic division

Describe the dual innervation opposing effects in the…

• Digestive tract

• Heart

• Lungs

• Eye

• Digestive tract - inhibited (symp), stimulated (para)

• Heart - stimulated (symp), slowed (para)

• Lungs - stimulated (symp), slowed (para)

• Eye - dilated pupil/contracted eye muscle (symp), constricted pupil/dilated eye muscle (para)

What is the complementary effect of dual innervation in the glands?

Both increase secretion, but symp increases mucus (dry mouth) while parasymp increases saliva (digestion)

What is the complementary effect of dual innervation in the reproductive system?

Erection (point) - parasymp

Ejaculation (shoot) - symp

What is autonomic tone and what is it caused by?

Normal basal rate activity of an organ caused by basal NT secretion

Which type of tone

• maintains smooth muscle tone in intestines

• holds resting heart rate

• stimulates digestive function

• stimulates urinary function

Parasympathetic tone

Which type of tone

• keeps most blood vessels partially constricted

• maintains bp

• excites heart

• inhibits digestive function

• inhibits urinary function

Sympathetic tone

What is denervation and its effect on its organ?

Cutting a nerve, organ loses its autonomic tone