Autonomic Nervous System Lecture Review

These flashcards encapsulate key concepts and facts about the autonomic nervous system, its divisions, functions, and related pharmacology to aid in exam preparation.

What does the autonomic nervous system (ANS) consist of?

The ANS consists of motor neurons that innervate smooth muscles, cardiac muscle, and glands.

What Pathway does the ANS use

Two-neuron pathway

what neurons are involved in the 2 neuron pathway of the ANS

• Preganglionic (presynaptic) neuron

• Posyganglionic (postsynaptic) neuron

Is the postsynaptic neuron found in or outside the CNS

Outside

What are the two divisions of the autonomic nervous system?

The two divisions are the sympathetic division and the parasympathetic division.

What is the effect of ANS

Stimulatory or Inhibitory

what neurotransmitter does the presynaptic neuron of the ANS release

ACh

what neurotransmitter does the postsynaptic neuron of the ANS release

Norepinephrine or ACh

what is the function of the Sympathetic Div.

The sympathetic division mobilizes the body during activity

What is the primary function of the parasympathetic division?

The parasympathetic division promotes maintenance functions, conserves energy, and directs digestion, diuresis, and defecation.

What type of neurotransmitter is released by all somatic motor neurons?

All somatic motor neurons release acetylcholine (ACh).

What is the effect of ACh at nicotinic receptors?

The effect of ACh at nicotinic receptors is always stimulatory.

What characterizes the preganglionic fibers of the sympathetic division?

The sympathetic division has short preganglionic fibers and long postganglionic fibers.

What is dual innervation in the context of the ANS?

Dual innervation refers to all visceral organs being served by both the sympathetic and parasympathetic divisions, which cause opposite effects.

What are the two types of cholinergic receptors?

The two types of cholinergic receptors are nicotinic receptors and muscarinic receptors.

What effect does the sympathetic division have on blood vessels during stress?

The sympathetic division causes vasoconstriction in blood vessels to increase blood pressure.

What is the role of the hypothalamus in controlling the ANS?

The hypothalamus is generally the main integrative center of ANS activity.

What is Raynaud’s disease?

Raynaud’s disease is a disorder caused by hyperactivation of the sympathetic nervous system leading to extreme vasoconstriction of peripheral blood vessels.

What does atropine do in the context of the ANS?

Atropine is an anticholinergic drug that blocks muscarinic receptors.

How does the parasympathetic division affect gastrointestinal activity?

The parasympathetic division increases gastrointestinal tract activity.

What happens during sympathetic activation in terms of metabolism?

During sympathetic activation, metabolism rates increase, blood glucose levels rise, and fats are mobilized for use as fuels.

What is the nickname for the Sympathetic Div.

Fight or Flight system

What activates the Sympathetic Div.

Exercise, excitement, emergency, and embarassment

Where are Parasympathetic fibers found?

Craniosacral, in the brain and sacral spinal chord

Where are Sympathetic fibers found

Thoracolumbar, Thoracic and lumbar regions of the spine

What are the length of fibers in the parasympathetic div.

Long preganglionic, short post

What are the length of fibers in the sympathetic div.

Short Preganglionic, long post

Where are parasympathetic ganglia found

near their visceral effector organ

What nerve makes up for ~90% of all preganglionic parasympathetic fibers in the body?

The vagus nerve.

What is the primary function of the vagus nerve in the parasympathetic division?

The vagus nerve regulates a variety of bodily functions including heart rate, digestion, and respiratory rate.

Where does the vagus nerve originate?

The vagus nerve originates in the brainstem, specifically from the medulla oblongata.

What systems does the vagus nerve influence?

The vagus nerve influences the cardiovascular, respiratory, and digestive systems.

Where can some preganglionic fibers directly pass through without synapsing

The Adrenal medulla

What do medullary crlls secrete upon stimulation

Norepinephrine and epinephrine into the blood

What releases ACh

Cholinergic Fibers

Where is ACh released to

• All ANS preganglionic axons

• All parasympathetic postganglionic axons

What releases Norepinephrine

adrenergic fibers

Where is norepinephrine released to in the ANS

Almost all sympathetic postganglionic axons, except those at sweat glands

What 2 cholinergic receptors bind to ACh

• Nicotinic

• Muscarinic

Where are Nicotinic receptors found

• all postganglionic neurons

• Hormone producing cells of the adrenal medulla

• sacrolemma of skeletal muscle

Where are muscarinic receptors found

All effector cells stimulated bu postganglionic cholinergic fibers

What are the effects of ACh at muscarinic receptors

• Either inhibitory or excitatory depending on type of target organ

When Ach binds to Nicotinic receptors on sympathetic ganglionic fibers, what does it release

It releases norepinephrine onto adrenergic receptors.

When Ach binds to Nicotinic receptors on parasympathetic ganglionic fibers, what does it release

It releases Ach onto muscarinic receptors

What does atropine do, and what is it used for?

It blocks muscarinic receptors and used to prevent salivation during surgery, and to dilate pupils.

What does Neostigmine do and what is it used for?

It inhibits acetylcholinesterase and is used to treat myasthenia gravis

What is Myasthenia gravis

A neuromuscular disease that leads to fluctuating muscle weakness and fatigue

What is dual Innervation

The presence of Parasympathetic and sympathetic interactions in one organ

Do most visceral organs have dual innervation or no?

Yes

What is an antagonistic interaction

It is when action potentials continually fire down axons of both divisions.

What happens when both ANS divisions are partially active?

One division usually predominates, but in a few cases, divisions have a cooperative effect.

Which fibers are almost all blood vessels innervated by?

Sympathetic fibers

What is sympathetic tone?

The continual state of partial constriction of blood vessels

What does sympathetic tone allow for?

It allows the sympathetic sys. to shunt blood where needed.

What division usually dominates the heart and smooth muscle of digestive and urinary tract organs?

The parasympathetic division

What do organs that are dominated by the parasympathetic division exhibit?

Parasympathetic tone

What can the sympathetic division override in times of stress?

Parasympathetic tone

What happens when a drug blocks parasympathetic response?

It leads to increase heart rate and cause urinary and fecal retention

What organs recieve only sympathetic fibers?

Adrenal medulla, sweat glands, arrector pili muscles, kidneys, and almost all blood vessels

What are some unique roles of the sympathetic division

• Thermoregulatory responses

• Release of renin from kidneys

• Metabolic effects

Where is the ANS under control of the CNS

Brain stem, spinal cor, hypothalamus, and cerebral cortex.

In what way does cerebral input modify ANS

Subconsciously

What organ is the main inegrative center of ANS activity?

The hypothalamus

What do connections of the hypothalamus to lymbic lobe allow for?

Cortical influence on the ANS

What is biofeedback?

Awareness of physiological conditions with goal of consciously influencing them

What do many ANS disorders involve?

Deficient control of smooth muscle activity

What is hypertention on a control scale

Overactive sympathetic vasocontstrictor response to stress

What is raynauds disease?

Hyperactivation of the sympathetic nervous system causing extreme vasoconstriction of the peripheral blood vessels.

Where are spencial sensory receptors located?

They are found within a special sensory organ or a distict part of the epithelium

What receptors allow for olfaction (smell) and Gustation (taste)

Chemoreceptors

What do chemoreceptors respond to?

Chemicals in a solution

What kind of organ are taste buds?

Receptor organs

What shape are taste buds?

Flask shaped

How many epithelial cells make up taste buds and what kind of cells make up taste buds?

There are 50-100 and are made up of Basal and Gustatory cells

What is required for something to be tasted

• Must be dissolved in saliva

• Must contact gustatory hairs

Where is taste appreciated once its signal has been recieved?

THe Hypothalamus and limbic sys.

How does smell influence taste?

Taste is 80% smell

What interacts with the chemicals in air dissolved in mucus?

The Cilia of dendrites

What are Olfactory cells

Bipolar neurons with cilia

What do olfactory glands produce

They produce mucus

Where are mitral cells found and what do they do?

They are in the olfactory bulb and they recieve information from the axons of olfactory receptor neurons

What is the organ of smell in the roof of the nasal cavity?

Olfactory epithelium

What are the 3 parts of the ear?

External, middle/tympanic cavity, and Internal ear

What membranes are between the middle and inner ear?

The Oval and Round window

What does the oval window produce?

It produces fluid waves in the inner ear

What does the round window do?

It dissipates fluid waves in the inner ear

How are pitch and loudness measured and what are their normal ranges?

• Pitch is measured in Herts (Hz) ranging from 20-20,000Hz

• Loudness is measured in Decibles (dB) ranging from 0-120 dB

What is conduction deafness?

Blocked sound conduction to the fluids of the internal ear

What is sensorineural deafness?

Damage to the nerual structures like cochlear hair cells and auditory cortical cells

What is the tympanic membrane and what does it do?

The boundary between external and middles ears that vibrates in response to sound

What is the auditory tube and what does it do?

THe tube that connects the middle ear to the back of the throat. It equalizes pressure in the middle ear cavity with the external air pressure.

What are the 3 parts of the Internal ear?

• Semicircular canals

• Vestibule

• Cochlea

What does the vestibule house

The maculae

What receptor region does the ampulla of each canal hosue?

The crista ampullaris

What is the organ of corti and where is it?

Sensory organ of hearing, found in the cochlear duct of the cochlea

What are the 3 layers of the eye?

Fibrous, Vascular, and Sensory

What receptor cells are within the eyes?

Photoreceptor cells (rods, cones)

What do photoreceptors convert?

They convert light energy into nerve impulses

Why are there rods and cones instead of just one?

They respond to diff wavelengths of light

What are the 4 processes of image formation?

1) Refraction

2) Accommodation

3) Constriction

4) Convergence