Peripheral Nervous System Overview

These flashcards cover key concepts related to the peripheral nervous system, its structure, function, disorders, and autonomic nervous system interactions, aiding exam preparation.

What is the primary role of the peripheral nervous system (PNS)?

To serve as communication links between the CNS and the body.

What distinguishes afferent from efferent neurons in the PNS?

Afferent neurons carry sensory stimuli to the CNS, while efferent neurons transmit motor commands from the CNS.

How many cranial nerves are there?

There are 12 pairs of cranial nerves.

What neurotransmitter is primarily associated with the somatic nervous system?

Acetylcholine (ACh).

What does the autonomic nervous system control?

Involuntary functions such as heart rate, digestion, and respiratory rate.

What is the main neurotransmitter used by the sympathetic nervous system?

Norepinephrine.

Describe the fight or flight response.

A physiological reaction initiated by the sympathetic nervous system in response to perceived threat.

Which neurotransmitter is associated with the parasympathetic nervous system?

Acetylcholine (ACh).

How do sympathetic and parasympathetic systems affect heart rate?

Sympathetic increases heart rate; parasympathetic decreases heart rate.

What is the role of the sympathetic nervous system in relation to the urinary bladder?

Inhibits urination by relaxing the bladder wall and contracting the internal sphincter.

How does the parasympathetic nervous system affect pupil size?

It constricts the pupils (miosis).

Which cranial nerve is significant for parasympathetic functions such as reducing heart rate?

Cranial nerve X (Vagus nerve).

What is an example of how sympathetic and parasympathetic systems maintain homeostasis?

Both systems work together to regulate heart rate.

Identify a high-yield disorder of the peripheral nervous system.

Peripheral neuropathy.

What underlying dysfunction can lead to peripheral neuropathy?

Nerve damage due to conditions like diabetes.

What is Guillain-Barré Syndrome?

An autoimmune disorder that causes rapid muscle weakness and potentially paralysis.

What symptoms are associated with carpal tunnel syndrome?

Wrist/hand pain, tingling, and weakness, especially in the thumb and index finger.

What characterizes Bell's Palsy?

Sudden one-sided facial weakness or paralysis.

What does the spinal nerve root consist of?

Dorsal (sensory) and ventral (motor) roots.

What is the dorsal root ganglion?

A cluster of unipolar sensory neuron cell bodies located on the dorsal root.

What is a reflex arc?

The neural pathway that mediates an involuntary response to a stimulus.

How many spinal nerves are there?

There are 31 pairs of spinal nerves.

What distinguishes monosynaptic from polysynaptic reflexes?

Monosynaptic involves a single synapse between sensory and motor neurons; polysynaptic involves one or more interneurons.

Where are sympathetic preganglionic neurons located?

Thoracolumbar region of the spinal cord.

What initiates the fight or flight response in the body?

Activation of the sympathetic nervous system.

What mechanism does the body use for temperature regulation?

The hypothalamus coordinates heat loss and conservation based on temperature sensors.

Describe the parasympathetic effects on digestion.

Stimulates increased gastrointestinal motility and promotes secretion.

What happens during micturition regarding sympathetic and parasympathetic control?

Parasympathetic control predominates to contract the detrusor muscle and relax the internal sphincter.

What physiological effect occurs due to sympathetic input during emergency situations?

Increased heart rate and blood pressure.

What role does the vagus nerve play in autonomic functions?

It controls parasympathetic responses in various organ systems.

What are the effects of the sympathetic nervous system on blood vessels?

Constriction of skin and visceral vessels, dilation of skeletal muscle vessels.

What causes Raynaud's Disease?

Vasospasm triggered by cold or stress due to exaggerated sympathetic response.

What is Horner's Syndrome?

Disruption of sympathetic pathway leading to a droopy eyelid, constricted pupil, and lack of sweating.

What is the function of the enteric nervous system (ENS)?

Regulates gastrointestinal motility and secretion.

What characterizes autonomic neuropathy?

Damage to autonomic nerves leading to dysfunction in heart rate and digestion.

What effect does sympathetic activity have on adrenal medulla?

Releases epinephrine and norepinephrine into the blood.

What is the primary clinical feature of gastroparesis?

Delayed gastric emptying resulting in nausea and bloating.

How does the ANS regulate sweating?

Sympathetic stimulation controls sweat gland activity for thermoregulation.

What is bradycardia?

An abnormally slow heart rate often due to reduced sympathetic activity.

Define febrile convulsions.

Seizures triggered by fever in young children.

What are common symptoms of heat exhaustion?

Low blood pressure and fainting due to excessive sweating.

What triggers heat stroke?

Failure of sweating during extreme heat exposure.

What is autonomic dysreflexia?

An uncontrolled sympathetic response causing hypertension in spinal cord injury patients.

Define adrenergic neurons.

Neurons that release norepinephrine and act on adrenergic receptors.

What is a prototype agonist for beta-1 receptors?

Epinephrine.

What is the action of alpha-1 receptors on blood vessels?

Causes vasoconstriction.

What does the action of nicotinic receptors involve?

Opens Na+ and K+ channels, leading to depolarization.

What effect does acetylcholine have on the heart?

Slows heart rate via muscarinic receptors.

What is the primary neurotransmitter used in cholinergic transmission?

Acetylcholine (ACh).

How do adrenergic and cholinergic receptors differ?

Adrenergic receptors respond to norepinephrine; cholinergic receptors respond to acetylcholine.

What is the role of serotonin in the gastrointestinal tract?

Easily influences gut motility (90% of serotonin is in the gut).

What type of information do sensory neurons carry?

Afferent information from sensory receptors to the CNS.

What role do interneurons play in the reflex arc?

Interneurons connect sensory and motor neurons, allowing for complex reflex responses.

How does the adrenal gland function in the sympathetic response?

Releases epinephrine and norepinephrine directly into the bloodstream.

What happens to blood vessels in skeletal muscle during the fight-or-flight response?

They dilate to increase blood flow to muscles.

What is the effect of parasympathetic stimulation on salivary glands?

Increases watery secretion for digestion.

How do beta-2 adrenergic receptors affect airway passages?

Cause bronchodilation to increase airflow.

Describe the role of the ciliary ganglion.

Involved in parasympathetic control of pupil constriction and accommodation.

What is the significance of the myenteric plexus?

Regulates gut motility within the enteric nervous system.

What happens during sympathetic stimulation in terms of digestion?

Inhibits digestion by decreasing motility and secretion.

What is the primary role of the hypothalamus in temperature regulation?

Maintains body temperature homeostasis by orchestrating heat loss and conservation mechanisms.

What characterizes malignant hyperthermia?

A hypermetabolic state during anesthesia leading to drastic increases in body temperature and muscle rigidity.

What is the neurotransmitter released at adrenergic synapses?

Norepinephrine.

How does the autonomic nervous system impact respiratory function?

It controls the rate and depth of breathing during different physiological states.

Define the term 'neurotransmitter.'

Chemicals that transmit signals across a synapse from one neuron to another.

What is the distinction between central and peripheral control of ANS functions?

Central control originates from the brain and spinal cord; peripheral control acts at the level of the ganglia and target organs.

What characterizes a mixed cranial nerve?

Nerves that carry both sensory and motor fibers.

How do glucose levels in the blood change during sympathetic activation?

Increased glucose release from the liver to provide energy.

Define enteric nervous system dysfunction.

Disorders affecting the complex network of neurons that innervate the digestive tract.

What is the effect of hypothermia on the body?

Prolonged cold exposure leading to dangerously low body temperature.

What is an agonist in pharmacology?

A substance that activates a receptor to produce a biological response.

What is the primary function of the trigeminal nerve?

Facial sensation and control of muscles for mastication.

What role does substance P play in the nervous system?

A neuropeptide involved in pain transmission.