Untitled Flashcard Set

What is the overall function of the Peripheral Nervous System (PNS)?

It provides links to and from the world outside our bodies by consisting of all neural structures outside the brain and spinal cord.

Exteroceptors

Respond to stimuli outside the body (e.g., touch, taste).

Interoceptors

Respond to stimuli within the body (e.g., from the stomach).

Proprioceptors

Respond to stretch in muscles, tendons, and joints to inform the brain of body position.

What are the 5 components of a Reflex Arc?

Receptor, sensory neuron, integration center, motor neuron, and effector.

Stretch Reflex

Monosynaptic/ipsilateral reflex that causes muscle contraction in response to increased length (e.g., knee-jerk).

Tendon Reflex

Reflex that causes muscle relaxation in response to high tension.

Flexor (Withdrawal) Reflex

Polysynaptic/ipsilateral reflex initiated by painful stimuli.

Crossed-Extensor Reflex

Contralateral reflex that maintains balance during a withdrawal reflex.

How does the Autonomic Nervous System (ANS) differ from the Somatic Nervous System (SNS)?

SNS is voluntary, innervates skeletal muscles, always excitatory, and uses one motor neuron; ANS is involuntary, innervates smooth/cardiac muscle and glands, can be excitatory or inhibitory, and uses a two-neuron chain (pre/postganglionic).

Sympathetic Division

'Fight or Flight'; mobilizes body during activity; increases heart rate/blood glucose; originates in the thoracolumbar CNS.

Parasympathetic Division

'Rest and Digest'; conserves energy/promotes maintenance; decreases heart rate; originates in the craniosacral CNS.

Acetylcholine (ACh)

Released by cholinergic fibers (all preganglionic and all parasympathetic postganglionic).

Norepinephrine (NE)

Released by adrenergic fibers (most sympathetic postganglionic).

What is the main integration center of the ANS?

The Hypothalamus.

Trace the pathway of light through the eye.

Cornea → Aqueous humor → Pupil → Lens → Vitreous humor → Retina (Photoreceptors).

Rods

Dim light/peripheral vision; high sensitivity; low resolution; one type of pigment.

Cones

Bright light/color vision; low sensitivity; high resolution (fovea centralis); three types of pigments.

Myopia

Eyeball too long; focal point in front of retina; corrected with concave lens.

Hyperopia

Eyeball too short; focal point behind retina; corrected with convex lens.

Astigmatism

Blurred vision due to unequal curvatures of the lens or cornea.

Maculae

Structures that monitor head position and linear acceleration (gravity).

Cristae Ampullares

Structures that monitor head rotation/angular acceleration.

Tinnitus

Ringing or buzzing in the ears.

Otitis Media

Inflammation of the middle ear.

Ménière’s Syndrome

Labyrinth disorder causing vertigo, nausea, and hearing loss.