exam8

Nervous System

  1. What is the main difference between the CNS and PNS? What structures belong to each?

    • CNS (Central Nervous System): Includes the brain and spinal cord; processes and integrates information.

    • PNS (Peripheral Nervous System): Includes cranial nerves, spinal nerves, and ganglia; transmits sensory and motor signals to and from the CNS.

  2. List the three layers of the meninges in order from outermost to innermost. What is the function of each?

    • Dura mater: Tough outer layer that provides protection.

    • Arachnoid mater: Middle layer that contains cerebrospinal fluid (CSF) for cushioning.

    • Pia mater: Thin inner layer that directly covers the brain and spinal cord, providing nourishment.

  3. What is the structural difference between white matter and gray matter?

    • White matter contains myelinated axons that facilitate fast signal transmission.

    • Gray matter consists of neuron cell bodies, dendrites, and unmyelinated axons, involved in processing and integration.

  4. What is the function of the dorsal root vs. the ventral root of a spinal nerve?

    • Dorsal root: Carries sensory information into the spinal cord.

    • Ventral root: Carries motor information out to muscles and glands.

  5. What do the dorsal and anterior rami innervate?

    • Dorsal ramus: Innervates muscles and skin of the back.

    • Anterior ramus: Innervates muscles and skin of the front and limbs.

  6. What are the alternate names of the sympathetic and parasympathetic nervous systems based on spinal cord regions?

    • Sympathetic NS: Thoracolumbar division (T1-L2).

    • Parasympathetic NS: Craniosacral division (brainstem and sacral spinal cord).

  7. Where are the ganglia located in the sympathetic vs. parasympathetic nervous systems?

    • Sympathetic: Ganglia are near the spinal cord (sympathetic chain or collateral ganglia).

    • Parasympathetic: Ganglia are near or within the target organs.

  8. What neurotransmitters are used in the sympathetic and parasympathetic nervous systems?

    • Sympathetic: Uses norepinephrine (NE) at target organs (except sweat glands, which use acetylcholine).

    • Parasympathetic: Uses acetylcholine (ACh) at both ganglia and target organs.


Brain & Cranial Nerves

  1. Name the three parts of the brainstem and their functions.

    • Midbrain: Controls reflexes and processes sensory information.

    • Pons: Regulates breathing and relays information between the brain and spinal cord.

    • Medulla oblongata: Controls vital functions like heart rate and respiration.

  2. What is the function of the corpus callosum?

    • Connects the left and right cerebral hemispheres, allowing communication between them.

  3. How many cranial nerves are there? Name one that is purely sensory, one that is purely motor, and one that is mixed.

    • 12 cranial nerves total.

    • Sensory: Optic nerve (CN II) (vision).

    • Motor: Oculomotor nerve (CN III) (eye movement).

    • Mixed: Facial nerve (CN VII) (facial movement and taste).


Sensory System

  1. Match each receptor type with its function:

  • Chemoreceptors → Detect chemicals (e.g., taste, smell).

  • Thermoreceptors → Detect temperature changes.

  • Nociceptors → Detect pain.

  • Baroreceptors → Detect pressure changes (e.g., blood pressure).

  • Mechanoreceptors → Detect mechanical pressure and movement (e.g., touch, vibration).

  1. Describe the olfactory pathway. How does the sense of smell reach the brain?

  • Odor molecules → Olfactory receptors → Olfactory bulb → Olfactory tract → Olfactory cortex (temporal lobe).

  1. Describe the gustatory pathway. What structures are involved in taste perception?

  • Taste buds → Cranial nerves (VII, IX, X) → Medulla → Thalamus → Gustatory cortex in the insula.

  1. Compare and contrast rods and cones in the retina. How do they interact with bipolar cells?

  • Rods: Detect dim light, black and white vision, high sensitivity.

  • Cones: Detect color (red, green, blue), high acuity in bright light.

  • Both synapse onto bipolar cells, which transmit signals to ganglion cells and then the optic nerve.

  1. What is the function of the posterior chamber vs. the anterior chamber of the eye?

  • Posterior chamber: Produces aqueous humor.

  • Anterior chamber: Circulates aqueous humor to maintain intraocular pressure.

  1. What is the function of the optic chiasm?

  • It allows partial crossover of optic nerve fibers, ensuring visual information from both eyes is processed in both hemispheres of the brain.

  1. Name three structures that help protect the eye.

  • Eyelids, eyelashes, conjunctiva (mucous membrane that protects and lubricates the eye).

  1. What is the function of the fovea centralis?

  • Provides sharp central vision due to a high concentration of cones.


Hearing

  1. Describe the pathway of sound from the external ear to the brain.

  • External ear → Tympanic membrane → Ossicles (malleus, incus, stapes) → Oval window → Cochlea → Hair cells → Auditory nerve → Brainstem → Auditory cortex.

  1. What is the function of the semicircular canals?

  • Detect rotational head movements (balance and equilibrium).

  1. What is the function of the cochlea?

  • Converts sound waves into electrical signals for the brain to process.

  1. What are the three auditory ossicles, and what is their role in hearing?

  • Malleus, Incus, Stapes: Transmit vibrations from the eardrum to the oval window.

  1. What is the role of the Organ of Corti in hearing?

It contains hair cells that convert sound vibrations into electrical signals sent to the brain.