BIO 2311 Final Exam Study Guide

Spinal Cord and Spinal Nerves

• The spinal cord extends from the foramen magnum to the level of L1/L2 vertebrae.
• It features two enlargements:
  • Cervical enlargement: serves upper limbs.
  • Lumbar enlargement: serves lower limbs.
• The spinal cord terminates as the conus medullaris.
• Cross-section anatomy:
  • Inner gray matter: horns.
  • Outer white matter: funiculi (anterior, lateral, posterior) containing tracts.
• Meninges:
  • Dura mater.
  • Arachnoid mater.
  • Pia mater.
• Epidural space: fat-filled; used for epidural injections.
• Subarachnoid space: filled with cerebrospinal fluid (CSF); used for spinal taps.

Brain and Cranial Nerves

• Brain stem:
  • Mesencephalon (midbrain).
  • Pons.
  • Medulla oblongata.
• Lobes of the brain:
  • Frontal lobe.
  • Parietal lobe.
  • Temporal lobe.
  • Occipital lobe.
• Sulci:
  • Central sulcus: separates the frontal and parietal lobes.
  • Lateral sulcus: separates the temporal lobe from the other lobes.
• Brain ventricles:
  • Two lateral ventricles (in the cerebrum).
  • Third ventricle (in the diencephalon).
  • Fourth ventricle (in the brainstem/cerebellum).
• Connections between ventricles:
  • Interventricular foramen: connects the lateral ventricles to the third ventricle.
  • Cerebral aqueduct: connects the third and fourth ventricles.
• Hemispheric lateralization:
  • Left hemisphere: dominant for language and logic.
  • Right hemisphere: dominant for spatial reasoning and creativity.
• Brain waves (measured via EEG):
  • Alpha waves: associated with relaxation.
  • Beta waves: associated with alertness.
  • Theta waves: associated with light sleep.
  • Delta waves: associated with deep sleep.
• Diencephalon:
  • Epithalamus: contains the pineal gland which secretes melatonin.
  • Thalamus: serves as a relay center for sensory information.
  • Hypothalamus: regulates homeostasis.
• Cerebellum: coordinates movement.
  • Parts:
  • Vermis.
  • Hemispheres.
  • Cortex.
  • Arbor vitae.
• Brain development: develops from the neural tube.
  • Three primary vesicles:
  • Five secondary vesicles:
  • Telencephalon: forms the cerebrum.
  • Rhombencephalon: forms the brainstem and cerebellum.
• Cranial Nerves (selected):
  • I (Olfactory): sensory; function in smell.
  • II (Optic): sensory; function in vision.
  • III (Oculomotor): motor; controls eye movement.
  • IV (Trochlear): motor; controls eye movement.
  • VI (Abducens): motor; controls eye movement.
  • VIII (Vestibulocochlear): sensory; function in hearing and balance.
  • X (Vagus): mixed (sensory and motor); has a wide range of functions in the autonomic control of thoracic and abdominal viscera.

Nervous System Pathways

• Sensory pathway:
  • 1st order neuron: from the peripheral nervous system (PNS) to the spinal cord.
  • 2nd order neuron: crosses over (decussates) and projects to the thalamus.
  • 3rd order neuron: projects from the thalamus to the cortex.
• Sensory pathways (specific):
  1. Posterior Column Pathway: transmits fine touch and vibration sensations.
  2. Spinothalamic Pathway: transmits pain and temperature sensations.
  3. Spinocerebellar Pathway: transmits proprioception information (does not decussate).
• Somatic motor pathway: involves two neurons (upper and lower).
  • Lower motor neuron: connects to the muscle; damage leads to paralysis.
• Motor tracts:
  • Corticospinal (pyramidal) tract: enables conscious control of skeletal muscles.
  • Extrapyramidal tracts: involved in subconscious motor control.
  • Medial pathways
  • Lateral pathways

Autonomic Nervous System (ANS)

• Divisions:
  • Sympathetic: "fight or flight" response.
  • Features short preganglionic and long postganglionic neurons.
  • Uses acetylcholine (ACh) at the ganglion and norepinephrine at the effector organ.
  • Parasympathetic: "rest and digest" response.
  • Features long preganglionic and short postganglionic neurons.
  • Uses acetylcholine (ACh) at both the ganglion and the effector organ.
• Visceral pathway: preganglionic neuron -> autonomic ganglion -> postganglionic neuron -> effector organ.
• Sympathetic ganglia:
  • Sympathetic chain (paravertebral).
  • Collateral (prevertebral).
  • Adrenal medulla: does not have postganglionic fibers; releases epinephrine and norepinephrine directly into the bloodstream.
• Terminal ganglia: associated with cranial nerves (e.g., CN III, VII, IX); intramural ganglia are found in organs (innervated via the vagus and sacral nerves).

Special Senses

• Special senses: vision (retina), gustation (taste buds), olfaction (nasal epithelium), hearing and balance (ear).
• General senses: touch, pain, pressure, temperature; receptors are distributed throughout the body.
• Receptors:
  • Exteroceptors: detect external stimuli.
  • Interoceptors: detect internal stimuli.
  • Proprioceptors: detect body position and movement.
• Eye: The retina contains:
  • Rods: photoreceptors specialized for detecting light.
  • Cones: photoreceptors specialized for detecting color.
  • Pigments include rhodopsin.
• Ear:
  • Outer ear: auricle.
  • Middle ear: ossicles (malleus, incus, stapes).
  • Inner ear:
  • Cochlea: for hearing.
  • Vestibule and semicircular canals: for balance.
  • Innervated by CN VIII (vestibulocochlear nerve).