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Anatomy & Physiology: Nervous System, Endocrine System, and Neurophysiology

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Termini in questo insieme (32)

  • Rami communicantes
    Autonomic nerve branches connecting the anterior ramus of a spinal nerve to the sympathetic chain ganglion; white rami carry myelinated preganglionic sympathetic axons (T1-L2), gray rami carry unmyelinated postganglionic axons (all spinal levels).
  • Typical reflex arc pathway
    Sensory receptor → sensory (afferent) neuron → integration center in spinal cord gray matter → motor (efferent) neuron → effector organ (muscle or gland).
  • Location of ascending and descending tracts
    Found exclusively in the white matter columns (posterior, anterior, lateral funiculi) of the spinal cord; ascending tracts carry sensory signals to the brain, descending tracts carry motor commands from the brain.
  • Subarachnoid space
    The space between the arachnoid mater and pia mater that contains cerebrospinal fluid (CSF).
  • Composition of a spinal nerve
    A mixed nerve formed by the fusion of the dorsal (sensory) root and ventral (motor) root exiting the intervertebral foramen.
  • Tendon reflex (Golgi tendon reflex)
    A polysynaptic reflex that monitors muscle tension and prevents damage by causing relaxation of the contracting muscle.
  • Muscle spindles
    Specialized stretch receptors within skeletal muscles that detect changes in muscle length and trigger the stretch reflex to maintain posture.
  • Reflex classification criteria
    Classified by development (innate vs. acquired), processing site (spinal vs. cranial), motor response (somatic vs. autonomic), and circuit complexity (monosynaptic vs. polysynaptic).
  • Number of spinal nerve pairs
    31 pairs total: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
  • Phrenic nerve origin and function
    Originates from cervical spinal segments C3, C4, and C5; innervates the diaphragm to control breathing.
  • Anterior rami innervation
    Innervate the skin and muscles of the ventrolateral body wall and limbs, often forming nerve plexuses.
  • Denticulate ligaments
    Paired extensions of pia mater that anchor the spinal cord laterally to the dura mater, preventing side-to-side movement.
  • Cervical and lumbar enlargements
    Regions of spinal cord with increased gray matter for limb control: cervical for upper limbs, lumbar for lower limbs.
  • Gray commissure
    Crossbar of gray matter surrounding the central canal connecting left and right spinal cord gray matter, containing decussating axons.
  • Components of white matter
    Bundles of myelinated and unmyelinated axons organized into columns and tracts.
  • Components of gray matter
    Neuronal cell bodies, dendrites, unmyelinated axons, neuroglia, and synapses.
  • Order of meninges from inner to outer
    Pia mater → Arachnoid mater → Dura mater.
  • End of the spinal cord
    Terminates at the conus medullaris between lumbar vertebrae L1 and L2.
  • Monosynaptic vs. polysynaptic reflex
    Monosynaptic: single synapse between sensory and motor neuron (e.g., stretch reflex). Polysynaptic: multiple synapses with interneurons (e.g., withdrawal reflex).
  • Anterior root fibers
    Contain motor (efferent) fibers transmitting commands from spinal cord to effectors.
  • Posterior root fibers
    Contain sensory (afferent) fibers carrying signals from receptors to the spinal cord.
  • Hormone definition
    Chemical messengers secreted by endocrine cells into blood to regulate specific physiological activities in distant target cells.
  • Anterior pituitary hormones
    Six main hormones: TSH, ACTH, FSH, LH, GH, and Prolactin.
  • Posterior pituitary hormones
    Antidiuretic Hormone (ADH) and Oxytocin (OXT), produced by hypothalamus and released by posterior pituitary.
  • Function of Growth Hormone (GH)
    Stimulates protein synthesis, cell division, bone and muscle growth, lipolysis, glycogen breakdown, and tissue repair.
  • Role of antidiuretic hormone (ADH)
    Increases kidney water reabsorption, reduces urine volume, conserves body water, and causes vasoconstriction to raise blood pressure.
  • Insulin and glucagon secretion triggers
    Insulin released when blood glucose is high to promote uptake and storage; glucagon released when blood glucose is low to stimulate glucose release.
  • Cells secreting insulin and glucagon
    Beta cells secrete insulin; alpha cells secrete glucagon in the pancreas.
  • All-or-none principle of action potentials
    An action potential fires at full amplitude if threshold is reached; no action potential occurs if stimulus is below threshold.
  • Seven steps of an action potential
    1. Depolarization to threshold, 2. Na+ channel activation, 3. Rapid depolarization, 4. Na+ channel inactivation & K+ channel activation, 5. K+ efflux repolarizes, 6. Hyperpolarization, 7. Resting potential restored.
  • Function of voltage-gated sodium channels
    Contain activation gates that open at threshold and inactivation gates that close at peak depolarization, creating the absolute refractory period.
  • Saltatory conduction
    Rapid action potential propagation along myelinated axons by jumping between Nodes of Ranvier.