Anatomy Exam 2

• Frequency


  Number of waves per second
• Amplitude

  Intensity: peak to trough
• Energy associated with sound waves

  Kinetic mechanical energy
• Anatomy of the ear


  • Outer
  • Middle
  • Inner
• Outer ear


  • Pinna
  • External auditory meatus
  • Auditory canal
  • Tympanic membrane
  • Tensor tympani
• Middle ear


  • Ossicles (Malleus, Incus, Stapes)
  • Eustachian tube
• Inner ear

  • Cochlea
  • Vestibular apparatus
• Mechanisms used by the middle ear to amplify force of sound wave

  1. Ossicles (Malleus, Incus, Stapes)

  2. Surface area differences between the tympanic membrane and oval window
• The tympanic membrane has a big surface area, and the oval window has a small surface area, allowing for greater amplification of sound waves
• Anatomy of the cochlea

  • Fluid-filled internal chambers (Scala tympani, Scala media, Scala vestibuli)
  • Membranes that separate chambers (Basilar membrane, Vestibular membrane)
  • Oval and round windows
• Oval window


  Associated with Scala vestibuli; marks the beginning of sound waves traveling through cochlea
• Round window


  Associated with Scala tympani; acts as an endpoint for sound waves to travel
• Characteristics of the basilar membrane

  • Stiffer at the base, more flexible toward the apex
  • Base responds to higher frequencies, apex responds to lower frequencies
• Anatomy of the Organ of Corti

  • Basilar membrane
  • Hair cells
  • Tectorial membrane
• Transduction of mechanical forces into neural-based signals

  1. Shearing of hair cells

  2. Mechanical gating of K+ channels

  3. Transductional events that cause neurotransmitter release
• Sound localization

  • MSO (coincidence detection for low-frequency sound)
  • LSO/MNTB (for high-frequency sound)
• Amplitude encoding

  • Proportion of activated hair cells
  • Firing of individual hair cells
• Types of somatic receptors

  • Proprioceptors
  • Touch receptors (Pacinian, Meissner's corpuscle, Ruffini's ending, Mercel's disks)
  • Thermoreceptors
  • Nociceptors
• Spinal cord organization

  • Segments (Cervical, Thoracic, Lumbar, Sacral)
  • Dermatomes
• Somatic sensory information processing pathways

  • Spinal thalamic (ST) pathway (pain and temperature)
  • Dorsal column medial lemniscal (DCML) pathway (touch and proprioception)
• DCML pathway

  • Ascends through the dorsal column on the ipsilateral side, synapses in the medulla, crosses over and ascends via the medial lemniscus to the thalamus (Ventral Posterior), projects to the cortex
• ST pathway

  • Crosses to the contralateral side in the spinal cord, ascends via the spinothalamic tract, synapses in the thalamus (Ventral Posterior), projects to the cortex
• Information carried in each somatic sensory pathway remains segregated all the way to the cortex
• Upper and lower motor neurons

  • Upper motor neurons are in the brain, control lower motor neurons and parts of the brain
  • Lower motor neurons are in the ventral horn of the spinal cord, innervate muscles and glands, send information to upper motor neurons
• Rigid paralysis

  Muscles are contracted and become rigid and immoveable
• Flaccid paralysis


  Muscles are relaxed and become floppy
• Possible injury sites for diagnosing spinal cord

  • Spinal nerve
  • Ventral root or horn
  • Dorsal root or DRG
  • Dorsal column
  • Spinal pathway
  • Lateral horn
  • Spinal cord hemi section
• Types of glands

  • Endocrine
  • Exocrine
• Endocrine glands


  • Ductless, secrete hormones into surrounding tissue fluid, receive hormones through vascular or lymphatic drainage
• Examples of endocrine glands

  • Pituitary
  • Thyroid
  • Parathyroid
  • Adrenal
  • Pineal
  • Thymus
  • Pancreas
  • Gonads
  • Hypothalamus
• Exocrine glands

  Have ducts, secrete nonhormonal products directed to membrane surfaces
• Characteristics of hormonal secretions

  • Chemical substances secreted by cells into extracellular fluids, regulate metabolic function of other cells in the body
• General classes of hormones

  • Amino acid-based hormones
  • Steroid hormones
• Actions of hormones

  • Alter plasma membrane permeability
  • Alter protein or regulatory molecule synthesis
  • Activate or inactivate enzyme
  • Induce secretory activity
  • Stimulate mitosis
• Mechanisms of hormone effects

  1. G-protein linked receptor activation of intracellular second messengers (amino acid-based hormones)

  2. Direct gene activation (steroid hormones)
• Target cell specificity

  Presence and location of specific protein receptors
• Factors determining response to a hormone

  • Hormonal levels
  • Number of receptors on the target cell
  • Receptor affinity
• Stimuli causing hormonal release

  • Humoral (fluid)
  • Neural
  • Hormonal
• Anterior pituitary hormones

  • Growth hormone (GH)
  • Thyroid-stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Gonadotropins (FSH and LH)
  • Prolactin
• Posterior pituitary hormones

  • Oxytocin