Nervous System

  1. What are the three types of cell to cell communication and the qualities of each?
    1. Neurotransmitters: rapid, specific, direct

    2. Local mediators: paracrine, intermediate, released into interstitium

    3. Hormones: endocrine, released into circulation, slow, diverse actions 
  2. Can neurons divide? Why? 
    No, because they are too specialized
  3. What is special about neurons in relation to metabolism?
    They use facilitated transport to obtain glucose...but independently of insulin. 
  4. Signal transduction order in neurons.
    • 1. Signal received in dendrites 
    • 2. Travel to axo hillock (Site of AP generation)
    • 3. Travel down axon to synapse  
  5. Na+/K+ pump
    • 3 Na+ out 
    • 2K+ in
  6. Steps of AP
    Image Upload 1
  7. What kind of cells work via AP mechanisms?
    • 1.Neuronal 
    • 2.Muscle
    • 3.Cardiac  
  8. What kind of synapses do most neurons employ?
    1. Chemical, unidirectional synapses
  9. Unique distinction of vertebrates?
    Only vertebrates have MYLENATED axons! 
  10. Where do sensory and motor neurons lie in the spinal cord?
    Sensory neurons: dorsally 

    Motor/somatic NS neurons: ventrally  
  11. What is the autonomic NS regulated by?
    The hypothalamus 
  12. ACh receptors
    a) Found ALL throughout the PNS except for sympathetic neuroeffector synapses 

    b) Nicotinic: muscles

    c) Muscarinic: found in the parasympathetic NS  
  13. What is the major role of sensory receptors?
    Transduction of physical stimuli to neural stimuli 
  14. What kind of lens is the eye?
    Converging ; objects behind focal point are REAL and INVERTED
  15. What effect do the contraction/relaxation of ciliary muscles have on the lens and focal point?
    Contraction: Bends the lens, makes more spherical, moves focal point CLOSER to lens

    Relaxation: straightens lens, flattens, moves focal point AWAY from lens, harder to see closer objects, happens in old age when muscles tire
  16. What kind of photoreceptors does the fovea contain?
    Only cones 
  17. Cornea 
    First place light hits the eye ; nonvascular and made of collagen ; where most bending of light occurs because it is highly refractive 
  18. Path of light
    Iris/Pupil --> Cornea --> Aqueous humor --> Lens --> Vitreous humor --> Retina 
  19. Path of sound
    Pinna (outer) --> Tympanic mem. (middle) --> Malleus, incus, stapes --> Cochlea (stereocilia + Organ of Corti)
  20. Where is sound transduced?
    By the hair cells of the Organ of Corti in the Cochlea
  21. Lever system in the ear?
    Malleus, Incus, and Stapes are 3 small bones acting as levers. 

    Their displacement from sound is small, making the force from sound much larger and more easily transduced.
  22. Semicircular canals
    Important in vestibular information
  23. Somatic vs. Autonomic NS 
    Somatic NS is in control of SKELETAL MUSCLES

    Autonomic is in control of smooth and cardiac muscles ! 
  24. What NS control simple reflex arcs?
  25. What controls shivering?
    Somatic NS because shivering involves the contraction of skeletal muscles to generate heat 
  26. Sweating is controlled by...?
    Autonomic NS (both branches) 
  27. ACh actions on heart?
    Acts via vagus nerve to increase time between contractions, slowing down HR
  28. Acclimatization
    Endocrine system because it happens over time
  29. By which cells is the myelin sheath made in the CNS and the PNS? 
    CNS = Oligodendrocytes 

    PNS = Schwaan Cells  
  30. Why is the membrane potential negative?
    3Na+ out, 2K+ in
  31. What makes testosterone?
    Adrenal glands
  32. What makes estrogen?
  33. Reflex arcs 
    Involve CNA - but also involve both the excitation and inhibition of muscle groups. 

    Remember that they involve CNA because they go through the spinal cord!
Card Set
Nervous System
MCAT Biology