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					Animal Form & Function
      Physiology
        AP Biology
Nerve Impulse Transmission
p Resting potential
p More negative inside cell than outside
    n   Why?
    n   Large negatively charged proteins & nucleic
        acids
    n   Na+/K+ pumps maintain high [Na+] outside
        cell and high [K+] inside cell
Nerve Impulse Transmission
p Resting potential
p Membrane potential = -70 mV
Nerve Impulse Transmission
p Depolarization
p Stimulus causes Na+ gates to open
p Na+ rushes into cell
Nerve Impulse Transmission
p Repolarization
p Na+ gates close
  & K+ gates open
p K+ rushes out of
  cell
p High [Na+] inside
  cell
p High [K+]
  outside cell
Nerve Impulse Transmission
p Hyperpolarization
p K+ gates slow to close
p More K+ moved out
  than necessary
Nerve Impulse Transmission
p Refractory
  period
p Na+/K+ pumps
  move
    n   Na+ out of cell
    n   K+ into cell
p   Restores resting
    potential
    distribution of
    Na+ and K+
Transmission Across a Synapse
p Synapse
p Gap between neurons
Transmission Across a Synapse
p   Stimulus reaches synaptic end bulb
Transmission Across a Synapse
p Ca2+ gates open
p Ca2+ enters end bulb
Transmission Across a Synapse
p   Vesicles with neurotransmitter
    migrate to presynaptic membrane
Transmission Across a Synapse
p   Vesicle fuses with presynaptic
    membrane
Transmission Across a Synapse
p   Neurotransmitter released into
    synaptic cleft
Transmission Across a Synapse
p   Neurotransmitter diffuses across
    cleft
Transmission Across a Synapse
p   Neurotransmitter binds to receptor
    protein
Transmission Across a Synapse
p   Postsynpatic neuron depolarizes
Muscle Contraction
p   Sliding filament model
Muscle Contraction
p Sliding filament model
p Depolarization of muscle causes
  sarcoplasmic reticulum to release Ca2+
Muscle Contraction
p Sliding filament model
p Ca2+ exposes binding sites on actin
p Myosin heads bind to actin
p Cross bridges form
Muscle Contraction
p Sliding filament model
p Myosin heads lose ADP + P
p Myosin heads change shape
p Actin pulled toward center of sarcomere
p Muscle contracts
Muscle Contraction
p Sliding filament model
p ATP binds to myosin heads
p Cross bridges break
p Muscle relaxes
Muscle Contraction
p   Sliding filament model
Steroid Hormone
p   Steroid hormone
    enters cell
Steroid Hormone
p Steroid hormone
  enters cell
p Binds to receptor
Steroid Hormone
p Steroid hormone
  enters cell
p Binds to receptor
p Hormone-receptor
  complex enters
  nucleus
p Causes
  transcription

                      DNA transcribed
                      RNA translated
Protein Hormone
p   Protein hormone
    too big to enter cell
Protein Hormone
p Protein hormone
  too big to enter cell
p Binds to receptor
Protein Hormone
p Protein hormone
  too big to enter cell
p Binds to receptor
p Activates enzyme
Protein Hormone
p Protein hormone
  too big to enter cell
p Binds to receptor
p Activates enzyme
p Enzyme used to
  make cyclic AMP
Protein Hormone
p Protein hormone
  too big to enter cell
p Binds to receptor
p Activates enzyme
p Enzyme used to
  make cyclic AMP
p Cyclic AMP
  targets cell
  responses
Kidney
p Filtration
p Formation of
  filtrate
p Waste, nutrients,
  water, ions,
  proteins move
  from the blood
  into the Bowman’s
  capsule
Kidney
p Reabsorpton
p Nutrients, ions, &
  water move from
  filtrate back into
  blood
Kidney
p Secretion
p Ions & wastes
  more from the
  blood into the
  filtrate
Kidney
p Bowman’s capsule
p Filtrate production
p Blood pressure forces
  small solutes, water &
  ions from blood into
  capusule
Kidney
p Proximal convoluted
  tubule
p Reabsorption of water,
  ions, and all organic
  nutrients
Kidney
p Loop of Henle
p Descending limb
p Water reabsorbed
p Wall permeable to water
  but not solutes
Kidney
p Loop of Henle
p Ascending limb
p Wall impermeable to
  water and solutes
p Cells actively pump Na+
  and Cl- out of tubular
  fluid
Kidney
p Distal convoluted
  tubule
p Secretion of ions, acids,
  drugs, toxins
p Variable reabsorption of
  water and Na+
Kidney
p Collecting duct
p Variable reabsorption of
  water and ions
p Variable secretion of
  water and ions
p Balancing act -
  homeostasis

				
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posted:12/9/2013
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