Today:

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Today

• Response and feedback loops setpoints
• Speed and specificity of control systems
• Patterns of control pathways
• The organization of the nervous system
• Neurons
• Midterm test
• Monday Oct. 7 830 920
• multiple choice questions
• Location A- P in the Education Gym
• Q-Z in Erie Hall (lecture hall)

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Setpoints can vary

• Acclimatization adaptation to a given set of
  environmental conditions (first day of spring
  like weather)
• Acclimation adaptation to laboratory setting

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Endocrine and Nervous Reflexes

• Specificity of target cells
• Nature of signal
• Speed
• Duration of action
• Stimulus intensity coding

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Specificity of target cells
A neuron has a specific target cell. Many
tissues may have receptor proteins for a hormone
and may respond to the hormone.
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Nature of signal
In neurons, electrical signals travel long
distances and chemical signals
(neurotransmitters) move to the target cell.
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Nature of signal The endocrine system uses
chemical signals.
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Nature of signal Neuroendocrine
Electrical signals travel long distances and
chemical signals (neurohormones) move into blood
vessels.
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Speed

• Electrical signals conducted very quickly
• Rapid signal transduction with many
  neurotransmitters
• Hormones move by diffusion from endocrine cell to
  target (slower)
• Some responses take quite a long time

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Duration of action

• Nervous control is shorter than endocrine control
• Nervous usually neurotransmitter is rapidly
  removed

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Stimulus intensity coding

• Intensity is coded by neuronal firing frequency?
  amount of neurotransmitter
• The amount hormone that is released codes the
  intensity.

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Knee jerk reflex Lactation,
oxytocin Autonomic stimulation of insulin
release Growth hormone
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Testosterone Low glucose and beta cells
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Organization of the nervous system

• Sensory Receptors ? afferent pathway ? central
  nervous system (CNS, brain and spinal cord ?
  efferent neurons (peripheral nervous system PNS)?
  target
• PNS
• Somatic motor division
• Autonomic division
• Sympathetic
• Parasympathetic

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Cells of the nervous system -neuron