(Lesson-7)

• Integration – an animal needs to function like a coherent organism, not like a loose collection of cells and intracellular mechanisms
• coherency and result in harmonious function = summation and coordination.
• Cellular integration – refers to processes within the cells
• Whole-animal integration – refers to the selective combination and processing of sensory, endocrine, and central nervous system (CNS) information in ways that promote the harmonious functioning of the whole organism. Carried out

  by nerve and endocrine cells.
• Control system – occupy a central place in the achievement of integration; sets the level of a particular variable (temperature, blood pressure, muscle force, and so on) that is being controlled
• Neuron – a signal travels electrically along a cell process all the way to its target; transmission is very fast and spatially highly defined
• Neurotransmitter – a chemical substance released when the electrical signal arrives at the end of the neuron process
• Neuron

  – a cell that is specially adapted to generate an electrical signal

  – most often in the form of a brief, self propagating impulse called an action potential

  – that travels from place to place in a cell.
• What are the four parts of a Nueron

  • Dendrites
  • Soma / Cell Body
  • Axon
  • Presynapthic Terminals
• Dendrites – branching processes where synaptic input occurs
• Cell body – the part of neuron where signal integration and impulse generation occur
• Axon – long, slender part which is the conduction component of a neuron, serving to propagate action potentials along its length
• Presynaptic terminals - where axon ends; neuronal output occurs
• Three type of neuron that performs sensory function.

  • Afferent neurons
  • Efferent neurons
  • Interneurons
• Afferent neurons – neurons that relay signals to integrative centers of the CNS (afferent, “to bring toward”)
• Efferent neurons – relay control signals (instructions) from the CNS to

  target cells that are under nervous control, such as muscle cells or secretory cells.
• Interneurons – neurons that are entirely within the CNS
• Neuronal control has two essential features: it is fast and addressed
• Endocrine system – signals produced are broadly distributed throughout the

  animal’s body.
• Hormones are released into the blood and these chemicals are carried throughout the body by the blood, bathing the tissues and organs at large.
• a hormone to elicit a specific response from a cell, the cell must posses

  receptor proteins for that hormone. Thus cells of only certain tissues or organs respond to a hormone and are called target cells.
• Endocrine control has two essential features: it is slow and broadcast
• Action potential is a momentary reversal of membrane potential from about –65 mV (inside-negative) to about +40 mV (inside-positive).