Chapter 13: Coordination and Response: I The nervous System in Mammals

%%Sensitivity%% is the ability to respond to a stimulus (change)

Nervous System of Mammals:

comprises:

  • %%Central Nervous System (CNS)%% - brain and spinal cord.
  • %%Peripheral Nervous System (PNS)%% - cranial nerves, spinal nerves from spinal cord and sense organs.
  • %%Receptors%% are sense organs that receive stimuli.
  • %%Effectors%% are muscles.
Neurones:
  • %%Sensory neurons%% - transmit impulses from sense organs to CNS.
  • %%Relay neurons%% - transmit nerve impulses from sensory neurons to motor neurons - found in CNS.
  • %%Motor neurons%% - transmit nerve impulses from CNS to the effector.
  • %%Synapse%% is the junction b/w two neurons.
Human Brain:
  • %%Forebrain%%   * @@Cerebrum@@     * Concerned with intelligence, memory, learning and overall control of voluntary actions.   * @@Hypothalamus@@     * Concerned with body temperature and blood osmotic pressure, appetite, sleep and emotions.     * Produces ADH
  • %%Midbrain%%   * Concerned with visual reflexes e.g movement of eyeball.
  • %%Hindbrain%%   * @@Cerebellum@@     * Concerned with muscular coordination and maintaining body balance.   * @@Medulla@@     * Concerned with involuntary actions such as heartbeat, peristalsis, rate of respiratory movements and contraction.

 

\

Reflex Actions:

Is an immediate ^^response^^ to a ^^specific stimulus without conscious control.^^

 

\

Spinal and Cranial Reflexes:
  • ^^spinal^^ - controlled by the spinal cord.
  • ^^cranial^^ - controlled by brain.
Reflex Arc

consists of:

  1. a receptor or sense organ
  2. receptor neuron
  3. reflex centre
  4. an effector neuron
  5. an effector (muscle or gland)
Conditioned Reflex:

Is a ^^reflex action^^ acquired ^^from past experience or learning^^ with a stimulus which is originally ineffective in producing the response.