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.