12 : Coordination & Response in Humans

• Motor neurone sends nerve impulses from the central nervous system to effectors.
• Response is how the body reacts to a change in the environment.
• Coordination is the regulation of all organ and system activities within the body.
• System that is involved in the coordination of the human body is the nervous system and the endocrine system.
• Components involved in coordination and response includes :

  • stimulus
  • receptors
  • integration centre
  • effectors
  • response
• Chemoreceptor detect chemicals stimuli.
• Mechanoreceptor detect pressure stimuli.
• Photoreceptor detect light stimuli.
• Thermoreceptor detect changes in temperature.
• Nociceptor detect pain stimuli.
• Importance of Response and Coordination :

  • adapt to changing environment
  • protect itself from danger
  • ensure survival
  • regulate internal environment through homeostasis
• The cerebrum controls the voluntary action.
• Cerebellum maintains body balance and coordination of muscle contraction for body movement.
• Medulla oblongata controls involuntary actions and reflex actions.
• Hypothalamus coordinates homeostasis.
• Sensory neurone transmit nerve impulse from the receptors to the spinal cod via dorsal root.
• Relay neurone transmit nerve impulses from the sensory neurone to the motor neurone.
• Dorsal root contains axons for sensory neurone.
• Dorsal root ganglion contains the cell body of sensory neurone.
• The spinal nerve contains the sensory neurone and motor neurone.
• Grey matter looks like the letter ”H”
• White matter consists of axons covered with myelin sheath.
• Ventral root contains the motor neurone
• Somatic nervous system control voluntary action in the body. It also control the contraction of skeletal muscle and body movement.
• Autonomic nervous system control involuntary actions. It control the contraction of smooth muscle and cardiac muscle.
• Dendrite receive nerve impulse form another neurone.
• Cell body integrate nerve impulse and control neurone activity (nucleus).
• Axon carry impulses out from the cell body to the another neurone.
• Myelin sheath does :

  • protect neurone from injuries
  • insulator for electrical impulse
  • provide nutrients to the axon
• sensory neurone has short axons
• motor neurone has long axons
• The cell body of sensory neurone is located in the middle of the axon and at the dorsal root ganglion.
• Synapse is a narrow gap that separates the synaptic knob from neurone dendrites.
• Synaptic knob is a swelling at the end of the axon branch.
• Impulse are transmitted chemically across synapses instead of electrically.
• Involuntary actions involving the skeletal muscle are controlled by the cerebral cortex.
• Reflex action is a fast response of stimulus without being controlled by brain.
• Nerve pathway involved in a reflex action is called the reflex arc.
• Alzheimer disease involve a progressive decline of memory and thinking skills due to the deaths of neurones.
• ASL is a disease involving damage to motor neurones, inhibiting movement of muscles in the body.