2.85 Reflexes

• Sensory neurons connect to motor neurons through interneurons in the Central Nervous System.
• The sensory neuron carries the message from the receptor to the motor neuron which carries the message to the effector to make the interneurons work.

2.84 Responses

• A reflex is an action that is performed as a response to a stimulus and without conscious thought.
• The sensory nerve sends an electrical impulse to the Central Nervous System.
• The motor nerve sends the signal to the effector and your body reacts to it.

2.83 Central Nervous System

• The Central Nervous System consists of the Spinal Cord and the Brain.  
• Nerves are linked to the spinal cord which carry electrical impulses sent by the brain to sense organs by nerves.

2.82 Communication

• The nerve impulse is carried along inside the nerve from the cell body to the Synaptic Knob where it connects to the muscle.
• In mammals the axon is surrounded by a Schwann Cell which contains a great deal of fat.
• The Myelin Sheath increases nerve conduction.
• The endocrine gland produces a chemical known as a hormone.
• Hormones can be proteins or steroids eg. Adrenal Gland.

2.77b Thermoregulation

• The Negative feedback loop is a method of control and retaining constant conditions.
• The average body temperature of a human is 37/38 degrees centigrade. 
• The hypothalamus responds to a stimulus which is the temperature of the body or blood. 
• Body temperature feeds into the brain and is compared to the theoretical level of control.
• If the body temperature needs to be increased of decreased then it is brought about through the action of the effector such as the skin.

2.77a Thermoregulation

• Homeothermic: Same Temperature.
• Homeostasis: Conditions are kept the same or are constant.
• If the environmental temperature increases or decreases a mouse's body temperature remains constant.
• Homeothermic carries out a process called Thermoregulation.
• Mammals remain the same body temperature. 

2.76 Sensitivity

• Sensitivity is the characteristic of the organisms respond to changes in their environment. 
• Changes in the environment include: Light, temperature, pressure and chemical.
• Organisms are required to have receptors and effectors such as muscles and glands.
• Response is used to survive the changes in the environment.