Coordination and Response

• Homeostasis


  Homeostasis is the maintenance of a stable internal environment, basically keeping things the same. For example, keeping body temperature at a steady 37 degrees
• Stimuli receptors and effectors


  Organisms react to changes in any of the above environmental conditions. Any coordinated response requires a stimulus, a receptor and an effector. In humans, the nervous system controls our response to external changes. It is made up of two parts; the central nervous system, which includes the brain and spinal cord, and the peripheral nervous system which contains receptors connected to nerves or neurons and effectors, also connected to neurons. Receptors are the first to respond to stimuli and are found in our sense organs. They are connected to the central nervous system via peripheral neurons. Effectors are mainly muscles and organs that secrete hormones - called glands; these are also connected to the central nervous system via neurons
• The nervous system


  The human body is an amazing piece of biological machinery; it not only constantly responds to external stimuli (far more quickly than plants!) but also keeps itself in balance internally too, without us even thinking about it.Our nervous system controls our response to external changes. It is made up of two parts; the central nervous system, which includes the brain and spinal cord, and the peripheral nervous system which contains receptors connected to nerves or neurons and effectors, also connected to neurons.Receptors are the first to respond to stimuli and are found in our sense organs. They are connected to the central nervous system via peripheral neurons. Effectors are mainly muscles and organs that secrete hormones called glands; these are also connected to the central nervous system via neurons.
• Thyroid gland


  Iodine is required by the thyroid gland to make thyroxine, a hormone which controls our metabolic rate and which is often termed the "growth hormone". Fish and shellfish are rich in iodine, as are most vegetables that have been grown in iodine rich soil.
• Pituitary gland


  This is situated in the brain. It is an important gland and produces several hormones, most of which control the action of other endocrine glands.
• Pancreatic gland


  The pancreas is a gland of the digestive system, but it also contains an endocrine gland which produces the hormones insulin and glucagon. The target organ of both these hormones is the liver. Insulin causes glycogen to be broken down to glucose; glucagon causes glucose to be converted to glycogen. The secretion of the right hormone depends on the level of glucose in the blood.
• Adrenal glands


  These are situated just above each kidney. They produce adrenaline, often called the 'fight or flight' hormone, which act when the body is under stress, either mentally or physically