Coordination and Response

• Coordination refers to how our bodies link the information from different parts of the body and respond accordingly.
• The nervous system and the endocrine system are the primary systems responsible for this.
• Coordination in the body helps to maintain stability in varying environments, a concept known as homeostasis.

The Nervous System

• Involves detecting changes in the environment (stimuli) and responding to them.
• Consists of the central nervous system (the brain and spinal cord) and the peripheral nervous system (nerves connecting the central nervous system to the entire body).
• When a stimulus is detected, nerves carry electrical signals, or nerve impulses, to and from the brain and spinal cord.

The Endocrine System

• Comprises glands that secrete hormones into the blood; hormones travel to specific target cells in the body.
• Endocrine glands include the pituitary, thyroid, adrenal glands, ovaries in women and testes in men.
• Hormones regulate body functions like metabolism, growth, and reproduction.
• An example is insulin, a hormone produced by the pancreas that controls blood glucose levels.

Homeostasis

• The body needs to maintain a stable internal environment, despite changes in the external environment; this is homeostasis.
• Examples of homeostasis include regulation of body temperature, water balance, and blood sugar levels.
• Both the nervous and endocrine systems play crucial roles in homeostasis by detecting changes and triggering responses.

Nervous Responses and Reflex Arcs

• A reflex is a rapid, automatic response to a stimulus.
• Reflexes often involve a simple nerve pathway called a reflex arc, bypassing the brain to protect from harm.
• Reflex actions ensure immediate response to potentially harmful stimuli, like touching something hot.
• In a reflex arc, the pathway involves sensory, relay, and motor neurons.

Plant Responses to Stimuli

• Plants respond to stimuli too, a process known as tropism.
• Two main types of tropism are phototropism (response to light direction) and geotropism or gravitropism (response to gravity).
• Phototropism causes shoots to grow towards the light and roots to grow away from it.
• Gravitropism ensures roots grow downwards into the soil and shoots grow upwards against gravity.