biology yr 11 notes

• Coordination in the human body refers to the integration of various systems to maintain homeostasis, ensuring survival and efficiency despite environmental changes.
• Homeostasis is the process by which biological systems maintain stability while adjusting to conditions that are optimal for survival.
• The nervous system and the endocrine system are the two primary coordinating systems that work together to regulate bodily functions.
• The nervous system responds quickly to stimuli through electrical impulses, while the endocrine system provides slower, longer-lasting hormonal responses.
• The hypothalamus acts as a critical link between the nervous and endocrine systems, particularly in regulating the pituitary gland's activities.
• The fight or flight response exemplifies the coordination of both systems, preparing the body for immediate action in response to perceived threats.
• The central nervous system (CNS) consists of the brain and spinal cord, serving as the main control centre for processing sensory information and coordinating responses.
• The peripheral nervous system (PNS) connects the CNS to limbs and organs, facilitating communication throughout the body.
• A reflex action is an automatic response to stimuli that bypasses higher brain functions, ensuring rapid reactions crucial for survival.
• Neurons are specialized cells that transmit nerve impulses; they come in three main types: sensory neurons, motor neurons, and relay neurons.
• The transmission of impulses occurs via synapses, where neurotransmitters play a vital role in signal propagation between neurons.
• Reflex arcs consist of a series of neurons that allow for quick responses to stimuli, typically involving sensory, relay, and motor neurons.
• Excitatory neurotransmitters increase the likelihood of generating an impulse in the postsynaptic neuron, while inhibitory neurotransmitters decrease that likelihood.
• Protective mechanisms, such as the skull and vertebrae, safeguard the CNS from physical damage, while the peripheral nerves are more vulnerable.
• Understanding the differences between the nervous and endocrine systems is essential for grasping how the body maintains homeostasis and responds to challenges.