Nervous system

• The nervous system enables humans to react to their surroundings and to coordinate their behaviour.
• The nervous system comprises millions of neurones and uses electrical impulses to communicate very quickly.
• Homeostasis is the maintenance of steady conditions, the ability of the body to maintain a constant internal environment, such as temperature and blood glucose concentration.
• Homeostasis maintains optimal conditions for enzyme action throughout the body, as well as all cell functions.
• The human nervous system consists of the central nervous system (CNS) which includes the brain and spinal cord, and the peripheral nervous system which includes nerve cells that carry information to or from the CNS.
• The nervous system enables humans to react to their surroundings and to coordinate their behaviour.
• The nervous system comprises millions of neurones and uses electrical impulses to communicate very quickly.
• Homeostasis is the process by which the conditions inside our body are controlled if the body is to function effectively.
• Homeostasis is controlled in two ways with chemical and nervous responses.
• All control systems include cells called receptors which close receptors, organs which recognise and respond to stimuli, and something that sets off a reaction in the nervous system, for example, light, heat, sound, gravity, smell, taste, or temperature.
• Changes in the environment are detected by receptors in an organism.
• The coordination centre, such as the brain, spinal cord or pancreas, which receives and processes information from receptors around the body, is a crucial part of the control system.
• Effectors are the organs, tissues or cells that produce a response, which restore optimum levels, such as core body temperature and blood glucose levels.
• Effectors include muscles and glands, and so responses can include muscle contractions or hormone release.
• Nerve cells, also known as neurones, carry an electrical message or impulse when stimulated.
• Nerve cells are adapted to carry electrical impulses from one place to another.
• A bundle of neurones is called a nerve.
• Information from receptors passes along neurones, as electrical impulses to co-ordinators such as the central nervous system or CNS.
• Motor neurones have a long fibre (axon) which is insulated by a fatty (myelin) sheath.
• A muscle can contract to move an arm, a muscle can squeeze saliva from the salivary gland, and a gland can release a hormone into the blood.
• Hormones are chemicals produced by the endocrine system that act as messengers between cells.
• The CNS includes the brain and spinal cord.
• Sensory neurones are long so they can carry messages up and down the body.
• Sensory neurones have a long fibre (axon) which is insulated by a fatty (myelin) sheath.
• Tiny branches (dendrons) branch further as dendrites at each end of sensory neurones, receiving incoming impulses from other neurones.
• Effectors include muscles and glands that produce a specific response to a detected stimulus.
• Homeostasis is the process that maintains a constant internal environment despite changes in the external environment.
• Homeostasis in humans involves maintaining a constant internal environment despite changes in the external environment.
• A reflex arc is a sequence of events that occur when a stimulus is received by a receptor, causing an electrical impulse to be sent to a co-ordinator, which then sends an impulse to an effector, causing a response.
• Hormones in human reproduction are chemicals produced by the endocrine system that act as messengers between cells.
• Relay neurones have a long fibre (axon) which is insulated by a fatty (myelin) sheath.
• There are three main types of neurone: sensory, motor and relay.
• The nervous system enables humans to react to their surroundings and to coordinate their behaviour.
• The nervous system comprises millions of neurones and uses electrical impulses to communicate very quickly.
• Homeostasis is the process by which the body maintains a stable internal environment.
• Homeostasis involves the regulation of body temperature, pH, and the maintenance of fluid and electrolyte balance.
• Homeostasis is a process that occurs at all levels of biological organisation, from the cell to the organism.
• Homeostasis is essential for the survival of the body.
• Homeostasis is a dynamic process that adjusts to changes in the body's internal and external environment.
• Homeostasis involves the integration of various body systems, including the nervous system, endocrine system, and immune system.