2.2 Flashcards
Multicellular organism
an organism that is composed of many cells. Most plants and animals are multicellular.
Homeostasis
the maintenance of a relatively constant internal physiological environment of the body or part of the body (e.g. blood glucose level, pH, body temperature) in varying external conditions
Stimulus response model
a system in which any changes or variations (stimuli) in the internal environment are detected (by receptors); if a response is required, this is communicated to effectors to bring about some type of change or correction so the conditions can be brought back to normal
Negative feedback
a response that reduces the original stimulus
Glucose
a simple carbohydrate and the simplest form of sugar
Pancreas
a large gland in the body that produces and secretes the hormone insulin and an important digestive fluid containing enzymes
Insulin
hormone that removes glucose from the blood and stores it as glycogen in the liver and muscles
Positive feedback
a reaction in which the response is in the same direction as the stimulus—for example, during childbirth the onset of contractions activates the release of the hormone oxytocin, which stimulates further contractions
Oxytocin
hormone secreted from the pituitary gland that assists in the formation of bonds between mothers and their babies, and perhaps between people in close relationships
Nervous system
the system of nerves and nerve centres in an animal in which messages are sent as an electrical and then a chemical impulse. It comprises the central nervous system and the peripheral nervous system.
Endocrine
the body system of glands that produce and secrete hormones into the bloodstream in order to regulate processes in various organs
Signalling molecules
a chemical involved in transmitting information between cells
Central nervous system
the part of the nervous system composed of the brain and spinal cord
PNS
made up of sensory and motor neurons. It connects the central nervous system to the rest of the body, and detects and responds to change.
Motor sensory neurons
the nerve cell that causes an organ, such as a muscle or gland, to respond to a stimulus
