Chapter 2- Control and Cooridination 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
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
Glycogen
the main storage carbohydrate in animals, converted from glucose by the liver and stored in the liver and muscle tissue
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 System
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
Peripheral nervous system
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.
Sensory neurons
a nerve cell in the sense organs. It detects change in the environment and sends a message to the central nervous system.
Motor neurons
the nerve cell that causes an organ, such as a muscle or gland, to respond to a stimulus
Neurotransmitters
chemical released from the axon terminals into the synapse between your nerve cells (neurons) during a nerve impulse
Endocrine glands
organs that produce hormones. Endocrine glands release their hormones into the bloodstream for transport to target organs.
Hormones
chemical substances produced by glands and circulated in the blood. Hormones have specific effects in the body.
Thermoregulation
the control of body temperature
Thermostat
device that establishes and maintains a desired temperature automatically
Sense organs
a specialised structure that detects stimuli (such as light, sound, touch, taste and smell) in your environment
Stimuli
changes in the environment that can be detected and responded to
Thermorereceptors
special cells located in your skin, part of your brain and body core that are sensitive to temperature
Mechanoreptors
special cells within the skin, inner ear and skeletal muscles that are sensitive to touch, pressure and motion, enabling you to balance, hear and sense pressure and movement
Chemoreceptors
special cells within a sense organ (especially the nose and tastebuds) that are sensitive to particular chemicals, giving you the sensations of smell and taste
Photoreceptors
a receptor cell located in your eye that is stimulated by light, converting it to electrical energy that is sent to the brain, giving you the sensation of light
Pain receptors
special cells located throughout the body (except the brain) that send nerve signals to the brain and spinal cord in the presence of damaged or potentially damaged cells, resulting in the sensation of pain
Hot thermoreceptors
a type of receptor in your skin that can detect an increase in skin temperature above 37.5°C (normal body temperature)
Cold thermoreceptors
type of receptor in your skin that can detect a decrease in skin temperature below 35.8 °C
Olfactory nerve
nerve that sends signals to the brain from the chemoreceptors in the nose
Pupil
a hole through which light enters the eye
Iris
coloured part of the eye that opens and closes the pupil to control the amount of light that enters the eye
Reflex action
a quick response to a stimulus. Reflex actions do not involve thought.
Cornea
the curved, clear outer covering of your eye