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Flashcards in Biology Deck (55):
1

Multicellular Organism

an organism that is composed of many cells. Most plants and animals are multicellular.

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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

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Stimulus response module

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

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Negative feedback

a response that reduces the original stimulus

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Glucose

a simple carbohydrate and the simplest form of sugar

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Pancreas

a large gland in the body that produces and secretes the hormone insulin and an important digestive fluid containing enzymes

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Insulin

hormone that removes glucose from the blood and stores it as glycogen in the liver and muscles

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Glycogen

the main storage carbohydrate in animals, converted from glucose by the liver and stored in the liver and muscle tissue

9

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

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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

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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.

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Endocrine system

the body system of glands that produce and secrete hormones into the bloodstream in order to regulate processes in various organs

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Signalling molecules

a chemical involved in transmitting information between cells

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Central nervous system

the part of the nervous system composed of the brain and spinal cord

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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.

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Sensory neurons

a nerve cell in the sense organs. It detects change in the environment and sends a message to the central nervous system.

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Motor neurons

the nerve cell that causes an organ, such as a muscle or gland, to respond to a stimulus

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Neurotransmitters

chemical released from the axon terminals into the synapse between your nerve cells (neurons) during a nerve impulse

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Endocrine glands

organs that produce hormones. Endocrine glands release their hormones into the bloodstream for transport to target organs.

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Hormones

chemical substances produced by glands and circulated in the blood. Hormones have specific effects in the body.

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Thermoregulation

the control of body temperature

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Thermostat

a device that establishes and maintains a desired temperature automatically

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Central nervous system

the part of the nervous system composed of the brain and spinal cord

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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.

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Neurons

Nerve cells

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Nerves

A bundle of neurons

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Sensory neurons

a nerve cell in the sense organs. It detects change in the environment and sends a message to the central nervous system.

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Interneurons

a nerve cell that carries nervous impulses through the central nervous system. They provide the link between sensory neurons and motor neurons.

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Motor neurons

the nerve cell that causes an organ, such as a muscle or gland, to respond to a stimulus

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Nucleus

central part of an atom, made up of protons and neutrons; roundish structure inside a cell that acts as the control centre for the cell. Plural = nuclei.

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Organelles

small structure in a cell with a special function

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Cytosol

the fluid found inside cells

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Cell membrane

structure that encloses the contents of a cell and allows the movement of some materials in and out

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Cell body

contains the nucleus of a neuron, also called grey matter

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Dendrites

structure that relays information towards the cell body of a neuron

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Axon

an appendage of the neuron that nervous impulses travel along to the next neuron or to an effector organ (muscle or gland)

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Myelin

a fatty, white substance that encases the axons (connecting branches) of the neurons in the nervous system

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Synapse

the gap between adjoining neurons across which electrical nervous impulses are sent

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Vesicles

a small cavity, usually filled with fluid

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Neurotransmitters

chemical released from the axon terminals into the synapse between your nerve cells (neurons) during a nerve impulse

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Effector

an organ that responds to a stimulus

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Reflex arc

a nervous pathway involving a small number of neurons. A reflex occurs when nervous impulses travel from the receptor to the spinal cord and then to the effector organ.

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Sense organs

a specialised structure that detects stimuli (such as light, sound, touch, taste and smell) in your environment

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Stimuli

changes in the environment that can be detected and responded to

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Thermoreceptors

special cells located in your skin, part of your brain and body core that are sensitive to temperature

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Mechanoreceptors

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

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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

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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

49

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

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Hot thermoreceptors

a type of receptor in your skin that can detect an increase in skin temperature above 37.5°C (normal body temperature)

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Cold thermoreceptors

a type of receptor in your skin that can detect a decrease in skin temperature below 35.8 °C

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Olfactory nerve

nerve that sends signals to the brain from the chemoreceptors in the nose

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Pupil

a hole through which light enters the eye

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Iris

coloured part of the eye that opens and closes the pupil to control the amount of light that enters the eye

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Reflex action

a quick response to a stimulus. Reflex actions do not involve thought.