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Year 9 Science > Biology > Flashcards

Flashcards in Biology Deck (72):
1

Multicellular Organisms

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

2

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 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

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Negative feedback

a response that reduces the original stimulus

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Glucose

simple carbohydrate and the simplest form of sugar

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Pancreas

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

10

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

11

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 systems

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

13

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

18

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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Thermorgulation

The control of body temperature

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Thermostat

device that establishes and maintains a desired temperature automatically

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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

27

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

29

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

30

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.

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Cornea

the curved, clear outer covering of your eye

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Lens

transparent curved object that bends light towards or away from a point called the focus. The eye has a jelly-like lens.

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Retina

curved surface at the back of the eye. It is lined with sight receptors.

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Short sightedness

the condition of not being able to see clearly things that are far away

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Long sightedness

the condition of not being able to see clearly things that are close

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Optic Nerve

large nerve that sends signals to the brain from the sight receptors in the retina

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Rods

sensory receptors in the retina that respond to low levels of light and allow you to see in black and white in dim light

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Cones

sensory receptors in the retina that respond to red, green or blue light. Cones are mainly in the central part of the retina.

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Colour blindness

an inherited condition, more common in males, in which a deficiency of one or more of the different types of cones may mean that you find it difficult to see a particular colour or combinations of colours

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Ear canal

the tube that leads from the outside of the ear to the eardrum

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Ear drum

a thin piece of stretched skin inside the ear that vibrates when sound waves reach it

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Ossicles

a set of three tiny bones that send vibrations from the eardrum to the inner ear. They also make the vibrations larger.

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Middle ear

the section of the ear between your eardrum and the inner ear, containing the ossicles

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Cochlea

the snail-shaped part of the inner ear. It is lined with tiny hairs that are vibrated by sound and stimulate the hearing receptors.

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Auditory nerve

a large nerve that sends signals to the brain from the hearing receptors in the cochlea

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Tongue

the sense organ responsible for taste

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Taste buds

nerve endings located in your tongue that contain receptors sensitive to sweet, salty, bitter, sour and savoury chemicals, allowing you to experience taste

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Papila

bumps on your tongue that are thought to contain tastebuds

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Dendrites

Structure that relays information towards the cell body of a neuron

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Cognition

another name for thinking or mental activity

56

Emotions

feelings, such as happiness, sadness and anger, that are interpreted by the brain

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Regulating

the process by which the brain detects and responds to the body’s internal and external environments

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Hindbrain

a continuation of the spinal cord

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Pons

part of the brain involved in regulating sleep, arousal and breathing, and coordinating some muscle movements

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Medulla obglonata

a part of the brain developed from the posterior portion of the hindbrain and continuing with the spinal cord; see also brain stem

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Reticular formation

a network of neurons that opens and closes to increase or decrease the amount of information that flows into and out of the brain

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Forebrain

consists of the cerebrum, cerebral cortex, thalamus and hypothalamus

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Cerebral cortex

the outer, deeply folded surface of the cerebrum

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Thalamus

part of the brain through which all sensory information from the outside (except smell) passes before going to other parts of the brain for further processing

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Hypothalamus

monitors internal systems and controls the release of hormones to maintain the normal body state (homeostasis)

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Hippocampus

part of the brain with a key role in consolidating learning, comparing new information with previous experience, and converting information from working memory to long-term storage

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Brain stem

the part of the brain connected to the spinal cord, responsible for breathing, heartbeat and digestion. Sometimes called the medulla.

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Cerebellum

the part of the brain that controls balance and muscle action

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Cerebrum

the largest part of the brain (about 90 per cent of total brain volume), responsible for higher order thinking, controlling speech, conscious thought and voluntary actions. It is made up of the frontal, temporal, parietal and occipital lobes.

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Cerebral hemisphere

the left and right halves of the brain

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Corpus callosum

a bridge of nerve fibres through which the two cerebral hemispheres communicate

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Synaethesia

a condition in which a sensation is produced in one physical sense when a stimulus is applied to another; affected people may associate letters with a flavour, numbers with a gender or sounds with colour