B4.1

Created by: mackymoo
Created on: 07-05-17 16:22

Homeostasis

Automatic control systems in the body keep conditions inside the body relatively constant.

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Control systems

Cells called receptors, which detect stimuli (changes in the environment).Coordination centres that receive and process information from receptors.Effectors, which bring about responses.

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Receptors are found in many organs

The eyes – sensitive to light. The ears – sensitive to sound, and to changes in position (which enables us to keep our balance). The tongue and in the nose – sensitive to chemicals (enable us to taste and to smell)

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Receptors are found in many organs

The skin – sensitive to touch, pressure, pain and to temperature changes. The brain – sensitive to blood temperature and the concentration of water in the blood.The pancreas – sensitive to the concentration of glucose in the blood.

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Coordination centres

The brain, spinal cord and the pancreas.

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Hormones

Hormones are secreted by glands and are usually transported to their target organs by the bloodstream.

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Hormones

Many processes are coordinated by hormones.

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Reflex actions

Automatic and rapid. They often involve sensory, relay and motor neurones.

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Simple reflex action (Step 1)

Impulses from a receptor pass along a sensory neurone to the central nervous system.

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Simple reflex action (Step 2)

At a junction (synapse) between a sensory neurone and a relay neurone in the central nervous system, a chemical is released that causes an impulse to be sent along a relay neurone.

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Simple reflex action (Step 3)

A chemical is then released at the synapse between a relay neurone and motor neurone in the central nervous system, causing impulses to be sent along a motor neurone to the effector.

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Simple reflex action (Step 4)

The effector is either a muscle or a gland: a muscle responds by contracting and a gland responds by releasing (secreting) chemical substances.

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Effectors

Muscles and glands.

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Simple reflex action

stimulus --------> receptor --------> co-ordinator --------> effector --------> response

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Internal conditions that are controlled

Temperature. The water content of the body. The ion content of the body.Blood glucose levels.

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Other cards in this set

Card 2

Front

Cells called receptors, which detect stimuli (changes in the environment).Coordination centres that receive and process information from receptors.Effectors, which bring about responses.

Back

Control systems

Card 3

Front

Back

Card 4

Front

Back

Card 5

Front

The brain, spinal cord and the pancreas.

Back

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