Homeostasis
Visão Geral
Step out of an air-conditioned classroom into the midday heat and the air around you may jump fifteen degrees in a single second. Your blood will not. By the time you reach the gate, the temperature deep inside you has moved by perhaps a tenth of a degree, and something has already begun putting even that small change back. Nobody decided any of it. You were thinking about lunch.
This lesson is about the machinery behind that steadiness. You will learn what homeostasis actually means, why your enzymes and your cells would be in serious trouble without it, and the three-part pattern that every automatic control system in your body is built from: something that detects, something that decides, something that acts. Once you can see that pattern, temperature control and blood glucose stop being two things to memorise and become two versions of one idea.
Objetivos
- Automatic control systems in the body keep conditions inside the body relatively constant.
- Control systems include: cells called receptors, which detect stimuli (changes in the environment); coordination centres that receive and process information from receptors; effectors, which bring about responses.
- Receptors are found in many organs, including: 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); 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. Knowledge and understanding of the structure and functions of sense organs such as the eye and the ear is not required.
- Coordination centres include the brain and spinal cord and the pancreas.
- Internal conditions that are controlled include: temperature; the water content of the body; the ion content of the body; blood glucose levels.
Mapa mental
Este tema esta mapeado para mostrar como as ideias se ligam.
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Nota de Aula
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Avaliação da Lição
Parabéns por concluir a lição em Homeostasis. Agora que você explorou o conceitos e ideias-chave, é hora de colocar seu conhecimento à prova. Esta seção oferece uma variedade de práticas perguntas destinadas a reforçar sua compreensão e ajudá-lo a avaliar sua compreensão do material.
Irá encontrar uma mistura de tipos de perguntas, incluindo perguntas de escolha múltipla, perguntas de resposta curta e perguntas de redação. Cada pergunta é cuidadosamente elaborada para avaliar diferentes aspetos do seu conhecimento e competências de pensamento crítico.
Use esta secção de avaliação como uma oportunidade para reforçar a tua compreensão do tema e identificar quaisquer áreas onde possas precisar de estudo adicional. Não te deixes desencorajar pelos desafios que encontrares; em vez disso, vê-os como oportunidades de crescimento e melhoria.
- Which statement best describes homeostasis? A. Keeping conditions outside the body constant B. Keeping conditions inside the body relatively constant C. Preventing any change in the body at all D. Increasing the rate of all reactions in the body Answer: B
- Which of these is a coordination centre named in the specification? A. The skin B. The eye C. The pancreas D. A sweat gland Answer: C
- Which organ contains receptors sensitive to the concentration of glucose in the blood? A. The liver B. The pancreas C. The kidney D. The spinal cord Answer: B
- Which of the following is NOT one of the internal conditions controlled by homeostasis in humans? A. Body temperature B. The water content of the body C. The ion content of the body D. The loudness of sounds reaching the ear Answer: D
- In an automatic control system, the response produced by the effectors: A. acts in the same direction as the original change B. acts in the opposite direction to the original change C. has no effect on the original change D. removes the need for receptors Answer: B
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