Biology Unit 1 Revision

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Biology Unit 1 Revision
  1. Why do we need to exercise?
    1. To stay fit and healthy so our bodies don't produce too much fat so that our bodies are unable to move or correspond.
    2. What is the nervous system?
      1. The nervous system enables humans to react to their surroundings and coordinate their behaviour. Information from receptors passes along cells (called neurones) in nerves to the brain. Nerve impulses are electrical signals that travel along neurones. Nerve impulses travel at high speed. Receptors detect stimuli which include light, sound, changes in position, chemicals, touch, pressure, pain and temperature. Sensory neurones – transmit nerve impulses from the receptors to the CNS when a stimulus is detected. Motor neurones – transmit nerve impulses from the CNS to effectors, to bring about a response. Effectors are muscles or glands.
      2. What are hormones?
        1. Hormones are many processes within the body that are coordinated by chemical substances called hormones. Hormones are secreted by glands and are transported to their target organs by the bloodstream. Hormones regulate the functions of many organs and cells.
          1. Types of hormones in the menstrual cycle are: 1) FSH – follicle stimulating hormone, produced at: pituitary gland, effects: egg matures in ovary; release of oestrogen from ovary 2) Oestrogen, produced at: ovaries, it's effects are: inhibits release of FSH, causes release of LH 3) LH – luteinising hormone produced at: pituitary gland, it's effects are: stimulates release of egg from ovary.
        2. What is the metabolic rate?
          1. The rate at which chemical reactions happen in the cells of your body. . The warmer it is, the lower your metabolic rate: we use less energy to keep our body temperature at 37° C. Therefore, the less exercise you take, and the warmer it is, the less food you need.
            1. One major metabolic reaction is respiration. This releases energy from the food we eat.
              1. The higher the proportion of muscle to fat in your body, the higher your metabolic rate: Muscle cells use more energy.
                1. Inherited factors affect metabolic rate: Some people inherit genes that give them a higher or lower metabolic rate than others.
                  1. The more exercise you do the faster your metabolic rate: More energy is needed
                2. Microorganisms as Pathogens
                  1. To be considered a pathogen it must: Gain entry then colonise the tissues, resist the defenses and cause damage to the tissues. Pathogens include bacteria, viruses and fungi.
                    1. How do microorganisms enter the body? Many pathogens enter through the gas exchange system (including ones that cause flu and TB). Food and water can carry pathogens into the stomach and intestines via the mouth and into the digestive system.
                  2. Digestive System
                    1. Roles of the major parts of the digestive system; -Mouth – starts carbohydrate digestion by adding amylase in saliva to it braking large carbohydrates down into maltose. -Stomach – contains enzymes (proteases) which digest proteins breaking them down into amino acids. It also produces a lot of mucus to prevent the stomach itself from getting digested by its own enzymes. -Small intestine – where most digestion happens. Lots of enzymes secreted either into it or by its walls. However it is adapted for the absorption of digestive products also occurs here. -Pancreas and salivary glands – produce enzymes, salivary glands produce saliva in the mouth which contains amylase and the pancreas produces pancreatic juice which contains proteases, lipase and amylase. To digest proteins, lipids and starch.
                      1. Two types of digestion, physical and chemical: -Physical digestion is food being broken down into smaller pieces by both the teeth and the churning of the stomach. This not only enables us to swallow food but increases the surface area of the food so enzymes can act on it better. -Chemical digestion is breaking down large insoluble molecules into smaller soluble ones. This is done by enzymes.
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