Biology- Human Biology

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Mind Map on Biology- Human Biology, created by Chelsea :) on 04/20/2014.
Chelsea :)
Mind Map by Chelsea :) , updated more than 1 year ago
Chelsea :)
Created by Chelsea :) almost 11 years ago
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Resource summary

Biology- Human Biology
  1. A Stimulus is a change in your environment. It is something that you have to react to.
    1. Your sense organs are:
      1. Eyes, ears, nose, tongue and skin.
        1. All of these sense organs contain different receptors. Receptors are groups of cells which are sensitive to a stimulus. A stimulus could be; light, sound, touch, pressure, pain, chemical or a change in position or temperature.
          1. The sense organs and the receptors they contain:
            1. Eyes: Light Receptors
              1. Ears: Sound and "balance" receptors.
                1. Nose: Smell receptors- sensitive to chemical stimuli.
                  1. Tongue: Taste receptors- chemical stimuli- sensitive to bitter, salt, sweet and sour.
                    1. Skin: Sensitive to touch, pressure and temperature changes.
    2. Your central nervous system (CNS) is where all the information from the sense organs is sent, and where your actions and reflexes are coordinated.
      1. The central nervous system consists of your brain and spinal cord only.
        1. Neurones (nerve cells) transmit the information- as electrical impulses- very quickly to and from the CNS.
          1. "Instructions" from the CNS are then sent to the effectors (muscles and glands which respond accordingly.
        2. Sensory Neurones- These are nerve cells that carry signals as electrical impulses from the receptors in the sense organs to the CNS.
          1. Motor Neurones- These are the nerve cells that carry signals to the effector muscles or glands.
            1. Effectors- Muscles and glands are known as effectors- these will respond in different ways. Muscles contract in response to a nervous impulse, whereas your glands secrete hormones.
        3. Reflexes help you to prevent injury.
          1. Reflexes are automatic responses to a certain stimuli. E.g. if someone shines a bright light in your eyes, your pupils automatically become smaller so that less light goes into your eye- which in turn stops them becoming damaged.
            1. The passage of information in a reflex (from your receptor to effector) is called a reflex arc.
              1. The reflex arc passes through your CNS. The neurones in reflex arcs go through the spinal cord or through an unconscious part of the brain.
                1. When a stimulus is detected by receptors an impulse is sent along a sensory neurone to the CNS.
                  1. When in the CNS the sensory neurone is passes on the message to another type of neurone- a relay neurone.
                    1. A relay neurone relays the impulse to a motor neurone.
                      1. The impulse then travels along the motor neurone to the effector. The muscle then contracts and moves hyour hand away from the problem (e.g.a bee).
                        1. Synapses connect neurones- The connection between two neurones is called a synapses.
                          1. The nerve signal is transferred by chemicals which diffuse (move) across the gap.
                            1. These chemicals then set off a new electrical signal in the next neurone.
          2. Hormones are chemical messengers sent in the blood.
            1. Hormones are carried in the blood plasma to other parts of the body, but they only affect particular cells;(these are called target cells).
              1. Hormones control things in organs and cells that need constant adjustment.
                1. Hormones are produced in various glands. They travel trough your body at 'the speed of blood'. Hormones have long- lasting effects.
                  1. The Pituitary Gland.
                    1. This produces many important hormones- including LH, FSH and ADH. ADH controls water content.
                      1. The Ovaries- (females only)
                        1. Produces oestrogen- this controls the menstrual cycle and promotes all female secondary sexual characteristics during puberty.
                          1. Pancreas
                            1. Produces insulin for the control of blood sugar.
                              1. Testes- (male only)
                                1. Produces testosterone which promotes all male secondary sexual characteristics at puberty- e.g. changes in body proportions.
                    2. Hormones are chemical messengers which travel in the blood to activate target cells.
                      1. Hormones and nerves do similar jobs however there are differences between the two.
                        1. Nerves: very FAST messages, act for a very SHORT TIME, act on a very PRECISE AREA.
                          1. Hormones: SLOWER message, act for a LONG TIME, act in a more GENERAL way.
                        2. The Menstrual Cycle
                          1. Stage 1: When the bleeding starts. - the uterus lining breaks down.
                            1. Stage 2: The lining of the womb builds up again.- Ready to receive a fertilized egg.
                              1. Stage 3: An egg is developed and then released from the ovary at around day 14.
                                1. Stage 4 The wall in the maintained for about 14 days, until day 28.
                            2. Hormones control the different stages.
                              1. FSH (Follicle- Stimulating Hormone)- This is produced by the pituitary gland. It causes an egg to mature in one of the ovaries and stimulates the ovaries to produce oestrogen.
                                1. Oestrogen: produced in the ovaries. This causes the pituitary gland to produce LH (Lutenising Hormone). It inhibits the further release of FSH.
                                  1. LH (Luteinising Hormone): This is produced by the pituitary gland. It stimulates the release of an egg at around the middle of the menstrual cycle.
                              2. Controlling Fertility.
                                1. Hormones can be used to increase or reduce fertility.
                                  1. Oestrogen can be used to prevent the release of an egg. The pill is an oral contraceptive that contains oestrogen.
                                    1. If oestrogen is taken every day to keep the level of it permanently high- it will inhibit the production of FSH. This means that after a while egg development and production stops and will stay stopped.
                                      1. Advantages:
                                        1. The pill is over 99% effective at preventing pregnancy.
                                          1. It reduces the risk of getting some types of cancer.
                                        2. Disadvantages:
                                          1. It isn't 100% effective- there's still a slight chance of getting pregnant.
                                            1. It can cause side effects like headaches, nausea, fluid retention and irregular menstrual cycle.
                                              1. It doesn't protect against sexually transmitted diseases (STD's).
                                      2. Some women have levels of FSH that are too low to cause their eggs to mature. This means that no eggs are released and the women can't get pregnant.
                                        1. The hormone FSH can be taken by these women to stimulate egg production in their ovaries.
                                          1. Advantages:
                                            1. It helps a lot of women to get pregnant.
                                            2. Disadvantages:
                                              1. It doesn't always work- some women may have to do it many times, which can be expensive.
                                                1. Too many eggs could be stimulated, resulting in unexpected multiple pregnancies (twins, triplets etc.)
                                        2. IVF (In-vitro fertilization) involves collecting eggs from the woman's ovaries and fertilizing them in a lab using the man's perm. These are then grown into embryos, which are transferred to the woman's uterus.
                                          1. Hormones are given before egg collection to stimulate egg production.
                                            1. Oestrogen and progesterone are often given to make implementation of the embryo into the uterus more likely to succeed.
                                              1. But the use of hormones in IVF can cause problems for some women:
                                                1. Some women have a very strong reaction to the hormones- including abdominal pain, vomiting and dehydration.
                                                  1. There have been some reports of an increased risk of cancer due to the hormonal treatment.
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