GCSE Biology - The Endocrine System (2027/28 exams) — Transcript

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1. 0:07In this video, we're looking at the
2. 0:08endocrine system, which is also
3. 0:11sometimes known as the hormonal
4. 0:13system. So, we're going to cover what
5. 0:16the endocrine system is and how it
6. 0:18works, the main glands in the body that
7. 0:21you need to know about, and finally, how
8. 0:24the endocrine system differs from the
9. 0:26nervous system.
10. 0:30In a nutshell, the endocrine system is
11. 0:33an important organ system that allows
12. 0:36different parts of the body to
13. 0:38communicate with each other. It consists
14. 0:41of a number of glands that are found
15. 0:43throughout the body. These glands each
16. 0:46secrete different types of hormones
17. 0:48which are small chemical molecules that
18. 0:50are released into the bloodstream and
19. 0:53then travel throughout the body.
20. 0:56Whilst in the bloodstream, the hormones
21. 0:58come into contact with a wide range of
22. 1:00tissues. Some of these tissues, but not
23. 1:03all of them, will have receptors that
24. 1:05are specific to the
25. 1:07hormones. This means that the hormones
26. 1:09will be able to bind to the receptors on
27. 1:11these target tissues, which allows the
28. 1:14hormones to act as signals to trigger
29. 1:17certain changes inside the cells.
30. 1:23Next, let's look at the main glands in
31. 1:25the endocrine system and see what each
32. 1:27of them
33. 1:28does. First, we have the pituitary
34. 1:31gland, which is sometimes called the
35. 1:34master gland. It produces multiple
36. 1:37different hormones, some of which
37. 1:39directly tell the body what to do, and
38. 1:42some of which tell other glands to
39. 1:44release their own hormones.
40. 1:47The pituitary gland is not actually part
41. 1:49of the brain but it is attached to the
42. 1:52brain. Next we have the thyroid gland
43. 1:55which produces the hormone thyroxine.
44. 1:58This regulates the rates of our
45. 2:00metabolism and also plays an important
46. 2:02role in growth and
47. 2:04development. You may remember from
48. 2:06earlier that we said the pituitary gland
49. 2:09releases hormones that influence other
50. 2:11glands.
51. 2:13Well, an example of this is thyroid
52. 2:15stimulating hormone or
53. 2:19TSH. If the pituitary gland detects low
54. 2:23levels of thyroxine, then it releases
55. 2:26TSH, which stimulates the thyroid to
56. 2:29produce more
57. 2:30thyroxine and brings the level of
58. 2:32thyroxine back up to normal.
59. 2:35We call this process negative feedback
60. 2:38because if thyroxine levels are too low,
61. 2:41they are stimulated to rise again and if
62. 2:43they get too high, they're brought back
63. 2:46down. Sitting on top of our kidneys, we
64. 2:49have our adrenal glands that produce
65. 2:52adrenaline. This is normally released
66. 2:54during the fight orflight response when
67. 2:56we're startled or scared.
68. 2:59It basically gets us ready to fight or
69. 3:02run by doing things like increasing our
70. 3:04heart rate and generally getting our
71. 3:06blood pumping
72. 3:09faster. Just in front of our kidneys, we
73. 3:11have the pancreas. The pancreas produces
74. 3:14the hormone insulin and this helps us
75. 3:17regulate our blood glucose
76. 3:19concentrations, which just means it
77. 3:21controls the amount of sugar in our
78. 3:22bloodstream.
79. 3:25The last two glands we need to talk
80. 3:27about are the testes and the ovaries.
81. 3:30The testes are only found in biological
82. 3:33males and we haven't shown them on this
83. 3:36diagram. They have two main jobs.
84. 3:39Producing the hormone testosterone which
85. 3:42controls puberty and producing the male
86. 3:45gametes called sperm for reproduction.
87. 3:49The ovaries meanwhile are only found in
88. 3:51biological
89. 3:53females. Their main roles are to produce
90. 3:56estrogen which influences puberty and
91. 3:58the menstrual cycle and also to produce
92. 4:01and hold the female gametes egg
93. 4:07cells. Last up we need to know how the
94. 4:10endocrine system differs from the
95. 4:12nervous system.
96. 4:14First we have the fact that one relies
97. 4:16on hormones which are small molecules
98. 4:19secreted by glands and transported in
99. 4:22the blood while the other relies mainly
100. 4:25on electrical impulses which are
101. 4:27transferred along nerve
102. 4:29cells. This means that hormones spread
103. 4:32more slowly and their effects last
104. 4:35longer whereas nerve impulses are sent
105. 4:38very fast and the effects don't last as
106. 4:40long often less than a second.
107. 4:44The other point is that hormones act
108. 4:46more generally. As we said earlier, they
109. 4:49spread throughout the entire body, which
110. 4:52means that they interact with loads of
111. 4:53different cells. By contrast, nerve
112. 4:56impulses are sent to one specific area,
113. 4:59such as the particular muscle that we
114. 5:01need to move our
115. 5:02arm. So, we often describe the nervous
116. 5:05system as being
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