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20-1
Endocrine System
20-2
Endocrine Glands
The endocrine system is made of glands
and tissues that secrete hormones.
Endocrine glands are ductl...
20-3
Hormones are chemicals that influence
metabolism of cells, the growth and
development of body parts, and
homeostasis....
20-4
Hormones (meaning “set in motion”) are
chemical regulators produced by cells of
endocrine glands in one part of the b...
20-5
There is a close association between the
endocrine and nervous systems.
Hormone secretion is usually controlled
by ei...
20-6
The Endocrine System
20-7
Chemical Signals
A chemical signal is any substance that
affects cell metabolism or behavior of
the individual.
Chemi...
20-8
Chemical signals
20-9
Chemical signals
20-10
The Action of Hormones
Steroid hormones enter the nucleus and
combine with a receptor protein, and
the hormone-recep...
20-11
Hormones trigger changes in their target cells when
they bind to receptor proteins on or within the cells.
A model o...
20-12
Action of a steroid hormone
20-13
Peptide hormones are usually received by a
hormone receptor protein located in the
plasma membrane.
Most often the r...
20-14
Action of a peptide hormone
20-15
• Hormone production will be regulated
in most cases by negative feedback
systems. Once the desired outcome is
reach...
20-16
The Endocrine System
20-17
Hypothalamus and Pituitary
Gland
The hypothalamus regulates the internal
environment through the autonomic
system an...
20-18
Posterior Pituitary
The posterior pituitary stores and releases
the antidiuretic hormone (ADH) and
oxytocin produced...
20-19
Posterior Pituitary
ADH is released when the blood plasma concentration is high
(and blood pressure is low). ADH sti...
20-20
Posterior Pituitary
Oxytocin causes uterine contractions
and milk release, and is controlled by
positive feedback.
20-21
Anterior Pituitary
The hypothalamus controls the anterior
pituitary by producing hypothalamic-
releasing hormones an...
20-22
2) adrenocorticotropic hormone (ACTH)
stimulates the adrenal cortex to
produce cortisol;
3) the gonadotropic hormone...
20-23
20-24
The next three anterior pituitary
hormones do not effect other
endocrine glands.
After childbirth, prolactin (PRL) c...
20-25
Hypothalamus and the pituitary
20-26
Effects of Growth Hormone
The quantity of GH is greatest during
childhood and adolescence; GH
promotes bone and musc...
20-27
Effect of growth hormone
20-28
Acromegaly
20-29
Adrenal Glands
Adrenal glands sit atop the kidneys and
have an inner adrenal medulla and an
outer adrenal cortex.
Th...
20-30
The adrenal glands release several hormones involved
in the body’s response to stress.
20-31
The adrenal medulla secretes
epinephrine and norepinephrine, which
bring about responses we associate
with emergency...
20-32
Adrenal glands
20-33
Glucocorticoids
Cortisol promotes breakdown of muscle
proteins to amino acids; the liver then
breaks the amino acids...
20-34
Mineralocorticoids
Aldosterone causes the kidneys to
reabsorb sodium ions (Na+
) and excrete
potassium ions (K+
).
W...
20-35
Regulation of blood pressure
and volume
20-36
Malfunction of the Adrenal
Cortex
Addison disease develops when the
adrenal cortex hyposecetes hormones.
A bronzing ...
20-37
Addison disease
20-38
Cushing syndrome
20-39
Pancreas
The pancreas is between the kidneys and the
duodenum and provides digestive juices and
endocrine functions....
20-40
Pancreas
20-41
Regulation of blood glucose level
20-42
Diabetes Mellitus
The most common illness due to
hormonal imbalance is diabetes
mellitus.
Diabetes is due to the fai...
20-43
Glucose tolerance test
20-44
TYPE I – insulin-dependent
• caused by lack of insulin production in
pancreas, hereditary but may skip
generations
•...
20-45
TYPE II- insulin-independent
• caused by decreased insulin
production, or too much glucose
produced by the liver (no...
20-46
• diabetes insipidous, which has nothing
to do with insulin, but ADH production
in the pituitary – a tumour or injur...
20-47
• only type I requires daily insulin injections, type II
and GDM are treated by changing diet & sometimes
sulfonamid...
20-48
Thyroid and Parathyroid Glands
The thyroid gland is a large gland located
in the neck, where it is attached to the
t...
20-49
The thyroid gland secretes hormones that regulate cell
metabolism, growth, and development.
20-50
Thyroid Gland
The thyroid gland requires iodine to
produce thyroxine (T4) which contains
four iodine atoms, and trii...
20-51
Thyroxine secretion is regulated by the release of
thyroid-stimulating hormone (TSH) from the anterior
pituitary. TS...
20-52
Effects of Thyroid Hormones
Iodine is required to synthesize thyroxine
If too little iodine in the diet  thyroid
sw...
20-53
Simple goiter
20-54
If the thyroid is overactive (Grave’s
disease) an exophthalmic goiter
develops.
• too much thyroxine is present 
hy...
20-55
Hypothyroidism in childhood produces
cretinism; in adulthood it causes
myxedema.
• too little thyroxine is present ...
20-56
Cretinism
20-57
Calcitonin
The thyroid gland also produces
calcitonin, which helps lower the blood
calcium level when it is too high...
20-58
Parathyroid Glands
Parathyroid glands secrete
parathyroid hormone (PTH), which
raises the blood calcium when it is
i...
20-59
Regulation of blood calcium
level
20-60
Other Endocrine Glands
Testes and Ovaries
Testes, located in the scrotum, produce
the male hormone testosterone.
Ova...
20-61
The effects of anabolic steroid
use
20-62
Prostaglandins
Prostaglandins are produced within cells
from arachidonate, a fatty acid.
Prostaglandins act close to...
20-63
Chapter Summary
Hormones are chemical signals that
affect the activity of target glands or
tissues.
Endocrine glands...
20-64
The anterior pituitary produces several
hormones, some of which control other
endocrine glands.
Growth hormone is pr...
20-65
The distinct parathyroid glands produce
a hormone that raises blood calcium
level.
Adrenal glands produce hormones t...
20-66
Diabetes mellitus occurs when cells are
unable to take up glucose and it spills
over into the urine.
The gonads prod...
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Endocrine Notes

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Endocrine Notes

  1. 1. 20-1 Endocrine System
  2. 2. 20-2 Endocrine Glands The endocrine system is made of glands and tissues that secrete hormones. Endocrine glands are ductless organs, producing their messengers and secreting them directly into the bloodstream, whereas other glands (exocrine glands) produce their chemicals and excrete them into a duct (ex. digestive enzymes, sweat).
  3. 3. 20-3 Hormones are chemicals that influence metabolism of cells, the growth and development of body parts, and homeostasis. Hormones can be classified as protein or steroids.
  4. 4. 20-4 Hormones (meaning “set in motion”) are chemical regulators produced by cells of endocrine glands in one part of the body that affect cells in other parts of the body. They can be divided into two types: - target hormones – affect specific cells in the body (e.g. gastrin stimulates stomach cells) - nontarget hormones – have broad effects in the body (e.g. growth hormone – affects the growth of long bones)
  5. 5. 20-5 There is a close association between the endocrine and nervous systems. Hormone secretion is usually controlled by either negative feedback or antagonistic hormones that oppose each other’s actions, and results in maintenance of a bodily substance or function within normal limits.
  6. 6. 20-6 The Endocrine System
  7. 7. 20-7 Chemical Signals A chemical signal is any substance that affects cell metabolism or behavior of the individual. Chemical signals can be used between body parts, between cells, and between individual organisms (pheromones). Underarm secretions may be slightly attractive and may be involved in synchronizing the menstrual cycles of women who live together.
  8. 8. 20-8 Chemical signals
  9. 9. 20-9 Chemical signals
  10. 10. 20-10 The Action of Hormones Steroid hormones enter the nucleus and combine with a receptor protein, and the hormone-receptor complex attaches to DNA and activates certain genes. Transcription and translation lead to protein synthesis.
  11. 11. 20-11 Hormones trigger changes in their target cells when they bind to receptor proteins on or within the cells. A model of a hormone (A) bound to its protein receptor (B). Each hormone of the endocrine system has a unique molecular shape, which fits into a specific receptor protein on its target cells.
  12. 12. 20-12 Action of a steroid hormone
  13. 13. 20-13 Peptide hormones are usually received by a hormone receptor protein located in the plasma membrane. Most often the reception of a peptide hormone leads to activation of an enzyme that changes ATP to cyclic AMP (cAMP). cAMP, as a second messenger, then activates an enzyme cascade. Calcium is also a common second messenger. Hormones work in small quantities because their effect is amplified by enzymes.
  14. 14. 20-14 Action of a peptide hormone
  15. 15. 20-15 • Hormone production will be regulated in most cases by negative feedback systems. Once the desired outcome is reached, the outcome will inhibit the hormone release. • Hormones are also classified as: – Tropic: have endocrine glands as their target – Non-tropic:don’t have endocrine glands as their target
  16. 16. 20-16 The Endocrine System
  17. 17. 20-17 Hypothalamus and Pituitary Gland The hypothalamus regulates the internal environment through the autonomic system and also controls the secretions of the pituitary gland. The pituitary has two portions: the anterior pituitary and the posterior pituitary.
  18. 18. 20-18 Posterior Pituitary The posterior pituitary stores and releases the antidiuretic hormone (ADH) and oxytocin produced by the hypothalamus. ADH is secreted during dehydration and causes more water to be reabsorbed by the kidneys; the secretion of ADH is regulated by negative feedback.
  19. 19. 20-19 Posterior Pituitary ADH is released when the blood plasma concentration is high (and blood pressure is low). ADH stimulates the kidneys to absorb more water, which dilutes the blood plasma (and increases blood pressure).
  20. 20. 20-20 Posterior Pituitary Oxytocin causes uterine contractions and milk release, and is controlled by positive feedback.
  21. 21. 20-21 Anterior Pituitary The hypothalamus controls the anterior pituitary by producing hypothalamic- releasing hormones and hypothalamic- inhibiting hormones. The anterior pituitary produces six hormones. Three of these six hormones have an effect on other endocrine glands: 1) Thyroid-stimulating hormone (TSH) stimulates the thyroid to produce thyroid hormones;
  22. 22. 20-22 2) adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to produce cortisol; 3) the gonadotropic hormones (FSH and LH) stimulate the gonads to produce sex cells and hormones. In these three instances, the blood level of the last hormone exerts negative feedback control over the secretion of the first two hormones.
  23. 23. 20-23
  24. 24. 20-24 The next three anterior pituitary hormones do not effect other endocrine glands. After childbirth, prolactin (PRL) causes mammary glands to produce milk. Growth hormone (GH) promotes skeletal and muscular growth. Melanocyte-stimulating hormone (MSH) causes skin color changes in fishes, amphibians, and reptiles.
  25. 25. 20-25 Hypothalamus and the pituitary
  26. 26. 20-26 Effects of Growth Hormone The quantity of GH is greatest during childhood and adolescence; GH promotes bone and muscle growth. Pituitary dwarfism results from too little GH during childhood. Giants result from too much growth hormone during childhood. If growth hormone is overproduced in an adult, it causes acromegaly.
  27. 27. 20-27 Effect of growth hormone
  28. 28. 20-28 Acromegaly
  29. 29. 20-29 Adrenal Glands Adrenal glands sit atop the kidneys and have an inner adrenal medulla and an outer adrenal cortex. The hypothalamus uses ACTH-releasing hormone to control the anterior pituitary’s secretion of ACTH that stimulates the adrenal cortex. The hypothalamus regulates the medulla by direct nerve impulses.
  30. 30. 20-30 The adrenal glands release several hormones involved in the body’s response to stress.
  31. 31. 20-31 The adrenal medulla secretes epinephrine and norepinephrine, which bring about responses we associate with emergency situations. On a long-term basis, the adrenal cortex produces glucocorticoids similar to cortisone and mineralocorticoids to regulate salt and water balance. The adrenal cortex also secretes both male and female sex hormones in both sexes.
  32. 32. 20-32 Adrenal glands
  33. 33. 20-33 Glucocorticoids Cortisol promotes breakdown of muscle proteins to amino acids; the liver then breaks the amino acids into glucose. Cortisol also promotes metabolism of fatty acids rather than carbohydrates, which spares glucose. Both actions raise the blood glucose level. High levels of blood glucocorticoids can suppress immune system function.
  34. 34. 20-34 Mineralocorticoids Aldosterone causes the kidneys to reabsorb sodium ions (Na+ ) and excrete potassium ions (K+ ). When blood sodium levels and blood pressure are low, the kidneys secrete renin; the effect of the renin-angiotensin- aldosterone system is to raise blood pressure.
  35. 35. 20-35 Regulation of blood pressure and volume
  36. 36. 20-36 Malfunction of the Adrenal Cortex Addison disease develops when the adrenal cortex hyposecetes hormones. A bronzing of the skin follows low levels of cortisol, and mild infection can lead to death; aldosterone is also hyposecreted, and dehydration can result. Cushing syndrome develops when the adrenal cortex hypersecretes cortisol. The trunk and face become round; too much aldosterone results in fluid retention.
  37. 37. 20-37 Addison disease
  38. 38. 20-38 Cushing syndrome
  39. 39. 20-39 Pancreas The pancreas is between the kidneys and the duodenum and provides digestive juices and endocrine functions. Pancreatic Islets of Langerhans secrete: - insulin, from the beta cells, which lowers the blood glucose level - insulin makes cells more permeable to glucose - glucagon, from the alpha cells, which increases the blood glucose level - glucagon causes the conversion of glycogen to glucose
  40. 40. 20-40 Pancreas
  41. 41. 20-41 Regulation of blood glucose level
  42. 42. 20-42 Diabetes Mellitus The most common illness due to hormonal imbalance is diabetes mellitus. Diabetes is due to the failure of the pancreas to produce insulin or the inability of the body cells to take it up. Hyperglycemia symptoms develop, and glucose appears in the urine. Diabetes is diagnosed using a glucose tolerance test.
  43. 43. 20-43 Glucose tolerance test
  44. 44. 20-44 TYPE I – insulin-dependent • caused by lack of insulin production in pancreas, hereditary but may skip generations • treated with insulin injections and rigid blood monitoring • since insulin is a protein it would be digested if taken orally • must monitor both hypoglycemia (need glucagon or glucose) and hyperglycemia (need insulin) • in research: islet transplants, gene therapy (thought to have found gene)
  45. 45. 20-45 TYPE II- insulin-independent • caused by decreased insulin production, or too much glucose produced by the liver (not enough compensation by pancreas), insulin resistance • gestational diabetes, during pregnancy, mother develops symptoms – at a greater risk for type II later in life
  46. 46. 20-46 • diabetes insipidous, which has nothing to do with insulin, but ADH production in the pituitary – a tumour or injury causes ADH or response to ADH, causing frequent urination (up to 30 L per day). Treat with ADH nasal spray
  47. 47. 20-47 • only type I requires daily insulin injections, type II and GDM are treated by changing diet & sometimes sulfonamides • symptoms of type I and II – fatigue (not enough glucose inside cells to provide an energy source – must use fat & protein) – excessive thirst & urination (glucose in urine pulls out water by osmosis) – increased appetite (& weight loss – type I) – increased susceptibility to infection • *** in type II, since it onsets slowly, there may be no symptoms initially • diabetes causes many complications due to fluctuations in blood sugar and ketoacidosis (products of fat breakdown which are toxic to the body)
  48. 48. 20-48 Thyroid and Parathyroid Glands The thyroid gland is a large gland located in the neck, where it is attached to the trachea just below the larynx. The four parathyroid glands are embedded in the posterior surface of the thyroid gland.
  49. 49. 20-49 The thyroid gland secretes hormones that regulate cell metabolism, growth, and development.
  50. 50. 20-50 Thyroid Gland The thyroid gland requires iodine to produce thyroxine (T4) which contains four iodine atoms, and triiodothyronine (T3) which contains three iodine atoms. Thyroid hormones increase the metabolic rate, and stimulate all body cells to metabolize and use energy at a faster rate.
  51. 51. 20-51 Thyroxine secretion is regulated by the release of thyroid-stimulating hormone (TSH) from the anterior pituitary. TSH is regulated by negative feedback by thyroxine on the hypothalamus and pituitary. 1. Releasing hormone from hypothalamus stimulates anterior pituitary 2. Anterior pituitary releases TSH into bloodstream 3. TSH targets thyroid 4. Thyroid secretes thyroxine into bloodstream 5. High levels of thyroxine cause negative feedback, shutting down production of TSH
  52. 52. 20-52 Effects of Thyroid Hormones Iodine is required to synthesize thyroxine If too little iodine in the diet  thyroid swells (goiter) • swelling is due to the continued stimulation by TSH (no thyroxine made), causes increase in thyroid size in an attempt to make more thyroxine - iodized salt helps prevent simple goiters.
  53. 53. 20-53 Simple goiter
  54. 54. 20-54 If the thyroid is overactive (Grave’s disease) an exophthalmic goiter develops. • too much thyroxine is present  hyperthyroidism (Grave’s disease) – jittery, weight loss, fast heart rate, feel warm, mood swings, hair loss, bulging eyes – treated by removing a portion of the thyroid gland (surgically or chemically)
  55. 55. 20-55 Hypothyroidism in childhood produces cretinism; in adulthood it causes myxedema. • too little thyroxine is present  hypothyroidism – cold, fatigue, dry skin, hair loss, weight gain, sleep a lot (myxedema) – in children, leads to abnormal mental and physical development , growth retardation (cretinism)
  56. 56. 20-56 Cretinism
  57. 57. 20-57 Calcitonin The thyroid gland also produces calcitonin, which helps lower the blood calcium level when it is too high. The primary effect of calcitonin is to bring about the deposit of calcium in the bones; it does this by temporarily reducing the activity and number of osteoclasts. When the blood level of calcium is returned to normal, the release of calcitonin is inhibited.
  58. 58. 20-58 Parathyroid Glands Parathyroid glands secrete parathyroid hormone (PTH), which raises the blood calcium when it is insufficient, and decreases the blood phosphate level. PTH acts by stimulating the activity of osteoclasts, thus releasing calcium from bone, and stimulates the reabsorption of calcium by the kidneys and intestine. Insufficient parathyroid hormone will cause serious loss of blood calcium and
  59. 59. 20-59 Regulation of blood calcium level
  60. 60. 20-60 Other Endocrine Glands Testes and Ovaries Testes, located in the scrotum, produce the male hormone testosterone. Ovaries in the female produce estrogens and progesterone. Secretions from the gonads are controlled by the anterior pituitary hormones. These sex hormones maintain the sex organs and secondary sex characteristics.
  61. 61. 20-61 The effects of anabolic steroid use
  62. 62. 20-62 Prostaglandins Prostaglandins are produced within cells from arachidonate, a fatty acid. Prostaglandins act close to where they are produced. They cause uterine muscle contraction and are involved in the pain of menstrual cramps; aspirin is effective against the pain by countering prostaglandins.
  63. 63. 20-63 Chapter Summary Hormones are chemical signals that affect the activity of target glands or tissues. Endocrine glands are ductless and distribute hormones by the bloodstream. The hypothalamus is a part of the brain that controls the functioning of the pituitary gland.
  64. 64. 20-64 The anterior pituitary produces several hormones, some of which control other endocrine glands. Growth hormone is produced by the anterior pituitary; giants are due to overproduction of growth hormone during childhood, and pituitary dwarfs are due to underproduction of growth hormone. The thyroid produces two hormones that speed metabolism and another hormone that lowers the blood calcium level.
  65. 65. 20-65 The distinct parathyroid glands produce a hormone that raises blood calcium level. Adrenal glands produce hormones that help us respond to stress. Malfunction of the adrenal cortex leads to the symptoms of Addison disease and Cushing disease. The pancreas secretes hormones that regulate the blood glucose level.
  66. 66. 20-66 Diabetes mellitus occurs when cells are unable to take up glucose and it spills over into the urine. The gonads produce sex hormones that control secondary sex characteristics. Many other tissues, although not traditionally considered endocrine glands, secrete hormones. Hormones influence the metabolism of their target cells.

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