Chemical Coordination
Chapter 34
Hormones
A hormone is a chemical signal that is
secreted into the circulatory system and
communicates regulatory messages...
Systems of Internal Communication
Animals have two systems of internal
communication and regulation:
The nervous system
...
Systems of Internal Communication
The nervous system conveys high-
speed electrical signals along
specialized cells calle...
Hormones
Advantages of using chemical
messengers:
Chemical molecules can spread to all
tissues through the blood.
Chemi...
Glands
Many hormones are secreted by
ductless endocrine glands.
Obtain raw materials from and secrete
hormones directly ...
Hormones
Hormones convey information via the
bloodstream to target cells throughout
the body.
Pheromones carry messages ...
Hormones
Three major classes of molecules
function as hormones in vertebrates:
Proteins and peptides
Amines derived fro...
Hormones
Signaling by any of these molecules
involves three key events:
Reception
Signal transduction
Response
Hormones
The hypothalamus regulates the
neuroendocrine system, maintaining
homeostasis in the body.
The hypothalamus can...
The Chain of Command
 The hypothalamus produces seven different
“releasing” hormones that travel to the
pituitary gland.
...
Membrane-Bound Receptors
 Many hormones are too
large, or too polar, to
pass through plasma
membranes.
 Bind to transmem...
Nuclear Receptors
 Steroid hormones are
lipid soluble molecules
that bind to hormone
receptors in the
cytoplasm of the ta...
Nuclear Receptors
 Thyroid hormones
and insect-molting
hormone (ecdysone)
also act through
nuclear receptors.
 Binds to
...
Control Pathways and Feedback
Loops
 A common feature of
control pathways is a
feedback loop
connecting the
response to t...
Invertebrate Hormones
 Ecdysone
regulates
molting in
insects.
 Juvenile
hormone
favors the
retention of
juvenile
charact...
The Pituitary
 The pituitary gland
is located below the
hypothalamus.
 Nine major
hormones are
produced here.
 These ho...
The Pituitary
The posterior lobe of the pituitary
regulates water conservation, milk
letdown, and uterine contraction in
...
The Anterior Pituitary
 Thyroid stimulating hormone (TSH) – stimulates the
thyroid gland to produce thyroxine which stimu...
The Anterior Pituitary
 Follicle-stimulating hormone (FSH) – plays
an important role in the menstrual cycle. In
males, it...
The Anterior Pituitary
Growth hormone (GH) – stimulates the
growth of muscle and bone.
Prolactin – stimulates milk produ...
The Posterior Pituitary
 Antidiuretic hormone
(ADH) regulates the
kidney’s retention of
water.
 Oxytocin initiates
uteri...
Biological Clocks
 The pineal gland is
located in the brain
of most vertebrates.
 Evolved from a light
sensitive “third ...
Biological Clocks
 In other vertebrates it functions as an
endocrine gland secreting melatonin.
 Melatonin controls colo...
The Thyroid
 The thyroid gland, located
in the neck, produces:
 Thyroxine – increases
metabolic rate and
promotes growth...
The Thyroid
 The hypothalamus
and anterior pituitary
control the secretion
of thyroid hormones
through two negative
feedb...
The Thyroid
 The thyroid
hormones play
crucial roles in
stimulating
metabolism and
influencing
development and
maturation.
The Parathyroids
 The parathyroid glands are
four small glands attached
to the thyroid.
 The hormone they produce
is par...
Calcium Homeostasis
 Two antagonistic
hormones,
parathyroid
hormone (PTH) and
calcitonin, play the
major role in calcium
...
Calcium Homeostasis
 Calcitonin, secreted by the thyroid gland,
stimulates Ca2+
deposition in the bones and
secretion by ...
The Adrenals
 Mammals have an adrenal gland above each kidney.
 Adrenal medulla is the inner core which produces
adrenal...
Adrenal Medulla
The adrenal medulla releases adrenalin
(epinephrine) and norepinephrine in
times of stress.
Identical to...
Adrenal Cortex
The adrenal cortex produces the steroid
hormone cortisol (hydrocortisone).
Reduces inflammation.
 Synthe...
Adrenal Cortex
The adrenal cortex also produces
aldosterone.
Aldosterone acts in the kidney to
promote the uptake of sod...
The Pancreas
 The pancreas is located
behind the stomach and
is connected to the small
intestine by a small tube.
 It se...
Glucose Homeostasis
 The islets of
Langerhans in the
pancreas secrete
insulin and glucagon.
 Insulin removes
glucose fro...
Diabetes
Diabetes mellitus, perhaps the best-
known endocrine disorder, is caused by
a deficiency of insulin or a decreas...
Diabetes
 Type I diabetes mellitus (insulin-dependent
diabetes) is an autoimmune disorder in which
the immune system dest...
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  1. 1. Chemical Coordination Chapter 34
  2. 2. Hormones A hormone is a chemical signal that is secreted into the circulatory system and communicates regulatory messages within the body. Hormones may reach all parts of the body, but only certain types of cells, target cells, are equipped to respond.
  3. 3. Systems of Internal Communication Animals have two systems of internal communication and regulation: The nervous system The endocrine system
  4. 4. Systems of Internal Communication The nervous system conveys high- speed electrical signals along specialized cells called neurons. The endocrine system, made up of endocrine glands, secretes hormones that coordinate slower but longer-acting responses to stimuli.
  5. 5. Hormones Advantages of using chemical messengers: Chemical molecules can spread to all tissues through the blood. Chemical signals can persist longer than electrical ones. Many different kinds of chemicals can act as hormones; different hormones can target different tissues.
  6. 6. Glands Many hormones are secreted by ductless endocrine glands. Obtain raw materials from and secrete hormones directly into the bloodstream. Exocrine glands have ducts for discharging secretions onto a free surface. Sweat glands, salivary glands, enzyme- secreting glands in the digestive tract.
  7. 7. Hormones Hormones convey information via the bloodstream to target cells throughout the body. Pheromones carry messages outside the body – to other individuals.
  8. 8. Hormones Three major classes of molecules function as hormones in vertebrates: Proteins and peptides Amines derived from amino acids Steroids
  9. 9. Hormones Signaling by any of these molecules involves three key events: Reception Signal transduction Response
  10. 10. Hormones The hypothalamus regulates the neuroendocrine system, maintaining homeostasis in the body. The hypothalamus can use motor nerves to send short-lived electrical messages or hormones to send chemical messages with a longer duration.
  11. 11. The Chain of Command  The hypothalamus produces seven different “releasing” hormones that travel to the pituitary gland.  Each releasing hormone stimulates the pituitary to release a corresponding hormone which travels to an endocrine gland and causes it to start producing a particular endocrine hormone.
  12. 12. Membrane-Bound Receptors  Many hormones are too large, or too polar, to pass through plasma membranes.  Bind to transmembrane proteins that act as receptor sites on target cell membranes.  Hormone is first messenger.  Causes activation of a second messenger in the cytoplasm.  cAMP
  13. 13. Nuclear Receptors  Steroid hormones are lipid soluble molecules that bind to hormone receptors in the cytoplasm of the target cell.  Site of activity is the nucleus.  Steroids are manufactured from cholesterol.  Estrogen, progesterone, testosterone, cortisol.
  14. 14. Nuclear Receptors  Thyroid hormones and insect-molting hormone (ecdysone) also act through nuclear receptors.  Binds to transmembrane protein that uses ATP to move it into the cell.
  15. 15. Control Pathways and Feedback Loops  A common feature of control pathways is a feedback loop connecting the response to the initial stimulus.  Negative feedback regulates many hormonal pathways involved in homeostasis.
  16. 16. Invertebrate Hormones  Ecdysone regulates molting in insects.  Juvenile hormone favors the retention of juvenile characteristics.
  17. 17. The Pituitary  The pituitary gland is located below the hypothalamus.  Nine major hormones are produced here.  These hormones act primarily to influence other endocrine glands.
  18. 18. The Pituitary The posterior lobe of the pituitary regulates water conservation, milk letdown, and uterine contraction in women. The anterior lobe regulates the other endocrine glands.
  19. 19. The Anterior Pituitary  Thyroid stimulating hormone (TSH) – stimulates the thyroid gland to produce thyroxine which stimulates oxidative respiration.  Luteinizing hormone (LH) plays an important role in the menstrual cycle. It also stimulates the production of testosterone in males.
  20. 20. The Anterior Pituitary  Follicle-stimulating hormone (FSH) – plays an important role in the menstrual cycle. In males, it causes the testes to produce a hormone that regulates sperm production.  Adrenocorticotropic hormone (ACTH) – stimulates the adrenal gland to produce steroid hormones. Some regulate glucose production, others balance sodium & potassium in the blood.
  21. 21. The Anterior Pituitary Growth hormone (GH) – stimulates the growth of muscle and bone. Prolactin – stimulates milk production. Melanocyte-stimulating hormone (MSH) – in reptiles & amphibians, this hormone stimulates color change.
  22. 22. The Posterior Pituitary  Antidiuretic hormone (ADH) regulates the kidney’s retention of water.  Oxytocin initiates uterine contraction during childbirth and milk release in mothers.  These hormones are actually synthesized in the hypothalamus and stored in the posterior pituitary.
  23. 23. Biological Clocks  The pineal gland is located in the brain of most vertebrates.  Evolved from a light sensitive “third eye”.  Primitive fish & some reptiles still have a third eye.
  24. 24. Biological Clocks  In other vertebrates it functions as an endocrine gland secreting melatonin.  Melatonin controls color change in amphibians & reptiles.  Release of melatonin is controlled by light/dark cycles.  The primary functions of melatonin appear to be related to biological rhythms associated with reproduction.  Circadian rhythms – 24 hours long.
  25. 25. The Thyroid  The thyroid gland, located in the neck, produces:  Thyroxine – increases metabolic rate and promotes growth.  Two iodine-containing hormones, triiodothyronine (T3) and thyroxine (T4).  Calcitonin – stimulates calcium uptake by bones.
  26. 26. The Thyroid  The hypothalamus and anterior pituitary control the secretion of thyroid hormones through two negative feedback loops.
  27. 27. The Thyroid  The thyroid hormones play crucial roles in stimulating metabolism and influencing development and maturation.
  28. 28. The Parathyroids  The parathyroid glands are four small glands attached to the thyroid.  The hormone they produce is parathyroid hormone (PTH) which regulates the level of calcium in the blood.  Essential that calcium is kept within narrow limits for muscle contraction, including the heart.
  29. 29. Calcium Homeostasis  Two antagonistic hormones, parathyroid hormone (PTH) and calcitonin, play the major role in calcium (Ca2+ ) homeostasis in mammals.
  30. 30. Calcium Homeostasis  Calcitonin, secreted by the thyroid gland, stimulates Ca2+ deposition in the bones and secretion by the kidneys, thus lowering blood Ca2+ levels.  PTH, secreted by the parathyroid glands, has the opposite effects on the bones and kidneys, and raises Ca2+ levels.  Also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food.
  31. 31. The Adrenals  Mammals have an adrenal gland above each kidney.  Adrenal medulla is the inner core which produces adrenaline (epinephrine) and norepinephrine.  Adrenal cortex is the outer shell that produces the steroid hormones cortisol and aldosterone.
  32. 32. Adrenal Medulla The adrenal medulla releases adrenalin (epinephrine) and norepinephrine in times of stress. Identical to the effects of the sympathetic nervous system, but longer lasting.  Accelerated heartbeat, increased blood pressure, higher levels of blood sugar and increased blood flow to heart and lungs.
  33. 33. Adrenal Cortex The adrenal cortex produces the steroid hormone cortisol (hydrocortisone). Reduces inflammation.  Synthetic derivatives such as prednisone are used as anti-inflammatory agents. Stimulates carbohydrate metabolism.
  34. 34. Adrenal Cortex The adrenal cortex also produces aldosterone. Aldosterone acts in the kidney to promote the uptake of sodium & other salts from the urine. These salts are important in nerve conduction. Aldosterone and PTH are the only two hormones essential for survival.
  35. 35. The Pancreas  The pancreas is located behind the stomach and is connected to the small intestine by a small tube.  It secretes digestive enzymes into the digestive tract (exocrine function).  Endocrine function – production of insulin and glucagon.
  36. 36. Glucose Homeostasis  The islets of Langerhans in the pancreas secrete insulin and glucagon.  Insulin removes glucose from the blood.  Glucagon returns glucose to the blood.
  37. 37. Diabetes Diabetes mellitus, perhaps the best- known endocrine disorder, is caused by a deficiency of insulin or a decreased response to insulin in target tissues. Marked by elevated blood glucose levels.
  38. 38. Diabetes  Type I diabetes mellitus (insulin-dependent diabetes) is an autoimmune disorder in which the immune system destroys the beta cells of the pancreas.  Type II diabetes mellitus (non-insulin- dependent diabetes) is characterized either by a deficiency of insulin or, more commonly, by reduced responsiveness of target cells due to some change in insulin receptors.

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