1. CHAPTER 45 CHEMICAL SIGNALS IN ANIMALS
The endocrine system and the nervous system are structurally, chemically, and functionally related

2. Why have a hormonal/endocrine system?
Homeostasis - regulation of body functions - keeps body “ON TRACK”

3. Endocrine glands:
Ductless glands, release hormones into BLOODSTREAM
Exocrine glands:
Glands with ducts, release enzymes into a lumen/cavity;
Ex. salivary glands
Paracrine secretions:
Local regulators

4. Local regulators affect neighboring target cells- Paracrine secretions
Growth factors: proteins and polypeptides that stimulate cell division
Nitric oxide (NO)- neurotransmitter, it kills bacteria and cancer cells, it dilates the walls of blood vessels (Viagra!!!)
Prostaglandins secreted by the placenta stimulate uterine contractions during childbirth; important in inflammatory response
Example: nerve growth factor (NGF) affects certain embryonic cells, developing white blood cells, and other kinds of cells
Nitric oxide (NO)
Though a gas, NO is an important local regulator.
When secreted by neurons, it acts as a neurotransmitter.
When secreted by white blood cells, it kills bacteria and cancer cells.
And when secreted by endothelial cells, it dilates the walls of blood vessels.

5. Hormones are chemical signals.
The endocrine system consists of:
Endocrine cells- hormone- secreting cells and
Endocrine glands- hormone-secreting organs.
Secrete their hormones into blood stream and affect target cells
Specific target cells respond to specific hormones = receptors involved and second messenger system (chp 11).

6. Neurosecretory cells (neurons that can produce hormones) secrete hormones into the blood.
Located in hypothalamus
Epinephrine - can signal nerves and act as a hormone

7. Feedback regulation is a feature of both the endocrine and nervous systems (negative and positive feedback loops).
Negative regulation - hormone decreases the stimulus causing its production:
Calcium can be stored in bone or released to cells via blood (like glycogen-glucose)
Blood Calcium level high (stimulus)
Thyroid makes calcitonin
Enters blood
Calcium goes from blood to bone
Calcium level falls (stimulus decreases)
Hormone release causes stimulus to decrease- negative feedback

8. Positive feedback loop- Stimulus makes the hormone to be released, and hormone release increases stimulus strength
Sucking of baby (stimulus)
Hypothalamus makes Oxytocin
Enters blood
Smooth muscle contraction at nipple releasing milk
Baby sucks more!!
Positive feedback- not seen as often as negative feedback

9. Invertebrates: Ecdysone- promotes the development of adult features.
Neurosecretory cells in the brain produce brain hormone (BH), which regulates the secretion of ecdysone.
Juvenile hormone (JH) promotes the retention of larval characteristics.
An example from hydra:
One hormone stimulate asexual reproduction.
Another hormone prevents sexual reproduction.
An example from a mollusk:
The hormone that regulates egg laying also inhibits feeding and locomotion.
Fig. 45.2

10. Signal transduction
- Most chemical signals bind to plasma-membrane proteins, initiating signal transduction pathways like G protein and phosphorylation cascade (water soluble hormones)

11. Signal- transduction pathways allow for small amounts of a hormone to have a large effect.
Fig.11.16

12. Signal transduction
Steroid hormones, thyroid hormones, and some local regulators enter target cells and bind to intracellular receptors in the cytoplasm. Next they activate transcription factors - these bind to DNA in the nucleus and cause mRNA to be produced which in turn produces proteins (lipid soluble)

13. Lipid soluble Hormones: Enter target cells and bind to intracellular receptors Examples: estrogen, progesterone, vitamin D, NO. Usually, the intracellular receptor activated by a hormone is a transcription factor. Leads to changes in DNA transcription Final effect - protein synthesis
Water soluble Hormones: Bind to plasma membrane receptors on target cells Examples: Insulin, epinephrine Leads to activation of G proteins, second messengers (cAMP), protein kinases - enzymes that activate various proteins including some transcription factors May lead to changes in DNA transcription Final effect - protein activation or synthesis
Fig. 45.3b

14. Different signal-transduction pathways in different cells can lead to different responses to the same signal.
Fig. 45.4

15. CHAPTER 45 CHEMICAL SIGNALS IN ANIMALS
Section C: The Vertebrate Endocrine System
1. The hypothalamus and pituitary integrate many functions of the vertebrate endocrine system
2. The pineal gland is involved in biorhythms
3. Thyroid hormones function in development, bioenergetics, and homeostasis
4. Parathyroid hormone and calcitonin balance blood calcium
5. Endocrine tissues of the pancreas secrete insulin and glucagon, antagonistic hormones that regulate blood glucose
6. The adrenal medulla and adrenal cortex help the body manage stress
7. Gonadal steroids regulate growth, development, reproductive cycles, and sexual behavior

16. Introduction
Tropic hormones - produced by hypothalamus and pituitary gland - MASTER GLAND>target other endocrine glands and are important for chemical coordination.
Humans have nine endocrine glands.
Fig. 45.5

17. Hypothalamus and pituitary integrate endocrine system
Hypothalamus Tropic Hormones:
B) Releasing hormones produced by hypothalamus stimulate the anterior pituitary (adenohypophysis) to secrete hormones. (FSH, TSH, ACTH)
C) Inhibiting hormones prevent the anterior pituitary from secreting hormones.
D) Nontropic Hormones - Prolactin, MSH, Endorphins, GH
Hypothalamus and pituitary integrate endocrine system
A) Neurosecretory cells of the hypothalamus produce hormones- ADH and Oxytocin. Reach posterior pituatary gland for storage

18. Hypothalamus and pituitary integrate endocrine system
A) Neurosecretory cells of the hypothalamus produce hormones- ADH and Oxytocin. Reach posterior pituatary gland for storage

19. Hormones manufactured by the hypothalamus and released by the posterior pituitary.
Oxytocin: a peptide.
Stimulates contraction of the uterus (birthing/parturition) and mammary glands (for milk).
Secretion regulated by the nervous system.
Antidiuretic hormone (ADH): a peptide (in excretion chapter 44)
Promotes retention of water by the kidneys.
Secretion regulated by water/salt balance.

20. Pituatary hormones:
Fig. 45.6b

22. Table 45.1 (continued)
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23. Anterior pituitary hormones.
Growth hormone (GH): a protein.
Stimulates growth and metabolism.
Secretion regulated by hypothalamic hormones.
Acts directly on tissues or acts via growth factors.
Gigantism: excessive GH during development.
Acromegaly: excessive GH production during adulthood.
Hypopituitary dwarfism: childhood GH deficiency.

24. Thyroid-stimulating hormone (TSH): a glycoprotein.
Stimulates thyroid gland.
Secretion regulated by thyroxine in blood.
Secretion regulated by hypothalamic hormones.
Adrenocorticotropic hormone (ACTH): a peptide
Stimulates adrenal cortex secretion of glucocorticoids
Secretion regulated by glucocorticoids and hypothalamic hormones.

25. Prolactin (PRL): a protein.
Stimulates milk production and secretion.
Secretion regulated by hypothalamic hormones.
Gonadotropins: glyocoproteins.
Follicle-stimulating hormone (FSH).
Stimulates production of sperm and ova.
Luteinizing hormone (LH).
Stimulates ovaries and testes.

26. Melanocyte-stimulating hormone (MSH): a peptide.
May play a role in fat metabolism.
Endorphins: peptides.
Inhibit pain perception.
Effects mimicked by heroin and other opiate drugs.

27. 2) The pineal gland is a small mass of tissue near the center of the mammalian brain.
The pineal gland secretes the hormone, melatonin, an amine.
Involved in biological rhythms associated with reproduction.
Secretion regulated by light/dark cycles.

28. Thyroid gland:
Produces thyroxine hormone

29. 3. Thyroid hormones function in develop-ment, bioenergetics, and homeostasis
The thyroid gland of mammals consists of two lobes located on the ventral surface of the trachea.
Triiodothyronine (T3) and thyroxine (T4): amines.
Stimulates and maintain metabolic processes.
Secretion regulated by TSH hormones.
Fig. 45.8

30. Fig. 45.9
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31. Thyroid in Amphibians:
Thyroid hormone functions:
A) metamorphosis in amphibians
B) Bone and brain development in some other animals
C) Homeostasis in humans - metabolism control

32. Increased bowel movements Light or absent menstrual periods Fatigue
Hyperthyroidism - Grave’s disease- eyes protrude
Palpitations
Heat intolerance
Nervousness
Insomnia
Increased bowel movements
Light or absent menstrual periods
Fatigue
Fast heart rate
Trembling hands
Weight loss
Muscle weakness
Sweating

33. An insufficient amount of thyroid hormones is known as hypothyroidism.
Infants: cretinism.
Adults: weight gain, lethargy, cold intolerance.
Goiter: often associated with iodine deficiency (no negative feedback!)
What is Thyroid Eye Disease? This is a disorder where the fat and muscles behind and around the eyes become swollen. There is still much that we do not know about it. However it seems to occur only in people who have a certain type of thyroid problem called an auto-immune disorder. Most commonly, it happens in people with an overactive thyroid gland; a condition called Graves' disease . To begin with either one eye or both have only a "stary" appearance. They may water and be sensitive to light and especially wind. They may feel sticky in the mornings and gritty during the day. In more severe cases the lids may not close properly. If the muscles which make the eyes move also get inflamed and swollen, the eyes are pushed forward and you may get double vision. This may only be on looking in one direction, but it can worsen so that double vision is there all the time. If the eyes protrude a lot, the white of the eye becomes red (like conjunctivitis). If they protrude even further, vision can be affected. This happens either because the front of the eye (the cornea) gets dried out, or because the optic nerve which carries the images back to the brain is stretched.How does it occur ? In this condition, like all auto-immune disorders, white blood cells called lymphocytes collect in the fat and muscles around the eye. They make a chemical (protein) which causes swelling by allowing seepage of fluid into the fat and muscle tissue. Why does it occur? We do not really know. In some people it happens at the same time as the overactive thyroid gland; in some it happens before the thyroid gland becomes overactive, or even with an underactive or apparently normal thyroid gland. In some people it only comes on months or years after the original thyroid condition has been diagnosed and treated. We don't know why it may affect only one eye, or one eye more than the other. It is certainly not caused directly by having too much thyroid hormone. Treating the overactive thyroid gland does not usually affect the way the eyes behave: in fact the eyes may get briefly worse, particularly if the thyroid is allowed to become temporarily underactive. It tends to run in families; more so in females. It is also more common in smokers.Treatment Involved Your doctor will want to check a few points. A special x-ray called a CT scan may be done to confirm the diagnosis and make sure there is no other cause for your eye problem. An eye specialist may use a special chart to record how your eyes move and will ensure that the pressure in the eye is not high (glaucoma). He will also want to make sure that the optic nerve which carries the seeing image back to the brain is not affected. In mild cases, your doctor may not wish to do more than give you lubricating eye drops (artificial tears). Sometimes taping down the lid overnight with a mild adhesive strip like micropore helps to reduce the discomfort next morning. It avoids the eye drying out. You could try propping yourself up on more pillows or tilting the head end of the bed up on one or two bricks (about 6 inches: 15 cm). Some doctors will prescribe a diuretic to offload water to help reduce the swelling. Double vision is annoying, and special spectacles with prisms can be made to help correct this problem. If the eyes are getting worse, your doctor may suggest steroids (anti-inflammation tablets). These may need to be taken for some months, but often in reducing dosage. They are usually very effective. Some doctors will also suggest radiotherapy to the eyes. This is not because you have any sort of cancer cells, but because radiotherapy can dampen down this type of inflammation. The treatment is given daily over a couple of weeks. Other so-called immune-blocking drugs may also help sometimes. Operations are necessary in certain cases, either because of severe protrusion of the eyes or because of affected vision. Sometimes they are done just for cosmetic reasons. One operation is done through the nose or gums. Bone is nibbled away from around the orbit of the eye to make more space for it. Another type of operation is done on the tendons of the eye muscles. One benefit of this is to allow the upper lid to "hang" lower and close more easily: other types of operation are done to reset the muscles into the eyes and improve double vision. Sometimes even "simple" plastic surgery to the lids can be done, since they tend to get rather baggy when the inflammation has settled.During Treatment Please tell your doctor immediately if your vision changes for the worse at any time. If you are being treated with steroids, indigestion can occur but can be quite easily treated. You will also tend to put on weight (temporarily) and may develop high blood pressure or diabetes, which your doctor will check for. After Treatment You will need careful checks regularly for some years through your doctor and eye specialist. More than one operation may prove to be necessary to get the right end-result. Be patient, although we appreciate how self-conscious you may feel. If Left Untreated In mild cases, nothing. Thyroid eye disease tends to "burn itself out" over a period of months or years in most patients. In more severe cases, abnormality of the eyes may be permanent. Although it is a rare event, once vision is lost, it cannot always be completely restored: prompt action lessens this risk. Effects on Family You may feel self-conscious, but it is probably less obvious to others than you think. Dark or tinted spectacles may help when you are out and about. back | top Last Update: Become A MemberWork in optics? Why not become a full Eyecare Trust member? 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34. 4) Parathyroid- embedded in the surface of the thyroid gland.
Parathyroid Hormone and Calcitonin:
Opposite effects- regulate calcium levels
-Secretion regulated by calcium in blood.
Parathyroid hormone (PTH), a peptide.
Raises blood calcium levels.
Causes osteoclasts to break down bone, releasing Ca2+ into the blood.
Stimulates the kidneys to reabsorb Ca2+.
Stimulates kidneys to convert vitamin D to its active form.
Hypoparathyoidism: tetany.- convulsive contraction of muscles

35. 5) Endocrine tissues of the pancreas secrete insulin and glucagon, antagonistic hormones that regulate blood glucose
The pancreas has both endocrine and exocrine functions.
Exocrine function: secretion of bicarbonate ions and digestive enzymes.
Endocrine function: insulin and glucagon secreted by islets of Langerhans.

36. Fig

37. Glucagon: a protein secreted by alpha cells.
Raises blood glucose levels.
Inhibits cells from taking up glucose from the blood
Stimulates glyogen breakdown in the liver and skeletal muscle.
Stimulates gluconeogenesis
Secretion regulated by glucose in blood (negative feedback
Insulin: a protein secreted by beta cells .
Lowers blood glucose levels.
Stimulates all body cells (except brain cells) to take up glucose from blood.
Slows glycogen breakdown.
Inhibits gluconeogenesis.
Secretion regulated by glucose in blood (negative feedback).

39. Hypoinsulinism: diabetes mellitus- “honey water”
Hereditary factors and obesity play a role in its development.
High blood sugar levels – sugar excreted in the urine.
Symptoms: excessive urination and excessive thirst.
If severe: fat substitutes for glucose as major fuel source  production of acidic metabolites  life threatening lowering of blood pH.

40. Type I diabetes mellitus (insulin-dependent diabetes).
Autoimmune disorder.
Usually appears in childhood.
Treatment: insulin injections.
Type II diabetes mellitus (non- insulin-dependent diabetes).
Usually due to target cells having a decreased responsiveness to insulin.
Usually occurs after age 40 – risk increases with age, weight, stress.
Accounts for over 90% of diabetes cases.

41. 6) The adrenal medulla and adrenal cortex help the body manage stress
The adrenal glands are located adjacent to the kidneys.
The adrenal cortex is the outer portion.
The adrenal medulla is the inner portion.

42. Developmentally and functionally related to the nervous system.
Adrenal cortex reacts to stress- especially long term.
Secretes corticosteroids
Glucocorticoids.
Raises blood glucose level.
Secretion regulated by ACTH (negative feedback).
Abnormally high doses are administered as medication to suppress the inflammation response
Mineralocorticoids (example: aldosterone, which affects salt and water balance).
Promotes reabsorption of Na+ and excretion of K+ in kidneys.
Secretion regulated by K+ in blood.
Adrenal medulla.
Developmentally and functionally related to the nervous system.
Epinephrine (adrenaline) and norepinephrine (noradrenaline).
Flight or fight response
Increased sugar in blood
Blood routed to skeletal muscles, heart, brain (and not skin, digestive organs)
Increased heart rate, stroke volume, breathing, dialtion of bronchioles…

43. Fig
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44. A third group of corticosteriods are sex hormones.
Androgens secreted by the adrenal cortex may account for the female sex drive.
The adrenal cortex also secretes small amounts of estrogens and progesterone.

46. 7. Gonadal steroids regulate growth, development, reproductive cycles, and sexual behavior
Testes.
Androgens (example: testosterone): steroids.
Supports sperm formation.
Promote development and maintenance of male sex characteristics.
Secretion regulated by FSH and LH.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

47. Ovaries secrete estrogens and progesterone.
Estrogens: steroids.
Stimulate uterine lining growth.
Promote development and maintenance of female sex characteristics.
Secretion regulated by FSH and LH.
Progestins (example: progesterone): steroids.
Promotes uterine lining growth.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings