Chapter 41: Animal Hormones

CHAPTER 41Animal Hormones

Chapter 41: Animal Hormones

Chapter 41: Animal HormonesHormones and Their ActionsHormones and Their Actions

Hormonal Control of Molting and Hormonal Control of Molting and Development in InsectsDevelopment in Insects

Vertebrate Endocrine SystemsVertebrate Endocrine Systems

Mechanisms of Hormone ActionMechanisms of Hormone Action

Chapter 41: Animal Hormones

Hormones and Their Actions• Endocrine cells secrete chemical Endocrine cells secrete chemical

messages called hormones, which bind messages called hormones, which bind to receptors on or in target cells. See to receptors on or in target cells. See Figure 1Figure 1

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Chapter 41: Animal Hormones

Hormones and Their Actions • Most hormones diffuse through Most hormones diffuse through

extracellular fluids, are picked up by extracellular fluids, are picked up by the blood, and distributed throughout the blood, and distributed throughout the body. the body.

• Some diffuse to targets near the Some diffuse to targets near the secretion site. secretion site.

• Autocrine hormones influence the cell Autocrine hormones influence the cell that secretes them that secretes them

• Paracrine hormones influence nearby Paracrine hormones influence nearby cells. Review Figure 41.1cells. Review Figure 41.1

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Chapter 41: Animal Hormones

Figure 41.1

Figure 41.1Figure 41.1

figure 41-01.jpg

Chapter 41: Animal Hormones

Hormones and Their Actions • Hormones cause different responses in Hormones cause different responses in

different target cells.different target cells.

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Chapter 41: Animal Hormones

Hormones and Their Actions • The chemical structures of hormones The chemical structures of hormones

have changed little through evolution, have changed little through evolution, but their functions have changed but their functions have changed dramatically.dramatically.

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Chapter 41: Animal Hormones

Hormones and Their Actions • Hormones may be secreted by single Hormones may be secreted by single

cells or by cells organized into discrete cells or by cells organized into discrete endocrine glands. Review Figure 41.2endocrine glands. Review Figure 41.2

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Chapter 41: Animal Hormones

Figure 41.2

Figure 41.2Figure 41.2

figure 41-02.jpg

Chapter 41: Animal Hormones

Hormonal Control of Molting and Development in Insects• Insects molt their exoskeletons to Insects molt their exoskeletons to

grow. grow. • Two diffusible substances, brain Two diffusible substances, brain

hormone and ecdysone, control hormone and ecdysone, control molting. Review Figure 41.3molting. Review Figure 41.3

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Chapter 41: Animal Hormones

Figure 41.3 – Part 1

Figure 41.3 – Part 1Figure 41.3 – Part 1

figure 41-03a.jpg

Chapter 41: Animal Hormones

Figure 41.3 – Part 2

Figure 41.3 – Part 2Figure 41.3 – Part 2

figure 41-03b.jpg

Chapter 41: Animal Hormones

Hormonal Control of Molting and Development in Insects • Juvenile hormone, another diffusible Juvenile hormone, another diffusible

substance, prevents maturation so substance, prevents maturation so that juvenile instars molt into bigger that juvenile instars molt into bigger juvenile instars. juvenile instars.

• When juvenile hormone level falls low When juvenile hormone level falls low enough, the juvenile molts into the enough, the juvenile molts into the adult form.adult form.

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Chapter 41: Animal Hormones

Hormonal Control of Molting and Development in Insects • Some insects go through complete Some insects go through complete

metamorphosis. metamorphosis. • When juvenile hormone drops to a low When juvenile hormone drops to a low

level, the larval form becomes a pupa. level, the larval form becomes a pupa. • Because no juvenile hormone is Because no juvenile hormone is

secreted during pupation, the pupa secreted during pupation, the pupa molts into an adult. molts into an adult. Review Figure 41.4 Review Figure 41.4

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Chapter 41: Animal Hormones

Figure 41.4

Figure 41.4Figure 41.4

figure 41-04.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems• Vertebrates have nine endocrine Vertebrates have nine endocrine

glands that secrete many hormones. glands that secrete many hormones. Review Figure 41.2, Table Review Figure 41.2, Table 41.141.1

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Chapter 41: Animal Hormones

Table 41.1 – Part 1Table 41.1 – Part 1Table 41.1 – Part 1

table 41-01a.jpg

Chapter 41: Animal Hormones

Table 41.1 – Part 2

Table 41.1 – Part 2Table 41.1 – Part 2

table 41-01b.jpg

Chapter 41: Animal Hormones

Table 41.1 – Part 3

Table 41.1 – Part 3Table 41.1 – Part 3

table 41-01c.jpg

Chapter 41: Animal Hormones

Table 41.1 – Part 4

Table 41.1 – Part 4Table 41.1 – Part 4

table 41-01d.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • The pituitary gland is divided into two The pituitary gland is divided into two

parts. parts.

• The anterior pituitary develops from The anterior pituitary develops from embryonic mouth tissueembryonic mouth tissue

• The posterior pituitary develops from The posterior pituitary develops from the brain. the brain.

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Chapter 41: Animal Hormones

Vertebrate Endocrine Systems

• The posterior pituitary secretes the The posterior pituitary secretes the neurohormones vasopressin and neurohormones vasopressin and oxytocin. Review Figure 41.5oxytocin. Review Figure 41.5

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Chapter 41: Animal Hormones

Figure 41.5

Figure 41.5Figure 41.5

figure 41-05.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • The anterior pituitary secretes: The anterior pituitary secretes:

• Tropic hormones (thyrotropin, Tropic hormones (thyrotropin, adrenocorticotropin, and two adrenocorticotropin, and two gonadotropins), and gonadotropins), and

• Growth hormone, prolactin, Growth hormone, prolactin, melanocyte-stimulating hormone, melanocyte-stimulating hormone, endorphins, and enkephalins.endorphins, and enkephalins.

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Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • The anterior pituitary is controlled by The anterior pituitary is controlled by

neurohormones produced by cells in neurohormones produced by cells in the hypothalamus and transported the hypothalamus and transported through portal blood vessels to the through portal blood vessels to the anterior pituitary. Review Figure 41.7, anterior pituitary. Review Figure 41.7, Table 41.2Table 41.2

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Chapter 41: Animal Hormones

Figure 41.7

Figure 41.7Figure 41.7

figure 41-07.jpg

Chapter 41: Animal Hormones

Table 41.2

Table 41.2Table 41.2

table 41-02.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • Hormone release in the Hormone release in the

hypothalamus/pituitary/endocrine hypothalamus/pituitary/endocrine gland axis is controlled by many gland axis is controlled by many feedback loops. Review Figure 41.8feedback loops. Review Figure 41.8

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Chapter 41: Animal Hormones

Figure 41.8

Figure 41.8Figure 41.8

figure 41-08.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • The thyroid gland is controlled by The thyroid gland is controlled by

thyrotropin and secretes thyroxine, thyrotropin and secretes thyroxine, which controls cell metabolism. which controls cell metabolism. Review Figure 41.9 Review Figure 41.9

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Chapter 41: Animal Hormones

Figure 41.9

Figure 41.9Figure 41.9

figure 41-09.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • Calcium levels in the blood are Calcium levels in the blood are

regulated by two hormones. regulated by two hormones.

• Calcitonin, produced by the thyroid, Calcitonin, produced by the thyroid, lowers blood calcium. lowers blood calcium.

• Parathormone, produced by the Parathormone, produced by the parathyroid glands, raises it. parathyroid glands, raises it. Review Figure 41.10 Review Figure 41.10

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Chapter 41: Animal Hormones

Figure 41.10

Figure 41.10Figure 41.10

figure 41-10.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • The pancreas secretes three The pancreas secretes three

hormones. hormones.

• Insulin stimulates glucose uptake by Insulin stimulates glucose uptake by cells and lowers blood glucosecells and lowers blood glucose

• Glucagon raises blood glucoseGlucagon raises blood glucose• Somatostatin slows nutrient absorption Somatostatin slows nutrient absorption

rate from the gut.rate from the gut.

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Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • The adrenal gland has two portions. The adrenal gland has two portions.

• The hormones of the adrenal medulla, The hormones of the adrenal medulla, epinephrine and norepinephrine, epinephrine and norepinephrine, stimulate the liver to supply glucose to stimulate the liver to supply glucose to the blood, as well as other fight-or-the blood, as well as other fight-or-flight reactions. Review Figure 41.11flight reactions. Review Figure 41.11

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Chapter 41: Animal Hormones

Figure 41.11

Figure 41.11Figure 41.11

figure 41-11.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • The adrenal cortex produces three The adrenal cortex produces three

classes of corticosteroids: classes of corticosteroids: glucocorticoidsglucocorticoids mineralocorticoidsmineralocorticoids small amounts of sex steroids. small amounts of sex steroids.

Review Figure 41.12Review Figure 41.123737

Chapter 41: Animal Hormones

Figure 41.12

Figure 41.12Figure 41.12

figure 41-12.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • Aldosterone is a mineralocorticoid that Aldosterone is a mineralocorticoid that

stimulates the kidney to conserve stimulates the kidney to conserve sodium and to excrete potassium.sodium and to excrete potassium.

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Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • Cortisol is a glucocorticoid that Cortisol is a glucocorticoid that

decreases glucose utilization by most decreases glucose utilization by most cells.cells.

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Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • Sex hormones are produced by the Sex hormones are produced by the

gonads in response to tropic gonads in response to tropic hormones. hormones.

• Sex hormones control sexual Sex hormones control sexual development, secondary sexual development, secondary sexual characteristics, and reproductive characteristics, and reproductive functions. Review Figure functions. Review Figure 41.1341.13

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Chapter 41: Animal Hormones

Figure 41.13

Figure 41.13Figure 41.13

figure 41-13.jpg

Chapter 41: Animal Hormones

Vertebrate Endocrine Systems • The pineal hormone melatonin is The pineal hormone melatonin is

involved in controlling biological involved in controlling biological rhythms and photoperiodism. rhythms and photoperiodism. Review Figure 41.14 Review Figure 41.14

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Chapter 41: Animal Hormones

Figure 41.14

Figure 41.14Figure 41.14

figure 41-14.jpg

Chapter 41: Animal Hormones

Mechanisms of Hormone Action• The responses of a cell to a hormone The responses of a cell to a hormone

depend on what receptors it has and depend on what receptors it has and what signal transduction pathways what signal transduction pathways those receptors activate. those receptors activate. Review Table 41.3 Review Table 41.3

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Chapter 41: Animal Hormones

Table 41.3

Table 41.3Table 41.3

table 41-03.jpg

Chapter 41: Animal Hormones

Mechanisms of Hormone Action • Receptors for water-soluble hormones Receptors for water-soluble hormones

are on the cell surface, and receptors are on the cell surface, and receptors for lipid-soluble hormones are inside for lipid-soluble hormones are inside the cell.the cell.

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Chapter 41: Animal Hormones

Mechanisms of Hormone Action • Cell sensitivity to hormones can be Cell sensitivity to hormones can be

altered by up- or downregulation of the altered by up- or downregulation of the receptors in that cell.receptors in that cell.

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Chapter 41: Animal Hormones

Mechanisms of Hormone Action • Sensitivity and time course of hormone Sensitivity and time course of hormone

response depend on many factorsresponse depend on many factors receptor numbersreceptor numbers properties of signal transduction properties of signal transduction

pathwayspathways other hormonesother hormones binding of the hormone to carrier binding of the hormone to carrier

proteinsproteins elimination of the hormone through elimination of the hormone through

degradation and excretion.degradation and excretion.4949

Chapter 41: Animal Hormones

Mechanisms of Hormone Action • Important tools for characterizing Important tools for characterizing

hormone action are dose–response hormone action are dose–response curves and measurements of half-life. curves and measurements of half-life. Review Figure 41.15 Review Figure 41.15

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Chapter 41: Animal Hormones

Figure 41.15

Figure 41.15Figure 41.15

figure 41-15.jpg