1Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings.

THE ENDOCRINE SYSTEM

PARTH

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Hormones: Come from endocrine glands Circulate in the blood stream Act on specific cells in the body

Endocrine Functions: Hormones

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Access to every cell Each hormone acts only on specific

cells (target cells) Only specific cells have receptors for

specific hormones Endocrine control slower than nervous

system Endocrine and nervous systems

interact

Endocrine System Characteristics

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Steroid Hormone Action on a Target Cell

Figure 13.2

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Steroid Hormones: Lipid soluble, chemically derived from

cholesterol Enter target cells Activate specific genes to produce

specific proteins Slower acting than nonsteroid hormones,

minutes to hours

Classification of Hormones: Steroid

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Nonsteroid Hormone Action on a Target Cell

Figure 13.3

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Nonsteroid hormones: Water soluble Bind to receptors on target cell

membranes Work through intermediate

mechanisms to activate existing enzymes

Faster action than steroid hormones, seconds to minutes

Classification of Hormones: Nonsteroid

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Example of a Negative Feedback

Loop:

Homeostasis

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Location of Major Endrocrine OrgansLocation of Major Endrocrine Organs

Slide 9.14Figure 9.3

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Hormones of the Pituitary Gland

Table 13.1

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Hypothalamus and the Anterior Pituitary Gland

Figure 13.7

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Anterior pituitary Connection to hypothalamus: releasing

and inhibiting hormones from hypothalamus travel to pituitary through pituitary portal system

Hormones ACTH: stimulates adrenal cortex TSH: acts on thyroid gland FSH, LH, Prolactin: related to control of

reproductive cycles and lactation Growth Hormone: widespread effects on

body

Hypothalamus and the Anterior Pituitary Gland

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Posterior pituitary Connection to hypothalamus: hormones

made in hypothalamus, stored in posterior pituitary

Hormones: nonsteroidal Antidiuretic hormone (ADH): conserves water

in kidneys, regulates water balance in body Oxytocin: causes uterine contractions during

labor and milk ejection through neuroendocrine reflex

Hypothalamus and the Posterior Pituitary Gland

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Gigantism: hypersecretion of growth hormone

Pituitary Dwarfism: hyposecretion of growth hormone

Pituitary Disorders

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Pituitary Gigantism

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Pituitary Dwarfism

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Structures: islets of Langerhans

Hormones: nonsteroidal Glucagon: made by alpha cells, raises

blood sugar Insulin: made by beta cells, lowers blood

sugar

Pancreas: Endocrine Functions

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Location of Major Endrocrine OrgansLocation of Major Endrocrine Organs

Slide 9.14Figure 9.3

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Roles of Insulin and Glucagon in Regulating Blood Glucose

Figure 13.9

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Location of Major Endrocrine OrgansLocation of Major Endrocrine Organs

Slide 9.14Figure 9.3

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Adrenal cortex Secretion: mediated through

hypothalamus-pituitary secretions Hormones: steroidal

Glucocorticoids: cortisol – blood glucose regulation

Mineralocorticoids: aldosterone – sodium/fluid/urine

Adrenal Glands: Cortex

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Secretion of Cortisol

Figure 13.10

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Cushings Disease

Oversecretion of Cortisol

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Adrenal medulla: neuroendocrine organ

Secretion: sympathetic nervous system Hormones: nonsteroidal

Epinephrine and Norepinephrine: enhance function of sympathetic nervous system (Fight or flight)

Adrenal Glands: Medulla

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Roles of the Hypothalamus and Adrenal Roles of the Hypothalamus and Adrenal Glands in the Stress ResponseGlands in the Stress Response

Slide 9.31

Figure 9.12

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Secretion: controlled through hypothalamus-pituitary secretions

Steroidal hormones: Thyroxine (T4) and Triiodothyronine

(T3): both regulate production of ATP from glucose, affects metabolic rate

Calcitonin: lowers blood calcium levels

Thyroid Gland

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Grave’s Disease – overactive thyroid

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Secretion: response to lowered blood calcium levels

Hormone: Parathyroid hormone (PTH), nonsteroidal

Removes calcium and phosphate from bone

Increases absorption of calcium by the digestive tract

Increases renal retention of calcium and excretion of phosphate

Parathyroid Glands

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Location of Major Endrocrine OrgansLocation of Major Endrocrine Organs

Slide 9.14Figure 9.3

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Hormone: testosterone (steroidal) Functions:

Regulates development and normal functioning of sperm, male reproductive organs, male sex drive

Development of male secondary sex characteristics

Testes

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Hormones (steroidal) and functions: Estrogen: initiates development of secondary sex characteristics, regulates menstrual cycle

Progesterone: regulates menstrual cycle

Ovaries

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Ovarian Cycle

Figure 16.6