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The Endocrine System
Ch. 13 Endocrine Functions: Hormones
 Hormones
 Come from endocrine glands
 Circulate in the bloodstream
 Act on specific cells in the body
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Endocrine Functions: Hormones
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Figure 13.1
Steroid Hormone Action on a Target Cell
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Figure 13.2
Nonsteroid Hormone Action on a Target Cell
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Figure 13.3
Role of Negative Feedback Loops
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Figure 13.4
Hypothalamus and the Anterior Pituitary
Gland
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Figure 13.7
Hypothalamus and the Posterior Pituitary
Gland
 Posterior pituitary
 Connection to hypothalamus
 Hormones made in hypothalamus, stored in
posterior pituitary
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Hypothalamus and the Posterior Pituitary
Gland
 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
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Hypothalamus and the Anterior Pituitary
Gland
 Anterior pituitary
 Connection to hypothalamus
 Releasing and inhibiting hormones from
hypothalamus travel to pituitary through
pituitary portal system
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Hypothalamus and the Anterior Pituitary
Gland
 Anterior pituitary hormones: nonsteroidal
 ACTH
 Stimulates adrenal cortex
 TSH
 Acts on thyroid gland
 FSH, LH, prolactin
 Related to control of reproductive
cycles and lactation
 Growth hormone
 Has widespread effects on body
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Hormones of the Pituitary Gland
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Table 13.1
Pituitary Disorders
 Diabetes insipidus
 Hyposecretion of ADH, inability to conserve water
appropriately
 Gigantism
 Hypersecretion of growth hormone in childhood
 Acromegaly
 Excessive growth hormone over long period in adults
 Pituitary dwarfism
 Hyposecretion of growth hormone
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Roles of Insulin and Glucagon in Regulating
Blood Glucose
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Figure 13.10
Pancreas: Endocrine Functions
 Islets of Langerhans hormones:
nonsteroidal
 Glucagon
 Made by alpha cells, raises blood sugar
 Insulin
 Made by beta cells, lowers blood sugar
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Adrenal Glands: Cortex
 Adrenal cortex
 Secretion
 Mediated through hypothalamus-pituitary
secretions
 Hormones: steroidal
 Glucocorticoids
 Cortisol
 Mineralocorticoids
 Aldosterone
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Adrenal Glands: Medulla
 Adrenal medulla
 Neuroendocrine organ
 Secretion
 Sympathetic nervous system
 Hormones: nonsteroidal
 Epinephrine and norepinephrine
 Enhance function of sympathetic
nervous system (fight-or-flight
response)
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Adrenal Glands: Medulla
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Figure 13.11
Thyroid Gland
 Secretion: mediated through
hypothalamus–pituitary secretions
 Steroidal hormones
 Thyroxine (T4) and Triiodothyronine (T3)
 Both regulate production of ATP from
glucose, affect metabolic rate
 Calcitonin
 Lowers blood calcium levels
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Negative Feedback Control of Thyroxine
Secretion
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Figure 13.13
Homeostatic Regulation of Blood Calcium
Concentration
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Figure 13.15a
Homeostatic Regulation of Blood Calcium
Concentration (cont.)
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Figure 13.15b
Other Hormone Sources
 Digestive system
 Gastrin
 Secretin
 Cholecystokinin
 Kidney
 Erythropoietin
 Renin
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Disorders of the Endocrine System
 Diabetes mellitus
 Type 1
 5–10% of all cases
 Inadequate insulin
 Type 2
 90–95% of all cases
 Insulin resistance
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Disorders of the Endocrine System
 Thyroid
 Hypothyroidism
 Children: cretinism
 Adults: myxedema
 Hyperthyroidism
 Graves’ disease
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Disorders of the Endocrine System
 Adrenal glands
 Addison’s disease
 Failure of adrenal cortex
 Cortisol deficiency
 Cushing’s syndrome
 Excessive cortisol
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