Hole’s HumanAnatomy and Physiology

Tenth Edition

Chapter 13

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Endocrine System

Chapter 13Endocrine System

• __________ glands are ductless• __________ glands have ducts

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Endocrine Glands

Endocrine glands• release hormones• ______________ through blood to targets

Paracrine secretions• act locally• ____________________

Autocrine secretions• affect only the __________

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Comparison of Nervous System and Endocrine System

• Neurons release neurotransmitters into a synapse, affecting postsynaptic cells• Glands release _______________ bloodstream • Only target of ________________

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Chemistry of Hormones

Steroid Hormones• derived from ___________• sex hormones• adrenal cortex hormones

Nonsteroid Hormones• amines• ________• peptides• _____________• most hormones

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Structural Formulas of Hormones

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Types of Hormones

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Actions of Steroid Hormones

• hormone crosses membranes

• hormone combines with receptor in nucleus

• ________________ activated

• mRNA enters cytoplasm to direct synthesis of protein

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Actions of Nonsteroid Hormones

• _____________________

• hormone binds to receptor on cell membrane

• ATP converted to cAMP

• cAMP promotes a series of reactions leading to cellular changes

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Prostaglandins

• paracrine substances• ___________• __________________• regulate cellular responses to hormones • can activate or inhibit adenylate cyclase• wide variety of functions

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Control of Hormonal Secretions

• primarily controlled by negative feedback mechanism

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Negative Feedback

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Major Endocrine Glands

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Pituitary Gland

Two distinct portions• ________________ (adenohypophysis)• __________________ (neurohypophysis)

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Pituitary Gland Control

• Hypothalamic releasing hormones stimulate cells of anterior pituitary to release hormones• Nerve impulses from hypothalamus stimulate nerve endings in the posterior pituitary gland to release hormones

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Hypothalamic Hormones

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Anterior Pituitary Hormones

Growth Hormone (GH)• stimulates increase in size and rate of body cells• enhances movement of amino acids through membranes• promotes growth of long bones• ______________________________• secretion stimulated by growth hormone-releasing hormone

Prolactin (PRL)• sustains milk production after birth• __________________________• secretion inhibited by prolactin release-inhibiting hormone

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Anterior Pituitary Hormones

__________________________________• controls secretions of hormones from the thyroid gland• controlled by thyrotropin-releasing hormone

Adrenocorticotropic Hormone• controls secretions of some hormones of adrenal cortex• _______________________-releasing hormone

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Anterior Pituitary Hormones

Follicle-Stimulating Hormone (FSH)• stimulates development of egg-containing follicles in ovaries• stimulates follicular cells to secrete estrogen• ______________________________• controlled by gonadotropin-releasing hormone

_____________________• promotes secretions of sex hormones• ________________________• promotes growth of long bones• _____________________________________

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Posterior Pituitary Hormones

Antidiuretic Hormone (ADH)• _________________________________• in high concentration, raises blood pressure• controlled by hypothalamus in response to changes in blood water concentration and blood volume

Oxytocin (OT)• stimulates uterine contractions• ___________________________________• controlled by hypothalamus in response to stretch in uterine and vaginal walls and stimulation of breasts

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Thyroid Gland

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Thyroid Gland Hormones

Thyroxine (T4) and Triiodothyronine (T3)• ________________________________ carbohydrates• increases rate of protein synthesis• accelerates growth• stimulates activity in the nervous system• __________________

Calcitonin• __________________ and phosphate ion concentrations by inhibiting release of calcium and phosphate from bones• increases rate at which calcium and phosphate are deposited in bones 13-22

Thyroid Gland Disorders

Cretinism• ______________ in infants• leads to small stature and mental retardation

General Hyperthyroidism• high metabolic rate• ___________• weight loss• protruding eyes

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Thyroid Gland Disorders

Myxedema• ________________• low metabolic rate• sluggishness

Simple Goiter• deficiency of iodine• leads to deficiency of thyroid hormones• gland enlarges

Grave’s disease• overstimulation of gland by antibodies• hyperthyroidism

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Parathyroid Glands

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Parathyroid Hormone

• PTH• increases blood calcium levels• decreases blood phosphate levels• _________________________________• ____________________• stimulates kidneys to retain calcium and excrete phosphate• promotes calcium absorption into intestine

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Parathyroid Glands

Mechanism by which PTH promotes calcium absorption in the intestine

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Parathyroid Gland Disorders

Hyperparathyroidism• caused by tumor• ________• __________________• altered mental functions• bone weakening

Hypoparathyroidism• caused by injury or removal of gland• muscle cramps• seizures• _______________levels

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Adrenal Glands

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Adrenal Medulla Hormones

______________________________• release controlled by sympathetic nervous system• increases heart rate and blood pressure• dilates respiratory airways• promotes breakdown of glycogen• activates reticular formation• __________________

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Adrenal Cortex Hormones

Aldosterone• _________________________ and pressure by promoting conservation of sodium ions and water

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Adrenal Cortex HormonesCortisol

• _____________________________• increases fatty acid release• stimulates glucose synthesis from noncarbohydrates• controlled by _______________ and ACTH from anterior pituitary

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Adrenal Cortex Hormones

Adrenal androgens• supplement sex hormones from the gonads• __________________________

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Pancreas

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Pancreatic Hormones

Glucagon• secreted by alpha cells of pancreatic islets• _________________________________________• stimulates liver to convert noncarbohydrates into glucose• stimulates break down of fats• controlled by blood glucose concentrations

Somatostatin• secreted by delta cells of pancreatic islets• ___________________

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Pancreatic Hormones

Insulin• secreted by beta cells of pancreatic islets• promotes formation of glycogen from glucose• inhibits conversion of noncarbohydrates into glucose• enhances movement of glucose into adipose and muscle cells• decreases blood glucose concentrations• _______________________________• _____________________________• ____________________________________

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Insulin and Glucagon

Insulin and glucagon function together to stabilize blood glucose concentrations

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Other Endocrine Glands

Pineal Gland• secretes ___________• _______________________• may control onset of puberty• helps regulate female reproductive cycle

Thymus Gland• secretes thymosins• ________________________________________

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Other Endocrine Glands

Reproductive Glands• _______ secrete estrogen and progesterone• ______________________• placenta secretes estrogen, progesterone, and gonadotropins

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Stress

Types of Stress• ___________• ________________

Responses to Stress• hypothalamus triggers sympathetic impulses to various organs• epinephrine is released• cortisol is released to promote longer-term responses

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Responses to Stress

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Life-Span Changes

• endocrine glands shrink• ___ levels even out, muscular strength decreases• ADH levels increase due to slow break down• calcitonin levels decrease• _____ increases, osteoporosis risk increases• insulin resistance may develop• changes in melatonin secretion affect the body clock• thymosin production declines increasing risk of infections

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Clinical Application

Growth Hormone Ups and Downs

• __________ - hypersecretion of GH in children • Acromegaly – hypersecretion of GH in adults• ___________ – hyposecretion of GH in children

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