Chapter 10 Endocrine System • Endocrine glands are ductless • releases hormones • hormones released to target organs • Exocrine glands have ducts 10-1
Dec 31, 2015
Chapter 10Endocrine System
• Endocrine glands are ductless• releases hormones• hormones released to target organs
• Exocrine glands have ducts
10-1
Chemistry of Hormones
Steroid Hormones• derived from cholesterol• sex hormones• adrenal cortex hormones
Nonsteroid Hormones• amines• proteins• peptides• glycoproteins• most hormones
10-2
Actions of Steroid Hormones
• hormone crosses membranes
• hormone combines with receptor in nucleus
• synthesis of mRNA activated
• mRNA enters cytoplasm to direct synthesis of protein
10-3
Actions of Nonsteroid Hormones
• adenylate cyclase activated
• hormone binds to receptor on cell membrane
• ATP converted to cAMP
• cAMP promotes a series of reactions leading to cellular changes• second messenger
10-4
Control of Hormonal Secretions• primarily controlled by negative feedback mechanism
10-5
Negative Feedback
10-6
Major Endocrine Glands
10-7
Pituitary Gland
Two distinct portions• anterior pituitary (adenohypophysis)• posterior pituitary (neurohypophysis)
10-8
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
10-9
Hypothalamic Hormones
10-10
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• slows carbohydrate catabolism; increases blood glucose levels
Prolactin (PRL)• sustains milk production after birth• secretion inhibited by prolactin release-inhibiting hormone 10-11
Anterior Pituitary Hormones
Thyroid Stimulating Hormone (TSH)• controls secretions of hormones from the thyroid gland• controlled by thyrotropin-releasing hormone
Adrenocorticotropic Hormone• controls secretions of some hormones of adrenal cortex• controlled by corticotropin-releasing hormone
10-12
Anterior Pituitary Hormones
Follicle-Stimulating Hormone (FSH)• stimulates development of egg-containing follicles in ovaries• stimulates follicular cells to secrete estrogen• stimulates production of sperm cells• controlled by gonadotropin-releasing hormone
Luteinizing Hormone (LH)• promotes secretions of sex hormones• stimulates release of egg from ovary (ovulation)• stimulates corpus luteum to produce progesterone• controlled by gonadotropin-releasing hormone
10-13
Posterior Pituitary Hormones
Antidiuretic Hormone (ADH)• causes kidneys to reduce water excretion• 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• stimulates mammary glands to release milk• controlled by hypothalamus in response to stretch in uterine and vaginal walls and stimulation of breasts
10-14
Thyroid Gland
10-15
Thyroid Gland Hormones
Thyroxine (T4) and Triiodothyronine (T3)• increases rate of energy release from carbohydrates• accelerates growth• stimulates activity in the nervous system• controlled by TSH
Calcitonin• lowers blood calcium concentrations by inhibiting release of calcium from bones• increases rate at which calcium isdeposited in bones
10-16
Thyroid Gland Disorders
General Hyperthyroidism• high metabolic rate• hyperactivity• weight loss• protruding eyes
10-17
Simple Goiter• deficiency of iodine• leads to deficiency of thyroid hormones• gland enlarges
Parathyroid Glands
10-18
Parathyroid Hormone
• PTH• increases blood calcium levels• stimulates bone resorption by osteoclasts• inhibits osteoblasts• stimulates kidneys to retain calcium • promotes calcium absorption into intestine
10-19
Adrenal Glands
10-20
Adrenal Cortex Hormones
Aldosterone• increases blood volume and pressure by promoting conservation of sodium ions and water
10-21
Adrenal Cortex Hormones
Cortisol• decreases protein synthesis• increases fatty acid release• stimulates glucose synthesis from noncarbohydrates• controlled by CRH from hypothalamus and ACTH from anterior pituitary• maintain normal blood pressure• anti-inflammatory effect• released during long term stress
10-22
Adrenal Medulla Hormones
Epinephrine and Norepinephrine• release controlled by sympathetic nervous system• increases heart rate and blood pressure• dilates respiratory airways• promotes breakdown of glycogen• increases metabolic rates
10-23
Adrenal Cortex Hormones
Adrenal androgens• supplement sex hormones from the gonads• may be converted to estrogen• female sexual drive
10-24
Pancreas
10-25
Pancreatic HormonesGlucagon• secreted by alpha cells of pancreatic islets• stimulates liver to break down glycogen• stimulates liver to convert noncarbohydrates into glucose• controlled by blood glucose concentrations
10-26
Insulin• secreted by beta cells of pancreatic islets• promotes formation of glycogen from glucose• enhances movement of glucose into adipose and muscle cells• decreases blood glucose concentrations• controlled by blood glucose concentrations
Other Endocrine Glands
Reproductive Glands• ovaries secrete estrogen and progesterone• testes secrete testosterone• placenta secretes estrogen, progesterone, and gonadotropins
10-28
Other Endocrine Glands
Pineal Gland• secretes melatonin• regulates sleep/wake cycles• may control onset of puberty• helps regulate female reproductive cycle
Thymus Gland• secretes thymosins• promotes development of certain lymphocytes
10-28
Clinical Application
Growth Hormone Ups and Downs
• Gigantism - hypersecretion of GH in children • Acromegaly – hypersecretion of GH in adults• Dwarfism – hyposecretion of GH in children
10-29
Clinical Application
Diabetes Mellitus
10-30
3 Cardinal signs• polyuria• polyphagia• polydipsia