The Endocrine System

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Endocrine Functions ƒ Maintains homeostasis by producing and releasing chemicals called hormones ƒ Controls long-term processes examples: ƒ Growth & development ƒ Reproduction ƒ Metabolism

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Types of Glands ƒ Exocrine Glands ƒ Formed from epithelial tissue. ƒ Release their products at the body’s surface or into body cavities through ducts.

ƒ Endocrine Glands ƒ Formed from epithelial tissue. ƒ Release their products - hormones -into the blood or lymph - ductless glands

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What are Hormones? ƒ Chemical messengers secreted by endocrine glands. ƒ Responsible for specific regulatory effects on certain parts or organs.

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Mechanisms of Hormone Action 1 ƒ Hormones affect only certain target tissue cells or organs (specificity) ƒ Note: blood-borne hormones circulate to all body organs

ƒ Hormones interact with specific receptors in specific target cells

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Mechanisms of Hormone Action 2 ƒ Receptor Responses: ƒ Stimulate synthesis of proteins or certain regulatory molecules in cell ƒ Activate or inactivate enzymes ƒ Stimulate mitosis

ƒ Increase or decrease the rate of normal cell function ƒ NOT new function

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Control of Hormone Release ƒ Negative feedback mechanism 1. Hormone secretion triggered by some stimulus. 2. Rising hormone levels inhibit further hormone release. 3.Hormones vary only within a very narrow range.

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Endocrine Gland Stimuli 1. Hormonal stimulus ƒ

Endocrine gland prodded into action by other hormones

2. Humoral stimulus ƒ

Changing blood levels of certain ions and nutrients may stimulate hormone release

3. Neural stimulus ƒ

Nerve fibers stimulate hormone release

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Major Endocrine Organs ƒ Hypothalamus

ƒ Pancreatic islets

ƒ Pituitary Gland

ƒ Pineal Gland

ƒ Thyroid Gland

ƒ Thymus

ƒ Parathyroid Glands

ƒ Ovaries

ƒ Adrenal Glands

ƒ Testes

Anterior & Posterior Pituitary Gland

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Hypothalamus hormones stimulates Anterior pituitary stimulates Thyroid Adrenal cortex Gonads

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Posterior Pituitary Hormones ƒ Oxytocin ƒ Acts on ƒ mammary glands ƒ uterus

ƒ ADH - antidiuretic hormone ƒ Acts on kidney tubules

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Anterior Pituitary Hormones ƒ TSH - thyroid stimulating hormone ƒ FSH & LH - follicle stimulating hormone & luteinizing hormone ƒ ACTH - adrenocorticotropic hormone ƒ MSH - melanocyte stimulating hormone ƒ PRL - prolactin stimulating hormone ƒ GH - growth hormone

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FSH and LH ƒ Females ƒ FSH – stimulates follicle development ƒ LH – triggers ovulation of egg

ƒ Males ƒ FSH – stimulates sperm development ƒ LH – stimulates testosterone production

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Male Gonads ƒ Testes ƒ Suspended in scrotal sac ƒ Produces: ƒ Sperm ƒ Androgens ƒ testosterone

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Female Gonads ƒ Ovaries ƒ Produces: ƒ Eggs ƒ Steroid hormones ƒ estrogens ƒ progesterone

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Adrenal Medulla ƒ Stimulated by Sympathetic NS ƒ “fight or flight”

ƒ Secretes two (2) hormones (catecholamines) ƒ Epinephrine ƒ Norepinephine

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Adrenal Cortex ƒ

Secretes 3 different corticosteroids 1. Mineralocorticoids ƒ

Increases salt & water levels in blood ƒ

aldosterone

2. Glucocorticoids ƒ

Increases blood glucose levels ƒ

cortisol

3. Androgens ƒ

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males & females

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Aging Baby Boomers turn to hormone Some doctors concerned about growing 'off-label' use of drug Sabin Russell, Chronicle Staff Writer Monday, November 17, 2003 ©2003 San Francisco Chronicle

Aging Baby Boomers turn to hormone / Some doctors concerned about growing 'off-label' use of drug Runner and equestrian Hanneke Hops mounts her horse, C.C., near her Hayward home. Hops says her daily injections of HGH give her energy and a sense of well being.

Injecting HGH keeps Hanneke Hops, 56, feeling young. Hops holds a syringe she uses to take the drug.

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Growth Hormone ƒ Youth - promotes bone and muscle growth ƒ final body size

ƒ Adulthood – promotes repair ƒ Hypersecretion ƒ youth - gigantism ƒ adult - acromegaly

ƒ Hyposecretion

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Pancreas ƒ location ƒ mixed gland ƒ endocrine ƒ insulin & glucagon

ƒ exocrine ƒ digestive enzymes

ƒ pancreatic islets ƒ beta cells ƒ alpha cells

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Thyroid Gland ƒ Location ƒ Most cells of body have receptors for thyroid H ƒ Produces: ƒ thyroid hormone ƒ increases rate of O2 use ƒ Basal metabolic rate (BMR)

ƒ increases use of glucose ƒ for ATP production

ƒ Calcitonin ƒ calcium homeostasis ƒ increases osteoblast activity

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Hyperthyroidism

NORMAL

GOITER • Graves’ Disease • Low iodine intake

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Parathyroid Gland ƒ Location & Number ƒ Produces parathyroid hormone ƒ calcium homeostasis ƒ increases blood calcium levels ƒ increases osteoclast activity

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Pineal Body ƒ Location: in epithalamus of diencephalon ƒ Functions: (some uncertainty) ƒ biological clock ƒ inhibits sexual maturation in childhood ƒ inhibits secretion of FSH & LH

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Thymus Gland ƒ Location: posterior to sternum ƒ Size relative to age ƒ Functions: ƒ promotes immune system development and function ƒ T-lymphocytes maturation

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Potential Negative Side Effects of Anabolic Steroids

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Kelli White

Slide 46 1987

Barry Bonds 1987-2000 2000 210lbs 49HR

1999 1998 206lbs

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210lbs

Barry Bonds 2001-03 2001 73HR 228lbs

2002 228lbs

2003 228lbs

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Body Growth The following hormones stimulate body growth and development of nervous tissue: ƒ Growth hormone ƒ Insulin ƒ Thyroid hormones

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Aging and Endocrine Function Pituitary gland ƒ decrease GHÆmuscle atrophy

Thyroid gland ƒ decrease thyroxinÆdecrease metabolism Æ increase fat deposition

Pancreas ƒ decrease insulinÆpoorer control of glucose levels

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