Unit 9: The Endocrine System Amy J. Hilbelink, Ph.D.

Endocrine System Objectives  Anatomy; exocrine vs. endocrine  Steroid and non-steroid hormone action  How negative and positive feedback regulate secretions  Mechanism of action  Principle Function of glands  Conditions and treatments

Endocrine System defined This system encompasses the production and secretion of hormones from the glands. The Greek word “orme” means “to excite”. Hormones activate specific target cells, causing a response. Endocrinology – the study of….

Anatomy Exocrine glands  These are not part of the Endocrine system  Exocrine secrete products into ducts that empty onto surface  Example: sweat and salivary glands Endocrine glands  Ductless  Secrete hormones into cellular spaces, then into blood  Hormones in blood find a specific receptor (target organ cell)  Example, thyroid gland

Anatomy Hormones = The main regulators of metabolism, growth and development, reproduction and other important body functions. Endocrine glands, hormones and their functions – Table 11-1 in text.

How Hormones work… Non-Steroid vs. Steroid

Hormones - examples Steroid  Sex Hormones Androgens Testosterone Estrogen Prolactin Non-Steroid Calcitonin TSH

Anatomy

Negative Feedback Reverse deviations from normal i.e. an in blood glucose triggers secretion of insulin. Insulin promotes glucose uptake by cells. Blood glucose level is restored to its lower, normal level; decreased

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Basic Anatomy - brain

Functions of Pituitary gland  Located in the brain  The master gland of the endocrine system  Anterior and posterior portions  Table 11-1 lists target tissues of both anterior and posterior

Functions of Hypothalamus  Located in the brain  Links nervous system to endocrine system  Water balance, metabolism of fat and carbs, body temp., appetite and emotions.  Responsible for release of ADH and oxytocin from the pituitary gland.

Anterior gland Posterior gland ADH Oxytocin FSH LH Prolactin TSH

Mechanism of Action

Conditions of pituitary and hypothalamus gland Hyperfunction results in  Giantism and acromegaly Hypofunction of pituitary results in dwarfism.

Treatments of pituitary and hypothalamus Removal of tumor Growth hormone therapy Diabetic treatments due to lack of anti- diuretic hormone (ADH) secretion

Functions of Pineal gland  Located in the brain.  Production and secretion of melatonin  Targets hypothalamus Regulates the sleep-wake cycle Large in children, smaller in adults Affected by light Melatonin effects linked to beginning of puberty and menstrual cycle

Functions of Thyroid gland  Located at the base of the neck.  Production and secretion of T4, T3 and calcitonin  Trigger rate of metabolism of proteins, fats and sugars.  Important in growth and homeostasis of body  Calcitonin important for regulation of calcium, which is important for muscle contractions, nerve impulses and blood clotting.

Functions of Parathyroid gland  Located behind thyroid gland  Made up of two sets of secreting glands  Regulate calcium levels in blood via release of PTH.  Capable of drawing calcium from bone to increase overall concentrations in blood.

Conditions of parathyroid glands Hyperparathyroidism (excess of parathyroid hormones)  Increase of calcium into blood, away from bone, causing bone weakening  Paget’s disease; softening of bone, and osteoporosis  Kidney stones, muscle weakness, heart conduction changes Hypoparathyroidism (low secretion of parathyroid hormones)  Decrease of calcium leading to muscle spasm, irregular heart contractions, and alteration of normal nerve conduction.

Thyroid Diseases Hypothyroidism Fatigue Frequent, heavy menstrual periods Forgetfulness Weight gain Dry, coarse skin and hair Hoarse voice Intolerance to cold Hyperthyroidism Irritability/nervousness Muscle weakness/tremors Infrequent, scant menstrual periods Weight loss Sleep disturbances Enlarged thyroid gland Vision problems or eye irritation Heat sensitivity Source: Cleveland Clinic:

Functions of Adrenal gland  Located atop kidneys  Made of two separate glands  Secrete steroids and catecholamines  Adrenal Medulla – center Secrete catecholamine, norepinephrine, and epinephrine i.e. fight or flight.  Adrenal Cortex – outer portion Secrete glucocorticoids, mineralcorticoids and the sex hormones (androgens and estrogens).

Conditions of adrenal glands Hypersecretion  Cushing’s syndrome ( oversecretion of glucocorticoids) Obesity, flushing of face, hypertension, thick, scaling skin.  Overproduction usually caused by tumor  Or caused by overmedication with steroids Hyposecretion  Caused by autoimmune disease, infections or tumors of gland.  Addison’s disease; total necrosis of adrenal gland Fatigue, weight loss, nausea, syncope (fainting)

Cushing Syndrome: Before and After Treatment Results from hypersecretion of glucocorticoid hormone by a tumor of the middle zone of the adrenal cortex.

Functions of Pancreas  The largest organ of endocrine system  Maintains energy homeostasis throughout the body.  Secretes glucagon in response to low blood sugar.  Triggers release of glucagon from liver when energy is low.  When blood glucose is high, triggers release of insulin which causes glucose uptake by liver, muscle and fat.

Conditions of pancreas glands Diabetes mellitus Caused by inability of pancreas to secrete insulin or a resistance to insulin, affecting glucose levels. Can lead to renal disease, blindness, gangrene – leading to amputation.  Insulin-dependent diabetes mellitis (IDDM) Usually early onset  Non-insulin-dependent diabetes mellitus (NIDDM) * more common Usually adult onset

Treatments - pancreas IDDM =insulin-dependent diabetes mellitus  usually in young  Natural insulin  Synthesized human insulin  Typical insulins prescribed NIDDM non-insulin dependent diabetes mellitus  usually adult onset  Change of lifestyle  Insulin in more severe cases BLOOD GLUCOSE METER

Functions of Ovaries and Testes  Two ovaries produce and secrete eggs.  Ovaries secrete estrogen and progesterone Secondary sex characteristics  Two testes produce and secrete sperm  FSH released as puberty begins  Testosterone – change in voice, and muscle development. Secondary sex characteristics

Conditions of testes  Testosterone deficiency  Delayed onset of puberty  Certain types of Anemia Treated with testosterone

Conditions of ovaries Estrogen deficiency Decreased ovarian functioning Post-menopausal osteoporosis  Treat with estrogens Amenorrhea Dysmenorrhea Endometriosis  Treat with progesterone

Possible endocrine treatments Surgery Reduce Ca intake HRT Medication Growth hormone replacement Radiation Insulin Diet Male hormones Female hormones

Reflexology, just for fun…