Endocrine System Created By: Lauren Covey, Sophia Yang, Delaney Sullivan, Lena Tahir, Michael Chen

General Characteristics The main functioning unit of the endocrine system is the hormone. – Travels through interstitial fluid and blood to reach target cells. – Secreted by endocrine glands. Ex: Pituitary, Thyroid, etc.

Characteristics of Hormones Steroid hormones – Formed from cholesterol – Lipids – Doesn’t use second messengers to transmit signal to cell nucleus – Examples: Sex hormones, such as testosterone

Hormones (cont.) Nonsteroid hormones – Amines Derived from the amino acid thyrosine Ex: Epinephrine, Norepinephrine – Protein Long chains of amino acids Ex: PTH – Peptide Short chains of amino acids Ex: ADH – Glycoproteins Proteins and carbohydrates Ex: FSH

Hormone Action Steroid – Nonpolar, so are able to pass through cellular and nuclear membranes – Binds with receptors in the nucleus to activate the hormone-receptor complex, that activates certain sequences of DNA.

Hormone Action (cont.) Nonsteroid hormones – Polar substances – Make use of second messengers to relay message Most common is cAMP. Hormone → G-protein → Adenylate cyclase → cAMP cAMP activates protein kinases within the cytoplasm

Control Sources General method used is negative feedback – Although, oxytocin uses positive feedback Three methods of signaling hormone release: 1.Tropic Hormones from the pituitary and hypothalamus 2.Direct stimulation of the gland by the nervous system 3.Direct response to the surrounding conditions

Pituitary Gland Attached to the base of the hypothalamus Anterior: – Stimulated by tropic hormones from the hypothalamus – Hormones released include: GH, TSH, ACTH, FSH, prolactin, LH Posterior: – Stimulated by direct nervous pathways from the hypothalamus – Hormones released include: ADH and oxytocin

Thyroid Gland Located at the base of the throat Stimulated by both TSH (T3 and T4) and the surrounding environment (calcitonin). Regulates metabolism Hormones secreted: T3, T4, calcitonin

Parathyroid Gland Located within the thyroid in patches Stimulates osteoclasts Hormones secreted: PTH PTH is released with low blood calcium levels – Releases calcium from bones into the blood stream – Antagonist to calcitonin

Adrenal Glands Located on top of the kidneys Cortex – Outer layer of Adrenal glands – Stimulated by ACTH – Reacts to long-term stress – Releases glucose into the blood stream over time – Hormones released: aldosterone, cortisol Aldosterone acts in the renin-angiotensin system Medulla – Inner section of adrenal glands – Stimulated by direct nervous connection to the brain – Responds to short term stress – Hormones released: epinephrine and norepinephrine

Pancreas Controls the glucose levels within the bloodstream Has small groups within called the Islets of Langerhans – Contain two types of secreting cells: Alpha – releases glucagon Beta – releases insulin

Pineal Gland Located in the third ventricle of the brain Stimulated by the interpretation of light levels outside the body Regulates the sleep/wake cycle of the body Hormones released: Melatonin

Thymus Posterior to the sternum and above the heart Largest in infants Regulates the development of white blood cells, and facilitates the growth of T-cells. Release hormones called thymosins.

Gonads Ovaries – Stimulated by LH and FSH – Produces estrogen, progesterone Testes – Produces testosterone

It sucks to get old Hormone levels decrease with age – GH production decreases dramatically Menopause is caused by lack of efficiency of the ovaries Blood glucose regulation becomes very inefficient.

Disorders of the Thyroid Gland Hyperthyroid – Graves Disease: Low TSH level and high Thyroxin level, autoimmune, Symptoms: irritation, bulging eyes (exophthalmia), feel warm Hypothyroid – Cretinism: developmental problems in infants, mental retardation – Goiters: lack of iodine in food supply, huge thyroid gland

Disorders of the Adrenal Cortex Cushing Syndrome: too much ACTH – Gain weight, moon face, thinning of hair, weakness of limbs Addison’s Disease: not enough ACTH, weakness, fatigue, anorexia, elevated red blood cell count,

Diseases of Pancreas Islets Diabetes I: inability to produce insulin, autoimmune disorder in which immune system attacks pancreatic beta cells Diabetes II: Excessive weight gain, cells lose the ability to respond to insulin because receptors are blocked