The Endocrine System PDF

Endocrine System Unit 8  Introduction The endocrine system is a network of glands that secrete hormones, which travel in the bloodstream and affect the functioning target cells. Hormones - the body’s chemical messengers that travel in the bloo...

Endocrine System Unit 8  Introduction The endocrine system is a network of glands that secrete hormones, which travel in the bloodstream and affect the functioning target cells. Hormones - the body’s chemical messengers that travel in the bloodstream to tissues and organs Glands - an organ that makes and secretes one or more substances, such as hormones, digestive juices, sweat, tears, saliva, or milk General Characteristics of the Endocrine System The Endocrine System works to control body functions and regulate metabolic processes It is composed of a variety of endocrine glands, which are different from exocrine glands ○ Endocrine glands secrete their products (hormones) into body fluids (the internal environment) ○ Exocrine glands secrete their products into ducts that lead outside of the body (ie. sweat, tears, saliva, milk)  What are hormones? Hormones are chemical messengers that coordinate different functions in your body ○ They tell your body what to do and when to do it Several glands, organs, and tissues make and release hormones, many of which make up your endocrine system Hormones work to control things such as… ○ Metabolism ○ Homeostasis (ie. blood sugar regulation) ○ Growth and development ○ Reproduction ○ Sleep-wake cycle ○ Mood  What do hormones do? Hormones are chemical messengers that affect and manage hundreds of bodily processes These often involve a chain of several different hormones A hormone will only act on a part of your body if it “fits” Think of a hormone as a key and the cells of its target tissue as specifically shaped locks ○ If the hormone fits the lock (receptor) on the cell wall, then it’ll work - the hormone will deliver a message that causes the target site to take a specific action  Hormone Communication Hormones are used for two types of communication Type 1: Between two endocrine glands ○ One gland releases a hormone, which stimulates another gland to change the levels of hormones that its releasing ○ Ex: Communication between the pituitary gland and thyroid; pituitary gland releases thyroid-stimulating hormone (TSH), which triggers the thyroid gland to release its hormones Type 2: Between an endocrine gland and a target organ ○ Ex: When the pancreas releases insulin, which then acts on your muscles and liver to help process glucose  Glands of The Endocrine System 1. Hypothalamus 2. Pituitary Gland 3. Thyroid Gland 4. Parathyroid Glands 5. Adrenal Glands 6. Pancreas 7. Other Endocrine Glands a. Pineal Gland b. Thymus c. Reproductive Organs d. Digestive Glands e. Other hormone producing organs  Hypothalamus A small region of your brain that connects to your pituitary gland through the pituitary stalk It releases several hormones that control your pituitary gland  Hypothalamus Hormones Dopamine Affects emotions, behavior, and movement Known as the “feel-good” hormone, which means it helps give a sense of pleasure and gives your the motivation to do something Oxytocin The hypothalamus makes oxytocin, but the pituitary gland stores and releases it Somatostatin Works to inhibit the release of other hormones Regulates the activity of your GI tracts and prevents the rapid reproduction of cells Corticotropin-releasing hormone Gonadotropin-releasing hormone Growth hormone-releasing hormone Thyrotropin-releasing hormone  Pituitary Gland A pea-sized gland at the base of your brain, behind the bridge of your nose and directly below your hypothalamus It has two lobes - the posterior lobe and the anterior lobe Releases several hormones, many of which control the functions of other endocrine glands  Anterior Pituitary Hormones Growth hormone (GH) In children and adolescents, it stimulates the growth of bone and cartilage Helps maintain tissues and organs throughout life Prolactin Stimulates and sustains milk production Thyroid-stimulating hormone (TSH) Controls secretion of hormones from the thyroid gland Adrenocorticotropic hormone (ACTH) Controls secretion of hormones from the adrenal cortex, particularly cortisol, which regulates things such blood pressure and stress response Follicle-stimulating hormone (FSH) & Luteinizing hormone (LH) Act on the gonads (testes and ovaries)  Posterior Pituitary Hormones Antidiuretic hormone (ADH) Reduces the volume of water the kidneys excrete The hypothalamus regulates ADH secretions Oxytocin Contracts smooth muscle in the uterine wall Contracts myoepithelial cells that secrete and eject milk Helps to foster a bond between mom and baby Bodies also produce oxytocin when falling in love, which is why it is known as the “love hormone”  Thyroid Gland A small, butterfly-shaped gland located at the front of your neck under your skin Main job is to control the speed of metabolism (metabolic rate), which is the process of how your body transforms the food you eat into energy  Thyroid Hormones Thyroxine Controls how much energy your body uses (the metabolic rate) Involved in digestion, how your heart and muscles work, brain development, and bone health Triiodothyronine The active form of thyroxine Works together with thyroxine Calcitonin Helps regulate calcium levels in the blood  Parathyroid Glands Structure of The Glands On the posterior surface of thyroid gland Consists of secretory cells that are well supplied with capillaries Parathyroid Hormone Regulates blood calcium levels, as well as phosphorus and vitamin D levels  Adrenal Glands Structure of The Glands Located atop the kidneys Each gland consists of an adrenal medulla and an adrenal cortex These parts are functionally distinct and secrete different hormones  Hormones of The Adrenal Medulla Secretes epinephrine and norepinephrine, which have similar effects These play an important role in the fight or flight response ○ Physiological changes such as increased heart rate and blood pressure  Hormones of The Adrenal Cortex Aldosterone ○ Helps regulate blood pressure and balance the levels of sodium and potassium in the body Cortisol ○ Primary stress hormone ○ Helps the body respond to stress  Pancreas Structure of The Gland An organ in the back of your abdomen Part of your digestive system and endocrine system Attached to the small intestine Secretes glucagon and insulin  Hormones of The Pancreatic Islets Glucagon is released to stop blood sugar levels from dropping too low (hypoglycemia) Insulin is released to stop blood sugar levels from rising too high (hyperglycemia)  Other Endocrine Glands Pineal Gland Thymus Attached to the thalamus (part of the Lies behind the sternum and between brain) the lungs Secretes melatonin to help control Secretes thymosins, which affect the the sleep-wake cycle development of the immune system  Other Endocrine Glands Reproductive Organs Digestive Glands The testes secrete testosterone The ovaries secrete estrogens and Certain digestive glands of the progesterone stomach and small intestines secrete hormones Other Hormone Producing Organs Other organs, such as the heart and kidneys, also produce hormones