The Endocrine System Controls many body functions exerts control by releasing hormones into the bloodstream that are then delivered to cells Hormones aid in cell communication and helps regulate cell function Hormones affect other endocrine glands or body systems Works with the nervous system Hormones can promote or inhibit nerve impulses Derives its name from the fact that various glands release hormones directly into the blood, which in turn transports the hormones to target tissues via ducts Hormones are special chemical substances that are released in one part of the body and affect the activities of cell in another part of the body. They assist in cell to cell communication and help to coordinate the functions of cells Response to an endocrine signal occurs within minutes to hours The nervous system can stimulate or inhibit hormone release

Hormones Circulating hormones pass from the cells that make them into interstitial fluid Circulating hormones only affect the target cells They bind to particular receptors that are only found on the specific target cells

Local Hormones act on neighboring cells or the same cell that made it Local hormones do not enter the bloodstream

Hormones Lipid soluble hormones Water soluble hormones Steroid hormones Sex hormones Prostaglandins Estrogen & Testosterone Regulate salt Regulate blood pressure Hormones come in two molecular structures Who remembers what they are? – lipid soluble and the proteins fall into the water soluble category Lipid soluble include steroids, your thyroid hormones, and a specialized class of hormones called prostiglandins. Steroid hormones are made from cholesterol and include the sex hormones and hormones produced by the adrenal cortex like mineralocorticoids that are important in regulating the salt content of the blood. Prostaglandins are produced by virtually all cell membranes and act locally. They can for instance increase blood pressure by acting a vasoconstrictors The water soluble hormones include the amine, the peptide, and the protein hormones. The amine hormones are those derived from the amino acid tyrosine and they include your Thyroid hormones which are the body’s major metabolic hormones. Peptide hormones include those that regulate digestion and prorein hormones include insulin which regulated blood sugar levels. Water soluble hormones Amine hormones Peptide hormones Protein hormones Regulate digestion Metabolism Regulate blood sugar

The Endocrine System Two types of glands Reproduction Exocrine glands – secrete their hormones to target tissues via ducts. Endocrine glands - secrete their hormones into interstitial fluid Reproduction Growth & development Consists of several glands located in various parts of the body. There are two types of glands in this system Exocrine glands include sweat, digestive, mucous, and oil glands Endocrine glands include pituitary, thyroid, parathyroid, adrenal, and pineal glands Hormones regulate body functions like metabolism, energy balance, immune system, digestion. Hormones control growth and development and govern the operation of reproductive systems. Why do we sweat – we wouldn’t sweat without the help of the glands in the endocrine system. Hormones are essential in maintaining homeostasis. Metabolism Energy balance Immune system Digestion

The Endocrine System Thymus gland The main glands or organs associated with the endocrine system are the hypothalamus, pituitary, thyroid, thymus, adrenal glands, pancreas testes, and ovaries

Hypothalmus The hypothalamus is the “master” of the pituitary gland The hypothalamus sends signals to the pituitary telling it to secretes hormones directly into the bloodstream these hormones go to other organs (glands) directing them The hypothalamus is the “master” of the pituitary gland

Pituitary The Pituitary Gland is divided into two areas structurally and functionally different each area has separate types of hormone production. The pituitary gland hangs from a stalk coming off the hypothalamus. The pituitary gland is the one that send the signals to the other organs in the endocrine system to stimulate them to increase or decrease production. The gland is composed of two lobes the anterior and the posterior. Where is the anterior lobe located? – the front So the posterior is … in the back The hypothalmus and pituitary glands are the major link between the nervous and the endocrine system. Secretes hormones that directly regulate many body functions and controls functions of other glands Major connection between endocrine & nervous system

Pituitary ~ TSH TSH is produced by the anterior pituitary stimulates the thyroid to produce and secrete it’s hormones. The thyroxine regulates metabolic rate. What is the metabolic rate? The rate at which glucose is burned for energy Why might it be important that the rate be regulated? There are time when more energy is required by the cells. The Thyroid Stimulating Hormone stimulates the thyroid gland to release its hormones

Pituitary ~ Growth Hormone Growth Hormone is produced by the anterior pituitary. Growth hormone is a general metabolic hormone with its major effects on directing the growth of skeletal muscles and long bones of the body. It plays and important role in determining final body size. It also causes fats to be broken down for energy rather than glucose, this helps to maintain blood sugar homeostasis. Growth hormone (hGH) Growth of skeletal muscles and long bones of body, builds protein, stimulates cells to grow and divide, breaks down fats

Folicle stimulating hormone & Luteinizing hormone Pituitary ~ FSH & LH Both FSH and LH are produced by the anterior pituitary. FSH signals the ovaries to ripen an egg and LH signals the ovaries to release the ripened egg aa well as stimulates sperm production in the testes. Folicle stimulating hormone & Luteinizing hormone stimulate maturation & release of eggs from ovary, Stimulates sperm production

Pituitary ~ OT & PRL Oxytocin (OT) (the natural form of pitocin) Prolactin is produced by the anterior pituitary and signals the mamary glands and oxytocin is produced by the posterior pituitary and signals the uterus Oxytocin (OT) (the natural form of pitocin) stimulates uterine contractions during labor, causes “let down” of milk from the breast. Prolactin (PRL) Initiates milk production from mammary glands

Pituitary ~ ACTH & ADH Adrenocorticotropic Hormone (ACTH) Stimulates the adrenal cortex to release its hormones that increases blood sugar Antidiuretic Hormone (ADH) Causes the kidneys to reabsorb water from the forming urine and adding it back to the blood ACTH is produced by the anterior pituitary and ADH is produced by the posterior pituitary ACTH stimulates the adrenal glands and ADH works on the kidneys When might it be important to increase blood sugar? – if it has dropped below normal range, if there is demand for an increase in energy When might it be important to put water back into the blood stream? In higher doses ADH constricts the small arteries which raises the blood pressure. For this reason it is some times referred to as vasopressin Drinking Alcoholic beverages inhibits ADH secretion and results in the output of large amounts of urine. The dry mouth and intense thirst experienced “the morning after” is a result.

Thyroid Lies in the anterior neck just below the larynx Calcitonin Decreases blood calcium levels by causing calcium to be deposited in the bones Show me where your thyroid gland is. When you go to the Dr and he or she palpates your neck right there, it is your thyroid gland that is being examined. Two lobes, located on either side of the trachea, connected by a narrow band of tissue called the isthmus. Three important hormones are produced by the thyroid – calcitonin which regulates calcium levels in the blood, and thyroxine and triiodothyronine . Thyroxine (T4) & Triiodothyronine (T3) When stimulated (by TSH or by cold), these are released  the metabolic rate, important for normal tissue growth and development esp reproductive and nervous systems

Parathyroid Small, pea-shaped glands, located in the neck near the thyroid Usually 4 - number can vary Produce parathyroid hormone -  level of calcium in blood Where the thyroid’s production of calcitonin decreases the levels of calcium in the blood the parathyroid hormone increases calcium levels by removing calcium from the bones

Islets of Langerhans - include 3 cell types: Pancreas Located in the folds of the duodenum Both endocrine and exocrine functions Secretes several key digestive enzymes Duodenum Islets of Langerhans - include 3 cell types: alpha ( ) release glucagon, essential for controlling blood glucose levels. beta () release insulin (antagonistic to glucagon). delta () produce somatostatin, which inhibits both glucagon and insulin The Islets of Langerhans deals with the endocrine functions of the pancreas. There are three cell types involved each produces a different hormone all dealing with glucose levels in the blood When blood glucose levels fall, Alpha  cells increase the amount of glucagon in the blood The surge of glucagon stimulates the liver to release glucose stores (from glycogen and additional storage sites). Also, glucagon stimulates the liver to manufacture glucose Insulin  the rate at which various body cells take up glucose. Thus, insulin lowers the blood glucose level

Adrenal glands Adrenal Medulla secretes epinephrine and norepinephrine Adrenal Cortex secretes 3 classes of steroidal hormones – gluticocorticoids, mineralocorticoids and Androgens 2 small glands that sit atop both kidneys. Each has 2 divisions, each with different functions. The adrenal medulla secretes epinephrine aka adrenalin and norepinephrine or noradrenaline. These hormone do all kinds of things to assist the nervous which help you cope with stressful situations system like the fight or flight response Gluticocorticoids,  the level of glucose in the blood released in response to stress, injury, or serious infection - like the hormones from the adrenal medulla Mineralocorticoids: work to regulate the concentration of potassium and sodium in the body. Androgens are the sex hormones estrogen, progesterone and testosterone and they help regulate reproduction

Gonads & Ovaries The Ovaries are located in the abdominal cavity adjacent to the uterus. Under the control of LH and FSH from the anterior pituitary they manufacture estrogen protesterone The Testes are located in the scrotum Under the control of LH and FSH from the anterior pituitary they manufacture sperm testosterone The endocrine glands associated with the reproductive systems of males and females – the gonads produce sperm and the ovaries produce eggs. Estrogen and Progesterone have several functions, including sexual development and preparation of the uterus for implantation of the egg. Testosterone promotes male growth and masculinization

Homeostatic Imbalance Growth hormone imbalance Thyroxin imbalance If the pituitary gland is not functioning properly, homeostasis can not be maintained which causes a whole host of problems Producing too much or too little growth hormone is a disorder of the pituitary gland. Too much is gigantism and too little can result in Pituitary dwarfism. This is Robert Wadlow he was 8 foot 10 inches and still growing when he died at the age of 22. If the thyroid id over stimulated and produces too much thyroxine Graves disease may develop – some symptoms may include enlarged thyroid gland, bulging eyes, rapid heart rate, and intolerance of heat

Neural and Hormonal Controls Pituitary is signaled Hypothalmus Pituitary releases ADH When your blood pressure and blood osmolarity (a fancy way of saying the salt content in your blood) increases beyond the normal range, your hypothalmus senses it and signals the pituitary, the pituitary releases antidiuretic hormone which signals the kidneys to hold on to water. This cause you to decrease your urine output, your urine becomes more concentrated and you become thirsty. Your kidneys put the extra water into your bloodstream which does what to the salt concentration? And causes your blood pressure to come down. When your blood pressure get to the set point the hypothalmus will receive the signal, contact the pituitary, the pituitary will shut off the ADH, the kidneys will release the water, your urine output will increase and your blood pressure will remain normal Increased blood pressure Blood pressure decreases Kidneys hold on to water

Effector  Response OR act as a Stimulus  Receptor Receptor  Effector Effector  Response OR act as a Stimulus  Receptor Adrenal gland Kidney When blood osmolarity and blood pressure are low JuxtaGlomerular Apparatus which is part of the kidney releases renin which activates angiotensinogen. Angiotensinogen is an inactive protein but in this process is activated, becoming angiotensin (zymogen). The angiotensin constricts blood vessels and triggers the aldosterone which increases the absorption of salt and water in the kidneys. As the salt and water is taken out of the blood the blood pressure increases. Take a look at this and I need a volunteer to come up and match one of these parts of the feedback cycle [STIMULUS; RECEPTOR; EFFECTOR; RESPONSE] with the correct action JuxtaGlomerular Apparatus