CCMA training notes: Endocrine System

Endocrine system: produces hormones that work together to maintain homeostasis in the body. Homeostasis refers to maintaining a constant internal environment.  

Anatomy 

Hypothalamus: Is closely associated with the pituitary gland in the forebrain. It is a region of the brain more than a specific structure or gland; however, its function is in controlling the actions of the pititary, so it is a significant part of endocrine system  

Pituitary Gland: Is located near the hypothalamus, it is pea-sized and divided into two lobes: the anterior lobe and posterior lobe. The lobes hang from a stalk under the hypothalamus  

Pineal Gland: Is found in the central portion of the brain and is shaped like a pinecone.  

Thyroid glands: Is butterfly-shaped and links on either side of the larynx below the thyroid cartilage  

Parathyroid glands: Are located on the back or posterior side of the thyroid gland. There are four of them each about the size of a grain of rice.  

Thymus: Is found near the midline in the anterior portion of the thoracic cavity behind the sternum and superior to the heart  

Pancreas: Is an organ located posterior to the stomach. Note that it functions both in the digestive system and the endocrine system. Includes: pancreatic islets, which are small masses within the pancreas body and perform the endocrine system functions.  

Adrenal Glands: Also called suprarenal because of their location superior to the kidneys are attached to the top of each kidney. Each is formed so that there is an adrenal cortex surrounded by a capsule. Within the cortex is the adrenal medulla. The adrenal cortex and the adrenal medulla severe very different and separate functions.  

Ovary (in female):  

Gonads: are gamete-producing glands 

The gonads in the female are the ovaries 

They are found attached to the Fallopian tubes which are extensions of the uterus in the female body 

Placenta (during pregnancy)  

An organ that develops in the uterus during pregnancy.  

It is structured so that it can provide oxygen and nutrients to the growing baby and remove waste products from the baby’s blood. 

The placenta attaches to the baby via the umbilical cord  

Testicle (in male)  

Gonads: are gamete-producing glands that are two egg shaped testicles that sit beneath the penis 

The scrotum is a sac of skin that hangs outside of the body under the penis, surrounds, and protects the testicles. 

Associated with them are the following structures:  

Seminiferous tubules  

Rete testis  

Efferent ducts  

Tunica vasculosa, albuginea, and vaginalis  

Physiology 

Hypothalamus: Is part of the nervous system that produces hormones that control many of the body’s functions.  

Pituitary gland: Hangs just below the hypothalamus and works together to secrete many hormones from the pituitary. These hormones control the activity of other endocrine glands throughout the body to respond to nervous stimuli from the neurohormones secreted by the hypothalamus. Together, they work to perform checks and balances functions for the body with the goal of maintaining homeostasis, or a balanced internal body environment.  

Anterior Lobe:  

Adrenotropic hormone (ACTH): This stimulates growth and secreations of the adrenal cortex.  

Focile-stimulinghoromone (FSH): Stimulates the secretion of estrogen and the growth of ova in the ovaries of the female. It stimulates the production of sperm in the testicles of males.  

Growth hormone (GH): Stimulates the growth of bone, muscle, and other body tissues.  

Lactogenic hormone (LTH): Also called prolactin, stimulates and maintains the secretion of breast milk in the mother after childbirth.  

Luthazing hormone (LH): Stimulates ovulation in the female. Stimulates the secretion of testosterone in males.  

Melanocyte-stimulating hormone (MSH): Increases the production of melanocytes leading to the darkening of the skin pigmentation.  

Thyroid-stimulating hormone (TSH): Stimulates the secretion of hormones by the thyroid gland  

Posterior lobe:  

Antidiuretic hormone (ADH): Is secreted by the hypothalamus and stored in the pituitary gland. It helps control blood pressure by reducing the amount of water excreted through the kidneys.  

Oxytocin (OXT): Stimulates uterine contractions during childbirth.  

Pineal gland: Secretes the hormone melatonin that influences the sleep-wakefulness porition of the circadian cycle.  

Thyroid gland: Regulates the body’s metabolism through the secretion of thyroxine and triiodothyronine. Secretion of these two horomones from the thyroid is regulated by the thyroid-stimulating hormone from the anterior lobe of the pituitary gland. The thyroid also secretes calcitonin to help in decreasing calcium levels in the blood and calcium into storage in bones and teeth.  

Parathyroid gland: Secrete parathyroid hormone or PTH which works with calcitonin to regulate calcium levels in the blood required for the smooth functioning of the muscular and nervous systems.  

Thymus Gland: Secretes a hormone that functions as a part of the immune system to help the body's immune response before birth and into childhood. After puberty, it slowly turns into fatty tissue. It secretes the hormone thymosin.  

Pancreas: Functions both in the endocrine system and the digestive system. As an endocrine function, the pancreas works to control blood glucose levels and glucose metabolism.  

Glucagon: The pancreas secretes this hormone that responds to low levels og glucose in the blood. It increases the glucose level by stimulating the liver to convert glycogen or stored glucose into glucose or blood sugar.  

Insulin: The pancreas also secretes the hormone insulin. When energy is needed, insulin allows glucose to enter the cells of the body so that it can be used as a fuel source for energy. If the enegy is not needed by the body, insulin stimulates the liver to convert glucose into glycogen or stored blood sugar so that it can be used later when the energy is needed.  

Adrenal glands: Main function is to control the electrolyte levels in the body. Electrolytes are minerals such as calcium, chloride, magnesium, phosphorous, sodium, and potassium. They also help regulate metabolism and the body’s responses to stress.  

Adrenal cortex: Secretes androgens, which are sex hormones. It also secretes corticosteroids which are steriod hormones. Aldosterone regulates sodium and water levels in the body. Cortisol performs anti-inflammatory functions and helps to regulate the metabolism of carbohydrates, fats, and proteins.  

Adrenal medulla: Secretes epinephrine and norepinephrine. Epinephrine or adrenaline stimulates the sympathetic nervous system in response to physical injury or stress. Norepinephrine plays an important role in the fight or flight response.  

Ovary (in female): They shelter and protect the eggs that the female is born with until they are ready for use. Under normal conditions it is thought females are born with their lifetime supply of eggs. They also produce female reproductive hormones: estrogen and progesterone as well as relaxin and inhibin. These develop adult female characteristics and help in function of the menstrual cycle. Relaxin and inhibin function during pregnancy, labor, and delivery.  

Placenta: To provide oxygen and nutrients from the mother’s blood to the growing baby and to remove the waste products from the baby’s blood.  

Testicle (in male): Important for production and storage of the sperm until they are mature enough for ejaculation. They also produce the endocrine hormone testosterone, which is responsible for the male sex drive, fertility, for puberty, and for the development of muscle and bone mass.    

Common Diseases and Disorders 

Pituitary Gland Conditions:  

Hyperpituitarism: the over secretion of pituitary hormones 

Acromegaly: a very rare, chronic disease where there is an abnormal enlargement of the hands and feet caused by too much secretion of growth hormone after puberty  

Gigantism: An abnormal growth of the entire body that is caused by a secretion of growth hormones prior to puberty  

Galactorrhea: This condition is caused by an excess of prolactin causing the breasts to produce/milk spontaneously without childbirth  

Short stature: Formerly called “dwafism” and refers to a deficient secretion of growth hormone  

Prolactinoma: a benign tumor in the pituitary gland causing it to produce too much prolactin and can cause infertility in females with v but erectile dysfunction in males with t  

Pituitary adenoma: this is a tumor in the pituitary gland  

Diabetes insipidus: Results from an insufficient production of the antidiuretic hormone ADH or by the inability of the kidneys to respond to ADH resulting in too much fluid excreted by the kidneys  

Pineal Gland Condition(s):  

Pinealoma: a tumor of the pineal gland that can disrupt the production of melatonin causing insomnia and disruption of the circadian rhythms.  

Thyroid Gland Conditions:  

Hyperthyroidism: Is caused by an overproduction of thyroid hormones leading to increased metabolic rate, sweating, nervousness, and weight loss.  

Grave’s disease: Caused when the immune system attacks the thyroid gland causing it to make excessive thyroid hormone. It often results in a goiter, exophthalmos, or both.  

Hashimoto's disease: Is an autoimmune disease where the body’s own antibodies attack and destroy the cells of the thyroid gland leading to hypothyroidism. It is called chronic lymphocytic thyroiditis.  

Hypothyroidism: A deficiency of thyroid secretion causing fatigue, depression, sensitivty to cold, and low metabolic rate.  

Cretinism: a congenital form of hypothyroidism resulting in arrested physical and mental development  

Myxedema: also called adult hypothyroidism and results from an extreme deficiency of thyroid hormone secretion  

Parathyroid Glands Conditions:  

Hyperparathyroidism: An overproduction of the parathyroid hormone causing hypercalcemia  

Hypoparathyroidism: A condition caused by insufficient or even absent secretion of the parathyroid hormone causing hypocalcemia  

Thymus Gland Conditions:  

Thymitis: an inflammation of the thymus gland  

Pancreas Conditions:  

Insulinoma: a benign tumor causes hypoglycemia by secreting excess insulin  

Pancreatitis: An inflammation of the pancreas often caused by long-term alcoholism  

Hyperglycemia: A high concentration of glucose in the blood  

Hypoglycemia: An abnormally low concentration of glucose in the blood  

Polydipsia: Refers to excessive thirst  

Polyphagia: Refers to excessive hunger  

Polyuria: Refers to urination  

Hyperinsulinism: Refers ro excessive secretion of insulin into the bloodstream  

Diabetes – there are four types of diabetes mellitus: 

Adrenal Gland Conditions:  

Addison’s disease: Occurs when the adrenal glands do not produce enough of the hormone cortisol and aldosterone. Patients show severe fatigue and muscle weakness, appetite loss, low blood pressure, and weight loss.  

Adrenalitis: Is an inflammation of the adrenal glands  

Aldosteronism: Is an abnormal imbalance of electrolytes caused by excessive secretion of aldosterone.  

Conn’s syndrome (KON): This disorder of the adrenal glands is caused by excessive production of aldosterone causing weakness, cramps, and convulsions  

Cushing’s syndrome: this is hypercortisolism by pro-longed exposure to high levels of cortisol from overpopulation of cortisol or prolonged use of corticosteroids.  

Gonad Conditions:  

Hypergonadism: Is caused by excessive secretion of hormones by the sex glands 

Hypogonadism: Is caused by a deficient secretion of hormones by the sex glands