Term | Definition |
Endocrine system | Ductless glands; secrete hormones directly into the bloodstream (to relay messages) |
Endocrine system | Responds slowly |
Endocrine system | Exerts long-lasting effects |
Endocrine system | Adapts slowly to continual stimulation |
Exocrine glands | Have ducts that carry secretions to the body's surface |
Steroid hormone | Pass easily through a cell's membrane; once inside the cell, they bind to receptors in the nucleus |
Nonsteroid hormone | Can't penetrate the cell wall; they bind to receptors on the cell surface |
Second messenger | A cascade of processes that influences a cell's response to a hormone |
Pituitary gland | Influences more body processes than any other endocrine gland |
Anterior pituitary | Larger than the posterior and consists of glandular tissue |
Anterior pituitary | It synthesizes and secretes a number of hormones under the direction of the hypothalamus |
Anterior pituitary | Hormones synthesized in the hypothalamus stimulate the anterior pituitary to secrete its hormones or to supress secretion of its hormones |
Anterior pituitary | Hormones of the anterior pituitary stimulate other endocrine cells to release their hormones. |
Thyroid-stimulating hormone (TSH) | or thyrotropin |
Thyroid-stimulating hormone (TSH) | Stimulates the thyroid gland to secrete thyroid hormone |
Prolactin | Stimulates milk production in the mammary glands in females |
Andrenocorticotropic hormone (ACTH) | Stimulates the adrenal cortex to secrete corticosteroids |
Follicle-stimulating hormone (FSH) | Stimulates the production of eggs in the ovaries of females |
Luteinzing hormone (LH) | Stimulates ovulation in females |
Growth hormone (GH) | or somatotropin |
Growth hormone (GH) | Acts on the entire body to promote protein synthesis, lipid and carbohydrate metabolism, and bone and skeletal muscle growth |
Posterior pituitary | Instead of synthesizing hormones, it stores the hormones antidiuretic hormone (ADH) and oxytocin which are synthesized by hypothalamus |
Oxytocin | Stimulates contractions of the uterus during childbirth and triggers the release of milk from the breasts during lactation |
ADH | or vasopressin |
ADH | acts on the kidneys to reduce urine volume and prevent dehydration |
Negative feedback | Pituitary stimulates gland to release hormone
Hormone is fed back to pituitary, which halts release of tropic hormone |
Negative feedback | mechanism where one endocrine gland stimulates another endocrine gland to secrete a hormone, which in turn, causes the first endocrine gland to stop production of its hormone. |
Pineal gland | Produces melatonin, a hormone that rises at night (when sunlight is absent) and falls during the day. May also regulate the timing of puberty. |
Thymus | The only glad that is a member of the endocrine system and the immune system |
Thyroid | Exposure to cold stimulates release of this hormone. It increases the body's metabolic rate, which in turn increases heat production. |
T3 (Triiodothyronine)
T4 (Thyroxine)
Calcitonin | Thyroid hormones secreted by thyroid gland: |
Thyroid follicle | Cells lining the sacs secrete the two main thyroid hormones Triiodothyronine and thyroxine |
Parafollicular cells | Secrete calcitonin in response increasing blood calcium triggersthe deposition of calcium in bone and thus, promotes bone formation |
Bones
Kidneys
Intestines | Parathyroid hormone exerts influence on: |
Bone | Inhibits new bone formation and stimulates the breakdown of old bone |
Kidneys | Reabsorb calcium; activate vitamin D |
Intestines | Vitamin D is important for intestinal absorption of calcium |
Parathyroid glands | Lie on the posterior surface of the thyroid |
Parathyroid glands | Secrete parathyroid hormone (PTH) in response to low blood levels of calcium |
Tetany from hypocalcemia | typically occurs following the accidental removal of the parathyroid glands during thyroid surgery. |
Zona fasciculata | Secretes glucocorticoids; most active during stress. |
Mineralocorticoids
Glucocorticoids
Sex steroids | Classes of adrenal cortex hormones |
Mineralocorticoids | Aldosterone |
Mineralocortcoids | Acts on kidneys to promote Na+ retention and K+ excretion; also causes water retention |
Glucocorticoids | Cortisol |
Glucocorticoids | Aid in the repair of damaged tissue
Have an anti-inflammatory effect
Aid in maintaining normal blood pressure
Suppress the immune system if secreted over a long term |
Pancreas | Sits just behind the stomach |
Pancreas | Contains both endocrine and exocrine tissue; majority acts as an exocrine gland |
Pancreas | Secretes digestive enzymes into the small inestine |
Pancreas | Islets contain several different types of cells...main ones are alpha, beta, and delta |
Alpha Cells | Secrete the hormone glucagon between meals, when blood glucose levels decline |
Beta Cells | Secrete the hormone insulin; stimulates cells to take up more glucose |
Glucagon
Catecholamines
Glucocorticoids | Hormones that boost blood glucose levels |
Glucagon | When blood sugar falls, it stimulates lever cells to convert glycogen into glucose |
Catecholamines | Boost glucose levels by breaking down glycogen |
Glucocorticoids | Convert fat and protein to glucose |
Insulin | It triggers the cells to take up more glucose |
Insulin | It causes the lever to take up glucose and store it as glycogen |
Type 2 Diabetes | A loss of insulin receptors on target cells leading to insulin resistance |
Type 1 Diabetes | Deficiency of insulin resulting from the destruction of beta cells of the pancreatic islets |