Endocrine System Mostly comprised of glands Secretes hormones that move through the bloodstream to target cells Results in a slow but a prolonged response Chapter 15 Endocrine System From source gland to target organ gland or tissue Pituitary gland muster gland Decides actions of other glands throughout the body What is a target cell Receptors are like lock and key specific geometrical configuration Receptors are made of proteins Nontargeted cells do not have specific shapes for hormones 5 minutes in recorder Exocrine vs endocrine glands Exocrine glands secrete their products enzymes into ducts that carry these products to other organs or outside the body Their action is local where it s secreted where it acts Not carried through bloodstream Endocrine glands secrete their products hormones directly into the bloodstream Hormones Chemical signals that promote communication between cells body parts and even individuals Two major types of hormones Peptide hormones bind to a receptor in the plasma membrane causing the formation of cAMP which activates a cascade of enzymes cAMP activates or deactivates for the downstream protein These need to be binded to receptors because they are proteins Steroid hormones are lipids that enter a cell and affect gene activity and thus protein synthesis Diffuse y its own through plasma membrane because it is a lipid itself and the plasma membrane is made of a lipid bilayer Peptide hormones Steroid hormones Peptide Binding of receptor to hormone first messenger activates another enzymes which catalyzes production of ATP which creates cAMP second messenger activates a cascade of enzymes which break down other molecules Proteins are activated not produced Steroid activates or deactivates protein synthesis depending on the need of cell or body Protein result is produced or not produced The hypothalamus and pituitary Glands affected by the pituitary hormones Pituitary hormones Portal transportation of proteins ADH and Oxytocin are stored in the posterior pituitary it doesn t secrete them Hypothalamus Regulates internal environment through the autonomic nervous system HOMEOSTASIS o Helps control heartbeat o Helps control body temperature o Helps control water balance o Controls glandular secretions Posterior Pituitary Gland Stores antidiuretic hormone ADH and oxytocin that are produced by neuroendocrine cells in hypothalamus ONLY STORED produced by hypothalamus o ADH regulates water balance by reabsorbing water into the bloodstream o Oxytocin causes uterine contractions during childbirth and allows milk to be released during nursing Anterior Pituitary Gland face Thyroid Gland Controlled by hypothalamic releasing and hypothalamic inhibiting hormones Hormones produced by the anterior pituitary Thyroid stimulating hormone TSH stimulates the thyroid to produce thyroid hormones Adrenocorticotropic hormone ACTH stimulates the adrenal cortex to produce cortisol Gonadotropic hormones stimulate gonads to produce sex cells and hormones Prolactin PRL stimulates mammary glands to develop and produce milk only after childbirth Melanocyte stimulating hormone MSH causes skin color changes in many fishes amphibians and reptiles having melanophores special skin cells that produce color variations Growth hormone GH promotes skeletal and muscular growth What happens when the body produces too much or too little GH Pituitary dwarfism too little GH is produced during childhood results in small stature Gigantism too much GH is produced during childhood results in poor health not enough sources to keep the big body healthy Acromegaly overproduction of GH as an adult results in larger than normal feet hands and It is a large gland located below the larynx Vocal chords Close to trachea Iodine is needed in the diet to allow the thyroid gland to produce its hormones It produces o Thyroid hormones T3 T4 which regulate metabolism o Calcitonin which helps lower blood Ca2 levels by stimulating the deposition of calcium in the bones Thyroid abnormalities o Simple goiter thyroid enlarges due to lack of iodine in the diet doesn t produce hormones o Hypothyroidism low blood levels of thyroid hormones Metabolism disorders Congenital hypothyroidism thyroid does not develop properly and is characterized in a short stocky person who may have mental retardation Myxedema hypothyroidism in adults characterized by lethargy weight gain loss of hair cold intolerance and thick puffy skin o Hyperthyroidism excess thyroid hormones in the blood eyes hyperactivity and insomnia Thyroid tumor can also cause hyperthyroidism Exophthalmic goiter characterized by enlargement of the thyroid gland protrusion of the Parathyroid glands Small glands embedded on the surface of the thyroid gland Produces parathyroid hormone PTH Balance between calcitonin and parathyroid hormone o Causes blood Ca2 level to increase by promoting osteoclast activity o Promotes reabsorption of Ca2 by the kidneys Adrenal glands supadrenal glands superior to kidneys Glands that sit on top of the kidneys 2 parts of each gland Adrenal medulla controlled by the nervous system o Inner portion of the adrenal glands o Hypothalamus initiates stimulation of hormone secretion in the adrenal medulla o Produces hormones that allow a short term response to stress fight or flight response like Epinephrine adrenaline and Norepinephrine Adrenal cortex portions are controlled by ACTH from the anterior pituitary o Outer portion of the adrenal glands o When activated by ACTH from Anterior pituitary gland produces hormones that provide a long term response to stress o 2 major types of hormones Glucocorticoids Fights stress regulate carbohydrate protein and fat metabolism suppress the body s inflammatory response e g cortisol and cortisone Mineralocorticoids regulate salt and water balance minerals e g aldosterone increases Sodium reabsorption by kidney Malfunctions Addison disease hyposecretion of glucocorticoids by the adrenal cortex characterized by bronzing of the skin less Cushing syndrome hypersecretion of glucocorticoids by the adrenal cortex characterized by weight gain in the trunk of the body but not the arms and legs more Pancreas Fish shaped organ behind the stomach between the kidneys Composed of 2 tissues Exocrine produces and secretes digestive juices enzymes Endocrine islets of Langerhans produces and secretes hormones o Insulin secreted when blood glucose is high stimulates the uptake of glucose by cells o Glucagon secreted when blood glucose
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