Endocrine System - Hormones

" Secrete products into Ducks ??!? "

Exocrine - Secrete products into ducts. Sweat glands, salivary glands.

Endocrine - Ductless glands, secrete hormones into circulatory system.

Hormone - Chemicals that are produced and secreted by endocrine glands that travel through the circulatory system and act only on a specific target cell.

          Target cell - Cells with a receptor for a specific hormone.

          Steroid hormones - Are lipid (fat) soluble. They can diffuse through the plasma membrane (made of lipids), and act inside the cell to make new enzymes or proteins.

          Protein hormones - Are not lipid soluble and cannot diffuse into the cell. They interact with the cell by attaching to a receptor on the cell surface.

Hypothalamus - Links the nervous and endocrine systems.

Pituitary gland - The master gland of the body (pea sized). Makes and stores hormones.

          *Oxytocin - It targets the breast and uterus of mammals. It stimulates milk release into the ducts and stimulates uterine contraction during birth.

          *Antidiuretic Hormone (ADH) - Its target is the kidney. The function is to regulate water balance in the kidney. It actively causes us to retain water.

          *Thyroid Stimulating Hormone (TSH) - Its target gland is the thyroid. It causes the thyroid to release thyroxine (a hormone).

                    *Thyroxine - Stimulate your metabolic rate, growth and development. Need iodine to make throxine.

                              Goiter - Iodine is needed to synthesize thyroxine so a lack of iodine in the diet causes an enlargement of thyroid gland (too little thyroxine - too much TSH).

          *Growth hormone (GH) - It target is muscle and bone. If there is not enough present in children it causes dwarfism. If there is too much present it causes gigantism in children.

                    Acromegaly - Over secretion of GH in adults - they can't get taller but do get larger hands, feet, and face.

          *Follicle Stimulating Hormone (FSH) - in females the target is the ovary and it causes egg development, in men target is the testis and causes sperm development

          *Luteinizing Hormone (LH) - in women (ovary) causes ovulation, in men (testis) causes production and release of testosterone.

Pineal gland - A gland in the brain that releases melatonin.

          *Melatonin - Controls your biological clock (sleep and eating patterns and body temperature). Released at night.

                    Seasonal Affective Disorder (SAD) - Depression during the winter when there is shorter day length you release more melatonin.

Pancreas - Regulates blood sugar levels.

          islets of Langerhans - Islands of cells that release glucagon and insulin.

                    *Glucagon - Increases blood sugar by targeting the liver cells to release glucose.

                    *Insulin - decreases blood sugar levels by targeting the liver, also fat and muscle to take up glucose from the blood.

          Diabetes mellitus - High blood sugar .

                    Type 1 - (childhood onset) The body can not produce insulin - correct with insulin injections to lower blood sugar.

                    Type 2 - (adult onset - usually overweight and over 30) The body can not respond to insulin (correct with diet and exercise).

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Last updated on 2 January 2018