The Endocrine System

Transcription

1 The Endocrine System The nervous system allows the body to respond to various stimuli in a quick manner and this allows for homeostasis. The endocrine system, using hormones also allows the body to respond to various stimuli. The endocrine systemʼs response however, is typically slower than the nervous systemʼs but, is still required by the body to maintain homeostasis. The best way to study the endocrine system is to study it in the following way: Identify the gland / tissue that is producing the hormone Identify the hormone produced Identify the target for that hormone--whereʼs the hormone going in the body Identify the function of that hormone--what is that hormone going to cause the body to do Keep these concerns in mind as you study the following tables.

2 The Pituitary Gland The pituitary gland is considered the master gland because it releases hormones that control the action of other glands of the body. The following tables indicate hormones released by the pituitary, their target and function.

3 Hormone Target Antidiuretic Hormone (ADH) Kidney Tubules ( nephrons ) Oxytocin (OT) Uterus and mammary tissue Growth Hormone (GH) somatotropin General body cells Prolactin (PRL) Mammary tissue Thyroid Stimulating Hormone (TSH) Thyroid gland Adrenocorticotropic Hormone (ACTH) Cortex of the adrenal gland Follicle Stimulating Hormone (FSH) Targets the seminiferous tubules in male testes Targets the ovaries in females Luteinizing Hormone (LH) Targets special cells in male testes Targets follicles inside female ovaries

4 Hormone Function Antidiuretic Hormone (ADH) Prevents the kidney nephrons from losing water, so prevents dehydration Oxytocin (OT) Causes the uterus to contract during labor and the mammary tissue to release milk during nursing Growth Hormone (GH) somatotropin Causes protein synthesis needed for growth Prolactin (PRL) Causes the mammary tissue to produce milk

5 Hormone Thyroid Stimulating Hormone (TSH) Function Causes the thyroid gland to release hormones like calcitonin, thyroxine and triiodothyronine Adrenocorticotropic Hormone " " " " (ACTH) Causes the adrenal cortex to release a group of hormones called glucocorticoids Follicle Stimulating Hormone (FSH) Causes the seminiferous tubules in males to produce sperm Causes the maturation of the egg in females Luteinizing Hormone (LH) Causes the release of testosterone in males important in secondary sex characteristics Causes the follicles to release (ovulate) the egg in females

6 Other Endocrine Glands There are other glands in the body that release certain hormones which have profound effects on the body. The following tables list some of these as well as their targets and function. Gland Hormone Released Thyroid Parathyroid Calcitonin, thyroxine (T4) & triiodothyronine (T3) Parathormone or parathyroid (PTH) Thymus Thymosin Pancreas Insulin & glucagon Adrenal medulla Adrenal cortex Epinephrine (adrenalin) & norepinephrine (noradrenalin) Glucocorticoids & aldosterone Kidney Erythropoietin (EPO)

7 Target for Select Hormones Hormone Hormone Target Calcitonin Thyroxine and triiodothyronine Parathormone (PTH) Bone cells (osteoblasts) General body cells Bone cells (osteoblasts) c osteoclast Thymosin Lymphocytes (a specific white blood cell)

8 Target for Select Hormones Hormone Hormone Target Insulin Cell membrane protein channels Glucagon Liver cells Adrenalin and noradrenalin (Epinephrine and norepinephrine) Glucocorticoids Aldosterone Erythopoietin General body cells General body cells Nephrons of the kidneys Bone marrow (specifically the erythroblasts within the bone marrow)

9 Calcitonin Thyroxine and triiodothyronine Parathormone (PTH) Thymosin Insulin Functions for Select Hormones Hormone Hormone Function Causes the osteoblasts to remove calcium ions from the bloodstream for the purpose of making bone material. (inhibits osteoclasts) Increases cellular metabolism. Causes the osteoclasts to remove calcium ions from the bones. Calcium ions then enter into the bloodstream. This increases blood calcium ion levels. (inhibits osteoblasts) Converts lymphocytes to T cells involved in the immune system. Causes protein channels within the membrane to form pores thereby letting glucose enter into the cell for metabolism. This decreases the blood glucose levels.

10 Glucagon Adrenalin and noradrenalin (Epinephrine and norepinephrine) Glucocorticoids Aldosterone Erythopoietin Functions for Select Hormones Hormone Hormone Function Causes the liver cells to break down glycogen to form glucose. The glucose then enters the bloodstream. This increases the blood glucose levels. Causes cells to increase their metabolic rates. Causes the mobilization of glucose into the bloodstream to be used by cells. Causes cells to increase their metabolic rates. Causes an increase in glucose production from non-carbohydrate products (gluconeogenesis). Causes the nephrons of the kidneys to put water and sodium ions back into the bloodstream. This results in the conservation of water and sodium ions. Causes the erythroblasts to begin the formation of erythrocytes (red blood cells).