Regulation The Endocrine System Regulation: The Endocrine System

Endocrine System Function Coordinate body functions using chemical messages (Hormones) Works with the nervous system to provide homeostasis Slower to respond than Nervous System Effect lasts longer than Nervous System

Endocrine System Example: Glucagon from the pancreas (hormone) and the liver hepatocytes (targets) Endocrine glands: Secrete hormones into bloodstream Ductless Target Cells: Cells with appropriate receptors that respond to the hormone

ENDOCRINE SYSTEM: Major Organs

Hypothalamus and Pituitary gland Hypothalamus (part of CNS) –controls the hormonal secretions of the pituitary gland. Pituitary gland – The Master Gland –secretes hormones that regulate other endocrine glands. –For example: Follicle-Stimulating Hormone (FSH): Causes reproductive organs (ovaries, testes) to produce gametes & hormones.

Hypothalamus and Pituitary

ENDOCRINE SYSTEM: Major Organs Adrenal gland : Epinephrine [formerly adrenalin] Mobilizes body for action: –increases heart rate, blood pressure, and breathing rate Pancreas : Insulin - Causes cells to take up glucose from blood Glucagon – Causes liver to release glucose to blood

ENDOCRINE SYSTEM: Major Organs Thyroid: Thyroxin Increases overall metabolic rates Needs iodine to make thyroxin

ENDOCRINE SYSTEM: Major Organs Gonads (Sex Cell Organs) Ovary Estrogen - Promotes development of female sex organs & secondary sexual characteristics. Progesterone - causes uterus to thicken & become vascularized [once every menstrual cycle] Testis Testosterone - Promotes development of male sex organs & secondary sexual characteristics.

Endocrine System Control Feedback loop systems The level of a hormone controls its release Example: Hypothalamus tells pituitary to send out TSH when thyroxin levels are low TSH tells the thyroid to release thyroxin High levels of thyroxin reduces the amount of TSH released

Control of Blood Sugar After a meal, blood glucose levels are high Pancreas secretes insulin to lower it Glucose is stored as glycogen in the liver and muscles Before a meal, blood glucose levels are low Pancreas secretes glucagon to raise it Glucose is released from the liver

calcitonin Bones take up Ca 2+ from blood. Thyroid gland secretes calcitonin into blood. Regulation of Blood Calcium Level Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Homeostasis normal blood Ca 2+ high blood Ca 2+ low blood Ca 2+ Kidneys reabsorb Ca 2+ from kidney tubules. Intestines absorb Ca 2+ from digestive tract. activated vitamin D Bones release Ca 2+ into blood. parathyroid hormone (PTH) Parathyroid glands release PTH into blood. Blood Ca 2+ rises. Blood Ca 2+ lowers.

Label the Glands of the Endocrine System Pituitary Thyroid Parathyroid Adrenal Pancreas Ovary Testes