The Endocrine System Presented By: Jess C. Alex B. Aleeya W.

Function The Endocrine System produces hormones that control many body functions as well as help maintain homeostasis.

Exocrine.vs. Endocrine ExocrineEndocrine Hormones release to an external environment. Ducts carry hormones Hormones release to an internal environment. Ductless

Hormones Hormones are substances that are secreted by endocrine glands and are transported by blood. Most hormones are either steroids (synthesized from cholesterol), or they are amines, peptides, proteins, or glycoproteins (synthesized from amino acids).

Steroid Hormones

Nonsteroid Hormones

Secretion Regulation The three types of hormone secretion regulation, regulate using negative feedback. I.The Hypothalamus controls the anterior pituitary gland’s release of hormones, which in turn regulates other endocrine gland hormone secretion. II.The nervous system regulates some glands directly. III.Other glands respond to the changing of internal environment.

Nervous System Gland Regulation The Nervous System controls glandular secretion by either stimulating the gland directly or by changing the internal environment, initiating secretion.

Negative Feedback Mechanisms A Negative Feedback mechanisms is a loop system in which the system responds to perturbation in the opposite direction.

Locations

Pineal Gland The Pineal gland is regulated by the nervous system directly. Pineal Gland secretes:  Melatonin – acts on certain brain regions and helps regulate circadian rhythms.

Pituitary Gland The pituitary gland’s secretions are regulated by both the nervous system and the hypothalamus. Anterior Pituitary secretes:  Growth Hormone (GH) – stimulates cells to increase in size.  Prolactin (PRL) – stimulates & sustains milk production.  Thyroid Stimulating Hormone (TSH) – controls thyroid gland secretions.  Adrenocorticotropic Hormone (ACTH) – controls certain cortex adrenal gland hormones.  Follicle-stimulating/luteinizing Hormone (FSH) (LH) – exert actions on the gonads (reproductive organs).

Pituitary Gland (Continued) Posterior Gland secretes:  Antidiuretic Hormone (ADH) – decreases urine formation.  Oxytocin (OT) – contracts smooth uterine wall muscles.

Thyroid Gland Secretions are regulated by the other hormones from the anterior pituitary gland, and changes in the internal environment. Thyroid Hormones:  Thryoxine (T4) – Increases rate of energy released from carbohydrates, increases protein synthesis rate, accelerates growth.  Triiodothyronine (T3) – same as T4, 5 times more potent.  Calcitonin – inhibits release of calcium and phosphate ions from bones.

Parathyroid Glands Secretions are regulated by changes in the internal environment of the body. Parathyroid Hormone (PTH) – increases blood calcium concentration and decreases blood phosphate ion concentrations.

Adrenal Glands Adrenal glands are regulated by the nervous system. Adrenal Medulla Hormones:  Epinephrine (adrenalin) –increases heart rate, skeletal muscle vessels dilate, blood pressure rises, airways dilate, breaks down glycogen to glucose, metabolism increases.  Norepinephrine (noradrenalin) – increases heart rate, blood flow to muscles increases, blood pressure increases, airways dilate, metabolism increases.

Adrenal Glands (Continued) Adrenal Glands are regulated by the nervous system. Adrenal Cortex Hormones:  Aldosterone – causes the kidney to conserve sodium ions and excrete potassium ions.  Cortisol – increases blood concentration of amino acids, increases the utilization of fatty acids as an energy source, and increases the blood glucose concentration.

Pancreas (Endocrine) The Pancreas’ secretions are regulated by changes in the internal environment. Endocrine:  Glucagon stimulates the liver to break down glycogen into glucose.  Insulin – stimulates the liver to form glycogen from glucose.

Pancreas (Exocrine) The exocrine glands of the Pancreas secrete digestive juices.

Reproductive Glands The secretions of these glands are regulated by the hypothalamus and pituitary. Ovaries:  Estrogens – stimulate enlargements of accessory organs.  Progesterone – promotes changes in the uterus during a reproductive cycle.

Reproductive Glands (Continued) Testes:  Testosterone – increases growth of body hair, enlargement of larynx and vocal chords, thickening of the skin, increased muscular growth, thickening of bones.

Disorders and Diseases Diabetes Mellitus – a metabolic derangement that arises from lack of insulin or an inability of cells to recognize it. The insulin deficiency of diabetes disturbs the metabolism of carbohydrates, proteins, and fats. The disturbed metabolism leads to dehydration, increased hunger, stunted growth, and other adverse effects.