ENDOCRINE SYSTEM

ENDOCRINE SYSTEM

Goiter: When the thyroid gland becomes enlarged

POSTERIOR PITUITARY HORMONES

Oxytocin: induces uterine contractions and the release of milk.

Antidiuretic Hormone (ADH): enhances water reabsorption from collecting ducts in kidneys resulting less water urine. Balance osmotic pressure of blood.

Secretion of ADH is controlled by negative feedback mechanism as follws:
Less water in blood -> hypothalamus -> ADH -> kidney -> reabsorbs water makes blood more dilute/ makes urine more concentrated

ADH deficiency leads to the syndrome of Diabetes Insipidus.

leads

negative feedback mechanism

ANTERIOR PITUITARY HORMONES

Prolactin (PRL):stimulates lactation, growth of mammary glands and production of milk. It also plays a role in carbohydrate and fat metabolism.

Melanocyte-stimulating hormone (MSH):influences skin pigmentation in some vertebrates and fat metabolism in mammals.

Growth Hormone (GH): it promotes growth directly and has diverse metabolic effects. It stimulates muscles, bones and cartilage grow.

During childhood; an excess of GH can cause gigantism, while lack of GH can caus dwarfism

During adulthood, excess GH can cause acromegaly

cause

Thyroid-stimulating hormone (TSH): controls secretion of hormones from thyroid gland.

excess TSH stimulates thyroid gland more, and more hormone produced in thyroid glands which eventually cause increase in thyroid gland cells and thyroid gland enlargement

cause

Adrenocorticotropic hormone (ACTH): controls secretion of steroid hormones from cortex region of adrenal glands.

Follicle-stimulating hormone (FSH): stimulate follicle growth and estrogen hormone production during menstrual cycle in females

Luteinizing hormone (LH): stimulate ovulation and corpus luteum formation. Controls production of estrogen and progesterone hormones from corpus luteum in females. Stimulates testosterone hormone production in testes in males.

both FHS and LH are also called GONADOTROPINS

THYROID GLANDS

Thyroxine: stimulate metabolism and influence development and maturation. Increase blood pressure and heart beat and metabolic rate. There is no one target organ, all organs respond.

NEGATIVE FEEDBACK

Malfunctions of Thyroxine:

Hypothyrodism: low secretion of thyroid hormones

Goiter: When the thyroid gland becomes enlarged

Cretinism: is caused by thyroxine deficiency during childhood

Hyperthyroidism: excessive secretion of thyroid hormones causes high body temperature weight loss...

Graves Disease: is a form of hyperthyroidism but it is toxic goiter

Calcitonin: decreases the Ca level of blood. It stimulates Ca deposition in bones and decreases reabsorbtion of Ca in kidneys and increases excretion of Ca by urine.

Works antagonistacally with the parathyroid hormone to balance calcium in the blood of mammals.

PARATHYROID GLAND

Parathormone (PTH): stimulates the release of calcium by bones into the bloodstream. Absorption of calcium from food by the intestines. Conservation of calcium by the kidneys. Work antagonistacally with calsitonin hormone.

Malfunctions of Parathormone:

Tetany: Low Ca level increases excitability of nerve without rest and this results in continuous muscle contraction.

Excess: Bones become weak and brittle and kidneys has a kidneys stones.

ADRENAL GLANDS

Adrenal Medulla Hormones:

Epinephrine (adrenaline):

Norepinephrine (noradrenaline):

Trigger the release of glucose and fatty acids into the blood. Increase oxygen delivery to body cells. Direct blood toward heart, brain, and skeletal muscles, and away from skin, digestive system, and kidneys

They are secreted in response to stress-activated impulses from the nervous system. They mediate various fight-or-flight responses.

Adrenal Cortex Hormones:

Cortisol: influences glucose metabolism and the immune system. It stimulates the production of glucose from fats and amino acids and reduces inflammation.

High levels of cortisol result in Cushing Syndrome.

Aldosterone: affect salt and water balance in the blood. Acts on the tubules of the kidney to stimulate reabsorption of sodium and water into the blood and excrete potassium.

Low levels of aldosterone results in Addison Disease characterized by low blood pressure, bronzing of skin and open to infections.

Androgenes: The adrenal cortex also produces small amount of steroid sex hormones; estrogen, progesteron and testosterone. Woman may have masculinization from oversecretion of adrenal males sex hormone

PANCREAS

GONADAL SEX HORMONES

Insulin:

Glucagon:

Works antagonistacally with each other to adjust blood glucose level

Diabetes mellitus (Type 1): Blood glucose level is above normal level. There is marked decrease in the number of beta cells in the pancreas, resulting in insulin deficiency.

Diabetes mellitus (Type 2): Enough insulin secretion but insulin receptors on target cells cannot bind to insulin. This disorder develops gradually, usually in overweight persons over the age of 40.

Testes Hormones: Male testes located in scrotum function as gonads and produce androgens. Testosterone is male sex hormone.

Ovarian Hormones: Estrogen is released from follicle and responsible for maintenance of the female reproductive system. Secreted at puberty stimulate maturation of ovaries and other sexual organs.

THYMUS GLAND

Thymic Hormone: Thymus is the primary lymphoid organ of the immune system. It secretes thymic hormone. It is needed for development of T-lymphocytes. Thymus is largest and most active during the neonatal abd pre-adolescent periods.

By the early teens the thymus begins to atrophy and thymic stroma is mostly replaced by adipose tissue.

PINEAL GLAND

Melatonin: The pineal gland, located in the brain, secretes melatonin, primarily at night. Light/dark cycles control the release of melatonin.

Melatonin may cause seasonal affective disorder where persons are depressed at onset of winter.

Serotonin: It is a contributor to feelings of well-being and happiness.

secretes

causes

secretes

cause

secretes

cause

secretes

cause

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Progesterone: Progesterone is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens and is the major progestogen in the body. Progesterone has a variety of important functions in the body.

secretes

Synthesis of female sex hormones

FSH

controlled by

Necessary for egg development. Responsible for development of female secondary sex characteristics; a layer of fat beneath skin, larger pelvic girdle, etc.

Stimulates development and maintenance of the male reproductive system. Stimulates development of male secondary sex characteristics: large vocal cords, pubic hair etc. Largely responsible for the sex drive and probably aggressiveness.

suckling

hypothalamus

oxytocin

positive feedback

release

sends a message

Decrease blood glucose level. Increase the permeability of cells to take glucose except for brain cells

Increase blood glucose level. Functions in conversation of glycogen to glucose into liver

Increases absorption of glucose in the ileum

Stimulates passage of glucose from cells into blood. Stimulate fat breakdown.

Stimulate conversion of glucose to glycogen as storage form in liver and muscles. Increase the glucose metabolism in cells

hypothalamus

pituitary

thyroid gland

thyroxine

It increases sexual desire. The activity of serotonergic neurons is slowest or absent during sleep and highest during states of alert wakefulness.

Serotonin may also important in the neural pathways controlling mood.

The primary functions of melatonin appear to relate to biological rhythms associated with reproduction.