Endocrine System

FunctionRegulates moodResponsible for growth and development Tissue functionMetabolismSexual function and reproductive processes

in the body

Foundations of the Endocrine SystemHormones

Transfers information and instructions from one set of cells to another

GlandsGroup of cells that produces and secretes, or

gives off, chemicals. A gland selects and removes materials from the blood, processes them, and secretes the finished chemical product for use somewhere in the body

Types of GlandsGlands can be divided into two groups:

Endocrine glands - glands that secrete their product directly onto a surface rather than through a duct.

Exocrine glands - secrete their products via a duct, the glands in this group can be divided into three groups:

- Apocrine glands - a portion of the secreting cell's body is lost during secretion - Holocrine glands - the entire cell disintegrates and secrete its substances - Merocrine glands - cells secrete their substances by exocytosis

Major Glands of the Endocrine SystemHypothalamusPituitary glandThyroidThymus glandParathyroidsAdrenal glandsPineal bodyReproductive glands (which include the

ovaries and testes)

HypothalamusCollection of specialized cells that is located in

the lower central part of the brainMaintains homeostasis

(examples: heart rate, body temperature, water balance, and the secretions of the pituitary gland)

Main link between the endocrine and nervous systems

Nerve cells in the hypothalamus control the pituitary gland by producing chemicals that either stimulate or suppress hormone secretions from the pituitary

Pituitary GlandLocated at the base of the

brain just beneath the hypothalamus

Often called the "master gland" because it makes hormones that control several other endocrine glands

The production and secretion of pituitary hormones can be influenced by factors such as emotions and changes in the seasons

Pituitary GlandThe pituitary is divided into two parts:

anterior lobe- regulates the activity of the thyroid, adrenals, and reproductive glands. The anterior lobe produces hormones such as: Growth hormone- stimulates the growth of bone and

other body tissues and plays a role in the body's handling of nutrients and minerals

Prolactin- activates milk production in women who are breastfeeding

Thyrotropin- stimulates the thyroid gland to produce thyroid hormones

Corticotropin- stimulates the adrenal gland to produce certain hormones

Pituitary Glandposterior lobe

helps control the balance of water in the body Produces oxyton: triggers the contractions of the

uterus in a woman having a baby

Secretes endorphins:chemicals that act on the nervous system and

reduce feelings of pain

ThyroidLocated in the front part of the lower neckShaped like a bow tie or butterfly Produces the thyroid hormones thyroxine and

triiodothyronine control the rate at which cells burn fuels from

food to produce energy.Help kids' and teens' bones grow and develop

Parathyroids

Four tiny glands that function together

Release parathyroid hormone: which regulates the

level of calcium in the blood

Adrenal GlandsTriangular shapedLocated above each kidneyEach gland has two parts:

Adrenal cortex, the outer part, produces hormones called corticosteroids that influence or regulate salt and water balance in the body, the body's response to stress, metabolism, the immune system, and sexual development and function.

Adrenal medulla, the inner part produces catecholamines such as epinephrine, also known as adrenaline. This increases blood pressure and heart rate when the body experiences stress.

Pineal GlandsLocated in the middle

of the brainSecretes melatonin:

hormone that may help regulate when you sleep at night and when you wake in the morning.

Reproductive GlandsMain source of sex hormones are the gonads:

sex gland in which gametes are producedMales

Male gonads, or testes are located in the scrotum

Secrete the hormone testosterone: Which affect many of the male characteristics such

as penis and height growth, deepening in the voice and growth in facial and pubic hair and sperm production.

Reproductive GlandsFemales

Female gonads, or ovaries are located on both sides of the uterus, below the opening of the fallopian tubes

Produce the hormones estrogen and progesterone Involved when a girl begins to experience breast

growth, accumulate body fat around the hips and thighs, a growth spurt. Estrogen and progesterone are also involved in the regulation of a girl's menstrual cycle and pregnancy

Thymus GlandLocated in the upper part of the chest cavity,

directly behind the sternumProcesses a type of white blood cell known as

a T-lymphocyte. They help cells recognize and destroy invading

bacteria, virus, and abnormal cell growth such as cancer, and foreign tissue.

PancreasAlso part of the digestive systemProduces two hormones:

Insulin and glucagon- work together to maintain a steady level of glucose in the blood and keep the body supplied with fuel to produce and maintain stores of energy

Negative Feedback MechanismsMain way to regulate blood levels of hormones.Rising hormone levels inhibit further hormone

release.

Example: The thyroid gland has secreted the right amount of thyroid hormones into the blood. The pituitary gland senses the normal levels of thyroid hormone in the bloodstream. Then the pituitary gland adjusts its release of thyrotropin, the hormone that stimulates the thyroid gland to produce thyroid hormones.

Gland Hormone Action Regulated byPineal Melatonin Sleep cycles Light and dark

Pituitary ADH Retention of water by kidneys Hypothalamus reponse to water/salt imbalance

oxytocin Uterine contractions Response to uterine stretching or baby suckling.

GH growth hypothalamus

Prolactin Milk production hypothalamus

FSH Production of ova and sperm hypothalamus

LH Stimulates ovaries and testes hypothalamus

TSH Stimulates thyroid Thyroxine in blood

ACTH Stimulates adrenals glucocorticoids

Thyroid T4 and T3 Stimulates metabolism TSH

Calcitonin Reduces blood Ca levels. Ca levels in blood.

Parathyroid PTH Raises blood Ca levels Ca levels in blood

Adrenal Epinephrine/norepinephrine Increase blood glucose, rate of metabolism; constrict blood vessels.

Nervous; sympathetic division

Steroids Promote reabsorption of Na and excretion of K in kidneys

Change in blood volume or pressure.

Pancreas Insulin Reduces glucose High glucose levels

Glucagon Raises glucose Low glucose levels

Testes Androgens Support sperm; male sex characteristics FSH and LH

Ovaries Estrogens Female sex characteristics; stimulate uterine lining growth

FSH and LH

Progesterone Growth of uterine lining FSH and LH

Homeostasis:Menopause

Late middle age, ovary function declines.Diabetes mellitusHypothyroidismHyperthyroidismAddison’s

Hyposecretion of all adrenal cortex hormonesCushing’s disease

Excessive output of glucocorticoids

Hypothyroidism

HyperthyroidismAcromegaly

By Amanda Gonzales

http://www.becomehealthynow.com/article/bodynervousadvanced/956/

http://kidshealth.org/teen/your_body/body_basics/endocrine.html#

http://www.innvista.com/health/anatomy/thymus.htmhttp://www.umm.edu/endocrin/reproduct.htmwww.endocrineweb.com/endocrinology/your-adrenal-glands http://parathyroid.com/parathyroid-function.htmhttp://www2.estrellamountain.edu/faculty/farabee/biobk/

biobookendocr.htmlAn Ingegrated Approach to Health Science-BookEssentials of Human Anatomy and Physiology

References