the endocrine system. endocrine introduction the endocrine system works with the nervous system to...

The Endocrine System

Endocrine Introduction

• The Endocrine System works with the Nervous System to maintain homeostasis.

• The Endocrine System consists of special organs called glands which secrete chemicals called hormones into the bloodstream

• The blood carries these chemicals to all parts of the body. • When these chemicals reach the intended organ, they initiate a chemical

reaction.

Endocrine Introduction

• Hormones do not ‘seek’out particular organs, but rather organs await the arrival of the hormone.

• Cells that react to a particular hormone have specific receptors for that particular hormone.

• The receptors combine with the hormone in a ‘lock-and-key’ fashion.

Endocrine Introduction

• Some of the regulatory functions of the endocrine system include:

• 1. Heart rate• 2. Blood pressure• 3. Immune system response to infection• 4. Reproduction• 5. Emotional state - mood• 6. Overall growth & development

Major Components of the Endocrine System

Glands

• Glands: organs which are specialized to produce chemical substances needed by the body.

– exocrine glands - glands produce chemicals which travel to target organ through channels or ducts. i.e. sweat glands, tear glands, salivary glands, mammary glands and secrete substances such as sweat, saliva, tears, milk, or digestive enzymes

– endocrine glands - chemicals produced by glands are released into the bloodstream and make their way all around the body.

–  -“ductless” system; glands secrete hormones directly into the bloodstream usually for maintaining longer term processes.

Hormones• Hormones: chemical signals that are sent to many

parts of the body; • examples are adrenaline and noradrenaline from the neurons of the

adrenal glands

• Referred to as ‘chemical messengers’• These chemicals travel throughout the body via the

blood stream and regulate overall metabolism, maintenance of homeostasis, reproduction and vital body functions.– Hormones are only able to produce their effect in the

specific target organ.-hormone production increases or decreases in response to changing metabolic needs of the body (fluid balance, infection, injury, stress, etc.)

• Target organ: organ that contains receptors for a particular hormone

• Intro: http://www.youtube.com/watch?v=eyO8Dim3T3U

Types of Hormones • (1) Steroid Hormones

– Secreted in the blood quickly by the endocrine organs that produce them.

– They are Fat soluble, and pass through the membrane of a target cell and the nuclear envelop.

– Inside the target cell steroid hormones attach to a protein receptor molecule in the cytoplasm.

– The hormone-receptor complex binds to a specific part of the cell’s DNA,

activating a gene. • This gene produces an enzyme which

causes the desired changes.

Types of Hormones • Non-steroid hormones

• Also called: first messenges• ex. Adrenaline, thyoxine, glucagons, etc.• Water soluble• Do not enter the cell.• They bind to receptors on the surface of target cell and cause ATP(adenosine triphosphate)

to change into cAMP (cyclic AMP) or second messenger. This cAMP activates an entire series of enzyme reactions in the cell, which results in the desired changes.

Hormone Solubility in Cell Membrane

Location of Receptors

End Result

Steroid Soluble Within cell Gene produces a Protien

Nonsteroid Insoluble Surface of cell cAMP causes chain reactions

Hormones

• Antagonistic Hormones– Hormones that work against each other or have

the opposite effects.• Insulin and glucagon

• Tropic Hormones– Hormones that regulate the hormone production

of many other glands.• Thyroid Stimulating hormone (TGH)

Hormone Problems/Disorders

• Hyposecretion- an under secretion of a hormone within the body

• Hypersecretion- an over secretion of a hormone within the body.

Gland Man

http://kidshealth.org/kid/htbw/_bfs_ESmoviesource.html

Pituitary gland

• called the “master gland”– It controls the function of other endocrine glands

• actually two glands: anterior and posterior • Anterior: Largest portion. Located towards the front of the head.

– Produces 6 different hormones: Human growth hormone, Adrenocorticotropic Hormone (ACTH), Prolactin, Thyroid Stimulating hormone (TSH), Follicle Stimulating hormone (FSH) and Lutenizing hormone (LH)

• Posterior: Smaller of the two glands. Located on the back. It stores hormones, but does not make any.

– Secreats 2 hormones : Oxytocin and Antidiuretis Hormone

Glands of the Endocrine System

Hypothalamus• controls the endocrine hormone system (as well as the autonomic

nervous system). • It monitors the blood and send out hormones from glands when

needed.• The hypothalamus plays a key role in the body’s response to stress.

It produces 2 hormones (both stored and secreted from the posterior pituitary gland)– 1. ADH (anti-diuretic hormone): controls water levels– 2. oxytocin: triggers muscle contractions in childbirth and promotes lactation

• interacts constantly with the pituitary gland

Thyroid Gland

• Located in the throat

• Butterfly, or bowtie

• Regulates metabolism and growth

• Produces Thyroxine and Calcitonin– Help increase metabolism rate and oxygen

consumption.

Parathyroid

• Located on the surface of thyroid gland• Regulates calcium levels• Produces Parathyroid Hormone

– Causes bones to release calcium into blood stream.

– Causes kidneys to reabsorbed calcium from blood, therefore increasing the amount of calcium in the body.

Pancreas (Islets of Langerhans)• Located near small intestine.• Helps regulate blood glucose levels.• Contain specialized endocrine cells called Islets of

Langerhans• Which are made up of Alpha and Beta cells.

• Secretes Insulin and Glucagons.

Pineal Gland

• Located deep in the brain

• Regulates circadian rhythm

• Produces Melatonin– Causes a feeling of “sleepiness” and aids with

sleep

Thymus Gland

• Located between the lobes of the lung in the upper chest.

• Helps regulate the immune system

• Produces thymosin– Casuses the production and maturation of

lymphocytes into T-cells (help fight infection)

Adrenal Gland• Located on top of kidneys• Regulates body’s metabolism• Two layers: -Outside: Adrenal Cortex

- Inside: Adrenal Medulla» Both are controlled by the Hypothalamus.

• Three Major Hormones:– Aldosterone: regulates blood pressure and salt levels in

blood

– Cortisol: Reduces inflammation and causes glucose to be made by the liver

– Sex Hormone: Males- hormone called “Androgens” Females: hormone called

“Estrogens”

Gonads: Ovaries and Testes

• Reproduction

• Ovaries- found in females• Produce: Estrogen-controls secondary sex characteristics in

females and prepares the uterus for pregnancy.

-Progesterone-Maintains uterus during pregnancy.

• Testes- found in males• Produces testosterone

» Controls secondary sex characteristics in males (traits that distinguish the two sexes of a species, but that are not directly part of the reproductive system)

Next class hormones

• melatonin• thyroxine• adrenaline• somatotropin (HGH–human growth

hormone)• insulin• glucagon