The Endocrine System Chapter 13

What is the Endocrine System? The endocrine system releases chemical hormones into the blood This system is slower in producing its effect than the nervous system, however, the effect lasts longer It helps to maintain homeostasis by monitoring changes in organs or tissues of the body.

What are hormones? Hormones are chemicals that circulate through the blood and affect every organ and tissue in the body.

How do hormones work? Hormones only affect organs and tissues if they have the correct receptor sites. The receptor will bind with the hormone (like a lock-and-key) An organ that contains receptors for a particular hormone is called a target organ.

What are the types of glands? (i) Endocrine glands - are ductless glands that secrete hormones directly into the bloodstream. (See diagram – next page) (ii) Exocrine glands - release their secretions through ducts or tubes (Exits the body). Examples: sweat glands, salivary glands, tear glands, mammary glands

Steroid Hormones Steroid hormones are fat-soluble which means they are able to pass through the cell membrane of the target cell easily. Once inside the cell, they bond to a protein receptor molecule in the membrane in the cytoplasm. (hormone-receptor complex)

The hormone receptor complex enters the nucleus and activates a specific gene on the cells DNA molecule. Examples: – cortisol – Progesterone Video: hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/ / /bio46.swf::Mechanism%20of%20Steroid%20Hormone%20Action

Turn to Page 2 in Booklet Explain how steroid hormones cause changes in target cells, using a diagram (Include: solubility in cell membrane, locations of receptors and the end result)

Draw Figure 13.5 A on page 425

Non-Steroid Hormones Non-steroid hormones are secreted from glands into the blood stream. These hormones are NOT fat-soluble and CANNOT pass through the cell membrane. Instead they work from outside the cell.

Non-steroid hormones are called first messengers. They bind to receptors on the surface of the cell and activate an enzyme. This enzyme triggers the production of the second messenger (cyclic-AMP). C-AMP causes a chain reaction to occur inside the cell. This is referred to as a biological amplifying system because a small amount of a hormone has a great effect.

Examples: – adrenaline – luteinizing hormone (LH) – follicle stimulating hormone (FSH)

Draw Figure 13.5 B on page 425

Turn to Page 3 in Booklet Explain how non-steroid hormones cause changes in target cells, using a diagram (Include: solubility in cell membrane, locations of receptors and the end result)

Anabolic Steroid Video: Steroids and their side effects 4&safe=active 4&safe=active Video: Steroid debate in baseball safe=active Video: Lance Armstrong &safe=active

Public Exam Practice Question The abuse of steroid hormones, such as testosterone, by athletes can lead to problems with homeostasis. Explain how this abuse can have a negative impact on the body. (2%)

How do stimulants interfere with the Endocrine System? Caffeine has stimulating properties, such as causing the heart muscle to contract Caffeine is also considered to be a diuretic (increases urine production) and as a result, leads to more calcium excretion.

Is caffeine making us crazy? - video hE&list=PLayDotgyoEYODnhGOQcDiM5i4B5kqnaeh&index=4 &safety_mode=true&safe=active&persist_safety_mode=1 hE&list=PLayDotgyoEYODnhGOQcDiM5i4B5kqnaeh&index=4 &safety_mode=true&safe=active&persist_safety_mode=1

Turn to page 4 in Booklet

Basic functions of the endocrine glands:

Pituitary gland: The master gland It has two parts: 1.Anterior Pituitary 2.Posterior Pituitary

The pea-sized pituitary gland is beneath the hypothalamus

Hormones found in the Anterior Pituitary 1.Somatotropin (Human Growth Hormone) – growth of bones and muscles 2.TSH (Thyroid Stimulating Hormone) – stimulates the thyroid to release hormones 3.ACTH – stimulates the adrenal glands

4. FSH (Follicle Stimulating Hormone) – stimulates the ovaries/testes to make eggs/sperm 5. LH (Luteinizing Hormone) – stimulates the ovaries/testes to release eggs/sperm

Hormones found in the Anterior Pituitary 1.Oxytocin – stimulates uterine contractions during labour 2.ADH (anti-direutic hormone) – leave out

Pineal Gland Melatonin – controls our sleep/wake cycle

Thyroid Gland Thyroxine – controls metabolism Calcitonine – absorbs calcium into our bones

Parathyroid Gland PTH (Parathyroid Hormone) – releases calcium from the bones

Thymus Gland Thymosine – stimulates the immune system

Adrenal Medulla Adrenaline – fight or flight response Adrenal Cortex Cortisol – prepares the body for long term stress

Pancreas Insulin – increases the uptake of glucose into cells (during and immediately after a meal) Glucagon – triggers the cellular release of glucose (when glucose levels are low)

Ovaries Hormones - Estrogen, progesterone Influences secondary sex characteristics and menstrual cycle

Testes Hormones – Testosterone and inhibin Influences secondary sex characteristics.

Who wants to be a millionaire? endocrine-system/millionaire-game- endocrine-system.html endocrine-system/millionaire-game- endocrine-system.html SAVE THIS GAME TILL THE END, AS REVIEW