Chapter 13 - The Endocrine System

13.1-The Endocrine System and Homeostasis

Chemical Regulation

In regulating homeostasis, the body uses the electrochemical impulses of the nervous system in combination with chemical messengers of the endocrine system. The endocrine system regulates growth, metabolism, reproduction, homeostasis, etc . It acts ______than nervous regulation, but its effects may last weeks, months, years.

Glands

  • Are organs made up of epithelial cells; specialize in the production and secretion of required substances
  • Types of Glands: ______- secrete substances into ducts which take them to where they are needed (example: salivary glands

______- secrete substances directly into the bloodstream which will take them to where they are needed (example: thyroid gland)

  • Secretions are called hormones; they are chemical signals which affect target organs

Hormones

Hormones are carried by the______throughout the body, but only affect target organs.They act as chemical messengers and regulate the target tissue to either increase or decrease its actions. There are 2 main classes of hormones:

1)______hormones

  • made up of lipid-like carbon rings derived from cholesterol molecules.
  • able to pass through cell ______and are ______likely to be stored in the body. (examples: estrogen, progesterone, testosterone).

2) ______hormones

  • Non-steroid hormones (a.k.a. protein type) are made of ______. They ______pass through cell membranes because they are too large. They are water soluble so they are ______likely to be stored in the body and can be excreted in urine.(examples - adrenaline, non-adrenaline, growth hormone, thyroxine, &insulin).

______- Local hormones that do not enter the bloodstream but may influence other hormones

Regulation of Hormone Secretion

Hormones are regulated by the nervous system and/or chemical stimuli (other hormones). A feedback system is used in which one change causes another change which in turn affects the original change.

Positive Feedback

In positive feedback, the original change is ______. For example, an increase [A] causes an increase in [B] which causes A] to increase. This amplifies the original change in A. Positive feedback doesn’t promote homeostasis and is not commonly used. (example of positive feedback: release of oxytocin during labor)

Negative Feedback

In negative feedback, the original change is ______. For example, an increase [A] causes an increase in [B] which causes a decrease in [A]. This type of feedback maintains homeostasis by keeping [A] relatively constant. Most hormone levels are regulated using negative feedback.

Mechanisms of Hormone Regulation

1) ______model – utilized by steroid type hormones with can pass through the cell membrane by binding to a protein carrier in blood to create a hormone-receptor complex. The steroid hormone can enter the cell’s nucleus, bind to specific regions of DNA to create its effect.

2) ______Model – utilized by protein type hormones which cannot enter the cell. Target cells have a receptor on the cell membrane which binds to the hormone causing a reaction on the inner side of the cell membrane. This produces a second messenger calledcAMP from a molecule of ATP which creates a cascade reaction of enzyme to create the desired effect.

3.2 - Endocrine Glands. Using your text book or other sources, complete your notes on each of the following human glands (location) and their hormones (steroid or protein, function, disorders associated with hypo or hypersecretion of its hormones)

1)Hypothalamus–

2)Pituitary gland- Anterior Lobe of Pituitary Hormones: Human Growth Hormone (HGH), Thyroid Stimulating Hormone (TSH), Adrenocorticotrophic Hormone (ACTH), Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), and Prolactin.

Posterior Lobe of Pituitary Hormones: Antidiuretic Hormone (ADH), Oxytocin-

3) Thyroid Gland– Thyroxine

4)Parathyroid Gland–Calcitonin

5)Pancreas Gland- Beta cells –Insulin, Alpha Cells -Glucagon

Section 13.3 - The Adrenal Glands

Adrenal Cortex (outer layer of gland) -Aldosterone (mineralcorticoid), Cortisol (glucocorticoid)

Adrenal Medulla (inner layer of adrenal gland)-Adrenaline (epinephrine) and Noradrenaline (norepinephrine)

OTHER GLANDS: Thymus Gland- Thymosin; Pineal Gland- Melatonin ; Gonads – testosterone,

estrogen, progesterone