The Endocrine System! Our hormones! Chemical messengers of the BODY! Help you to maintain Homeostasis! (constant internal environment)

Types of Glands: Exocrine Gland – produces secretions that are released into tubular ducts –i.e., digestive system Endocrine Gland – releases contents into blood stream and generally produces hormones

Purpose of the Endocrine System Control and regulation of body functions –through the use of glands and hormones Effects are slower than the nervous system, but tend to last longer

NS vs ES! NSES____________ fast actingslower short termlong term (lingers) neuron involvedhitches a ride on the circulatory system ElectrochemicalChemical comm. Very SpecificLess specific

Glands of the Endocrine System

How Homeostasis Works! Homeostasis is the term used to denote the constancy of the body’s internal environment! Human cells grow best under the following conditions: glucose concentration is 80mg/dL O 2 & CO 2 concentration are 100ml/L & 40 ml/L pH is 7.4 Na and K concentrations are 142 and 4 mg/L respectively Body temperature is 37 o C

Natural factors that disrupt Homeostasis include: Increases or decreases in temperature Excess intake or loss of fluids Influx of nutrients or medications after swallowing (or fasting) Stress Fatigue

Homeostasis Sample! Start on far left: It’s cold in here! Turn up the thermostat Furnace lights ‘er up Room heats up and thermostat is satisfied Furnace turns itself down until the next imbalance requires the above sequence to start over again! RU Ready?

Two types: Protein (polypeptide) and steroid hormones Target: Organs or cells. Cells with specific receptors to hormones (receptors combine with hormones in a lock-and-key fit) Origin (Gland)  Blood Stream  Target  Message/Function Hormones

Steroid Hormones Made from cholesterol (lipid) Ex. Sex hormones Not soluble in water, but are soluble in fat –Hormone diffuses through the cell membrane and attaches to a specific receptor molecule in the cytoplasm or nucleus –Hormone-receptor complex moves into the nucleus (bonds to DNA) and activates a specific gene –Gene sends a message to the ribosome and begins to produce a specific protein

Protein (Polypeptide) Hormone Made from proteins (aa) Activates existing enzymes in cells therefore rapid acting Soluble in water but not fat Ex, Insulin, hGH –Combines with specific receptors on the cell membrane –Results in production of cyclic AMP –Peptide hormone is the 1st messenger since it never enters the cell; c AMP is the 2nd messenger in the cytoplasm to carry out the function

How Hormones Communicate! Hormones are chemicals & their regulation is unique. If you increase production we call it  POSITIVE FEED BACK (rare) Symbol +ve = Positive feedback If your decrease production we call it  NEGATIVE FEEDBACK (common) Symbol –ve = Negative feedback

Feedback Loops Positive Feedback = reinforcing loop Is this good for homeostasis? Gland AHormone A released (targets Gland B) Gland BHormone B released (targets Gland A) Hormone B tells Gland A to keep releasing Hormone A +ve feedback is typical of disorders or periods of growth in the body.

Feedback Loops Negative Feedback = terminating loop Is this good for homeostasis? Gland AHormone A released (targets Gland B) Gland BHormone B released (targets Gland A) Hormone B tells Gland A to stop releasing Hormone A -ve feedback is typical for normal homeostatic regulation in the body. X

To Do: Textbook Q’s pg. 477 # 1-5

The Pituitary Gland: Referred to as the master gland because it has control over most other endocrine glands Connected directly to the hypothalamus (like a pendant on a necklace) Together they are called the PITUITARY-HYPOTHALAMUS COMPLEX

The Pituitary is divided into two different lobes: A) POSTERIOR PITUITARY LOBE PPG): (1/3 of gland) –Stores & releases hormones produced in the HYPOTHALAMUS –The hypothalamus stores the hormones in the PPG until needed

B) ANTERIOR PITUITARY LOBE (APG): (2/3 of gland) –It produces its own hormones (unlike the PPG) –Nerves from the hypothalamus extend into the APG to trigger hormone release –Hypothalamus contains the CHEMORECEPTORS necessary to identify a need to release APG hormones

Role of the Hypothalamus Does the “sensing” for the pituitary –Contains chemoreceptors

i. 8b/Biology-30-Instructional-Videohttps://sites.google.com/a/grccs.ca/mr-bado/science- 8b/Biology-30-Instructional-Video

Questions: 1. Define what a hormone is 2. Distinguish between a target & non-target hormone 3. Distinguish between endocrine & exocrine glands 4. Why is the pituitary gland called the master gland? 5. What is negative feedback and how does it work? 6. Describe the signaling action of a steroid hormone & and protein hormone. AND Pg. 477 #6-8