The Endocrine System! Our hormones! Chemical messengers of the BODY! Help you to maintain...
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Transcript of The Endocrine System! Our hormones! Chemical messengers of the BODY! Help you to maintain...
The Endocrine System! Our hormones! Chemical messengers of the BODY!
Help you to maintain Homeostasis! (constant internal environment)
http://www.youtube.com/watch?v=-S_vQZDH9hY
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!
NS ES____________ fast acting slower short term long term (lingers) neuron involved hitches a ride on the circulatory system Electrochemical Chemical comm. Very Specific Less 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 O2 & CO2 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 oC
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 B
Hormone 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 B
Hormone 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
http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter46/positive_and_negative_feedback.html
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. https://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