Biology 30 - Ch. 16 – Chemical Regulation Notes
The Endocrine System
 Controls many body functions
– Exerts control by releasing special chemical substances into the blood called
____________________
– ______________ affect _________________ or _________________
 _______________ glands release hormones ________________________.
 _________ glands - transport their hormones to target tissues via ________________.
 The Endocrine System consists of several glands located in various parts of the body.
 Hormones are produced by specialized endocrine glands and travel through the
circulatory system to their destination.
 Unlike the nervous system, the message delivered by the hormones is ____________
______________________________________________.
 The hormones are delivered throughout the body. When the hormone reaches the
target cell, receptors located on the target cell bind to the hormones. This causes some
change to occur in the organ targeted.
Types of Hormones
 _________________________
____________ based hormones consist of several ______________ strung together.
They are secreted by the ________________ located in the ___________. The
pituitary gland is the __________ controlling all other endocrine glands in the body.
 _________________ (also referred to as ________________)
_____________ based hormones are derived from ____________. Hormones such as
____________ secreted by the _______________ are a steroid based hormone.
Steroid based hormones have a similar structure.
Control of Hormone Secretion
Negative Feedback
 Negative feedback is the body’s response to __________________________ internal
conditions. An analogy for negative feedback is the thermostat in your home.
 Negative feedback mechanisms act like a thermostat in the home. As the temperature
decreases, the thermostat detects the change and triggers the furnace to cut in and
warm the house. Once the temperature reaches its thermostat setting, the furnace turns
off.
 The endocrine system uses cycles and negative feedback to regulate physiological
functions.
 Negative feedback regulates the secretion of almost every hormone.
 Cycles of secretion maintain _________________________ control. These cycles can
range from ______________________ in duration.
 Negative feedback helps to maintain an equilibrium in the body called ____________.
An example of negative feedback in the body:
 _____________levels in the bloodstream are regulated in part by the _____________
glands. When these glands sense that calcium levels are __________ they secrete a
hormone that causes the _____________ to release ___________________.
1
Biology 30 - Ch. 16 – Chemical Regulation Notes
 If the stimulus is high calcium levels, once again sensed by the parathyroid glands, it
causes the parathyroid glands to halt their production of the calcium-liberating
hormone.
Positive Feedback
 Positive feedback is _____________ in the body. It does not create as ____________
in the body as negative feedback does.
 In positive feedback the initial response ______________ the stimulus that gave rise
to it. Recall that in negative feedback the initial stimulus actually decreases the initial
stimulus.
Example - Childbirth
 During childbirth the uterus stretches due to pressure from the growing infant. This
causes release of the hormone _____________ which initiates a positive feedback
mechanism.
_____________ stimulates the uterus to _________________. The contraction of the
uterus stimulates further production of ___________ which stimulates further
contractions.
This process leads to more stretching until finally the loop is broken upon birth of the
baby.
The Endocrine System
 Pituitary gland: a small gland located on a stalk hanging from the base of the brain
 Often referred to as ______________________________
– Primary function is to ________________________.
– Produces many hormones.
– Secretion is controlled by the ___________________ in the base of the brain.
 The Pituitary Gland is divided into 2 areas, which differ
– ______________ and _______________________
– Each area has separate types of hormone production
 The two segments are:
– Posterior Pituitary:
 produces ______________________________________________
– Anterior Pituitary:
 produces _________________________________________________________
________________________________________________________________
________________________________________________________________
Posterior Pituitary
– Oxytocin
 Stimulates _______________________________________________
 causes ______________________________________
– _________________________ causes the _____________________________.
Anterior Pituitary
 Primarily regulates ________________________________________.
2
Biology 30 - Ch. 16 – Chemical Regulation Notes
 ______ stimulates the _________gland to release its hormones, thus ______________
 _______________ stimulates ________________________________________.
 Growth hormone (GH)
 ______________________________
 ____________________________________ as an energy source
 Hormone that stimulates ____________________ in children.
 Too much = _______________________
 Too Little = _______________________
Pineal Gland
The pineal gland is located near the _______________________, having the shape of
a tiny cone
Its hormone __________________ has significant effects on ________________ and
daily physiologic cycles, most notably the ______________________________.
The Thyroid Gland
– Lies in the ______________ just below the ___________________.
– Two lobes, located on either side of the trachea,
 When stimulated (by TSH or by cold), hormones are released into the
circulatory system and ___________________________.
 __________________, when released, lowers the amount of _________ in the blood.
Parathyroid Glands
– Small, pea-shaped glands, located in the neck near the thyroid
– Usually 4 - number can vary
– Regulate the level of _____________________ in the body
– Produces _____________________ - _________________________ in blood
– Hypocalcaemia can result if parathyroids are removed or destroyed.
Pancreas
– a large key gland located in the __________________________________
– has both ________________________________ functions
– secretes several key ____________________ through the ______________ into
the ____________________________.
 ______________________________
– specialized tissues in which the endocrine functions of the pancreas occurs.
Secretes 2 important hormones:
 _________________, essential for controlling ________________________.
 When blood glucose levels __________, ___the amount of _________ in the blood .
 The surge of ___________ stimulates the liver to release ______________________
(from __________________ and additional storage sites).
3
Biology 30 - Ch. 16 – Chemical Regulation Notes


__________________ (antagonistic to __________________).
_______________ the rate at which various body cells take up __________. Thus,
insulin _____________________________________________.
 Insulin is rapidly broken down by the ___________ and must be _______________.
Adrenal Glands
– 2 small glands that sit atop ______________________.
– Each has 2 divisions, each with different functions.
 the _________________ secretes the hormones _____________ and _____________.
 ________________ is also known as _____________________.
 Involved in the _______________________ reaction.
 ________________ speeds up ____________________________________________
____________________________________________________________________
 ________________________ counteracts the effects of _______________________.
 The ____________________ secretes 3 classes of hormones, all steroid hormones:
– Some  the level of _________________ in the blood
– Released in response to ______________________________________ - like the
hormones from the adrenal medulla.
– Work to regulate the concentration of _________________________ in the body.
Gonads and Ovaries:
– The endocrine glands associated with human reproduction.
– Female ovaries produce ______________
– Male gonads produce ________________
 Both have endocrine functions.
Ovaries:
– located in the abdominal cavity adjacent to the uterus.
 The ovaries are under the control of ____________ from the _________________
and they manufacture
 __________________________________________
 ____________and _______________ have several functions, including ___________
______________ and preparation of the uterus for __________________________.
Testes:
–located in the _____________________
–produce sperm for reproduction
–manufactures ________________ - promotes _____________ and _____________
–Controlled by ____________________ hormones ______________________
Endocrine Disorders:
Diabetes Mellitus
– one of the most common diseases in North America.
4
Biology 30 - Ch. 16 – Chemical Regulation Notes
– _________________ secretion by the _______________________ in the pancreas.
 Complications of Diabetes:
– ___________________________________________________________________
___________________________________________________________________
Hypoglycemia
 ____________________________ blood glucose levels.
 Body cannot mobilize stored glucose due to low levels of ____________________.
 Symptoms = ________________________________________________________.
Goiter:
 Enlarged __________________________
 Cause: Not enough _________________ ingested to make _____________________
Addison’s Disease
 Normal _____________ levels cannot be maintained due to low levels of _________.
 Results in incomplete digestion of ________________________________________.
 Symptoms = low blood sugar, weakness or sluggishness, weight loss, increased skin
pigmentation, reduced tolerance to stress.
Anabolic Steroids
 Anabolic steroids, which are synthetic versions of the primary male sex hormone
testosterone, can be injected, taken orally, or used transdermally.
 While anabolic steroids can enhance certain types of performance or appearance, they
are dangerous drugs, and when used inappropriately, they can cause a host of severe,
long-lasting, and often irreversible negative health consequences.
 Research has shown that the inappropriate use of anabolic steroids can have
catastrophic medical, psychiatric and behavioural consequences.
 These drugs can stunt the height of growing adolescents, masculinize women, alter
sex characteristics of men and may cause sterility.
 Anabolic steroids can lead to severe acne, premature heart attacks, strokes, liver
tumours, kidney failure and serious psychiatric problems.
 In addition, because steroids are often injected, users risk contracting or transmitting
HIV or hepatitis.
5