Download Endocrine Student Notes

The Endocrine System
Trillions of body cells must interact with one another since no cell operates in isolation.
Both the endocrine system & neurons work together in our bodies to allow this
interaction of cells.
Glands of the Endocrine System
A) What is the Endocrine System?
The Endocrine System achieves control of the body functions through chemical
substances (hormones), which are transported throughout the body in the blood.
Chemical coordination in animals involves:
1.
2.
3.
Hormone Analogy:
B) Hormones
HORMONES are chemical regulators produced by cells in one part of the body that
affect cells in another part of the body. The word hormone comes from the Greek
“hormon” meaning to excite or set into motion.
Endocrine hormones –
o Hormones are chemical messengers that are released into the _________.
o Each hormone regulates one or more reactions in the body.
o Most hormones are __________. These chemical messengers travel to a target
organ, tissue or cell and ___________________. Instead they attach to
receptors on the cell membrane which causes enzymes to become activated
inside the cell.
o Other hormones are ____________. They are able to ________________ and
enter the __________ where they can activate certain genes.
o This site must have the appropriate receptors on its membrane in order to be
able to respond to the specific hormones.
Endocrine glands –
Exocrine glands –
o Hormone action is _______________ impulses being sent throughout the body.
Hormones involve a sustained adaptation to change, i.e. growth, blood sugar
level.
o The nervous system, on the other hand, involves swift reactions to stimuli. i.e.
Moving a finger off a hot iron.
o ____________ is the only hormone whose action is considered to be immediate
as it is functional in life threatening situations.
•
•
Usually hormone action is slower.
• e.g. insulin alters the cell membrane to allow glucose easier passage into
the cell and to activate enzymes to convert glucose to glycogen
The number of receptors found on an individual cell may vary.
• e.g. liver & muscle cells have many receptor sites for insulin. There are
fewer receptor sites on less active cells like bone cells.
Different Types of Hormones:
Steroid Hormones and how they work
Homeostasis & Negative Feedback Loops
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Homeostasis –
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We must be able to respond to stress and respond in a self-preserving manner.
Homeostatic systems operate by means of _____________________.
These are a series of small repeated responses to a stimulus. Each
response becomes a new stimulus. These ultimately reduce the initial
stimulus or its effects.

Parts of a negative feedback system:

Hormone production is something that must be regulated. Once the hormone
produces the desired effect, hormone production must be halted (negative
feedback loop).
Example: Regulation of Urine Production via ADH

A positive feedback loop is also possible –
E) The Hypothalamus
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The hypothalamus gland regulates the ___________________ (the master
gland), through 1) _______________________ from the brain or 2) release of
________________________.
In response to either mechanism, the pituitary then
stimulates an endocrine gland to secrete a hormone.
High levels of this hormone will eventually trigger a
negative feedback that will affect the activity of the
hypothalamus.
Differs from other glands in that it synthesizes
hormones called ___________________. These
travel from the hypothalamus to the pituitary and
signal another specific hormone to be released.
Examples:
F) The Pituitary Gland

“Master Gland” because

Connected by a stalk to the _________________ (area of the brain associated
with homeostasis).
The pituitary has 2 lobes:
1) Posterior Pituitary
- Stores & releases ADH and oxytocin, which are produced by the
________________________.
ADH (Vasopressin)
Oxytocin
-
-
-
2) Anterior Pituitary
- Unlike the posterior pituitary, the anterior pituitary ____________
_______________________!
- The hypothalamus regulates the release of hormones from the anterior
pituitary by ______________________.
Summary of Pituitary Hormones
Hormone
Posterior Lobe
Anterior Lobe
Primary Function
The Adrenal Glands
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Located above each ______________.
Each adrenal gland is made up of two glands encased in a
The inner gland is the ___________________.
The outer casing is the __________________.
Adrenal medulla – regulated by _________________
Adrenal cortex – regulated by _________________
shell.
1) Adrenal Medulla
- Produces
-
In a _______________ situation, adrenaline & noradrenaline are released
from the medulla into the blood. This causes symptoms of the
___________________ response.
-
The release of adrenaline is caused by the stimulation of the
____________________________. This is the part of the nervous system
that responds to stressful situations.
2) Adrenal Cortex
- Regulates _________________________________________
- Produces three different types of hormones:
1) Glucocorticoids
Most important of these: _________________
- Function is to increase
-
Increased glucose levels help with ___________________. Any amino
acids not converted are available for protein synthesis. Proteins are also
used for cell recovery.
2) Mineralocorticoids
Most important of these: ______________________
- Increases ___________________ and _____________________ by the
kidney; therefore maintaining body fluid levels.
- Remember Bio 20: The nephron!!!
3) Small amounts of sex hormones known as ___________________
The Pancreas

Hormonal Regulation of Blood Sugar
o As part of ____________________, the body keeps your body glucose
concentration within a acceptable range.

Contains 2 types of cells:
- One type produces digestive enzymes (exocrine glands). Studied these in
Biology 20.
- Second type produces hormones (endocrine glands). We will be focusing
on these cells in Biology 30.
The hormone producing cells of the pancreas are the islets of Langerhans.
There are two types of islet cells:
1)

2)

Islet cells produce two hormones:
1) INSULIN
2) GLUCAGON

Summary diagram

Negative Feedback Loops
Diabetes
1)
Diabetes Mellitus
o Diabetes mellitus is a genetic disorder associated with
_______________________________________________.
o Without adequate insulin, blood sugar levels tend to _______ sharply
following meals.
o Diabetes mellitus is also called ____________________ , meaning too
much sugar.
(____________________ – too little sugar)
o Symptoms include:
-________________________ .
Even though there is a lot of glucose in the blood, since there are
inadequate amounts of insulin, the cells of the body are unable to
become _______________________. As a result there are ______
levels of glucose in the body cells. Cells of diabetics are often
starved of energy and as a result their bodies turn to
________________ to metabolize
o There are two forms of diabetes mellitus:
1) Type I diabetes/____________________________
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Caused by early degeneration of the ________________.
Only treated by _________________________.
Symptoms occur suddenly before the age of _____ when there is
insufficient production of insulin.
Can lead to
_____________________________________________________
___________________________________________
Run the risk of becoming _________________(low blood sugar
levels), if they inject too much insulin or do not eat enough
carbohydrates. This is why they should always carry candies or
sources of sugar in case of this. This can lead to death.
2) Type II diabetes/ ______________________________
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Occurs mostly after age _______.
These people are often _______________ and account for ______
of the known cases of diabetes mellitus.
These people have abnormally _______________________ on
target tissues, but the level of insulin is normal in their bodies.
Because of this, the cells of these individuals literally starve, they
may eventually suffer from brain damage and even death if the
condition goes untreated.
When sugars cannot be utilized, more _______ are mobilized
resulting in more ____________ in the blood. When the ketones
accumulate faster than they can be used, the blood pH drops,
resulting in _________________ and ketones begin to spill into the
urine. This severe condition can lead to coma or death.
Can be treated with oral drugs called sulfonamides.
The Thyroid
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Located at
Double lobed.
Produces THYROXINE –

Hypersecretion of thyroxine:

Hyposecretion of thyroxine:

Negative Feedback Loop

The thyroid also produces a hormone called _____________________.
The Parathyroid
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There are ________ parathyroid glands located within the thyroid.
Produce ______________________________________.
PTH promotes ________________________________________________
PTH also promotes ____________________________________________
Feedback Loops
Draw feedback loops for the following hormonal systems:
1. Stress Hormones (cortisol)
2. Blood sugar regulators (insulin/glucagon)
3. Metabolism (thyroid)
4. Growth Regulators (hGH)
5. Water regulators (ADH, aldosterone)
6. Calcium regulators (PTH, calcitonin)
7. Circadian cycle (melotonin)
L) Dysfunctions of the Endocrine System
1) Anterior Pituitary
hGH
Dwarfism
Gigantism
Acromegaly
2) Posterior Pituitary
ADH
Diabetes Insipidus
3) Thyroid Gland
Thyroxine
Cretinism
Adults with Hypothyroidism (Myxedema)
Adults with Hyperthyroidism
Graves’ Disease
Goitre
4) Pancreas
Insulin
Diabetes Mellitus Type I
Diabetes Mellitus Type II