Biology 3201
Unit 1
Endocrine System
Questions
Instructions:
1.
Complete each question as indicated. Use your book – chapeter 13
to help you. Either type your answers in Microsoft Word format or
write them on “plain” paper and scan it.
What are tropic hormones? Give an example of a tropic hormone and describe its
actions.
Tropic hormones are hormones that direct the actions of other hormones. An
example would be TSH. It directs the actions of Thyroxine.
2.
A child shows abnormal growth of bone tissue causing extra long legs and arms.
What is the probable cause of this condition and give two ways it can be treated?
The probable cause of this condition is a hypersecretion of HGH caused by a
problem with the anterior pituitary. This can be caused by a tumor etc. Two
ways to treat it is to use a) HGH blocking drugs or b) radiation treatment on
the pituitary to help cut down on amount of HGH being produced.
3.
Explain how a hormone knows which target cell it is intended to act upon.
A hormone knows which target cell it is intended to act upon because of the
Lock and Key system. Different cells recognize different hormones and only
certain hormones can fit the receptors of certain cells.
4.
How might a pancreatic islet cell transplant be more advantageous than daily
injections of insulin in treating type I diabetes?
This is most beneficial for a number of reasons. A few are listed.
No need for future insulin needles. This eliminates cost as well as
possible infections and side effects from using synthetic insulin. This
would allow someone to live a normal life.
Convenience. The person who receives this transplant does not need to
constantly think about modifying their diet and/or remembering to take
medication. Again, see above.
There is no fear of rejection. Since the person received stem cells there is
no fear of rejection as is associated with other transplants.
The solution is permanent unless disease strikes.
5.
In what three ways does the response of a nerve differ from the response of a
hormone?
They differ in the following ways:
Speed of Response
Type of Response
Duration of Response
6.
Nervous System
Very Fast
Electrical
Short
Endocrine System
Slow Acting
Chemical
Long
How is solubility of steroid hormones related to their function?
The solubility of a hormone relates to its function in that it either dictates
whether the action of the hormone is carried out on the surface or inside a cell.
In the case of steroid hormones, they are soluble in the cell membrane. This
allows them to pass directly into the cell where the hormone is able to carry out
its function. Non-steroid hormones are unable to dissolve in fat and cannot
cross the cell membrane. Because they cannot cross the cell membrane the site
of their action is located on the surface of a cell only.
7.
Define Hormone and Target Cell.
Hormone Æ A chemical messenger found within the blood stream of the
endocrine system. Hormones are either steroid or non-steroid in
nature.
Target cell Æ The cell on which a hormone carries out its action.
8.
Compare exocrine glands with endocrine glands.
Exocrine glands are glands that have ducts. Hormones are secreted into these
ducts from the gland.
Endocrine glands are “ductless” glands. Hormones from the gland are dumped
directly into the blood.
9.
Explain the differences in the way non-steroid hormones and steroid hormones
carry out their actions.
Steroid hormones carry out their actions by passing through the cell membrane.
When they pass through the cell membrane they bind with a protein receptor
complex within the cytoplasm. The hormone-receptor complex then travels to
and enters the nucleus. The complex causes a gene in the DNA to create an
enzyme that carries out several other reactions within the cell.
Nonsteroid hormones carry out their action on the surface of cells. When these
hormones reach the surface of cells they bind with the receptor. A hormone
receptor complex is created. This complex immediately causes the conversion of
ATP into cAMP. cAMP then causes a cascade of reactions within the cytoplasm
of the cell.
10.
How do feedback mechanisms help maintain homeostasis?
Feedback mechanisms help maintain homeostasis by trying to return the bodies
systems back to a normal range. For example, normal blood glucose levels are
between 75 – 100 mg/ml of blood. Whenever blood sugar levels rise or fall
below this normal range, the body responds to correct the imbalance and return
it to normal. This is what homeostasis is all about.
11.
Explain why glucagon and insulin are antagonistic hormones.
Glucagon and Insulin are antagonistic hormones because they carry out
opposite effects in the body. Insulin lowers blood sugar levels while glucagons
raises blood sugar levels.
12.
What is the function of the endocrine system?
The endocrine system acts as a control system in order to maintain homeostasis.
The endocrine system uses slow acting, long lasting chemical messengers
known as hormones to respond to stimuli. The purpose is to maintain a stable
internal environment in the human organism.
13.
Explain why the pineal gland is considered the "biological clock" of the body and
why the pituitary gland is considered the "master gland" of the body.
The pineal gland is considered the biological clock of the body because it
secretes Melatonin. Melatonin is responsible for telling the body when to go to
sleep or wakeup. If there is a lot of melatonin in the blood, this signals the brain
to go to sleep and vice versa. The pituitary is considered the master gland
because it secretes many hormones and these hormones work to control several
other glands/organs within the human body.
14.
Describe the malfunctions that cause Type I and Type II diabetes.
The malfunctions that cause Type 1 diabetes is the beta cells located within the
Islets of Langerhans of the Pancreas. In this case the beta cells have stopped
producing insulin. This results in high amounts of glucose in the blood because
insulin is needed in order to convert the glucose in the blood into glycogen.
Type II diabetics have a malfunction where their cells are unable to recognize
the insulin being made by the pancreas. As such, high amounts of glucose
remains in the blood because the cells are unable to use it.
15.
Explain the role of Adrenaline in relation to short term stress.
Adrenaline works with the sympathetic nervous system to prepare the body for
emergencies by doing the following:
a. Increasing heart rate.
b. increasing breathing rate
c. shuts down digestion
d. increases conversion of glycogen into glucose (liver does this)
e. dilates pupils
16.
Describe the role Banting and Best played in the discovery of Insulin.
Banting and Best worked together and discovered Insulin. Banting discovered
that certain cells within a pancreas called Islet cells were the key to helping
organisms use glucose found in the blood. These cells were discovered to help a
person from getting diabetes. Banting and Best worked together on dogs to
extract secretions from islet cells of healthy dogs and use it to treat dogs that
had diabetes. They discovered that dogs having diabetes could be treated with
secretions from dogs without diabetes. They eventually purified the extract and
tested humans. They called the extract insulin and it is used today to treat
diabetics the world over.