NURS 102 3(B) Assignment #5
Shawn Limber
June 13, 2012
Endocrine System
1. Differentiate between endocrine and exocrine glands.
The secretary processes of the endocrine and exocrine glands are vital to
communication and regulation for normal functioning and development to occur.
However both glandular systems produce, distribute and function very differently.
The endocrine glands releases hormones directly into the bloodstream, this is a
ductless system that circulates within intercellular spaces. Hormones in the glands are
distributed through out the body in the blood are attracted and bind to target organ
cells, that generate a chemical process that controls metabolic functions such as,
electrolyte balance and acid base stability, and initiates and regulates reproduction
and development. Feedback loops play a regulatory role in the management of
endocrine function. Major endocrine glands in the body include: the pituitary,
thyroid, pineal, adrenal, and thymus glands, the pancreatic islets and the ovaries and
testes.
The secreting cells within the exocrine glands are arranged into tubules that form
ducts and open onto a surface. Watery, or waxy chemical substances are produced
within the glands and eliminated onto or into a surface. Saliva and sweat are
examples of exocrine gland regulatory functions as are digestive juices. An organ that
has both the endocrine and exocrine glands functioning closely is the pancreas.
Within the pancreas the endocrine glands, or pancreatic islets function closely with
the exocrine cells in the pancreatic duct. Exocrine glands are not part of the endocrine
system, as seen clearly in the pancreas, endocrine glands secrete and transport
intercellularly in blood through veins, and exocrine cells secret and transport through
ducts. However the fact that these systems work closely together is evident in
hormone testing which is often done through saliva or other secretions of the exocrine
system.
2. Define or explain the following terms: hormone, target organ, hypersecretion, and hypo-secretion.
Hormones are chemical couriers within the body that are produced and secreted in the
endocrine glands and circulated within the blood stream. They initiate and control
almost all bodily functions from mood to food metabolism. Once in the blood system,
hormones bind to specific receptor cells called target organ cells within their
designated organs. The makeup or design of each type of hormone is specific to the
organ that it interacts via the receptor sites within or on the wall of the cell. Hormone
balance is the key to homeostasis, this balance is affected when glands become
diseased and malfunction creating an overproduction of hyper-secretion of a hormone
or insufficient or hypo-secretion of a hormone. Hormone secretion is most often
regulated by a negative feedback loop, chemicals are distributed within the system
that indicate the need for decreased productivity, based on the amount of the hormone
being produced the system regulates a negative production of a substance and keeps
the balance in check. However hypo or hyper secretion upsets this balance and will
affect hormone production and produce illness. Target cells malfunction can cause
imbalances within the endocrine system. Diabetes is an example of the effects hyposecretion that is sometimes the result of poor target cell reception or desensitization.
3. Explain why a secondary system is needed for non-steroid hormones but not
for steroid hormones
Steroid hormones are lipid soluble hormones that can go through a cell membrane
and directly to the nucleus, there it acts directly upon DNA to produce a new protein
within the cytoplasm. The newly formed protein then produces the designed affect in
the target cell. Non-steroid hormones or protein hormones communicate with target
cells indirectly; the process occurs in two phases and includes activation enzymes for
communication. The first phase the hormone connects with a membrane receptor in
the cell wall. This process is referred to as the first message, where the hormone fits
the receptor like a key fitting a lock. Chemical reactions follow the interplay between
the hormone and the receptor; molecules are activated within the cytoplasm. The
second messenger is the means of communicating with the target cell. The process of
impacting DNA directly takes place over a longer period of time, although the nonsteroid communication requires a first and second messenger the reaction within the
target cell is actually faster.
4. Pick a body function (regulation of glucose or calcium levels in the blood)
and explain how the interaction of hormones is used to help maintain
homeostasis.
Blood sugar regulation is a very important body function, and a homeostatic priority for
the body, without this balance a persona could present with diabetes or hypoglycemia or
another form of sugar related illness. The two major regulating hormones in blood sugar
balance are insulin and glucagon; both of these hormones are produced in the pancreas.
When glucose levels are low, the pancreas secretes the hormone glucagon which binds to
target cells in the liver and stimulates the release of glucose into the blood, thereby
balancing the blood glucose level. When the pancreas determines glucose levels to be
high, insulin is released into the bloodstream. There it accelerates the movement of
glucose into cell walls to be absorbed by organs such as the liver and other tissues that
are activated to metabolize glucose at a higher rate. This process removes the glucose
from the blood and returns the blood glucose levels to normal. During this process of
intense glucose metabolism if levels get low again then glucagon or another glucose
producing hormone would be produced to balance out the effects upon the blood. In this
process the hormones released from the pancreas work antagonistically to balance blood
glucose concentration
Reference:
Thibodeau, G. Patton, K. (2010) The endocrine system, The human body in health
and disease (5th ed. pp64-65, 309,-332,) St. Louise Missouri, Mosby Elsevier
http://www.nlm.nih.gov/medlineplus/hormones.html
Norman, J. (2011) Norman regulation of blood glucose, endocrine web,
http://www.endocrineweb.com/conditions/diabetes/normal-regulation-bloodglucose