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Chemical Aspects of Physiology
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Homeostasis it the body's ability to regulate its inner environment in response to the outside environment. It is a state of equilibrium for the body.
Homeostasis allows the the organs of the body to function effectively in a broad range of conditions. An example of this is the body's reaction to increased or
Most homeostasis regulations is controlled by the body's release of many different hormones into the bloodstream, but some regulation rely on a
process of simple diffusion to maintain the body's parameters of equilibrium.
Some of the body reactions for homeostasis include: Blood composition, blood sugar regulation, fluid balance and sleep timing.
An inability to maintain homeostasis may lead to disease or even death.
Homeostasis applies to me personally in my present career and will play an even bigger role in my profession after my education is complete. I
presently work as a telemetry tech in the CCU unit at our local hospital. I monitor the heart rhythms of very ill patients. The rhythms change with any
inability of the body to maintain homeostasis. After my education is complete, I hope to continue to work in the intensive care unit as a RN. In this
role, I will need to be alert to the different lab values a patient has, and what they mean. The labs test show different hormone levels, indicating what types of
homeostasis or homeostatic imbalances are occurring in the body.
Control mechanisms for Homeostasis
Control mechanisms of homeostasis have at least three components for the system being regulated. A receptor that senses a stimuli is needed, the control
center that determines the right response to the stimuli, and the effector that the control center sends the signal to. The effectors can be a muscle, organs or
other structures that receive the messages that a reaction is needed.
Positive feedback is the body's mechanism to enhance a output needed to maintain homeostasis. Positive feedback mechanisms push levels out
of normal ranges. Even thou this process can be beneficial, it is rarely used by body because of the risk of the increased stimuli becoming out
of control. An example of positive feedback is the release of oxytocin to increase and keep the contractions of child birth happening as long as needed
for the child's birth.Contractions of the uterus are stimulated by Oxytocin, produced in the pituitary gland, and the secretion of it is increased by positive
feedback, increasing the strength of the contractions.
Negative feedback works in the opposite way that positive feedback does. With negative feedback, any change from the normal range of function,
causes the negative feedback mechanisms to resist or oppose the change, bringing the function back to normal ranges.
Negative feedback requires a receptor, a control center, and a effector. The receptors are connected to the control center within the brain. When the brain
receives information that there is a deviation in the body's internal condition, it sends out a signal along nerve lines that prompt the changes
to bring the internal conditions back to normal ranges.
A good example of a negative feedback loop is the body's internal thermometer. When the temperature drops or raises above the range of the
set temperature, the body will initiate a homeostatic response. Some of these responses include sweating to cool down, and shivering
to warm up.
Another good example, is the regulation of blood pressure. Blood vessels can sense resistance of blood against the walls when blood pressure increases.
They in turn send a message to brain, which sends a message to the heart , which is an effector. The heart rate will decrease, changing the blood
pressure back to its normal range.
Another very important example of a negative feedback loop is the blood sugar regulation.
The body requires volumes of sugar to create ATP. ATP transports chemical energy within the cells. The body regulates the availability
of glucose to maximize its energy potential.
Hormones responsible for controlling the glucose in the blood are insulin and glucagon.The pancreas is responsible for monitoring glucose levels,
and sending messages to the receptors of the liver that more insulin or glucagon is needed.
The liver is the place for storage of glycogen, the storage form of glucose. When either of these hormones target the liver either insulin is released
as a result of increased glucose levels, and promotes the conversion of glucose into glycogen, or glucagon is released as a result of a decrease
in glucose, and therefore promotes the conversion of glycogen into glucose.
Human Physiology, Stuart Ira Fox
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