C.+HOMEOSTASIS

__Homeostasis __
**Homeostasis** is the regulation and maintaining of the body's internal environment. The levels need to be controlled so that the body can function properly, for example enzymes work at optimum temperatures/ pH levels around the body, so in order to function the internal environments must be controlled. It is essential that insulin and other molecules be regulated because your body can’t function if they are not. If you have too much insulin you will become sick and if homeostasis is not restored you will die.

Found a great power point presentation on YouTube.com its just over 6min. but if you have the time it does a nice job breaking down the ways our bodies maintain homeostasis such as thermoglobulation, control of blood glucose levels, osmoregulation, removal of nitrogenous waste, and an interesting section on the secretion of ammonia in fish. Enjoy the presentaion! media type="youtube" key="qDjTKCTvRJo?fs=1" height="385" width="480"

===Describe negative feedback and how insulin is controlled by a negative feedback inhibition. Why is it essential that insulin and other molecules be regulated ===



According to [], negative feedback is defined as occurring “when the output of a system acts to oppose changes to the input of the system; with the result that the changes are diminished. “ If the overall feedback of the system is negative, then the system will tend to be stable. Negative feedback is basically reversing a change in the body to maintain homeostasis. []

Insulin is controlled by a negative feedback loop. This means that if your body detects that your blood is low in glucose, it will release glucagon which will allow the liver to release stored glycogen into the blood stream; once the level to maintain homeostasis is met the body will stop the release of glucagon to prevent hyperglycemia. The opposite occurs when you have too much glucose in your blood; insulin will be release by beta cells from the Islets of Langerhans in the pancreas and the body will store the excess glucose in the liver to be stored as glycogen for future use or in fat cells which will also be used if needed in the future. This all happens involuntarily in order to maintain a narrow window of sugar in the blood. The normal range of glucose in the blood is 80-110mg/100ml. Glucose is the source of energy that our bodies use for energy and must be maintained in order to prevent complications. It is essential that blood glucose is maintained in order to prevent complications. Hyperglycemia is a complication of too much sugar in the blood and is more common in those who have diabetes. The body is not releasing insulin which is needed to get the glucose into the blood and into the cells, so they can use it for energy (basically your cells are starving without the glucose).

Sources: Fox, Stuart Ira. (2009). //Human Physiology//. New York, NY: McGraw-Hill.  Comerford, Karen and Donofrio, Jo. (2006). //Pathophysiology Made Incredibly Easy//. New York, NY:Lippincott Williams & Wilkins.

= CHAPTER 1 = =Chapter 1 is mainly over the Scientific Method starting with explaining a hypothesis and a theory and how to test that theory. The History of Physiology,The Homeostasis and Feedback Control which consists of Negative Feedback Loops, Positive Feedback, The primary muscle tissues, consisting of Muscle, Nervous, Epithelial and Connective. Chapter 1 also talks about organs and the systems. I am going to go over 3 main concepts on this page for Homeostasis. The key points I am going to talk about are: Homeostasis and Feedback Control and also The different Tissues.=

PHYSIOLOGY The study of biological function of how the body works, from cell to tissue, tissue to organ, organ to system, and of how the organsim as a whole accomplishes particular tasks that are essential for life. The word Physiology comes from the Greek word //physis//,which means nature and //logos//, which means study.

HOMEOSTASIS The regulatory mechanisms of the body that are shared by a single function which is maintaining constancy of the internal environment. Homeostasis is maintenance of a state of dynamic constancy which is regulated with Negative Feedback Loops.

Negative Feedback Loops consists of senors, integrating centers and effectors. Negative Feedback Loops play major parts in controlling Blood Pressure, body temperature, and blood sugar levels. Example of this would be your house thermostat. If the thermostat is set at 70 degrees Farenheit (set point) and the temperature of the house rises above that set point, the sensor of the thermostat will detect this (deviation) and will then send this information to the integrating center to activate the effector. In this case the effector may be an air condition that will react to reverse the rise in temperature and maintain the 70 degrees F, which is the set point. Below is an image of the 3 steps that occur to maintain homeostasis by a negative feedback loop.
 * ** Sensors: **the body has sensors to detect the deviation from the normal or set point.
 * ** Integrating Centers: **these centers are found more often in a particular region of the brain or spinal cord but can also be a group of cells in an endocrince gland. These centers recieve the information from the sensor.
 * ** Effector: **the effector responds to this information with either increasing or decreasing the activity and the effectors are generally found in the muscles or glands.
 * ** Antagonistic Effectors: **Effectors that are described as the "push-pull" where the increasing activity of one effector is accompanied by decreasing activity of an antagonistic effector. This consists of more control where you would switch one effector on and off. Ex. turning the AC or heater on or off.



Positive Feedback Loop Positive Feedback Loop also plays a part in Homeostasis in which it is the opposite of the negative feedback loop. With a positive feedback loop the action of the effector will amplify the changes that stimulated the effectors. Positive feedback loop plays parts in producing blood clots, ovulation and the uterus and oxytocin secretion during labor.

=__//** THE PRIMARY TISSUES **//__=
 * 1) ===**Muscle Tissue**===
 * 2) ===**Nervous Tissue**===
 * 3) ===**Epithelial Tissue**===
 * 4) ===**Connective Tissue**===

** MUSCLE TISSUE **
There are 3 types of muscle tissue: skeletal, cardiac and smooth.

__Skeletal Muscle__

 * =====**Also known as VOLUNTARY muscle because it is consciously controlled.**=====
 * **Striated, which are striations or stripes that extend across the width of the muscle cell.**
 * **Generally attached to bones at both ends by means of the tendson that produces contraction to promote movement of the skeleton, except for the tongue, superior portion of the esophagus, anal sphincter and diaphragm that do not produce movement of the skeleton**
 * **Myoblasts fuse together to form skeletal muscle fibers (myofibers) that are each a syncytium. These fibers fuse together to make bundles that extend parallel from one end to the other so they can be controlled individually, so a person contracts fewer or more muscle fibers to vary the strength of contraction of the whole muscle. This strength is needed for precise control of skeletal movemen[[image:rolstada:skeletal_muscle.jpg width="185" height="142" caption="skeletal_muscle.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DSkeletal%2Bmuscle&w=640&h=480&imgurl=www.uic.edu%2Fclasses%2Fbios%2Fbios100%2Flabs%2Fskeletal_muscle.jpg&rurl=http%3A%2F%2Fwww.uic.edu%2Fclasses%2Fbios%2Fbios100%2Flabs%2Fcelllab.htm&size=219KB&name=Human+Skeletal+M...&p=Skeletal+muscle&oid=6e0002c13640ae56a31aed917fffea9f&fr2=&no=3&tt=94600&sigr=11o7h7t2u&sigi=11pkhq6lk&sigb=11uhqkl46"]]**

__ Cardiac Muscle __

 * **Have myocardial cells that are short, striated and involuntary. They are branched to form a continuous fabric. Have intercalated discs between cells.**
 * **NOT individually controlled.**
 * **"Wholehearted" contraction. The way the heart is constructed, the stimulation of one myocardial cell results in the stimulation of all the cells in the mass.**

__ Smooth Muscle __

 * **NOT STRIATED**
 * **Involuntary**
 * **Found in digestive tract, blood vessels, bronchioles which are the small air passages of the lungs, and the ducts of the urinary and reproductive systems.**
 * **Have circular arrangements that produce constriction the the //lumen (cavity) when the muscle cells contract.//**
 * **Have longitudinal layers of muscle called peristalsis that pushed food from one end of the digestive tract to the other.**

** NERVOUS TISSUE **
Consists of: Neurons, Supporting or Glial cells.
 * __**Neurons**__: conduction of electrical events. Consist of 3 parts as shown below.
 * 1) Cell Body - contains the nucleus and serves as the metabolic center of the cell.
 * 2) Dendrites - "branches". Highly branched cytoplasmic extensions of the cell body that recieve input from other neurons or from receptor cells.
 * 3) Axon - single cytoplasmic extension of the cell body that can be as long as a few feet in length. Specialized for conduction nerve impulses from the cell body to another neuron or tan an effector (muscle or gland) cell. [[image:rolstada:Nervous_Tissue.jpg width="242" height="153" caption="Nervous_Tissue.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DNervoius%2Btissue%26fr2%3Dsg-gac-sy&w=640&h=480&imgurl=www.hartnell.edu%2Ffaculty%2Faedens%2FBio6L%2FWebNervous.jpg&rurl=http%3A%2F%2Fwww.hartnell.edu%2Ffaculty%2Faedens%2FBio6L%2FBio6Lnervous.html&size=463KB&name=Nervous+Tissue.&p=Nervoius+tissue&oid=b699f785c89f5838021123c758112bb0&fr2=sg-gac-sy&spell_query=Nervous+tissue&no=2&tt=61500&sigr=11uorqmh8&sigi=11kccmok4&sigb=12c4phhic"]]


 * __**Supporting cells**__- provide anatomical and functional support. Supporting cells in the brain and spinal cord are often called //neurologlial// or //glial cells.//

Functions of supporting cells:

 * 1) Do not conduct impulses but they do serve to bind neurons together.
 * 2) Modify the extracellular environment of the nervous system.
 * 3) Influence the nourishment and electrical activity of neurons.
 * 4) Five times more abundant than neurons.
 * 5) Maintain a limited ability to divide by mitosis throughout life.

Epithelial Tissue
Epithelial membranes are classified according to the number of layers the membrane has and the shape of the cells in the upper layer. Simple membranes are one layer thick. Stratified membranes are a number of layers. Explained below are the different types.
 * **Consist of cells that form membranes that cover and line the body surfaces, and of glands, that are derived from these membranes. There are two types of glands; exocrine (outside) and endocrine glands (inside).**
 * 1) __** Exocrine glands **__: secrete chemicals through a duct that leads to the outside of a membrane and thus to the outside of a body surface. Derived from epithelial membranes. Secretions are passed to the outside of the epithelial membranes to the surface of the body through ducts. the secretory units may be simple tubes or may be modified into clusters that are called acini which that form around branched ducts and are often surrounded by tentacle-like extensions of myoepithelial cells that contract and squeeze the secretions throught the ducts. Examples of exocrine glands are: lacrimal (tear) glands, sebaceous glands (secrete oily sebum into hair follicles), and sweat glands.
 * 2) __** Endocrine glands **__: secrete chemicals called hormones into the blood.
 * Squamous: epithelial cells are flattened.
 * Columnar: epilithelial cells are more tall than wide.
 * Cuboidal: epithelial cells are cube-shaped.
 * There are many different types of squamous epithelial membranes. Listed below are a few of the different types, their functions and their location.**
 * 1) __** Simple squamous epithelium **__: single layer of flattened, tightly bounded cells; diffusion and filtration. Located in the capillary walls; pulmonary alveoli of lungs; covering visceral organs; linings of body cavities.[[image:rolstada:simple_squamous.jpg caption="simple_squamous.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DSimple%2Bsquamous%2Bepithelium%26b%3D21%26ni%3D20%26xargs%3D0%26pstart%3D1%26fr2%3Dsg-gac-sy&w=700&h=467&imgurl=www.stegen.k12.mo.us%2Ftchrpges%2Fsghs%2Fksulkowski%2Fimages%2F10_Simple_Squamous_Apical_Epithelial_Tissue.jpg&rurl=http%3A%2F%2Fwww.stegen.k12.mo.us%2Ftchrpges%2Fsghs%2Fksulkowski%2FTissueSlides.htm&size=109KB&name=Simple+Squamous+...&p=Simple+squamous+epithelium&oid=732dc0269f408d8fdb6f6fd10279e931&fr2=sg-gac-sy&no=28&tt=2910&b=21&ni=20&sigr=125g23hk5&sigi=134os0mq8&sigb=13j2vpe5e"]]
 * 2) **__ Simple cuboidal epithelium __**: single layer of cube-shaped cells; excretion, secretion and absorption. Located on the surface of the ovaries; linings of kidney tubules, salivary ducts, and pancreatic ducts.[[image:rolstada:simple_cuboidal.jpg width="181" height="145" caption="simple_cuboidal.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DSimple%2Bcuboidal%2Bepithelium%26fr2%3Dsg-gac-sy&w=800&h=600&imgurl=www.technion.ac.il%2F%7Emdcourse%2F274203%2Fslides%2FEpithelium%2F2-Simple%2520Cuboidal%2520Epithelium%2520A.jpg&rurl=http%3A%2F%2Fwww.technion.ac.il%2F%7Emdcourse%2F274203%2Flect2.html&size=83KB&name=Epithelium+Simpl...&p=Simple+cuboidal+epithelium&oid=2438601ec8f0de4711e77e0819da77b3&fr2=sg-gac-sy&no=1&tt=560&sigr=11lq18br6&sigi=12ucu6sjj&sigb=12nkq06p8"]]
 * 3) __** Simple columnar epithelium **__: single layer of nonciliated, tall, column shaped cells; transportive role through ciliary motion. Is located in most of the digestive tract.[[image:rolstada:20_Simple_Columnar_Epithelial_Tissue.jpg width="365" height="171" caption="20_Simple_Columnar_Epithelial_Tissue.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DSimple%2Bcolumnar%2Bepithelium%26b%3D21%26ni%3D20%26xargs%3D0%26pstart%3D1%26fr2%3Dsg-gac-sy&w=700&h=467&imgurl=www.stegen.k12.mo.us%2Ftchrpges%2Fsghs%2Fksulkowski%2Fimages%2F20_Simple_Columnar_Epithelial_Tissue.jpg&rurl=http%3A%2F%2Fwww.stegen.k12.mo.us%2Ftchrpges%2Fsghs%2Fksulkowski%2FTissueSlides.htm&size=90KB&name=Simple+Columnar+...&p=Simple+columnar+epithelium&oid=c94f562a1f9e8224e3b0cfe641a249ff&fr2=sg-gac-sy&no=29&tt=3670&b=21&ni=20&sigr=125g23hk5&sigi=12tdqqek1&sigb=13jklqq5v"]]
 * 4) **__ Stratified squamous epithelium (keratinized) __**: numerous layers containing keratin, with outer layers flattened and dead. Serves as protection. Found in the epidermis of the skin. [[image:rolstada:squamous.jpg width="374" height="165" caption="squamous.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DStratified%2Bsquamous%2Bepithelium%2B%2528keratinized%2529%26fr2%3Dsg-gac-sy&w=474&h=523&imgurl=www2.victoriacollege.edu%2Fdept%2Fbio%2FAPTissue%2Fepithelial%2FStrSqKerScan.jpg&rurl=http%3A%2F%2Fwww2.victoriacollege.edu%2Fdept%2Fbio%2FAPTissue%2Fepithelial%2FStratSquKer.html&size=18KB&name=...+-+stratified...&p=Stratified+squamous+epithelium+%28keratinized%29&oid=dc34cd4251e9de38e784a62d485761ad&fr2=sg-gac-sy&no=4&tt=288&sigr=12d33deqd&sigi=1265vescs&sigb=13dn0804a"]]
 * 5) **__ Stratified squamous epithelium (non-keratinized) __**: numerous layers lacking keratin, with outer layers moistened and alive. Serves as protection and pliability. Found in linings of oral and nasal cavities, vagina and anal canal. No picture available to upload at this time.

**Other information related to epithelial membranes:**

 * Cover all body surfaces and line the cavity of every hollow organ.
 * Provide barrier between the external environment and internal environment of the body.
 * Simple epithelia are specialized so substances to get into the body by passing through an epithelial membrane.
 * Goblet cells are dispersed among the columnar epithelial cells and are specialized unicellular glands that secrete mucous.
 * The columnar epithelial cells in the uterine tubes (fallopian) of females and in the respiratory passages contain cilia that move in a coordinated fashion and aid the functions of these organs. Cilia: hairlike structures.
 * Keratinized (cornified)- The epidermis of the skin is keratinized because it is dry and exposed to the potentially desiccating effects of the air, the surface is covered with dead cells that are filled with a water-resistant protein known as keratin. The protective layer is constantly flaking off from the surface of the skin and must be constantly replaced by the division cells in the deeper layers of the epidermis. The entire epidermis is completely replaced every 2 weeks, whereas the stomach lining is renewed every 2-3 days.
 * Nonkeratinized- consists of all living cells.

** CONNECTIVE TISSUE **
Characterized by large amounts of extracellular material between the different types of connective tissue cells. The extracellular material is called the connective tissue matrix that varies in four primary types of connective tissue: 1. Connective tissue proper. 2. Cartilage. 3. Bone. 4. Blood. >
 * 1) Connective tissue proper: the matrix consists of protein fibers and a proteinaceous, gel-like substance that is divided into sub-types.
 * __** Loose connective tissue **__: also known as areolar connective tissue. protein fibers are composed of collagen and are scattered loosely in the ground substance which provides space for the presence of blood vessel, nerve fibers, and other structures. Adipose tissue (adipocytes) is a specialized type of loose connective tissue where the cytoplasm is stretched around a central globule of fat. The synthesis and breakdown of fat are accomplished by enzymes within the cytolasm of the adipocytes. Image shows adipose tissue. [[image:rolstada:Adipose.jpg width="349" height="136" caption="Adipose.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DLoose%2Bconnective%2Btissue&w=800&h=600&imgurl=clcpages.clcillinois.edu%2Fhome%2Fbio567%2Fpages%2Fnewtissues%2FAdipose%252004a.jpg&rurl=http%3A%2F%2Fclcpages.clcillinois.edu%2Fhome%2Fbio567%2Fpages%2Fnewtissues%2Fadiposeconnectivetissue.htm&size=85KB&name=Adipose+Connecti...&p=Loose+connective+tissue&oid=8bc4faaab6a3fa89cc2ad02b3cbcb7ff&fr2=&no=1&tt=3350&sigr=12o9imnb8&sigi=1276fv8t3&sigb=126p3l1lu"]]
 * __** Dense regular connective tissues **__: collagenous fibers are parallel to each other and densely packed in the extracellular matrix, leaving very little room for cells and ground substance. Examples of these tissues are tendons and ligaments.[[image:rolstada:35_Dense_Regular_Connective_Tissue.jpg width="597" height="167" caption="35_Dense_Regular_Connective_Tissue.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DDense%2Bregular%2Bconnective%2Btissues%26fr2%3Dsg-gac-sy&w=700&h=467&imgurl=classes.midlandstech.com%2Fcarterp%2FCourses%2Fbsr%2F210_gallery%2Fimages%2F35_Dense_Regular_Connective_Tissue.jpg&rurl=http%3A%2F%2Fclasses.midlandstech.com%2Fcarterp%2FCourses%2Fbsr%2F210_gallery%2Fpages%2F35_Dense_Regular_Connective_Tissue.htm&size=77KB&name=35_Dense_Regular...&p=Dense+regular+connective+tissues&oid=ddc20f4ea8d9e5cc4f476b1670db81b6&fr2=sg-gac-sy&no=3&tt=288&sigr=13cer2n4g&sigi=1368fano5&sigb=12tvmllaq"]]
 * **__ Dense irregular connective tissues __**: form tough capsules and sheaths around organs and contain densely packed collagenous fibers arranged in various orientations that resist forces applied from different directions.[[image:rolstada:Dense_Irregular.jpg width="196" height="144" caption="Dense_Irregular.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3Ddense%2Birregular%2Btissue&w=640&h=480&imgurl=bcrc.bio.umass.edu%2Fhistology%2Ffiles%2Fimages%2FIrregular%2520connective%2520tissue.preview.jpg&rurl=http%3A%2F%2Fbcrc.bio.umass.edu%2Fhistology%2F%3Fq%3Dnode%2F1115&size=86KB&name=Dense+Irregular+...&p=dense+irregular+tissue&oid=43e29c8985d943986c0f62ee89c34977&fr2=&no=6&tt=1700&sigr=11g6gcmnu&sigi=12l510abh&sigb=125kf0bk9"]]
 * 1) **__ Cartilage __**: consists of cells called chondrocytes surrounded by the semisolid ground substance that imparts elastic properties to the tissue. Type of supportive and protective tissue called "gristle" that forms the precurser to many bones that develop in the fetus and persists at the joint surfaces on the bones at all moveable joints in adults.[[image:rolstada:Cartilage.jpg caption="Cartilage.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DCartilage%2Btissue%26ei%3Dutf-8%26y%3DSearch&w=640&h=480&imgurl=bcrc.bio.umass.edu%2Fhistology%2Ffiles%2Fimages%2FHistology%2520Lab%25203.2_0.preview.JPG&rurl=http%3A%2F%2Fbcrc.bio.umass.edu%2Fhistology%2F%3Fq%3Dnode%2F1121&size=72KB&name=...+Cartilage+Co...&p=Cartilage+tissue&oid=9a0baf2ec01bc7d101835c2db4b1f29b&fr2=&no=8&tt=27100&sigr=11g1u1jjr&sigi=12da1vpom&sigb=12hktojf7"]]
 * 2) __** Bone **__: formed as concentric layers, or lamallae, of calcified material.
 * ==Osteoblasts: bone-forming cells.==
 * ==Osteocytes: trapped, inactive osteoblasts.==
 * ==Osteoclasts: the bone resorbing cells.[[image:rolstada:OVERALL_tissues.jpg width="618" height="675" caption="OVERALL_tissues.jpg" link="http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DHuman%2BBody%2BTissues&w=1052&h=878&imgurl=asweknowit.net%2Fimages_edu%2Fdwa5%2520tissues.jpg&rurl=http%3A%2F%2Fasweknowit.net%2FMIDDLE_SCH%2FDWA_1_%2520cells.htm&size=80KB&name=...+Tissue+lines...&p=Human+Body+Tissues&oid=898fd51df000f6c333b634988b10dcb4&fr2=&no=6&tt=45900&sigr=11jm41ppj&sigi=11c4mk69t&sigb=1213nenos"]]==

Sources:
Fox, Stuart Ira. (2009). //Human Physiology//. New York, NY: McGraw-Hill.

**Essential Questions**
Negative feedback is essential in maintaining homeostasis of the human body. Negative feedback consists of the sensor which detects the deviation from a set point then relays this information to the integrating center then goes to the effector which either increases or decreases the activity of the particular effector. When a persons blood sugar increases this stimulates the secretion of insulin and a lowering of BS caused by insulin's action prevents further insulin secretion. If insulin and other molecules were not maintained and regulated. The human body would not be able to function properly. For example, if a persons blood sugar increased and it could not be brought back to normal limits, the human body would be constantly showing reactions to this and in turn death would occur.
 * Describe negative feedback and how insulin is controlled by a negative feedback inhibition. Why is it essential that insulin and other molecules be regulated?**

__Application as a Nurse __
As a nurse I will need to understand how the body regulates things to maintain a stable medium or maintain homeostasis. An example of this would be when dealing with a patient with a diabetic condition. If a patient has a blood glucose level that is to high I would know that a shot of insulin is needed to return the patient to a healthy state.Now if the patient had a low blood glucose level I would know that insulin would not create a healthy homeostasis, but would rather cause serious harm and lower the blood glucose level even more.

Another way that a nurse should understand homeostasis is when the patient is under stress. Stress can cause symptoms such as rapid and shallow breathing, sweaty palms, muscle tension, dizziness, increased blood pressure as well as psychological effects like confusion, anxiety and depression. Excessive stress can also be related to diseases and disorders such as gastritis, asthma, HTN, cancer, eating disorders, sexual dysfunction and infection. When an individual us under more stress than the body can handle it can cause the immune system to weaken. This will cause the body to be vulnerable to invasion by pathogens. Knowing and understanding these symptoms, a nurse will be better able to understand and help treat her patient. The body will respond to long-term stress exposure by the general adaptation syndrome. The stages of this syndrome are the alarm stage, the stage of resistance, and the stage of exhaustion. In the alarm stage the body releases hormones to mobilize the body's defenses. Signs of this stage include slight temperature increase, decreased energy, anorexia, and malaise. In the second stage, the body is fighting for equilibrium. A prolonged length of time in this stage the body's response becomes maladaptive and pathologic conditions can occur. If the stress is severe enough or present long enough it can deplete the body's resources for adaptation, which is considered the stage of exhaustion and critical illness or death can occur. deWitt, Fundamental Concepts and Nursing Skills, Pg. 23-24

In my field of work as a nurse, it is very important to understand the body and how it is constantly attempting to maintain homeostasis. It is vital to understand how the body works and to be aware of changes in the body that can cause an adverse reaction to homeostasis, such as dehydration, arrhythmias, etc. For example, the kidneys play a vital role in homeostasis because they maintain a water and sodium balance in our blood; the kidneys remove excess water, salt, and waste products from the blood as the form of urine. If this did not occur, the blood in our bodies would be filled with waste products (urea) and our body cells would be filled with water, thus affecting the electrolyte balance of our blood (potassium and sodium). If the electrolytes potassium (3.5-5.0 mEq/L) and sodium (135-145 mEq/L) are not kept in their designated ranges in the blood, homeostasis is not met, complications such as dysrythmias, muscle weakness, cramps, confusion, and even death are likely to occur.

Working as a nurse it is important to understand how the body controls homeostasis. One example I think is important is our bodies ability to maintain a normal blood pressure. If the body is not in proper homeostasis the blood pressure can no longer be adequately controlled without medical interventions. If I have a resident at the assisted living facility suddenly become light headed and unbalanced there is a good chance they have low blood pressure and chances are sitting down for a minute will give their body the chance it needs to regulate the blood pressure on its own.

In my line of work as a nurse this chapter applies to me in the following ways: I will have to recognize that when a patients body is not in proper homeostasis, such as with Hyercalcemia. The body has two hormones that act that are called PTH (parathyroid hormone and calcitriol. Regulation of the calcium is done by PTH where the stimulation of secretion occurs when calcium is decreased, therefore acting on target receptors and increasing the efficiency of calcium absorption and enhances calcium resorption from mineralized bone and activates the conversion of vitamin D to calcitiol that increases intestinal absorption of calcium and phosphorus. There are also drugs that can keep homeostasis of calcium levels. This drug is called Calcitonin that acts as an antagonist to PTH to lower serum calcium and phosphorus and inhibits bone reabsorption. When homeostasis is not met and hypercalcemia occurs, it can affect the central nervous system, kidneys, bone, heart and GI systems.

__Home-- D. Chemical aspects of physiology__

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