Excretion+&+Homeostasis

Natalie, Tristan, Heath, Izzy, Sofia

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SPECIFIC ELIMINATION MECHANISMS
 * Process: What happens and why?**
 * Excretion is the removal of toxic material from the body.
 * This promotes homeostasis in the organisms environment.
 * There are three main waste materials in the human body: carbon dioxide, urea, and water.
 * In the human body there are 4 main structures that contribute to excretion: kidneys, bladder, ureters, and the urethra.
 * Animals must ingest energy-containing chemical compounds, extract a portion of the energy to power their life processes, and dispose of the unusable material formed during the energy-extraction process.
 * The alimentary canal is a pathway used almost exclusively for the elimination of solid wastes. Materials disposed of in this manner have not entered the tissues of the animal but rather are the residues of enzymatic and absorptive activities occurring in the digestive tract.
 * The respiratory pathway is concerned with the gaseous waste products of metabolism, which moves to the external environment by diffusing from the cells of origin. Certain aquatic animals are capable of eliminating gaseous ammonia, derived from protein breakdown, by way of specialized cells in their gill tissues.
 * The kidney is a microfilter that initially removes dissolved and some suspended materials from the circulatory system, along with large quantities of water. Animals such as freshwater fish absorb large quantities of water into their bodies excrete copious quantities of water in their urine. The reverse is true of many desert animals, who must conserve water and therefore have thick, semisolid urine.

**How does it depend on other life processes to function? Three specific examples.**
 * The excretory system is the release of liquid, therefore in order to excrete waste there has to be an intake of liquids.
 * The excretory system works with the respiratory system because carbon dioxide waste is breathed out.
 * The excretory system also works with the circulatory system because the blood is pumped around the body.
 * Its also works with the skin or the integumentary systems because waste, such as sweat is expelled through the skin.
 * The liver detoxifies and breaks down chemicals, poisons and other toxins that enter the body. Kidneys remove the nitrogenous waste from the blood. Urea, salts and excess water are removed from the blood and excreted in the form of urine. Bile helps to break down ethanol, fats and other acidic wastes including ammonia, into harmless substances. Large intestines collect waste from throughout the body. It extracts any remaining usable water and then it is removed as solid waste.


 * How organisms (unicellular, plants and animals) accomplish the process of excretion. Provide a specific example from each:**

Unicellular: PROTESTAS Plants: Animals (don't use a vertebrate): Describe three excretion adaptations in different lineages of multicellular animals (not mammals). For each adaptation, describe how excretion is accomplished, explain one benefit of the adaptation and one "tradeoff" that has resulted from it.
 * No specialized elimination mechanisms are present in algae, fungi, protozoans, and slime molds, the main groups of protists. Metabolic wastes, such as carbon dioxide, water, oxygen, and nitrogenous compounds, diffuse through the cell membranes of these unicellular organisms into the outside environment.
 * Carbon dioxide and oxygen are secreted in the same manner via diffusion through stomata and cell walls. Green plants in darkness or plants that do not contain chlorophyll produce carbon dioxide and water as respiratory waste products.
 * Animals which consist of a single layer of cells, waste disposal is accomplished by diffusion from the site of waste production to the outside environment.
 * In complex animals, wast elimination by diffusion through the body wall to the exterior is less efficient because individual cells are farther removed from the exterior surface of the organism. The presence of specialized mechanisms of elimination in higher animals enables wastes to be rapidly transported to the exterior surface of the body.


 * Specifically mammals:**

file://localhost/Users/Sofia/Desktop/glomerulus.jpg Waste products are transported in the blood by the plasma. Plasma serves as a transport medium for delivering nutrients to the cells of the various organs of the body and for transporting waste products derived from cellular metabolism to the lungs, liver for detoxification and to the kidneys for disposal.
 * Diagram a nephron and label it showing how it functions in excretion.**
 * How are waste products transported in the blood?**

The nephron is the basic functional and structural unit that produces urine in the process of extracting waste and unnecessary substances from the blood. Nephrons are tiny filtering units that make up the kidneys which are responsible for preventing the build up of wastes and extra fluid in the body. The nephrons each filter a small amount of blood and are made up of two smaller filters. The first one, the glomerulus, allows fluid and waste products to pass through it while preventing blood cells and larger molecules. Such as proteins, from passing through it. The fluid then flows through the tubules which sends minerals and other essential molecules back to the bloodstream while also filtering out waste. The final product of this process is urine, which is excreted from the body through the urthera. The excretory system is the system responsible for fliltering out waste and essential nutrients passing through the body. It controls the movement of water through the body as it makes its way from the mouth through the blood and circulatory system and out of the body through the urethra.
 * Why do waste products and water move out of the circulatory system at the nephron and how does the excretory system control this movement?**

Once carbon dioxide is carried away from the cells through the blood, it is dropped off in the lungs. Oxygen enters the blood from the lungs by attaching to the hemoglobin inside of the red blood cells. Hemoglobin contains iron which makes it a good bonding agent for transporting oxygen and carbon dioxide. As the blood flows through the body, the oxygen is released into the tissue from the hemoglobin and enters the cells. These substances are transported through the blood mainly through the use and binding of hemoglobin to transport it throughout the body.
 * Explain how oxygen and carbon dioxide are transported in the blood.**

An example of a regulatory feedback loop in a mammal’s Excretory System is one which involves the secretion of the Antidiuretic Hormone. In this negative feedback relationship, the arteries and veins that make up the circulatory system deliver the blood of the organism to these incredible, biological filters.
 * Explain how the respiratory system depends upon other body systems to accomplish the process of gas exchange. Provide three specific examples.**

First, the blood plasm goes through Ultrafiltration in the Nephron, this Primary Urine travels through the Proximal Convoluted Tubule, which reabsorbs a great deal of the needed water, sugar molecules, and ions from the Primary Urine in order to reduce the amount of vital materials lost in this ‘waste dump.’ From here, the Primary Urine leaves the outer-most layer of the Kidneys, known as the Cortex, and descends into the core of the Kidneys, known as the Medulla, via the Loop of Henle. As this tubular fluid descends through these increasingly, concentrated tissues. Since the tubular fluid is at approximately the same concentration as the blood plasm, an osmotic gradient is made between the tubular fluid and the tissue fluid surrounding the transport tubules in the Kidney. While this harpin design magnifies the amount of ions reabsorbed, it has also established the gradient that will be utilized to produce the Definitive Urine in the Collecting Duct, directly following the Distal Tubule.

This is where the feedback loop comes into play. If the tubular fluid, transporting the nitrogenous waste (Urea) as well as the excess water and ions, is very dilute, this information is transmitted up to the Hypothalamus (Brain section), telling it to reduce the amount of Antidiuretic Hormone that is released from the Pituitary Gland, which prevents water from diffusing through the Collecting Duct walls. This keeps this resultant, waste product (the Definitive Urine) in a dilute state, which is expelled as such from the body to return the body’s blood stream to a more ideal, concentrated state. If this same, resultant waste product were to reach the final point in the Kidney as a highly, concentrated fluid, then this would promote the Hypothalamus to secrete more of the Antidiuretic Hormone, which would induce a structural change in the Collecting Duct, making it water-permeable. Thanks to the established osmotic gradient by the Loops of Henle, the water would diffuse out of the Collecting Duct to return water to the currently, water-deficient blood stream. Meanwhile, rather than expelling a large amount of dilute fluid in response to an initial blood plasm that was too dilute, only a small amount of highly, concentrated waste fluid would be excreted to bring the blood plasm of the body back to a more dilute, yet ideal concentration.

The reason this relationship is considered a negative feedback loop is because it requires the production of a substance in response to a physiological imbalance to return the body to a state of homeostatic equilibrium.

One example of a diseased, excretory system is Acute Kidney Injury. This is occurs when the blood supply to the Kidneys is suddenly stopped and these organs become overrun with toxins. Such blockages can be a direct result of mistakes during surgeries elsewhere in the body that cut off blood supplies to these organs, heart disease, liver failure, severe dehydration, toxins like alcohol, blockages due to cholesterol deposits (ruptured plaques), as well as Bladder, Colon, Cervical, and Prostate Cancer. Symptoms can consist of: reduced urine output, swelling in your legs, ankles or feet, drowsiness, shortness of breath, fatigue, confusion, nausea, seizures, and chest pain. Depending on the cause of the Kidney failure, this condition can be successfully treated with Dialysis to remove toxins that have accumulated, medications to restore the fluid balance in the individual’s body like IV fluids for severely dehydrated cases or diuretics for those with dangerously, high volumes of fluid in their body, as well as medications to prevent accumulations of Potassium ions which can cause arrhythmias.
 * Describe two examples of disruptions to the excretory system (a “disease”). Address the cause, symptoms, and treatment of the conditions. **

Another example of a disease regarding the Excretory System is Kidney Cancer. Kidney cancer is caused by mutations caused by carcinogens in the organs environment as well as genetic predisposition which given the right, epigenetic stimulus (environmental factors), could induce the over propagation of cells this organ to ultimately result in a malignant tumor. Both of these scenarios would result in cancerous cells because they, one way or another, mutate the recipe that created Proto-oncogenes and/ or Tumor suppressors, crippling these cell-Cycle regulators. Symptoms of this condition consist of but are not limited to: Bloody urine, consistent, lumbar back pain, Weight loss, Fatigue, and periodically, occurring fevers. Ways of treating this disease include surgically removing the affected kidney (nephrectomy), a partial-nephrectomy which remove the cancerous tissue while sparing the nephron of the Kidney to prevent future complications if possible, biological therapy, as well as radiation therapy to name a few.


 * Explain how organisms (unicellular organisms, plants and animals) accomplish the process of excretion. Provide a specific example organism for each category. **

● Unicellular organisms

they accomplish excretion through diffusion, active transport, and osmosis.There are not any excretory organs in unicellular organisms. For example, when bacteria need to excrete waste, they use diffusion and osmosis to expel unwanted molecules and water over their semipermeable membrane.

● Plants

Plants need to excrete excess carbon dioxide and oxygen. Carbon dioxide is a waste product of aerobic respiration  in plant cells. Oxygen is a waste product of photosynthesis . Toxins are expelled from the plant through the stomata in the leaves. Water is taken in and expelled mostly through the roots. Plants that live deep in the ocean that don’t have chlorophyll expel water and carbon dioxide instead of oxygen. These plants still excrete it through their stomata. For example when a maple tree needs water, it sucks it up through its roots, and when unwanted byproducts are created from photosynthesis, it releases the toxins through its stomata in the leaves.

● Animals (don’t use a vertebrate).

the skin, lungs, and kidneys expel toxins and waste from the body in animals. In the skin, sweat glands expel sweat to cool the body down while it contains salt and urea. Urea is a nitrogenous waste present in other things such as urine.Water content in the blood is controlled by a hormone called ADH. ADH is released into the bloodstream according to the concentration of the blood plasma. The integumentary system helps release toxins through the hair, nails, skin. The top layer of the skin is just dead cells and is removed every day along with toxin containing sweat. Example: a dog.


 * Describe three excretion adaptations in different lineages of multicellular animals (not mammals). For each adaptation, describe how excretion is accomplished, explain one benefit of the adaptation, and one “tradeoff” that has resulted from the adaptation. **

A fish uses its gills to excrete ammonia. Since it can only live in water, it is forced to expel waste in the water in which it lives and cannot do so anywhere else. Birds cannot differentiate between solid and liquid waste, therefor when they consume water and food, it is expelled as one instead of separately. Earthworms must live in the ground to survive, since there move by feel and use their outside skin the most, they excrete toxins through their skin into the earth around them. This forces them to live in a dark, moist environment.