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Structure and Function of the Human Body – Respiration and Urinary Systems

1. Atmospheric air takes a specific pathway from the external environment to our internal lungs. Describe this pathway starting with external nares to the alveoli. What role does the trachea and surfactant play within the respiratory system?

The air is inhaled through the mouth and the nose. Then the air goes through the larynx and trachea, which is a tube that enters the chest cavity. Then the trachea splits into two tubes, bronchi, which split further into bronchial tubes. Bronchial tubes lead further to the lungs, where they divide in many smaller tubes which connect to tiny sacs called alveoli. The trachea and surfactant perform the function of preparing the air to enter the lungs through cleaning the air and warming it up.

2. Gas exchange within the lungs and body tissues is vital for life to exist. Briefly explain the gas exchange that occurs in the lung tissue and the body tissue for oxygen and carbon dioxide. What is the driving force for this movement of gas (think concentration gradient)? Finally, how does carbon monoxide disrupt the process of oxygen transport?

The oxygen diffuses in alveoli through capillaries and goes into the arterial blood. The waste-rich blood from veins, containing carbon dioxide releases carbon dioxide into alveoli. The carbon dioxide follows the same path out of the lungs. The diaphragm is essential for the gas exchange process. The diaphragm pumps carbon dioxide out of the lungs and pumps oxygen in the lungs. When the diaphragm relaxes, carbon dioxide releases from the lungs. When the diaphragm contracts, oxygen is pulled into the lungs.

3. One of the kidney’s main roles is elimination of wastes, where blood is filtered and the wastes are excreted via the urethra. Please describe the pathway a waste product in the blood takes (for example urea) starting with an afferent arteriole to the urethra. Finally, what is the difference between the male and female urethras and what complication could result in females because of this difference?

A waste product passes from an afferent arteriole to kidney, where urea passes through renal cortex, renal medulia, hilus. Then urea passes through ureter to urinary bladder. Finally, the urea is delivered from the urinary bladder to urethra with the help of medial umbilical ligament. Female urethra is shorter than male urethra. Female urethra is 1.5 inches, while male urethra is 8 inches. Hence, females are more vulnerable to urinary tract and bladder infections compared to males.

4. Urine formation consists of three basic processes; briefly describe each process and the parts of the nephron that are vital to that process. How does glomerular filtration rate correlate to urine formation?

Urine is formed through the following processes. Te first process is glomerular filtration. Glomerular filtration rate shows how much blood passes through the tiny filters in kidneys called glomeruli each minute. The second process is tubular reabsorption. The third process is tubular secretion and the fourth process is water conservation.

5. The kidneys also play a vital role in maintaining the volume of water and other solutes (like electrolytes) in our blood. How does the urinary system regulate the volume of water within our bodies? How does it regulate sodium?

Adrenal glands regulate the level of salt and water in human body. The level of sodium is regulated through the release of anti-diuretic hormone by kidneys.

 

References:
Baron J, Beach M, Mandel J, van Stolk R, Haile R, Sandler R, Rothstein R, Summers R, Snover D, Beck G, Bond J, Greenberg E (1999). “Calcium supplements for the prevention of colorectal adenomas. Calcium Polyp Prevention Study Group”. N Engl J Med 340 (2): 101–7
Curcio, C. A., K. R. Sloan, et al. (1990). “Human photoreceptor topography.” The Journal of Comparative Neurology 292(4): 497-523.
Marieb, Elaine N. & Hoehn, Katja (2007). Human Anatomy & Physiology (Seventh ed.). San Francisco, CA: Pearson Benjamin Cummings.