Which diagram correctly describe an effect of tar entering lungs?

Which diagram correctly describe an effect of tar entering lungs?

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Which flow diagram correctly describes the effect of tar entering lungs?

Tar is a cause of Chronic obstructive pulmonary disease (COPD) which includes both chronic bronchitis and emphysema and it is also a carcinogen, too. So, I think that A, B, and C would be correct answers, but the solution is A. Why B and C are incorrect?

Thank you very much!

COPD is not caused by an infection (which would require a pathogen) but by the inflammation reaction the body triggers because of the tar particles. Thus the statement "mucus accumulated causing infection" does not correctly describe the effect of tar on the lung. Consequently, B and C are incorrect.

Function and Disorders of the Alveoli

Sanja Jelic, MD, is board-certified in sleep medicine, critical care medicine, pulmonary disease, and internal medicine.

Alveoli are an important part of the respiratory system whose function it is to exchange oxygen and carbon dioxide molecules to and from the bloodstream. These tiny, balloon-shaped air sacs sit at the very end of the respiratory tree and are arranged in clusters throughout the lungs.

How does the respiratory system work?

The respiratory system allows people to breathe. It is made up of several organs and structures that transport air into and out of the lungs, exchanging oxygen with carbon dioxide.

While the respiratory system helps a person breathe, it also protects against the intake of harmful particles through coughing, sneezing, or swallowing.

This article examines the various parts of the respiratory system, some respiratory conditions, and how a person breathes. It also looks at lung function and the processes of inhalation and exhalation.

Click on the interactive Bodymap below to move around the model and read more about the respiratory system.

The respiratory system is divided into an upper and lower respiratory tract. The upper tract comprises:

The lower respiratory tract includes:

The sections below will look at each part of the respiratory system in more detail.

Nose and nasal cavity

Forming the main external opening of the respiratory system, the nose protects the anterior portion of the nasal cavity. The nose is also unique, as it is the only part of the system that is externally visible.

The nasal cavity is the uppermost part of the respiratory system, divided into two by the nasal septum. It is the best entrance for outside air, as hairs and mucus line the inside wall and operate as air cleansers.

Within this hollow space, the air is warmed, moisturized, and filtered before reaching the lungs. The nose prevents dust, mold, and other contaminants from reaching the lungs.


The paranasal (meaning around the nose) sinuses are four paired, hollow spaces above and below the eyes.

Connected to the nose by small openings, they regulate the temperature and humidity of inhaled air. These cavities also give tone to the voice.

Sinuses develop after birth and reach their final size around the age of 20.


The pharynx, or throat, is a versatile muscular tube, shaped like a funnel, that delivers air from the mouth and nose to the trachea, or windpipe. It also connects the nasal and oral cavities with the larynx and esophagus.

The pharynx is key to the respiratory and digestive systems. It allows inhaled air to pass from the nasal cavity to the larynx, trachea, and lungs.

A section of the pharynx called the nasopharynx hosts the epiglottis. This keeps the passage to the esophagus covered, preventing air from entering the digestive system.


The larynx has a dual function in the respiratory system: as an air canal to the lungs (while stopping food and drink from blocking the airway) and as the “voice box” (which contains vocal cords for speech).

The larynx is a 2-inch tube made up of nine cartilage pieces. It connects the pharynx with the trachea and is held together by ligaments, membranes, and fibrous tissue.


The lungs are the primary organs of the respiratory system, as they perform a vital role in breathing: gas exchange.

The air that a person breathes in through the nose and mouth contains oxygen and other gases. Oxygen enters the lungs, then the bloodstream, allowing the body to function normally. However, the lungs also take the carbon dioxide from the blood and release it into the air when a person breathes out.

The grape-like sacs called alveoli in each lung allow the exchange of oxygen and carbon dioxide to take place.


The trachea runs down the neck and upper chest. It is a wide, hollow tube that connects the larynx to the bronchi, or airways, of the lungs.

Its most vital function is to enable airflow to and from the lungs. The fibroelastic membrane expands and contracts during inhalation and exhalation.


The diaphragm is a dome-shaped sheet of muscle located below the lungs. It separates the chest from the abdomen.

The diaphragm operates as the major muscle of respiration and aids breathing . The parasympathetic nervous system regulates the contraction and relaxation of the diaphragm and intercostal muscles.

Pulmonary circulation

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Pulmonary circulation, system of blood vessels that forms a closed circuit between the heart and the lungs, as distinguished from the systemic circulation between the heart and all other body tissues. On the evolutionary cycle, pulmonary circulation first occurs in lungfishes and amphibians, the first animals to acquire a three-chambered heart. The pulmonary circulation becomes totally separate in crocodilians, birds, and mammals, when the ventricle is divided into two chambers, producing a four-chambered heart. In these forms the pulmonary circuit begins with the right ventricle, which pumps deoxygenated blood through the pulmonary artery. This artery divides above the heart into two branches, to the right and left lungs, where the arteries further subdivide into smaller and smaller branches until the capillaries in the pulmonary air sacs (alveoli) are reached. In the capillaries the blood takes up oxygen from the air breathed into the air sacs and releases carbon dioxide. It then flows into larger and larger vessels until the pulmonary veins (usually four in number, each serving a whole lobe of the lung) are reached. The pulmonary veins open into the left atrium of the heart. Compare systemic circulation.

What causes COPD?

COPD usually develops because of long-term damage to your lungs from breathing in a harmful substance, usually cigarette smoke, as well as smoke from other sources and air pollution. Jobs where people are exposed to dust, fumes and chemicals can also contribute to developing COPD.

You’re most likely to develop COPD if you’re over 35 and are, or have been, a smoker or had chest problems as a child.

Some people are more affected than others by breathing in noxious materials. COPD does seem to run in families, so if your parents had chest problems then your own risk is higher.

A rare genetic condition called alpha-1-antitrypsin deficiency makes people very susceptible to developing COPD at a young age.

What’s the difference between COPD and asthma?

With COPD, your airways have become narrowed permanently – inhaled medication can help to open them up to some extent. With asthma, the narrowing of your airways comes and goes, often when you’re exposed to a trigger – something that irritates your airways – such as dust, pollen or tobacco smoke. Inhaled medication can open your airways fully, prevent symptoms and relieve symptoms by relaxing your airways.

So, if your breathlessness and other symptoms are much better on some days than others, or if you often wake up in the night feeling wheezy, it may be that you have asthma.

Because the symptoms are similar and because people who have asthma as children can develop COPD in later life, it is sometimes difficult to distinguish the two conditions. Some people have both COPD and asthma.


Emphysema is a lung condition that causes breathing difficulties. This and chronic (or long-term) bronchitis are the two main components of COPD.

If you have emphysema, the walls of the air sacs in your lungs are damaged.

Healthy lungs are made up of millions of tiny air sacs (alveoli) with elastic walls. This is where oxygen is taken into the body and the waste gas, carbon dioxide, is expelled. Cigarette smoke and other particles you breathe in can damage the walls of these air sacs.

With emphysema, the sacs break apart and merge into each other, producing holes in the lung.

If the emphysema has caused extensive damage, it is sometimes called bullous emphysema. This is because a hole bigger than 1 cm across is called a bulla.

If the pattern of damage is fairly even throughout the lung, it is sometimes called homogenous emphysema.

Where the pattern of damage is uneven, it’s called heterogeneous emphysema.

The damaged parts of the lung are baggy and trap air. If you have emphysema, when you breathe in, the damaged part of your lung inflates more and can get in the way of the healthier parts of your lung. The increase in the amount of air inside your chest is called hyperinflation. You can find it uncomfortable to breathe as your chest becomes hyperinflated.

Further information:

Last medically reviewed: March 2020. Due for review: March 2023

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.

References & Further Reading

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3. Brochard L, Martin GS, Blanch L, et al. (2012). Clinical review: respiratory monitoring in the ICU—a consensus of 16. Critical Care, 16, 219. Find this resource:

4. Lyazidi A, Thille AW, Carteaux G, Galia F, Brochard L, and Richard JC. (2010). Bench test evaluation of volume delivered by modern ICU ventilators during volume-controlled ventilation. Intensive Care Medicine, 36, 2074–80. Find this resource:

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6. Diehl JL, Mercat A, Guerot E, et al. (2003). Helium/oxygen mixture reduces the work of breathing at the end of the weaning process in patients with severe chronic obstructive pulmonary disease. Critical Care Medicine, 31, 1415–20. Find this resource:

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10. Jonson B, Richard J-C, Straus C, Mancebo J, Lemaire F, and Brochard L. (1999). Pressure–volume curves and compliance in acute lung injury. Evidence of recruitment above the lower inflection point. American Journal of Respiratory and Critical Care Medicine, 159, 1172–8. Find this resource:

11. Matamis D, Lemaire F, Harf A, Brun-Buisson C, Ansquer JC, and Atlan G. (1984). Total respiratory pressure-volume curves in the adult respiratory distress syndrome. Chest, 86, 58–66. Find this resource:

12. Ranieri MV, Giuliani R, Fiore T, Dambrosio M, and Milic-Emili J. (1994). Volume–pressure curve of the respiratory system predicts effects of PEEP in ARDS: ‘Occlusion’ versus ‘Constant flow’ technique. American Journal of Respiratory and Critical Care Medicine, 149, 19–27. Find this resource:

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Labeled Diagram of the Human Kidney

The human kidneys house millions of tiny filtration units called nephrons, which enable our body to retain the vital nutrients, and excrete the unwanted or excess molecules as well as metabolic wastes from the body. In addition, they also play an important role in maintaining the water balance of our body.

The human kidneys house millions of tiny filtration units called nephrons, which enable our body to retain the vital nutrients, and excrete the unwanted or excess molecules as well as metabolic wastes from the body. In addition, they also play an important role in maintaining the water balance of our body.

Quick Facts

Size of an adult kidney:
Length: 11-12 cm
Width: 5.0-7.5 cm

Weight of an adult kidney:
Males: 125-170 g
Females: 115-155 g

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Located in the abdominal cavity, kidneys are the most efficient filters. They are an important component of the human excretory system, and help the body retain essential molecules and get rid of the unwanted ones. They play a vital role in maintaining the composition and volume of body fluids.

Cross-section of a Human Kidney

  • The vital structural components of a kidney are enclosed in a smooth but tough fibrous capsule called renal capsule.
  • Inside this capsule, two distinct regions can be observed: a pale outer region called renal cortex, and a dark inner portion called renal medulla.
  • The renal medulla comprises a set of 8-18 conical structures called renal pyramids that are surrounded by the cortex. Portions of the cortex between two adjacent pyramids are termed as renal columns.
  • Spread in these pyramids and the cortex, are the functional units callednephrons. The actual filtration of blood occurs in the nephrons.
  • The tips of the renal pyramids are called renal papilla, and are surrounded by cup-shaped drains called minor calyces (singular: calyx).
  • The minor calyces converge to form two or three larger drains called major calyces, which eventually converge to a structure called the renal pelvis. The renal pelvis is connected to the ureter.
  • The blood supply to all these structures occurs through the branches and sub-branches of the renal artery called interlobular arteries and arcuate arteries respectively. The interlobular arteries supply blood to the borders of the cortex and medulla, whereas the arcuate arteries diverge to form afferent arterioles that carry blood to the nephrons for filtration.
  • The filtered blood is ultimately collected through venules and sub-branches called interlobular veins and arcuate veins which converge into the renal vein.
  • The waste fluid or urine is collected in a common collecting duct of the nephrons and is emptied into the minor calyces. The minor calyces drain into the major calyces, which empty their contents into the renal pelvis. From here, it is carried by the ureter to the urinary bladder.

Structure of a Nephron

Each kidney contains more than 800,000 nephrons, each of which serves as the basic functional unit by performing three essential processes: filtration, reabsorption and secretion. The nephron essentially comprises renal corpuscle and renal tubule.

Renal corpuscle

  • It is made up of a network of capillaries called glomerulus which arise from the afferent arteriole, and exit the renal corpuscle as efferent arteriole and a cup-like sac called Bowman’s capsule that surrounds the glomerulus. The initial step of filtration occurs in the renal corpuscle.
  • The walls of the glomerular capillary are composed of a three-layered filter that allows the filtration of small molecules, and is not permeable to large macromolecules like albumin and blood cells.
  • A high pressure is created in the glomerular capillaries because the efferent arteriole has a smaller diameter as compared to the afferent arteriole. As a result of this high pressure, ions and water molecules are forced into the Bowman’s capsule, leaving behind concentrated blood containing blood cells and macromolecule.
  • The filtrate thus extracted into the Bowman’s capsule is termed glomerular ultrafiltrate. It passes from the Bowman’s capsule into the renal tubule, while the concentrated blood flows out of the glomerulus through the efferent arterioles.
  • The entire blood volume gets filtered about 20-25 times per day through such ultrafiltration process.

Renal tubule

  • It is a specialized tubular structure made up of proximal convoluted tubule, a U-shaped tube called Loop of Henle, and a distal convoluted tubule. These three tubular components are selectively permeable and only allow specific molecules to pass through them. The renal tubule is surrounded by capillaries called peritubular capillaries that arise from the efferent arterioles.
  • The renal tubule is the site for reabsorption and secretion. The substances essential for the body are reabsorbed from the tubules into the peritubular capillaries, and the unwanted or toxic molecules are secreted into the lumen of the renal tubule.
  • Water, sodium and potassium ions, urea, phosphate, citrate, as well as organic molecules like glucose and amino acids are reabsorbed from the proximal convoluted tubule. In addition, it is the site for formation of ammonium and also involves the secretion of excess medicines from blood.
  • This filtrate then enters into the descending loop of Henle, which lies in the medulla of the kidney. Here, reabsroption of water from the filtrate to the tissues takes place. This water is transferred by the cells to the capillaries surrounding them.
  • The filtrate then travels through the ascending loop of Henle which is impermeable to water. Hence, only ions diffuse out into the surrounding cells, which subsequently pass them into the surrounding capillaries.
  • While passing through the distal convoluted tubule, the surrounding tissues further facilitate the exchange of water and ions from the filtrate to the capillaries. They also absorb the excess potassium and hydrogen ions from the capillaries and secrete them into the filtrate.
  • The filtrate from several nephrons is then collected into the common collecting duct which empties into the minor calyces, and is subsequently collected into the bladder as urine.

The kidneys play a vital role in water and ion homeostasis, and contain fascinating biological filtration assembly. Any defects or discrepancies in the normal functioning of the kidneys takes a toll on the many cellular and physiological processes of the body.

Integumentary and Nervous Systems

The integumentary system, or skin, is the body's first line of defense. It regulates body temperature, protects underlying layers of tissue from sun damage and prevents pathogens from freely entering your body. The integumentary system is also home to millions of nerves that respond to touch, pressure and pain. There are two interconnected nervous systems: the central nervous system and the peripheral nervous system. The central nervous system includes the spinal cord and the brain, which gets the information from the body and sends out instructions. The peripheral nervous system includes all of the nerves and sends messages from the brain to the rest of the body. The nervous system controls both voluntary and involuntary, automatic activities and bodily functions.

Both the nervous system and endocrine system serve to integrate the body's various other systems, keeping things in synch. When the cardiovascular system is low on fluid, such as in severe dehydration, the skin loses its normal resiliency and can actually form a "tent" when pinched, instead of springing back into shape.

Defense Mechanisms of the Respiratory System

The average person who is moderately active during the daytime breathes about 20,000 liters (more than 5,000 gallons) of air every 24 hours. Inevitably, this air (which would weigh more than 20 kilograms [44 pounds]) contains potentially harmful particles and gases. Particles, such as dust and soot, mold, fungi, bacteria, and viruses deposit on airway and alveolar surfaces. Fortunately, the respiratory system has defense mechanisms to clean and protect itself. Only extremely small particles, less than 3 to 5 microns (0.000118 to 0.000196 inches) in diameter, penetrate to the deep lung.

Cilia, tiny muscular, hair-like projections on the cells that line the airway, are one of the respiratory system's defense mechanisms. Cilia propel a liquid layer of mucus that covers the airways.

The mucus layer traps pathogens (potentially infectious microorganisms) and other particles, preventing them from reaching the lungs.

Cilia beat more than 1,000 times a minute, moving the mucus that lines the trachea upwards about 0.5 to 1 centimeter per minute (0.197 to 0.4 inch per minute). Pathogens and particles that are trapped on the mucus layer are coughed out or moved to the mouth and swallowed.

Alveolar macrophages, a type of white blood cell on the surface of alveoli, are another defense mechanism for the lungs. Because of the requirements of gas exchange, alveoli are not protected by mucus and cilia—mucus is too thick and would slow movement of oxygen and carbon dioxide. Instead, alveolar macrophages seek out deposited particles, bind to them, ingest them, kill any that are living, and digest them. When the lungs are exposed to serious threats, additional white blood cells in the circulation, especially neutrophils, can be recruited to help ingest and kill pathogens. For example, when the person inhales a great deal of dust or is fighting a respiratory infection, more macrophages are produced and neutrophils are recruited.

Watch the video: How Smoking 30 PACKS of Cigarettes Wrecks Your Lungs You Must See This! (May 2022).