Breathing and respiration - class-IX

Larynx (voice box) is located between the pharynx and the trachea. It is the upper modified part of trachea and leads to trachea or windpipe. It has a framework of cartilage that protrudes in the front of the neck and sometimes is referred as the Adams apple. The larynx is considerably larger in males than in females; hence, the Adams apple is much more prominent in males. At the upper end of the larynx, vocal cords are present which help in production of speech. They are set into vibration by the flow of air from the lungs. A difference in the size of the larynx is what accounts for the difference between male and female voices; because male larynx is larger than a female larynx, usually male voice is lower in pitch. The nasal cavities, the sinuses, and the pharynx all serve as resonating chambers for speech, just as the cabinet does for a stereo speaker.

Whale is a mammal and mammals breathe with lungs. The whale’s lungs contain more alveoli and is surrounded by two layers of capillaries increasing the surface area for more efficient gas exchange.

In humans, the larynx is called the voice box. The larynx (voice box) is located between the pharynx and the trachea. It has a framework of cartilage, that protrudes in the front of the neck and sometimes is referred to as Adam's apple. The larynx is considerably larger in the male than in the female; hence, Adam's apple is much more prominent in the male. At the upper end of the larynx are the vocal cords, which serve in the production of speech. They are set into vibration by the flow of air from the lungs. 

In humans, the larynx (voice box) is located between the pharynx and the trachea. It has a framework of cartilage that protrudes in the front of the neck and sometimes is referred to as the Adam's apple. The larynx is considerably larger in the male than in the female. Hence, the Adam's apple is much more prominent in the male. At the upper end of the larynx are the vocal cords, which serve in the production of speech. They are set into vibration by the flow of air from the lungs. A difference in the size of the larynx is what accounts for the difference between the male and female voices; because a man's larynx is larger than a womans, his voice is lower in pitch.

Pleura is one of the two membranes around the lungs. These two membranes are called the visceral and parietal pleurae. The visceral pleura envelops the lung, and the parietal pleura lines the inner chest wall. 

The larynx (voice box) is located between the pharynx and the trachea. It has a framework of cartilage that protrudes in the front of the neck and sometimes is referred to as the Adam's apple. The larynx is considerably larger in the male than in the female; hence, the Adam's apple is much more prominent in the male. In human males ventral surface of thyroid cartilage make up the Adam's apple. 

The larynx is known as voice box or sound producing organ. A pair of membranous folds called vocal cords, stretch across the laryngeal cavity. In normal condition, the vocal cords lie apart so that the glottis remains widely open to allow free passage of respiratory air. For sound production, vocal cords come close together, they vibrate when air rushes out through glottis and produce voice.

The epiglottis is a flap-like structure made of elastic cartilage tissue covered with a mucous membrane, attached to the entrance of the larynx. The main function of the epiglottis is to close off the windpipe during eating which prevents the entry of the food into the respiratory tract so that food is not accidentally inhaled. Hence option D is correct.

The pulmonary vein is unique because it carries oxygenated blood from the lungs back to the left atrium of the heart. The pulmonary artery carries deoxygenated blood away from the heart to the lungs.

The Adam's Apple is the common name for the laryngeal prominence, which is a feature of the thyroid cartilage that surrounds the larynx. It is more prominent in males due to hormonal differences.

• The larynx (voice box) is a cartilaginous box which helps in sound production.
  
• It consists of 9 cartilages among them 3 are paired and 3 are unpaired.
• Vocal cords are composed of twin infoldings of mucous membrane stretched horizontally across the larynx. They vibrate, modulating the flow of air being expelled from the lungs during phonation.
• Hence vocal cords occur in Larynx.
• So, the correct answer is 'Larynx'.

Larynx is the voice box (a-r), Trachea is the wind pipe (b-s), Alveoli are air sacs (c-q), and the Epiglottis is the lid of the larynx (d-p). Option A correctly matches these anatomical terms.

The arytenoid cartilages are a pair of small cartilages, shaped roughly like three-sided pyramids, which are located toward the rear of the larynx and play a vital role in positioning and adjusting the vocal folds during speech.

The vocal cords (vocal folds) are two fibro-elastic bands located within the larynx. They stretch between the thyroid cartilage anteriorly and the arytenoid cartilages posteriorly.

In mammals, the larynx contains the vocal cords, which vibrate to produce sound as air passes through them. The syrinx is the vocal organ found in birds, not mammals.

The human larynx is composed of 9 cartilages: 3 paired (arytenoid, corniculate, cuneiform) and 3 unpaired (thyroid, cricoid, epiglottis).

Larynx is the voice box (a-r), Trachea is the wind pipe (b-s), Alveoli are air sacs (c-q), and the Epiglottis is the lid of the larynx (d-p). Option A provides the correct mapping.

• The epiglottis is a large, leaf-shaped piece of cartilage lying on top of the larynx. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally.
  
• During swallowing of food the larynx elevates, causing the epiglottis to fall on the glottis (opening into larynx) like a lid, closing it off, this prevents food from entering the windpipe (trachea). Hence The structure which prevents the entry of food particles into the respiratory passage is Epiglottis.
• So, the correct answer is 'Epiglottis'.
  

The process of breathing is divided into two phases: inspiration (inhalation) and expiration (exhalation). The diaphragm, ribs, external, the internal intercoastal muscles and the abdominal muscles that move the diaphragm are all involved in changing the size of the thoracic cavity either by contraction or relaxation thereby changing the air pressure and causing air to move in or out of the lungs. So, the correct option is 'larynx'.

• Larynx is a cartilaginous box containing nine pieces of cartilages.
• Glottis is the opening from where esophagus and trachea gets seperated.
• To prevent food from entering into the larynx while swallowing, the epiglottis covers the opening of the larynx.
• So, the correct option is (A).

The cricoid cartilage is a ring of hyaline cartilage located at the inferior aspect of the larynx and is the only complete ring of cartilage around the trachea. It has the shape of a signet ring, with a broad portion posterior to the airway (lamina of cricoid cartilage) and a narrower portion circling anteriorly (arch of cricoid cartilage). 

The diaphragm separates the thoracic cavity, containing the heart and lungs, from the abdominal cavity and performs an important function in respiration. As, the diaphragm contracts, the volume of the thoracic cavity increases and air is drawn into the lungs.  It is a dome-shaped sheet of muscle that is inserted into the lower ribs. 

Alveoli are the tiny, grape-like air sacs at the end of the bronchioles in the lungs where gas exchange occurs. A cluster of these is referred to as an alveolus or alveolar sac.

Vocal cords are located within the larynx, which is why the larynx is commonly called the voice box. Air passing through these cords creates sound.

• Some amount of air remains behind in the various parts of the respiratory tract.
• The air in the trachea and bronchi (where no diffusion occurs) is called dead space air.
• The air remaining in the alveoli or air sacs in alveolar air. The maximum volume of air that can be exchanged in one breath in and out is called the vital capacity. It is about 5000ml. 
  
  

Tidal Volume (TV) is the amount of volume of air that can be inspired / expired normally.

A person who is born and lives at sea level will develop a slightly smaller lung capacity than a person who spends their life at a high altitude. This is because the partial pressure of oxygen is lower at higher altitude which, as a result means that oxygen less readily diffuses into the bloodstream. In response to higher altitude, the body's diffusing capacity increases in order to process more air. 

The total lung capacity of the adult male is six liters. Tidal volume is the volume of air inhaled in a single, normal breath. Inspiratory capacity is the amount of air taken in during a deep breath, while residual volume is the amount of air left in the lungs after forceful respiration.

• The lungs are the primary organs of the respiratory system in humans and many other animals. Human lung size is determined by genetics, gender, and height. 
• Different animals exhibit different lung capacities based on their activities. For example, cheetahs have evolved a much higher lung capacity than humans in order to provide oxygen to all the muscles in the body, allowing them to run very fast. 
• Elephants also have a high lung capacity due to their large body and their need to take up oxygen in accordance with their body size. Hence, elephants and cheetahs have higher lung capacities than humans. 
  

During one breath in and out, the volume of gas exchanged is called the tidal volume. It is about 450ml during quiet breathing. The volume of air that can be drawn in after normal inspiration is about 1500 ml and is called as the inspiratory reserve volume (IRV) or complemental air.

During exercise, your lungs and respiratory system must provide more oxygen to the blood.  You will breathe harder and faster because: Respiratory muscles are stimulated by sympathetic nerves in order to increase the rate of breathing. If the exercise is intense, breathing rates may increase from a typical resting rate of 15 breaths per minute up to 40 – 50 breaths per minute. Hence, during heavy exercise, the breathing rate can increase up to 25 times.

• Normally the inspired air constitutes about 20.84% of oxygen whereas the expired air constitutes about 15.7% of oxygen. And even if one holds his or her breath, it is not possible to breathe out air totally without oxygen.

• The eustachian tube is a canal that connects the middle ear to the nasopharynx. It controls the pressure within the middle ear, making it equal to the air pressure outside the body. No one can breathe out air through eustachian tubes by closing both the nose and the mouth.

• Yes, one can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all.

• The lungs cannot be made fully empty by forcefully breathing out all air from them. Residual volume is always present in the lungs, even after the maximum forceful expiration effort. It is about 1500 ml of the air.

The thoracic chamber is formed dorsally by the vertebral column, ventrally by the sternum, laterally by ribs and lower side by the dome-shaped diaphragm, it is an air-tight chamber.

In insects, blood (haemolymph) does not contain an oxygen-carrying pigment. Hence it does not help in respiration. Instead, insects have spiracles and tracheae that carry $O _{2}$ to different tissues.

A man exhaled the air almost equivalent to the mixture of the atmosphere which contains 78% nitrogen, 16% oxygen, 0.09% argon and 4% carbon dioxide.

The laryngeal prominence (commonly referred to as Adam's apple), a feature of the human neck, is the lump or protrusion that is formed by the angle of the thyroid cartilage surrounding the larynx. The structure of the laryngeal prominence forms a bump under the skin. It is larger in adult men, in whom it is usually clearly visible and palpable. In women, the bump is much less visible and is hardly perceived on the upper edge of the thyroid cartilage. The laryngeal prominence is related to the deepening of the voice.

The larynx is known as voice box or sound producing organ. A pair of membranous folds called vocal cords, stretch across the laryngeal cavity. In normal condition, the vocal cords lie apart so that the glottis remains widely open to allow free passage of respiratory air. For sound production, vocal cords come close together, they vibrate when air rushes out through glottis and produce voice.