Chapter-14 The Respiratory System-1

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Discuss the generalized functions of the respiratory system.

The organs of the respiratory system are designed to perform two basic functions. They serve (1) as a air distributor and (2) as a gas exchanger for the body. This system also effectively (1) filters, (2) warms, and (3) humidifies the air we breathe. Sinuses influence sound production, and the nose makes the sense of smell possible.

List the major organs of the respiratory system and describe the function of each.

a. Nose—air enters the respiratory tract through the nostrils. The surface of the nasal cavities is moist from mucus and warm from blood flowing just under it, so as air passes through this area it is humidified and warmed. Nerve endings responsible for smell are located in the nasal mucosa.
b. Pharynx—air and food pass through the pharynx or throat on their way to the lungs and stomach, respectively. Two small masses of lymphatic tissue called tonsils are embedded in the mucous membrane of the pharynx.
c. Larynx—this structure is responsible for creating sound. It is covered with a piece of cartilage called the epiglottis, which closes the larynx during swallowing and prevents food from entering the trachea.
d. Trachea—this tube, often called the windpipe, furnishes part of the open passageway through which air can reach the lungs from the outside.
e. Bronchi—subdivisions of the trachea that lead to the lungs. In each lung they branch into smaller, or secondary, bronchi, which branch into bronchioles. Bronchioles subdivide into microscopic tubes called alveolar ducts. Each alveolar duct ends in several grapelike clusters called alveolar sacs. The wall of each alveolar sac is made up of extremely thin-walled structures called alveoli. Alveoli are lined with blood capillaries, so on their surface an exchange of gases between air and blood can take place.
f. Lungs—paired organs that provide an area where air and blood can come close enough to each other for oxygen to move out of the air into blood, whereas carbon dioxide moves out of the blood into air.

Compare, contrast, and explain the mechanism responsible for the exchange of gases that occurs during internal and external respiration.

In breathing, nerve impulses stimulate the diaphragm to contract. Its domelike shape flattens out as it moves down toward the abdominal cavity. This makes the chest cavity longer from top to bottom. Other muscle contractions raise the rib cage to make the chest cavity wider and greater in depth from front to back. As the chest cavity enlarges, the lungs expand along with it and air rushes into them and down into the alveoli. This phase of respiration is called inspiration. For expiration to take place, the diaphragm and other respiratory muscles relax, making the chest cavity smaller, thereby squeezing air out of the lungs. Changes in shape and size of the thoracic cavity result in changes in air pressure within the cavity and within the lungs. It is the difference in air pressure that causes movement of air into and out of the lungs.

List and discuss the volumes of air exchanged during pulmonary ventilation.

A spirometer is used to measure the amount of air exchanged in breathing. Ordinarily, we take 500 milliliters of air into our lungs. This amount is called tidal volume. The largest amount of air that we can breathe in and out in one inspiration and expiration is known as the vital capacity. The normal value of vital capacity is about 4800 milliliters. Expiratory reserve volume is the amount of air that can be forcibly exhaled after expiring the tidal volume. Inspiratory reserve volume is the amount of air that can be forcibly inspired over and above a normal inspiration. As tidal volume increases, both expiratory reserve volume and inspiratory reserve volume will decrease. Vital capacity can be calculated by adding together tidal volume, inspiratory reserve volume, and expiratory reserve volume. Residual volume is the air that remains in the lungs after the most forceful expiration.

Identify and discuss the mechanisms that regulate respiration.

a. Respiration depends on proper functioning of respiratory muscles. These muscles are stimulated by nervous impulses that originate in the respiratory control centers, which are located in the medulla and pons of the brain. In the medulla the two most important control centers are called the inspiratory center and the expiratory center.
b. The respiratory control centers in the brainstem control the rate and depth of breathing. In addition the brainstem receives input from other parts of the body, such as information from chemoreceptors and stretch receptors that can alter breathing patterns, as can emotions and sensory input stimuli. Even with these controls there are times that the cerebral cortex can and does override the "automatic" control of breathing.

What are the three divisions of the pharynx?

Nasopharynx, oropharynx, laryngopharynx

What is the scientific term for the voice box?

Larynx in humans and syrinx in birds

What keeps the trachea from collapsing?

The hyaline cartilage provide support to prevent it from collapsing.. im pretty sure they're also called "Rings of Cartilage"

What are the paranasal sinuses?What is their role?

1. rudimentary in human but of olfactory use in animals
2. give some assistance in olfactory function by evenly distributing the inspired air in the olfactory region
3. lighten the skull for better balance
4. resonators for voice
5. areas for the production of mucus to moisten the nasal chambers and inspired air

What are the primary functions of the respiratory system?

The major functions of the respiratory system are:
1. -Gas exchange: the respiratory system allows oxygen in the air to enter the blood and carbon dioxide to leave the blood and enter the air. The cardiovascular system transports oxygen from the lungs to the cells of the body and carbon dioxide from the cells of the body to the lungs.
2. -Regulation of blood pH, which can be altered by changes in blood carbon dioxide levels.
3. -Voice production as air moves past the vocal cords to make sound and speech.
4. -Olfaction, or the sense of smell, occurs when airborne molecules are drawn into the nasal cavity.
5. -Innate immunity, providing protection against some microorganisms by preventing their entry into the body or by removing them from respiratory surfaces.

Can you distinguish the upper respiratory tract from the lower respiratory tract?

Well, the primary difference is the location of the infection. Infections can be caused by a number of things, including bacteria, disease, and viruses. Frequently, pharmacists and doctors are able to better understand the nature of the conditions.
An upper respiratory tract infection would include infection of the nose, nasal cavity, nasal and paranasal sinuses, and the larynx and pharynx.
A lower respiratory tract infection would include infection of the trachea, bronchi or bronchial tree, and the lungs or pleural cavity.

What is the role of the respiratory membrane?

It is a barrier across which gases are excahnged betwween alveolar air and the blood. it helps prevent each alveolus from collapsing as air moves in and out during respiration.

What are bronchi? What is their role?

Bronchi is basically an organ from the respiratory system. It acts as a caliber for the airway by conducting air in to the lungs.
The bronchi is formed from the Trachea which is the wind pipe. In fact the trachea divides into two bronchi, one at the left and one at the right. These bronchi then keep on dividing until they form alveolar ducts. At the end of each alveolar duct an alveolar sac is attached. Alveolus is the place where exchange of gas takes place.
So as a matter of fact bronchi does not support any exchange of gases inside the lungs. It just supports the passage of air from the windpipe to the alveoli in the lungs where actual exchange of air takes place.

What is the function of the alveoli?

The alveoli are the places where carbon dioxide and oxygen are exchange between tiny capillaries.

Can you describe the structure and function of the pleura?

In human anatomy, the pleural cavity is the body cavity that surrounds the lungs. The pleura is a serous membrane which folds back upon itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity; it normally contains a small amount of pleural fluid. The outer pleura (parietal pleura) is attached to the chest wall. The inner pleura (visceral pleura) covers the lungs and adjoining structures, viz. blood vessels, bronchi and nerves.
The pleural cavity, with its associated pleurae, aids optimal functioning of the lungs during respiration. The pleural cavity also contains pleural fluid, which allows the pleurae to slide effortlessly against each other during ventilation. Surface tension of the pleural fluid also leads to close apposition of the lung surfaces with the chest wall. This physical relationship allows for optimal inflation of the alveoli during respiration. The pleural cavity transmits movements of the chest wall to the lungs, particularly during heavy breathing. This occurs because the closely opposed chest wall transmits pressures to the visceral pleural surface and hence to the lung itself.

How does the diaphragm operate during inspiration? During expiration?

During inhalation the diaphragm muscle contracts and this causes it to (effectively) move downwards, its previously upwardly curving shape becomes a flatter one, and this decreases the pressure in the thorax region (the region in which the lungs reside) because there is more air space. As a consequence, air rushes in from outside the body, via the nose and mouth, and fills the lungs with air. The alveoli in the lungs takes the air and sends it round the blood-stream.
Exhaling is, obviously, the opposite: The diaphragm relaxes, moves upwards to it's original, relaxed state, and thus increases the air pressure in the thorax area (because there is now less air space), this forces air that was not removed by the alveoli, and air that has returned to the lungs from the blood-stream, back into the atmosphere via the nose and mouth. Also, in and out of your nose ...air goes in and out
The diaphragm provides the main force for breathing.(other muscles are used during exercise, like the scalenes and the intercostals) When the diaphragm contracts it moves down into the abdomen by doing so it increases the volume of the thoracic cavity which in turn creates a negative pressure(compared to atmospheric) on the lungs(it actually creates a negative pressure in the intraplueral space). This negative pressure creates a pressure differential between the lungs and the atmosphere causing air to come into the lungs. During exhalation the diaphragm relaxes and the elastic force of the lung causes the air to be pushed outwards.

In what form does oxygen travel in the blood? What form of carbon dioxide?

Blood contains a specific pigment called haemoglobin which can bind to both oxygen and carbon dioxide, although it has higher affinity for oxygen. Oxygen binds with haemoglobin to form oxyhaemoglobin while carbon dioxide forms carbaminoglobin. Both these complexes are able to dissolve in blood and hence can be circulated through the body.

What is the vital capacity? How is it measured?

vital capacity VC; the volume of gas that can be expelled from the lungs from a position of full inspiration, with no limit to duration of inspiration; equal to inspiratory capacity plus expiratory reserve volume.Spirometry (meaning the measuring of breath) is the most common of the pulmonary function tests (PFTs), measuring lung function, specifically the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry is an important tool used for generating pneumotachographs, which are helpful in assessing conditions such as asthma, pulmonary fibrosis, cystic fibrosis, and COPD.

What is hyperventilation? Hypoventilation?

Also known as: Congeital central hypoventilation syndrom; CCHS; Late onset congenital central hypoventilation syndrome; LO-CCHS; Haddad syndrome; HVS
Hypoventilation syndrome
Congenital central hypoventilation syndrome (CCHS) is a rare disorder of respiratory control with autonomic nervous system dysregulation (ANSD). The autonomic nervous system is the portion of the nervous system that controls or regulates certain involuntary body functions including heart rate, blood pressure, temperature regulation, breathing, bowel and bladder control and more. Impaired breathing regulation (respiratory control) is the hallmark of CCHS.
Individuals with CCHS typically present in the newborn period with inadequate shallow breathing (alveolar hypoventilation) during sleep and, in more severely affected individuals, during wakefulness and sleep. Breathing complications occur despite the lungs and airways being normal.
A growing number of individuals are now being identified who present in later infancy, childhood or even adulthood and are called Late Onset Congenital Central Hypoventilation Syndrome (LO-CCHS).
Hyperventilation syndrome
Symptoms of hyperventilation usually last 20 to 30 minutes and may include:
•Feeling anxious, nervous or tense
•Frequent sighing or yawning
•Feeling that you can't get enough air (air hunger) or need to sit up to breathe.
•A pounding and racing heartbeat
•Problems with balance, lightheadedness or vertigo
•Numbness or tingling in the hands, feet or around the mouth
•Chest tightness, fullness, pressure, tenderness or pain
Hyperventilation is not a disease, but you may need to be checked by your doctor if you have repeated episodes of hyperventilation symptoms. If you have recurring symptoms, you might be diagnosed with a condition called hyperventilation syndrome (HVS).

What is a chemoreceptor? How does it influence breathing?

Chemoreceptors act most importantly to detect variation of the oxygen in the arterial blood, in addition to detecting arterial carbon dioxide and pH.
These nodes, called the aortic body and carotid body, are located on the arch of the aorta and on the common carotid artery, respectively and send information to the control centre in the medulla of the brain.
Chemoreceptors detect the levels of carbon dioxide in the blood. To do this, they monitor the concentration of hydrogen ions in the blood, which decreases the pH of the blood. This is a direct consequence of an increase in carbon dioxide concentration, because carbon dioxide becomes carbonic acid in an aqueous environment.
The response to increased CO2 is that the respiratory centre (in the medulla), sends nervous impulses to the external intercostal muscles and the diaphragm, via the intercostal nerve and the phrenic nerve, respectively, to increase breathing rate and the volume of the lungs during inhalation.Respiratory rate is influenced by almost everything, anatomically and environmentally. Anatomical causes of respiratory rate changes are ailments such as copd (chronic obstructive pulmonary disease) asthma, airway obstructions, diabetic coma or shock, congestive heart failure (back up of fluids through the venus supply), croup, anaphylaxsis, etc.
Environmental causes include airway anomallies, drug overdoses, inhaled poisons,smoking etc.

Where are the respiratory control centers located?

Respiratory control centers are located in the medulla and the pons. In the medulla the ventral respiratory group contains rhythm generators whose output drives respiration. Also in the medulla, the neurons of the dorsal respiratory group integrate peripheral sensory input and modify the rhythms generated by the VRG. The pons respiratory centers interact with the medulla centers to smooth the breathing pattern.
The respiratory center (RC), itself, is located in the medulla oblongata, the lowermost portion of the brainstem.

Differentiate between the respiratory membrane and the respiratory mucosa.

Respiratory membrane separates the air in the alveoli from the blood in surrounding capillaries. The respiratory mucosa is covered with mucus and lines the tubes of the respiratory tree.

List the functions of the paranasal sinuses.

The paranasal sinuses are membrane-linked, air-filled cavities in the bones of the skull that are connected to the nose by passageways. The four paranasal sinuses and the bones in which they are located are the frontal, ethmoid, maxillary, and sphenoid. These cavities lighten the weight of the bones and add resonance to the voice.

What is the function of the auditory tube?

The auditory tube (Eustachian tube) connects each middle ear to the throat. This tube conducts air between the tympanic cavity and the outside of the body by way of the throat and mouth. It also helps maintain equal air pressure on both sides of the eardrum, which is necessary for normal hearing. The function of the auditory tube can be experienced during rapid change in altitude. As a person moves from a high altitude to a lower one, the air pressure on the outside of the membrane becomes greater and greater. As a result, the eardrum may be pushed inward, out of its normal position, and hearing may be impaired. When the air pressure difference is great enough, some air may force its way up through the auditory tube into the middle ear. This allows the pressure on both sides of the eardrum to equalize, and the drum moves back to its regular position. An individual usually hears a popping sound at this time, and normal hearing is restored. A reverse movement of air occurs when a person moves from a low altitude to a higher one.

What is the function of the epiglottis?

The function of the epiglottis is to block off food and liquids from entering the trachea (windpipe).
Allows air to pass through larynx into the rest of the respiratory system.

Describe, in decreasing order of size, the structures that make up the air tubes of the lung.

Trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and alveoli!

Describe the pleura. What is the function of pleural fluid?

In human anatomy, the pleural cavity is the body cavity that surrounds the lungs. The pleura is a serous membrane which folds back upon itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity; it normally contains a small amount of pleural fluid. The outer pleura (parietal pleura) is attached to the chest wall. The inner pleura (visceral pleura) covers the lungs and adjoining structures, viz. blood vessels, bronchi and nerves.
The pleural fluid prevents friction between the lungs and the ribs when breathing.
it also keeps the lungs inflated

Differentiate between external respiration,internal respiration, and cellular respiration.

external refers to taking in air to the lungs.

internal refers to exchanging oxygen and carbon dioxide with the blood.

cellular is an energy making process where by the cell produces ATP from glucose and other orgainc monomers.

Explain the mechanical process of inspiration.

the diaphragm tightens (moves down) expanding the lungs. This expansion creates the pressure in the lungs to decrease. Since nature always strives for equilibrium, high pressure moves to low pressure areas --> air fills the lungs. the diaphragm relaxes, moving back up in the chest cavity, increasing the pressure on the contents in the lungs. The air escapes the lungs to reach the lower pressure area outside our body.

Explain the mechanical process of expiration.

Relaxation of external intercostal muscles & diaphragm > return of diaphragm, ribs, & sternum to resting position > restores thoracic cavity to preinspiratory volume > increases pressure in lungs > air is exhaled.

Define the term parital pressure (P) of a gas and explain how the parital pressure of oxygen (Po2) and carbon dioxide (Pco2) influence their diffusion.


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