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Lung Transplantation

Lung transplantation is a surgical procedure in which a patient’s diseased lungs are partially or totally replaced by lungs which come from a donor. While lung transplants carry certain associated risks, they can also extend life expectancy and enhance the quality of life for end-stage pulmonary patients.

Types of Lung Transplants

Lobe
A lobe transplant is a surgery in which part of a living donor’s lung is removed and used to replace part of recipient’s diseased lung. This procedure usually involves the donation of lobes from two different people, thus replacing a single lung in the recipient. Donors who have been properly screened should be able to maintain a normal quality of life despite the reduction in lung volume.

Single-lung
Many patients can be helped by the transplantation of a single healthy lung. The donated lung typically comes from a donor who has been pronounced brain-dead.

Double-lung
Certain patients may require both lungs to be replaced. This is especially the case for people with cystic fibrosis, due to the bacterial colonisation commonly found within such patients’ lungs; if only one lung were transplanted, bacteria in the native lung could potentially infect the newly transplanted organ.

Heart-lung
Some respiratory patients may also have severe cardiac disease which in of itself would necessitate a heart transplant. These patients can be treated by a surgery in which both lungs and the heart are replaced by organs from a donor or donors.

Procedure
A single lung transplant takes about four to eight hours, while a double lung transplant takes about six to twelve hours to complete. A history of prior chest surgery may complicate the procedure and require additional time.

Single Lung
In single-lung transplants, the lung with the worse pulmonary function is chosen for replacement. If both lungs function equally, then the right lung is usually favored for removal because it avoids having to maneuver around the heart, as would be required for excision of the left lung.
In a single-lung transplant the process starts out after the donor lung has been inspected and the decision to accept the donor lung for the patient has been made. An incision is generally made from under the shoulder blade around the chest, ending near the sternum. An alternate method involves an incision under the breastbone. In the case of a singular lung transplant the lung is collapsed, the blood vessels in the lung tied off, and the lung removed at t the bronchial tube. The donor lung is placed, the blood vessels reattached, and the lung reinflated. To make sure the lung is satisfactory and to clear any remaining blood and mucus in the new lung a bronchoscopy will be performed. When the surgeons are satisfied with the performance of the lungs, the chest incision will be closed.

Incision scarring from a double lung transplant.

Double Lung
A double-lung transplant, also known as a bilateral transplant, can be executed either sequentially, en bloc, or simultaneously. Sequential is more common than en bloc. This is effectively like having two separate single-lung transplants done. A less common alternative is the transplantation of both lungs en bloc or simultaneously.
The transplantation process starts after the donor lungs are inspected and the decision to transplant has been made. An incision is then made from under the patient’s armpit, around to the sternum, and then back towards the other armpit, this is known as a clamshell incision. In the case of a sequential transplant the recipients’ lung with the poorest lung functions is collapsed, the blood vessels tied off, and cut at the corresponding bronchi. The new lung is then placed and the blood vessels reattached. To make sure the lung is satisfactory before transplanting the other a bronchoscopy is performed. When the surgeons are satisfied with the performance of the new lung, surgery on the second lung will proceed. In 10% to 20% of double-lung transplants the patient is hooked up to a heart-lung machine which pumps blood for the body and supplies fresh oxygen.

Risks
The newly transplanted lung itself may fail to properly heal and function. Because a large portion of the patient’s body has been exposed to the outside air, sepsis is a possibility, so antibiotics will be given to try to prevent that.
Because the transplanted lung or lungs come from another person, the recipient’s immune system will “see” it as an invader and attempt to neutralize it. Transplant rejection is a serious condition and must be treated as soon as possible.

Signs of rejection:
1. Fever
2. flu-like symptoms, including chills, dizziness, nausea, general feeling of illness
3. increased difficulty in breathing
4. worsening pulmonary test results
5. increased chest pain or tenderness

Breathing

Breathing Part

Breathing takes oxygen in and carbon dioxide out of the body. Aerobic organisms require oxygen to create energy via respiration, in the form of the metabolism of energy-rich molecules such as glucose. The medical term for normal relaxed breathing is eupnea.

Breathing is only part of the processes of delivering oxygen to where it is needed in the body and removing carbon dioxide waste. The process of gas exchange occurs in the alveoli by passive diffusion of gases between the alveolar gas and the blood passing by in the lung capillaries. Once in the blood the heart powers the flow of dissolved gases around the body in the circulation.

As well as carbon dioxide, breathing also results in loss of water from the body. Exhaled air has a relative humidity of 100% because of water diffusing across the moist surface of breathing passages and alveoli.

In mammals, breathing in, or inhaling, is usually an active movement, with the contraction of the diaphragm muscle. This is known as negative pressure breathing. The diaphragm’s normal relaxed position is that of a recoiled one (decreasing the thoracic volume) whereas in the contracted position it is pulled downwards (increasing the thoracic volume). This process works in conjunction with the intercostal muscles connected to the rib cage. Contraction of these muscles lifts the rib cage, thus aiding in increasing the thoracic volume. Relaxation of the diaphragm compresses the lungs, effectively decreasing their volume while increasing the pressure inside them. The intercostal muscles hereby also relax, further decreasing the volume of the lungs.

With a pathway to the mouth or nose clear, this increased pressure forces air out of the lungs. Conversely, contraction of the diagraphm increases the volume of the (partially empty) lungs, decreasing the pressure inside, which creates a partial vacuum. Environmental air then follows its pressure gradient down to fill the lungs.

At rest, breathing out, or exhaling, is a combination of passive and active processes powered by the elastic recoil of the alveoli, similar to a deflating balloon, and the contraction of the muscular body wall. The following organs are used in respiration: the mouth; the nose and nostrils; the pharynx; the larynx; the trachea; the bronchi and bronchioles; the lungs; the diaphragm; and the terminal branches of the respiratory tree, such as the alveoli.

Extra Information

Artificial respiration is the act of simulating respiration, which provides for the overall exchange of gases in the body by pulmonary ventilation, external respiration and internal respiration. This means providing air for a person who is not breathing or is not making sufficient respiratory effort on their own. [It must be used on a patient with a beating heart or as part of cardiopulmonary resuscitation in order to achieve the internal respiration.

Pulmonary ventilation (and hence external respiration) is achieved through manual insufflation* of the lungs either by the rescuer blowing into the patient’s lungs, or by using a mechanical device to do so. This method of insufflation has been proved more effective than methods which involve mechanical manipulation of the patient’s chest or arms, such as the Silvester method. It is also known as Expired Air Resuscitation (EAR), Expired Air Ventilation (EAV) and mouth-to-mouth resuscitation.

*Insufflation.
Insufflation is also known as ‘rescue breaths’ or ‘ventilations’, is the act of mechanically forcing air into a patient’s respiratory system. This can be achieved via a number of methods, which will depend on the situation and equipment available.

Methods Include :

! Mouth to mouth – This involves the rescuer making a seal between their mouth and the patient’s mouth and ‘blowing’, in order to pass air into the patient’s body
! Mouth to nose – In some instances, the rescuer may need or wish to form a seal with the patient’s nose. Typical reasons for this include maxillofacial injuries, performing the procedure in water or the remains of vomit in the mouth
! Mouth to mouth and nose – Used on infants (usually up to around 1 year old), as this forms the most effective seal
! Mouth to mask – Most organisations recommend the use of some sort of barrier between rescuer and patient to reduce cross infection risk.
! Bag valve mask (BVM) – This is a simple device manually operated by the rescuer, which involves squeezing a bag in order to expel air into the patient.
! Mechanical resuscitator – An electric unit designed to breathe for the patient.

Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate to perform needed gas exchange. It generally causes an increased concentration of carbon dioxide (hypercapnia) and respiratory acidosis. It can be caused by medical conditions, by holding one’s breath, or by drugs, typically when taken in overdose. Hypoventilation may be dangerous for those with sleep apnea. [Sleep apnea is a sleep disorder characterized by pauses in breathing during sleep.]
The opposite condition is hyperventilation (too much ventilation), resulting in low carbon dioxide levels (hypocapnia).

Extra Extra Knowledge

In animal physiology, respiration is the transport of oxygen from the outside air to the cells within tissues and the transport of carbon dioxide in the opposite direction. This is in contrast to the biochemical definition of respiration, which refers to cellular respiration: the metabolic process by which an organism obtains energy by reacting oxygen with glucose to give water, carbon dioxide and ATP (energy). Although physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the animal, while physiologic respiration concerns the bulk flow and transport of metabolites between the organism and external environment.
In unicellular organisms, simple diffusion is sufficient for gas exchange: every cell is constantly bathed in the external environment, with only a short distance for gases to flow across. In contrast, complex multicellular animals such as humans have a much greater distance between the environment and their innermost cells, thus, a respiratory system is needed for effective gas exchange. The respiratory system works in concert with a circulatory system to carry gases to and from the tissues.
In air-breathing vertebrates such as humans, respiration of oxygen includes four stages:

! Ventilation, moving of the ambient air into and out of the alveoli of the lungs.
! Pulmonary gas exchange, exchange of gases between the alveoli and the pulmonary capillaries
! Gas transport, movement of gases within the pulmonary capillaries through the circulation to the peripheral capillaries in the organs, and then a movement of gases back to the lungs along the same circulatory route.
! Peripheral gas exchange, exchange of gases between the tissue capillaries and the tissues or organs, impacting the cells composing these and mitochondria within the cells.

Note that ventilation and gas transport require energy to power a mechanical pump (the heart) and the muscles of respiration, mainly the diaphragm. In heavy breathing, energy is also required to power additional respiratory muscles such as the intercostal muscles. The energy requirement for ventilation and gas transport is in contrast to the passive diffusion taking place in the gas exchange steps.

Thats all for Chapter 10 Respiration.

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Chapter 10.7

Gaseous Exchange In Green Plants

! No special breathing mechanisms for gaseous exchange
! Gaseous exchange occurs mainly through stomata of the leaves and young stems
! Lenticles are openings formed

Respiration
! Energy is released.
! Oxygen is used, and carbon dioxide and water are given off.
! A catabolic process, resulting in the breakdown of carbohydrate molecules.
! Occurs at all times in all cells, independent of chlorophyll and sunlight.
! Results in a loss of dry mass.

Photosynthesis
! Energy is stored in carbohydrate molecules.
! Carbon dioxide and water are used whereas oxygen is given off.
! An anabolic process, resulting in the building up of carbohydrate molecules.
! Occurs only in cells containing chlorophyll and in the presence of sunlight.
! Results in a gain of dry mass.

Chapter 10.6

Effects Of Tobacco Smoke On Human Health

Irritant particles
When we breathe through our nose, most irritant particles are filtered off by the hairs in our nose or trapped in the mucus.
But when they enter our lungs, it would cause violent coughing or sneezing reaction to expel the foreign particles.

Chemical in tabocco smoke:

Nicotine – addictive drug, causes the release of the hormone adrenaline, makes blood clot easily.
Effects: increases in heartbeat and blood pressure, increased risk of blood clot in blood vessels.

Carbon Monoxide – combines with haemoglobin to form carboxyhaemoglobin which reduces oxygen transport efficiency of red blood cells, increases the rate of fatty deposits on the inner arterial wall, damages the lining of blood vessels.
Effects: death if concentrations in the air are increased by 1%, increased risk of atherosclerosis, increased risk of blood clotting in the arteries.

Tar – contains cancer-causing (carinogenic) chemicals which induce uncontrolled cell division of the epithelium, paralyses cilia lining the air passages.
Effects: blockage in the air sacs and reduction in gas exchange efficiency, dust particles trapped in the mucus lining the airways cannot be removed.

Irritants (e.g. hydrogen cyanide, acrolein, formaldehyde) – paralyses cilia lining the air passages.
Effect: increased risk of chronic bronchitis and emphysema.

Chronic bronchitis
Signs of chronic bronchitis:
! The epithelium lining the airways, bronchi becomes inflamed
! Excessive mucus is secreted by the epithelium
! The cilia on the epithelium are paralysed. Mucus and dust cannot be removed.
! The airways become blocked, making breathing difficult.
! The person has to cough persistently to clear his airways in order to breathe. This increases the risk of getting his lung infections.

Emphysema
Signs of emphysema:
! Violent coughing breaks the partition walls between air sacs
! The surface area for gaseous exchange decreases
! The lungs become inflated with air
! The lung lose their elasticity
! Breathing becomes difficult. The person wheezes and suffers severe breathlessness.

Lung cancer
! The more cigarettes you smoke, the higher the risk of getting lung cancer.
! Cancer is an uncontrolled division of cells producing outgrowths or lumps of tissues.
! Apart from lung cancer, smoking also increases the risk of cancers of the mouth, throat, pancreas, kidneys and urinary bladder.

Chapter 10.5

Gaseous Exchange In Animals

Breathing mechanisms
Many animals possess special breathing mechanisms that increase the rate if gaseous exchange between the animals and the external environment. The breathing motions of an animal essentially consist of two phases:
! The taking in of air called inspiration (or inhalation)
! The giving out of air called expiration (or exhalation)

Gas exchange system in humans
Involve two lungs in the thorax and air passages leading to them. The air passages consist of the nasal passages, pharynx, larynx, trachea, bronchi and bronchioles. The thoracic cavity, ribs, diaphragm and related muscles are also vital parts of the gaseous exchange system.

! Air enters body through nostrils (external nares)
– fringe of hairs on the walls of nostrils
! Air led into two nasal passages lined with moist mucous membrane.
– dust or foreign particles, as well as bacteria are trapped by hairs in nostrils or mucus on mucous membrane.
! Air is warmed and moistened before entering lungs.
! Harmful chemicals may be detected by sensory cells.
! Nasal cavity leads to the pharynx, from which air passes through larynx into trachea through glottis.
! Trachea branches into two bronchi, which branch into bronchioles.
! The epithelium lining up the air ducts is covered by cilia and mucus (cilia move the junk back up to the esophagus)
! Bronchioles end in air sacs known as alveoli, which are well-supplied with blood capillaries for gaseous exchange.
! Oxygen and Carbon Dioxide diffuse through epithelium.

How are lungs adapted for efficient gaseous exchange?
! Numerous alveoli in lungs provides large surface area.
! The wall of the alveolus is only one cell thick to enable a faster rate of diffusion of gaseous through it.
! A thin film of moisture covering the surface of the alveolus, allowing oxygen to dissolve in it.
! Walls of alveoli are richly supplied with blood capillaries. The flow of blood maintains the concentration gradient of gases.

Chest Cavity
! supported by ribs and are attached dorsally to backbone (vertebral column) in a way that enables movements up and down.
! Two sets of muscles can be found between the ribs, the external and internal intercostals muscles.
! External intercostals muscles contracts when internal intercostals muscles relax, or vice versa.
! Thorax is separated from abdomen by diaphragm which flattens downwards when muscles contracts or arches upwards when muscles relax.
! The working of the intercostals muscles and the diaphragm changes the volume of the thoracic cavity.

Inspire
! Diaphragm contracts and flattens.
! External intercostals muscles contract while internal intercostals muscles relax.
! Ribs move upwards and outward. (Sternum also moves up and forward.)
! The volume of thoracic cavity increases.
! Air pressure in lungs cause them to expand to fill up the enlarged space in thorax.
! Expansion of lungs causes the air pressure inside them to decrease.

Expire
! Diaphragm relaxes and arches upwards.
! Internal intercostals muscles contracts while external intercostals muscles relax.
! Ribs move downwards and inwards. ( Sternum moves down to original position.)
!The volume of thoracic cavity decreases.
! Lungs are compressed and air pressure inside them increases as the volume decreases.
! Air pressure within the lungs is now higher than atmospheric pressure. The air is forced out of lungs to the exterior.

Gaseous Exchange in Alveoli
The physiology of respiration involves exchange of gases in lungs and tissues and their transport from lungs to the tissues and vice versa. Exchange of gases takes place by diffusion mainly based on concentration gradient.

How is oxygen absorbed in lungs?
! One cell-thick membrane separating the blood capillaries from the alveolar air is permeable to oxygen and carbon dioxide.
! Alveolar air contains higher concentration of oxygen than blood, thus oxygen dissolves in the moisture lining the alveolar walls and then diffuses into the blood capillaries.
! Reaction is reversible.
! Oxyhemoglobin is formed when the oxygen concentration in the lungs is high, shifting the reaction to the right.
! The reaction shifts to the left when blood passes through oxygen-poor tissues, releasing oxygen.
! Oxygen then diffuses through the walls of blood capillaries into the cells.

How is Carbon Dioxide removed from body?
! Carbon Dioxide reacts with water to form carbonic acid in red blood cells.
! Reaction is catalysed by enzyme carbonic anhydrase,
! Carbonic acid is converted into hydrogencarbonate ions which diffuses out of red blood cells into blood plasma.
! Hydrogencarbonate ions diffuse back into red blood cells in the lungs.
! Converted into carbonic acid, and then into water and carbon dioxide.
! Carbon dioxide diffuses out of blood capillaries into alveoli, and expelled when we exhaled.

Amount of air breathed in and breathed out
(1) Tidal air: It is the amount of air breathed in and breathed out during restful breathing.
(2) Complemental air: It is the amount of additional volume of air you breathe in from a deep breath.
(3) Supplement air: It is the amount of forced out after normal expiration
(4) Residual air: It is the amount of air which remains in the alveoli after forced maximal expiration.

Chapter 10.4

Studying Respiration

How do we know that living organisms respire?

In aerobic respiration, oxygen is consumed while energy, carbon dioxide and water are released. Therefore, if we can show that an organism consumes oxygen and gives off carbon dioxide and heat, we can say that it respires aerobically.
Anaerobic respiration in animals is difficult to detect as it does not require the consumption of oxygen and does not product carbon dioxide. However, microorganisms such as yeast do give off carbon dioxide when they respire anaerobically. Therefore, if we can show that a microorganism gives off carbon dioxide i the absence of oxygen, we can say that it respires anaerobically.

How do organisms obtain oxygen for aerobic respiration?
! Organism obtain oxygen for aerobic respiration through the process of gaseous exchange.

Definition:
Gaseous exchange is the exchange of gases between an organism and the environment. In human between ,the absorption of of atmospheric oxygen and the removal of carbon dioxide from the body occur in the air sacs in the lungs. Breathing is part of gaseous exchange process . It refers to the muscular contractions and movements of the ribs which results in air moving in and out if the lungs.

Definition:
Tissue respiration: Tissue respiration is the oxidation of organic food substances releasing energy , carbon dioxide and water within the cells or tissues of an organism. Tissue respiration provides higher animals and plants with all the energy the require.

Refers to Investigation 🙂

Chapter 10.3

Anaerobic Respiration

Definition:
Anaerobic Respiration is the breakdown of food substances in the absence of oxygen. Anaerobic respiration releases less energy than aerobic respiration.

Anaerobic respiration occurs in certain microorganisms, for example, yeast. Yeast respires aerobically in the presence of oxygen. Without oxygen, yeast carries out anaerobic respiration.
Anaerobic respiration releases less energy than aerobic respiration. The little amount of energy released is enough for the yeast to survive, though it cannot be very active under such conditions.

Equation for anaerobic respiration :
Glucose -> Ethanol + Carbon Dioxide + Small amount of Energy

Energy conversions in muscle cells

Muscle cells normally respire aerobically. When less oxygen is available, muscle cells will also respire anaerobically for a short period of time.
Muscle cells carry out anaerobic respiration to produce extra energy as maximum aerobic respiration is unable to produce energy fast enough to meet demands.

Equation for anaerobic respiration in your muscles:
C₆H₁₂O₆ (Glucose) -> 2C₃H₆O₃ (Lactic Acid) + Small amount of energy

The small amount of energy released in anaerobic respiration, together with that produced in aerobic respiration, is sufficient to keep the muscles contracting.
Since there is insufficient oxygen to meet the demands of vigorous muscular contractions, the muscles are said to incur an oxygen debt.
Lactic acid concentrations start to build up in the muscles and this causes fatigue and muscle pains.
Lactic acid is transported to the liver and oxidized to produce oxygen. This energy is used to convert the remaining lactic acid back into glucose when the body is no longer short of oxygen. When the lactic acid is used up, the oxygen debt is repaid.
Glucose is then transported back to the muscle.