Respiration

IntroductionA human body can survive without food for as much as several weeks, and without water for several days, but without breathing for three to six minutes, death is likely.Body tissues, especially the heart and brain, require a constant supply of oxygen.

The respiratory system delivers air containing oxygen to the blood and removes carbon dioxide.The respiratory system includes the lungs, and the several passageways leading from outside lungs, and the muscles that move air into and out of the lungs.

The term respiration has several meanings:1. Cellular respiration is the sum of biochemical processes by which the chemical energy of foods is released to provide energy for lifes processes.2. External respiration, which occurs in the lungs, is the exchange of gases between the blood and the lungs; oxygen from the lungs move into the blood, and carbon dioxide and water move from the blood to the lungs

3. Internal respiration is the exchange of the gases in the body tissues; carbon dioxide from the cells is exchanged for oxygen from the blood.In contrast to these physiological processes, VENTILATION or BREATHING, is the mechanical process that moves air into and out of the lungs. It includes two phases, INSPIRATION and EXPIRATION

It is helpful to think of the action of the respiratory system as a series of steps, even though in a living body they all take place at the same time and continuously.First, inhaled air, rich in oxygen and poor in carbon dioxide, travels through the respiratory tract deep into the terminal portions of the lungs; this is INSPIRATION.

There, oxygen diffuses from the lungs into the blood. From the lungs, oxygenated blood is carried to the heart, and then via the systemic circulatory system to all parts of the body.In the body tissues, oxygen moves from the blood into the cells, and carbon dioxide and other wastes are released from the cells into the blood.

Finally, deoxygenated venous blood, carrying its load of waters, is forced back to the lungs, where carbon dioxide is exhaled during EXPIRATION.

The respiratory tract includes the nose, nasal cavities, pharynx, larynx, trachea, and bronchi, which lead by way of bronchioles to the lungs.The respiratory mucosa of the nasal cavity is specialized to moisten and warm air and to capture particles like dust.The olfactory mucosa is specialized to sense odors.

The pharynx connects the nasal cavity and mouth with the rest of the respiratory tract and the esophagus.Pharynx is divide into the NASOPHARYNX, OROPHARYNX, and LARINGOPHARYNX.The larynx contains the vocal cords, which are largely responsible for producing soundAt the opening of the larynx, the glottis closes during swallowing and opens to allow air to pass.

The trachea or windpipe, carries air from the larynx to two bronchi.Trachea is mucosal and ciliated lining traps and removes dust particles and microorganisms before they can enter the lungs.The two bronchi are divided into smaller and smaller bronchi, and then into even smaller bronchioles, forming the respiratory tree.

Around the tiniest branches, called respiratory bronchioles, are minute air sacs known as ALVEOLI.Alveoli are the functional units of the lungs.Exchange of oxygen and carbon dioxide takes place through the walls of the alveoli and the walls of the pulmonary capillaries.

In the thoracic cavity, the two lungs are separated by the MEDIASTINUM.The right lung has three lobes, and the left lung has two.Each lobe is further divided into BRONCHOPULMONARY SEGEMENTS and the into LOBULES.The lungs are covered by the VISCERAL PLEURA, and the thoracic cavity by the PARIETAL PLEURA. Between these membranes is the PLEURAL CAVITY

Mechanics of Breathing1. VENTILATION is the mechanical process that moves air into and out the lungs.2. During INSPIRATION, air is pushed into the lungs by the pressure of the outside air when the size of the thoracic cavity is increased by contraction of the EXTERNAL INTERCOSTAL MUSCLES and the DIAPHRAGM and the raising of the RIBS.

3. During ordinary EXPIRATION, air is expelled from the lungs when the respiratory muscles are relaxed and the volume of the thoracic cavity is reduced

Other activities of respiratory system include:Coughing,Sneezing,Crying,Laughing,Yawning,Hiccuping, andSnooring

The effects of aging on the respiratory system:Aging is usually accompanied by a decrease in gas exchange, and a reduction in breathing and lungs capabilitiesEmphysema, lung cancer, chronic bronchitis, and pneumonia may become more prevalent with age.

Calculating energy in foodA given amount of any substance always requires the same amount of energy to produce a particular increase in temperature.

1000g of water needs..4.2 kJ to make its temperature rise by 1 oC

Calculating the energy content of foodsThe formula to calculate the energy release is4.2 x M x T

Now calculate the energy content of your foods1000M = mass of water (g)T=rise in temperature ( C)

The Chemistry of Respirationenergy and mitochondria clip

Adenosine triphosphateThe energy released during respiration is not used directly by cells.Instead it is used to make a molecule called ATP which stores the energy until it is needed.

ATP = Adenosine triphosphate

What does ATP do?ATP supplies energy for all the processes that need it. For example: movement chemical reactions growth.slow twitch/fast twitch investigation

Structure of ATP

Formation of ATP

ATP is made when another molecule called adenosine diphosphate (ADP) is bonded to a third inorganic phosphate (Pi) using the energy released from glucose.

EnzymesEnergy from respirationEnergy Rich bond formed

Summarised as:ADP + Pi ATP The whole process is under the control of enzymes

The role of ATPATP stores the energy in the third bond of the molecule

The energy is released when that bond is broken to release the third inorganic phosphate (Pi) .

Energy released to do workATPADPEnzymes

SummaryThe whole process is an enzyme controlled reaction.

Aerobic Respiration

Aerobic respiration = respiration with oxygen.

glucose + OXYGEN energy + carbon dioxide + water(to make ATP)

Aerobic respiration happens in 2 stages:

Stage 1 Glycolysis glyco lysis

glucose splitting

In glycolysis, a glucose molecule is broken down into pyruvic acid.energy released to make small quantity of ATP(2 molecules)

series of enzyme controlled reactions

pyruvic acidglucoseGlycolysis does not require oxygen

Stage 2 Breakdown of pyruvic acidThe pyruvic acid made in glycolysis (stage1) still contains a lot of energy

It can only be broken down to release the rest of the energy in the presence of oxygen.

energy released to make largequantity of ATP(36 molecules)series of enzyme controlled reactionspyruvic acid

carbon dioxide + water

ATP production summary36 ADP + 36 Pi =36 ATPglucose

pyruvic acid

carbon dioxide + water2 ADP + 2 Pi =2 ATP

Summary of ATP productionStage 1 and 2 release all the chemical energy in one molecule of glucose to make a total of 38 ATP molecules. 2 molecules ATP from glucose pyruvic acid 36 molecules ATP from pyruvic acid carbon- dioxide + water

Total 38 molecules ATP

Anaerobic Respiration(in animals)

anaerobic = in the absence of oxygen

In low oxygen conditions or during heavy exercise, when not enough oxygen can be supplied, muscle cells swap to anaerobic respiration

glycolysis still happens as it does not require oxygenin absence of oxygen pyruvic acid is turned into lactic acid.

pyruvic acid

lactic acid

glucose2 ADP + 2 Pi

2 ATP

A build up of lactic acid produces muscle fatigue.

Muscle fatigue makes muscles ache and contract less powerfully.

A recovery period is needed. During this time more oxygen is taken in to convert the lactic acid back into pyruvic acid again.

The volume of oxygen needed is called the oxygen debt.

Summaryoxygen debte.g. during hard exerciseoxygen debtrepaid during recovery time glucose

pyruvic acid

lactic acid

Anaerobic Respiration in plants

The same process occurs in plants and yeast in low oxygen conditions, e.g. muddy, flooded soils.

glycolysis still happens, producing 2 ATP moleculesThis time in absence of oxygen, pyruvic acid is turned into carbon dioxide and ethanol

glucose

pyruvic acid

ethanol + carbon dioxideThis is irreversible2 ADP + 2 Pi

2 ATP

Comparison of aerobic and anaerobic respiration

Aerobic respirationAnaerobic Respirationin animalsin plants and yeastOxygen required?yesnonoGlycolysis occursyesyesyesATP yield38ATP2ATP2ATPGlucose completely broke down?yesnonoEnd productsCarbon dioxide and waterLactic acidEthanol and carbon dioxide

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