2) During exhalation Air is cooled due to condensation and loses its moisture, depositing it on lining in trachea and nose

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Section 10: The Respiratory System A. Functions of the respiratory system: The organs of the respiratory system make sure oxygen enters the body and carbon dioxide leaves the body.

1 Section 10: The Respiratory System A. Functions of the respiratory system: The organs of the respiratory system make sure oxygen enters the body and carbon dioxide leaves the body. 2 stages: Inhalation (oxygen in) and exhalation (carbon dioxide out) 1) During inhalation Air is cleaned course hairs act as trap, cilia, mucus in nose Cilia and mucus in other parts, beat upward to move mucus and dust to pharynx for swallowing or expectoration Air is warmed heat from blood vessels Air moistened by wet surfaces of passages 2) During exhalation Air is cooled due to condensation and loses its moisture, depositing it on lining in trachea and nose B. Parts of the respiratory system: Upper respiratory tract: 1. Nose: Opens at the nostrils 2 sides separated by septum composed of bone and cartilage Air moves in and particles are trapped by the coarse hairs in the nose so that the particles don t go into the air passages and lungs The rest of the nasal cavities are lined with a mucus membrane that helps trap any particles missed by the hairs then this gets swept to the pharynx where it is swallowed or spit out

2 Under the mucus layer is the submucosa and this layer has blood vessels capillariesrunning through it which warms and moistens the air In the upper part of the nasal cavity there are special ciliated cells which act as odor receptors nerves lead from these cells to the brain where the impulses are interpreted as smell. Course your tear ducts are connected to your nasal cavity that s why when you cry your nose runs. 2. Pharynx: The pharynx is the back of the throat where the mouth connects to the nasal cavity and the trachea and esophagus. Tonsils are found in a ring around the oral cavity, or mouth, where it enters the pharynx tonsils are a type of lymph gland they act as primary defence during breathing because the air passes right over them Remember from the digestion chapter, the esophagus lies right beside the wind pipe or trachea and we talked about the epiglottis coming down over the glottis to close the door on the wind pipe while we are swallowing... The airway is usually open, it only closes during swallowing 3. Larynx: Larynx is the passageway between the pharynx and the trachea. It is made of cartilage like a triangular box also called your adams apple Also called the voice box because it houses your vocal chords The vocal chords are mucosal folds supported by elastic ligaments the slit or hole between the vocal cords is called the glottis When air goes through the glottis, causes the vocal cords to vibrate which produces sound tension of the cords that changes the pitch When you swallow, the larynx moves up under the epiglottis which is just the flap that protects your trachea from food or liquid going down it. Lower respiratory tract 4. Trachea: Tube connecting larynx to primary bronchi Walls are connective tissue and Smooth muscle reinforced by C shaped cartilaginous rings prevents trachea from collapsing Anterior to esophagus Mucus membrane lines trachea has simple ciliated epithelium Traps debris and moves mucus and debris to pharynx away from lungs 5. Bronchial Tree Trachea divided into left and right primary bronchi Then branch to secondary bronchi Then branch into bronchioles Terminates in elongated space enclosed by many alveoli (air sacs)

3 6. Lungs Paired cone shaped organs located in thoracic cavity Right = 3 lobes Left = 2 lobes makes room for the heart a. Pleura: Lungs are enclosed by 2 pleura =double layer of serous membranes that secretes serous fluid to keep lungs moist One pleura adheres to thoracic wall (parietal pleura) One adheres to surface of lungs (visceral pleura) Surface tension (surface tension is the tendency for water molecules to cling to one another due to hydrogen bonding between molecules ) between wet membranes holds pleura together therefore lungs follow movement of thoracic cavity when breathing occurs b. Alveoli Lungs have about 300 million alveoli basically the surface area of your lungs is about the size of a tennis court Alveoli cluster together in sacs Each sac surrounded by capillaries Walls of capillaries and sac are 1 cell layer thick therefore gas exchange occurs between them Oxygen diffuses from alveoli into bloodstream CO2 carbon dioxide diffuses from bloodstream into interior space of alveoli Alveoli are lined with surfactant that prevents them from closing surfactant is a film of lipoprotein that lowers the surface tension of water and prevents the alveoli from closing C. Mechanism of breathing Ventilation (another word for breathing) = 2 phases 1) Inhalation (aka inspiration) moves air into lungs 2) Exhalation (aka expiration) moves air out of lungs Conditions required: 1) Continuous column of air from pharynx to alveoli 2) Lungs in sealed thoracic cavity Ribs attached to sternum and vertebra Intercostal muscle between ribs Diaphragm form floor of thoracic cavity 3) Thoracic cavity has slight vacuum (lower pressure than atmospheric pressure) 4) Lungs adhere to thoracic cavity by pleura

4 Inhalation Exhalation Phase active passive Intercostal muscles and contract relax diaphragm Ribcage Up and out Down and in Volume increases decreases Pressure decreases increases Airflow in Out aided by elastic recoil of lungs D. Definitions Tidal volume = normal amount of air inhalated and exhalated =500ml when we are breathing normally there is only a small amount of air moving in and out Inspiratory and expiratory reserve volume the volume of air we can force in and out of our lungs over and above the tidal volume inspiratory reserve volume -is forced inspiration by expanding the chest and lowering the diaphragm to maximum extent possible -can add another ~ 2900ml of air above tidal volume of ~500ml - can also increase expiration by contracting the abdominal and thoracic muscles this is expiratory reserve volume which is about 1400ml Vital capacity = maximum amount of air that can be moved in and out of lungs during a single breath of deep breathing tidal volume + inspiratory and expiratory reserve volume when you breath in some air of course never reaches your lungs because it fills your nose, pharynx and trachea this is called dead space and at the same time, a certain amount of air never leaves your lungs this is called residual volume. Residual volume = amount of air that cannot be exhaled from lungs E. Gas exchange in the body Three types of respiration: 1. Cellular respiration 2. Internal 3. External 1. Cellular Respiration a) What is cellular respiration? Aerobic cellular respiration has an oxygen demand (needs oxygen) and produces waste carbon dioxide as a by-product of glucose breakdown Purpose of cell respiration =making ATP for energy Allows energy from breaking glucose chemical bonds to be released slowly and ATP produced gradually from the capture of energy from bond breaking So cellular respiration breaks down glucose to carbon dioxide + water + energy, 3 pathways are involved glycolysis, citric acid cycle, and the electron transport chain. All these pathways allow the energy in glucose to be released slowly cells would lose a lot of energy as heat if it was broken down quickly instead it is broken down slowly and the energy can be captured as ATP.

5 Process Glucose + oxygen energy + carbon dioxide + water C6H12O6 + O2 (g) ATP + CO2 (g) + H2O (l) Diffusion determines whether O2 leaves the bloodstream or CO2 enters the bloodstream therefore works on a conctrn gradient (remember exchange at capillaries) Based on the partial pressure of the gas Gases exert pressure if there is more O2 in blood than tissues, the partial pressure of O2 will be higher in blood therefore O2 moves from blood to tissues to balance partial pressure. CO2 is reverse Gases diffuse from area of high to area of low pressure b) Where cellular respiration takes place Occurs mostly in the Mitochondria: Cell powerhouse - Converts chemical energy of glucose to ATP Requires presence of O2, releases CO2 (carbon dioxide) as waste by product = cellular respiration during the process of converting glucose to ATP the mitochondria uses up oxygen and produces CO2 therefore it is called cell respiration just like our lungs, take in oxygen and produce co2 called respiration measure respiration you are measuring breathing Reminder : Structure of mitochondria Double membrane organelle Outer membrane=plasma membrane surrounding organelle Inner membrane folded to form cristae ATP production occurs here Matrix folds embedded in gel-like fluid contains enzymes for glucose breakdown c) Reminder: How enzymes work Metabolism = all chemical reactions that occur in cells Metabolism requires metabolic pathways which are carried out by enzymes enzyme Reactants products Enzyme (enzymes are a type of protein that brings reactants together thereby speeding up chemical rxns in cells specific for one type of rxn and only function at body temperature) molecule that has an active site = location where reaction occurs Reactants (aka substrates) occupy the active site An enzyme can be used to make or break up molecules: Degradation breakdown to smaller products Synthesis substrates combine to form larger products Enzyme is not used in the rxn therefore it is free to act over and over again Specific for one rxn because active site has a specific shape that will only fit 1 type of substrate Coenzymes non protein molecules that assist enzyme activity - these molecules may even accept or contribute atoms to the reaction vitamins are often components of coenzymes

6 d) 3 processes of cell respiration: 1) Glycolysis anaerobic (does not need oxygen) glucose 2 molecules of pyruvate C6H12O6 + O2 2 x 3C molecules **pyruvate is required in order to move into the citric acid cycle (Glucose moves into cell from the bloodstream by facilitated transport) Glycolysis means sugar splitting remember lysis means to break (this term was used when we were talking about hypotonic solutions and when water entered the cell and burst the cell broke the cell ) this stage does not require oxygen so is anaerobic NAD NADH Transfers e- and H + to electron transport chain 2 ATP are produced Occurs in the cytoplasm of the cell Is anaerobic because oxygen is not used in glycolysis 2) Citric acid cycle (used to be called Krebs cycle) Pyruvate (3 c molecule) bonds broken down Occurs in matrix of mitochondria Hydrogen + e- transfer by NADH to electron transport chain 2 ATP are produced Citric acid cycle completes the breakdown of glucose. It is a cyclical series of enzymatic rxns which occur in the matrix of the mitochondria and also involves the release of CO2, - hydrogen and e- are carried away by NADH When our cells run out of glucose, they usually substitute fatty acids for glucose as an energy source. Fatty acids yield C-C molecules that can enter the citric acid cycle. Proteins are also digested to amino acids whose carbon chains can easily enter the citric acid cycle but first the amino group has to be removed from the carbon chain this is mainly carried out in the liver in the liver the amino groups are converted to urea which is excreted by the kidneys, but when you eat a lot of protein your kidneys have to work overtime to excrete all the nitrogen. 3) Electron transport chain Located on cristae in mitochondria NADH deliver electrons and H + from glycolysis and citric acid cycle to the electron transport chain Carrier proteins are grouped into complexes and e- are passed from 1 complex to a lower energy complex -so each carrier of the electron transport chain accept 2 electrons and passes them on to the next carrier - Complexes are embedded in cristae e- lose energy as passed down the chain and forms high energy phosphate bond for ATP production

7 oxygen is final receiver of e-, after O2 receives e-, combines with H and forms water. Both citric acid cycle and Electron transport chain are Aerobic respiration because oxygen is required. O2 is not combined with anything during cell respiration its sole purpose is to receive e- at the end of the electron transport chain. Forms net 32 ATP/glucose molecule Each cell produces ATP in its mitochondria and therefore each cell uses the energy for its own purposes What happens if the cell runs out of oxygen? 4) Fermentation Anaerobic respiration Does not require O2 Therefore electron transport chain does not work because O2 cannot accept e- therefore inefficient production of ATP When oxygen is not available electron transport chain soon shuts down because O2 isn t there to accept e- at the end of the chain most cells have a fall back plan and are still able to make some ATP glycolysis still operates without oxygen, but instead of passing electrons on to electron transport chain NADH instead passes e- on to pyruvate molecules...then... Pyruvate is converted to another compound called lactate Fermentation can give us a burst of energy for a short time but only produces 2 ATP per glucose molecule as well... Cannot enter citric acid cycle therefore builds up in muscles and forms lactic acid causes muscles to cramp and fatigue If oxygen becomes present again...can be converted back to pyruvate by presence of O2 5) Summary of cellular respiration: Process Location Products Glycolysis (anaerobic) Cytoplasm of cell 6 C glucose broken into 2-3 carbon pyruvate Citric acid cycle (aerobic) Matrix of mitochondria 3 carbon pyruvate, has all bonds broken, H+, e- transported by NADH to e- chain, CO2 released Electron transport chain (aerobic) Cristae of mitochondria e- transported down chain & at end, O2 receives these e- and combines with H to form water. 32 ATP produced from energy released

8 2) Internal Respiration = gas exchange between bloodstream and tissue fluid surrounding cells. a) Conditions that favour internal respiration: temperature is warmer in tissues (38 C) compared to lungs, and ph (7.38) is lower - this favours O2 release by hemoglobin b) Exchange of oxygen Equation: Deoxyhemoglobin + Oxygen (aka reduced hemoglobin) oxyhemoglobin HHb + O2 HbO2 Internal respiration Oxygen diffuses out of blood into tissues because partial pressure of O2 in cells is lower than in bloodstream due to oxygen demand for aerobic cellular respiration Aided by decrease in ph (due to increase of H+ ions from CO2 being removed from tissues and coming in to blood) and increased temperature in tissues this encourages oxyhemoglobin to give up oxygen. c) Exchange of CO2 CO2 constantly produced as a waste by-product of aerobic cell respiration CO2 enters bloodstream from tissues because partial pressure of CO2 is greater in the tissues then blood moves from area of high pressure to area of lower pressure CO2 is carried in blood to lungs in 3 ways: % dissolved in plasma 2. ~20% Bonded to hemoglobin called carbaminohemoglobin CO2 + Hb HbCO2 3. ~70% as bicarbonate ion in plasma CO2 enters RBC combines with water in RBC to make carbonic acid which immediately changes to H+ ions and bicarbonate ions Equations: Carbon dioxide + water carbonic acid hydrogen ion and bicarbonate ion CO2 (g) + H2O(l) H2CO3 H + + HCO3 - internal respiration Breakdown of carbonic acid to H+ and HCO3 - is aided by an enzyme called carbonic anhydrase Bicarbonate ions leave the RBC and are carried to lungs in plasma Part of the hemoglobin combines with the H+ released from this reaction forming HHB - called reduced hemoglobin

9 3) External Respiration = gas exchange between continuous column of air in alveoli (external environment) and blood in capillaries surrounding alveoli in lungs a) Conditions that favour external respiration: temperature is cooler in lungs (37 C) compared to tissues, and ph (7.40) is higher (less acidic then in tissues)- this favours O2 uptake by hemoglobin b) Exchange of oxygen Blood in pulmonary capillaries has low oxygen concentration / lower pressure then atmospheric air pressure in alveoli therefore it diffuses from lungs into plasma and into red blood cells and is held by haemoglobin Equations: Deoxyhemoglobin + Oxygen oxyhemoglobin (aka reduced hemoglobin) HHb + O2 HbO2 External respiration O2 is then transported to cells in hemoglobin of RBC c) Exchange of CO2 blood in the capillaries of the lungs have a higher partial pressure of CO2 then the air in the alveoli (atmospheric air) therefore CO2 moves from bloodstream to lungs Equations: Carbon dioxide + water carbonic acid hydrogen ion and bicarbonate ion CO2 (g) + H2O(l) H2CO3 H + + HCO3 - External respiration Formation of carbonic acid from H+ and HCO3- is aided by an enzyme called carbonic anhydrase Bicarbonate reenters RBC, combines with H+ and is changed back to carbon dioxide CO2 diffuses from bloodstream into alveoli where it can be exhaled F. Control of breathing: 2 ways our breathing is controlled 1. nervous control 2. chemical control These 2 work together to bring O2 to our cells from outside and CO2 away from our cells and out of our bodies 1. Nervous control Normal adults breathing rate = ~ 12 to 20 breaths/minute Rhythm of breathing is controlled by respiratory control centre in medulla oblongata of the brain The respiratory control centre automatically sends out nerve signal via the phrenic nerve to the diaphragm and intercostal nerves to the muscles of the rib cage which contract and inhalation occurs

10 When nervous signal stops, muscles relax and exhalation occurs This is involuntary control we can voluntarily control our rate of breathing for a short period but if we try and hold our breath eventually body takes over again and we have to breath- All this occurs involuntarily or automatically our body knows when to do it, of course we can voluntarily control our breathing as well when we want to talk, or sing or hold our breath under water etc...so when we force an inspiration sends messages to our brain to inhibit or stop the automatic nerve impulse to tell us to breath this will temporarily stop the respiratory control centre from sending a signal to our diaphragm and intercostal muscles but eventually our body takes over again and we have to breath 2. Chemical control Cells produce CO2 as a waste product of cell respiration, this CO2 enters the bloodstream, enters the RBC where it combines with water in the RBC to form an acid- carbonic acid this acid immediately breaks down into hydrogen ions and bicarbonate ions The bicarbonate ion leaves the RBC and travels to the lungs in the plasma the H+ ion is carried in the RBC the amount of H+ in the blood changes the ph of the blood H+ ions make the blood more acidic CO2 (g) + H2O(l) H2CO3 H + + HCO3 - Carbonic acid the more CO2 we make when our cells are working hard the more H+ ions we will have entering our blood stream and the ph of the blood will become more acidic Chemoreceptors: There are 2 sets of chemoreceptors in your body which are sensitive to changes in ph: 1 set of Chemoreceptors in the medulla oblongata of the brain One set of chemoreceptors in the circulatory system called carotid bodies in carotid arteries and aortic bodies in the aorta both sets of chemoreceptors detect falling ph (more acid) this causes rate and depth of breathing to increase in order to decrease the concentration of CO2 in our blood. increased respiration means more O2 in and more CO2 out so ph can be returned to normal Chemoreceptors respond to the level of CO2 in our blood rather than the decreased level of O2 Recap: the chemical control side of respiration happens when the Oxygen is used up by our cells and is put back into the blood stream as CO2 the increased CO2 mixes in the blood with water to form acid in the form of H+ ions this acid decreases the ph in the blood this triggers the chemoreceptors in the brain and the circulatory system which triggers us to increase our rate of breathing increased respiration means more O2 in and more CO2 out and everything returns to normal - this is basically the trigger to override you holding your breath -most people can only hold their breath for about a minute then CO2 levels build up, chemoreceptors kick in and it forces us to breath and breath at an increased rate.

Human Biology Respiratory System

Human Biology Respiratory System Respiratory System Responsible for process of breathing Works in cooperation with Circulatory system Three types: 1. Internal Respiration 2. External Respiration 3. Cellular