respiration20112012
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Respiration
Easier version ata
Requirements for Respiration
• Respiratory medium– Medium that will transport the gases
• Respiratory surface– Where diffusion of the gases will occur
Respiratory medium
• Water – No problem of hydrating respiratory surface– Heavy– Less O2 per volume
• Air – Highly dehydrating– Light – High O2 concentration
Respiratory surface
• Should be moist• Should have high SA• Should be thin
WHY?
Other questions…..
• How does size of organism, its habitat and its metabolic activity affect the structure of its respiratory surface?
The lowly animals……
• Use of cell membrane as respiratory medium• Part of the body with direct contact with the
respiratory medium is used for respiration– E.g. poriferans, protists, cnidarians
Highly evolves animals (tayo yun)
• Use of a highly extensive respiratory structure– Respiratory medium is separated from blood and
capillaries– Give examples- student number 12
Cutaneous respiration
• How does this work student number 21?
The commoners (common respiratory organs)
• Tracheal system– Arthropods
• Gills– E.g. amphibians, fish
• Lungs – E.g. birds, mammals
Ang problema ng tubig, bow
• Due to low amount of oxygen per volume its energy cost is higher compared to air
• Ventilation is present if oxygen is minimal– Increased contact between respiratory medium
and respiratory surface– Without ventilation region of high O2 conc and
region of high CO2 conc will occur
Fish ventilation
• They swim against the current
What is the consequence of this method of ventilation?
Countercurrent exchange
• Water moves opposite the direction of blood
• Gills are highly extensive– Lessens the energy cost
Countercurrent exchange pa rin…..
• Ensures the presence of a diffusion gradient between the respiratory medium (water) and transporting medium (blood)
• Very efficient
Counter current pa rin, kaya dapat matandaan nyo to
Ayaw talaga pa awat ng countercurrent
(no) Air as a respiratory medium
Tracheal system
Tracheal system
• Direct transport of gas between respiring cells and respiratory medium
• Tubular structure• Trachea- large tube– Plural tracheae
• Spiracles- opening to the outside• Tracheole- fine tubes directly connected to
cells
Lungs
• Confined inside the body cavity• Circulatory system bridges the respiratory
medium and transport tissue• Respiratory structure- epithelium + dense
capillaries
The lungs
Bronchiole, alveoli and BVs
Mammalian respiration
• Give the sequence of structures where gases will travel from the environment to the body then back to the environment
Air we breath
• Filtered by hairs and cilia• Warmed, humidified and sampled for odors
Mammalian respiration….
• The act of swallowing moves the larynx upward tipping the epiglottis over the glottis
• Glottis- opening of the windpipe• Larynx- adapted as voicebox• Syrinx- vocal organ of birds– Found at the base of the trachea– Produce sound without the vocal chords found in
mammals
Sound Sound: produced when voluntary muscles stretch and vibrate during the processHigh-pitched sound: tight, rapid vibrationLow-pitched sound: less tense, slow vibration
The Phlegm
• Epithelial lining is covered with mucus and beating cilia
• Mucus traps contaminant, while, the cilia moves this to the pharynx where it can be swallowed
Breathing
• Negative vs Positive pressure breathing– Recitation of the whole process
Positive pressure breathingIn a breathing cycle:•Muscles lower the oral cavity floor (becomes
enlarge and draws air through the nostrils)• Closing of the mouth and nostril (oral cavity
floor rises and forces air into the trachea)• Air is force out/exhaled (elastic recoil of lungs
and muscular contraction of chest)
Negative pressure breathing
• Works like a suction pump (air is pulled rather than pushed)
• Negative pressure is produced due to action of chest muscle– Relaxation of chest muscle pushes air; contraction pulls air in
• Expansion of lungs is possible due to its double-walled sac– Inner sac adheres to the lungs– Outer sac adheres to the chest cavity walls– Space in between is filled with fluid
Surface tension
• Which is harder to separate: two plastics with water between them or two plastics without water between them
Inhalation
• Contraction of muscles (rib muscles and diaphragm)– Increases volume of chest cavity– Decreases alveolar air pressure– Rib cage expands (ribs pulled upward; breastbone
pushed forward)
Exhalation
• relaxation of muscles– Rib muscles and diaphragm relax – Lung volume is reduced– Inc in alveolar air pressure
Breathing
Overview
• http://www.youtube.com/watch?v=HiT621PrrO0
Factors that affect breathing
• Tidal volume- volume of air inhaled and exhaled in each breath– Ave human tidal volume is 500 ml
• Vital capacity- max tidal volume during forced breathing– 3.4 L female; 4.8 L male
• Residual volume- air left in the lungs during exhalation– Lungs hold more air than the vital capacity
Old age
• Age or disease decrease the elasticity of the lungs– Residual volume increases at the expense of vital
capacity– Max O2 conc in the alveoli decreases– Gas exchange efficiency is decreased
Bird breathing
• Presence of air sacs• Do not function directly in gas exchange; acts
as bellows• Lungs and air sacs- ventilated during breathing• Presence of parabronchi rather than alveoli– Air moves in one direction – Air is completely exchanged– Max O2 conc is higher in birds than in mammals
Bird respiration
Regulation of Breathing
• Breathing – controlled by the medulla oblongata and the pons
• This ensures that respiration is coordinated with circulation
• Medulla oblongata- major control center of breathing
• Control center in the pons works synergistic with the control center of the medulla oblongata
Regulation of Breathing
• Negative feedback- helps maintain breathing• Stretch sensors- found in the lungs send impulses to
the medulla (inhibits the breathing control center)• Medulla- monitors CO2 level of the blood – CO2 conc is detected through slight change in blood and
tissue fluid pH– Carbonic acid lowers pH– Drop in pH increases rate of rate and depth of breathing
Oxygen Concentration
• Oxygen Concentration- have little effect to breathing control center
• Severe depression of O2 conc stimulates O2 sensors in the aorta and carotid arteries to send alarm signals
• Breathing rate is increased by the control centers
• Increase in CO2 conc is a good indicator of decrease in O2 conc
Hyperventilation
• Excessive deep, rapid breathing inc CO2 conc in the blood
• Breathing centers temporarily stops working• Impulses to the rib muscles and diaphragm are
inhibited• Breathing resumes when CO2 conc inc
Different Factors Affect Breathing
• Nervous and chemical signals affects rate and depth of breathing
• Most efficient if it works in tandem with the circulatory system
• E.g. Exercise: inc cardiac output-inc breathing rate– Enhances O2 uptake and CO2 removal
Respiratory pigments: transports gases and buffers the blood
• Low solubility of O2- problem if O2 is transported via the circulatory system– E.g. Normal human consume 2L of O2 per minute– Only 4.5 ml of O2 can dissolve into a L of blood in the
lungs– If 80% dissolved O2 would be delivered, 500 L of
blood should be pumped per minute (a ton per 2 mins)
– Unrealistic!!!!– Special respiratory pigments are used
Respiratory Pigments
• Transports O2 instead of dissolving into a solution
• Inc O2 that can be carried in the blood (~200 mL O2 per L in mammalian blood)
• Decreases cardiac output (20-25 L per min)
Respiratory Pigments
• Binds O2 reversibly– Loads O2 from respiratory organ; unloads in other
parts of the body• Hemocyanin- found in hemolymph of
arthropods and many mollusks• Copper- acts as the oxygen-binding component• Hemoglobin- respiratory pigment of all
vertebrates
Hemoglobin
• Consists of four heme subunits• Iron acts as the binding site of O2• Loading and unloading of O2 depends on the
property of each subunits called cooperativity• Affinity is dependent to the conformation of each
subunit– Binding of one O2 molecule to one subunit induces the
inc in affinity of other subunits– Unloading of one O2 molecule decreases the affinity of
other subunits
Dissociation Curves of Gases
• Cooperativity of heme subunits is shown in a dissociation curve
• Steep slope- slight change in Po2 causes substantial loading or unloading of O2
• Because of cooperativity, slight drop in Po2
causes a relatively large inc in O2 to be unloaded
The Bohr Shift
• A shift to the right of the oxygen hemoglobin dissociation curve
• Brought about by increase CO2 or low blood pH• Decrease in affinity of hemoglobin to O2• Greater efficiency of O2 unloading
Carbon Dioxide transport
• Hemoglobin- also transports CO2 not only O2– Assists in buffering the blood
• Blood released by respiring cells:– 7%- transported in the solution of blood plasma– 23% - bind to amino group of hemoglobin– 70% - transported in the blood in the form of
carbonic acid
Carbon Dioxide Transport
• CO2- converted in the red blood cells into bicarbonate– Reacts first with water to form carbonic acid (carbonic
anhydrase)– Dissociates into H+ and bicarbonate– H ions- attach to different sites in the Hb and other
proteins– Bicarbonate ions- diffuse into the plasma– Movement of blood through the lungs reverses the
process favoring the conversion of bicarbonate to CO2
Deep-diving air breathers
• Stockpile oxygen- O2 is reserved in the blood and muscles (e.g. Weddell seal)
• High percentage of myoglobin• Dec heart rate and O2 consumption• 20-min dive- O2 in myoglobin is used up– Energy is derived from fermentation rather than
respiration