Respiration and Gas exchange
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Transcript of Respiration and Gas exchange
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RESPIRATION AND GAS EXCHANGE
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Key concepts Types of respiration
Cellular Respiration is the chemical breakdown of food substances to yield ATP. Different organisms use different kinds of breathing mechanisms in order to
transport oxygen throughout their bodies. Evolutionary adaptations of gas exchange systems and respiration
Different plant adaptations in acquiring CO2 from the environment evolved: C3, C4, and CAM pathways.
Structural adaptations of respiratory apparatus depend on the animal’s habitat. The three most common respiratory organs are gills, tracheae, and lungs.
The respiratory system and circulatory system cooperate directly with each other.
Mammalian respiration The respiratory system is divided into the upper respiratory tract (nasal
passages, mouth, throat, larynx and trachea) and lower respiratory tract (bronchi and the lungs).
Air enters (inhalation) the respiratory system due to a pressure drop inside the lungs (negative pressure).
Air exits (exhalation) the respiratory system due to an increase in pressure inside the lungs.
Breathing is regulated by control centers in the brain (medulla oblongata and pons)
Gases are transported via passive diffusion throughout the body. Respiratory diseases and their prevention
Respiratory disorders may be congenital or environmental. Respiratory disorders can be prevented through a combination of proper diet
and lifestyle change.
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Vocabulary words aerobic respiration air sacs alveolus anaerobic respiration asthma blood pH Bohr shift breathing bronchiole bronchus C3 pathway C4 pathway CAM pathway cell respiration countercurrent exchange cutaneous respiration diaphragm dissociation curve
emphysema epiglottis gas exchange gills glottis glycolysis hemocyanin hemoglobin larynx (voicebox) lung Cancer lungs medulla oblongata myoglobin nasal cavity negative pressure breathing nose parabronchi partial pressure
pharynx photosynthesis pharynx pneumonia pons positive pressure
breathing residual volume respiratory medium respiratory pigments respiratory surface rib muscles spiracle surface tension syrinx thoracic cavity tidal volume trachea or windpipe tracheae tuberculosis ventilation vital capacity vocal cords of the
larynx
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Cellular Respiration- Transformation of chemical energy into ATP- Overall Reaction: C6H12O6 +6O2 → 6CO2 +6H2O + 36 ATP
1 Glucose molecule (6C) from digestionGlycolysis in the
cytoplasm 2 pyruvate
molecules (3C)2 ATPsAerobic
Respiration in the
mitochondriaKrebs Cycle
(2 ATPs)Electron
Transport Chain
(32 ATPs) CO2+ H2O
Anaerobic
Respiration in the cytosol ethanol/
lactic acid/CO2
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NADH and FADH2 are e- donors that enable the formation of ATP
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Photosynthesis Method of converting
sun energy into chemical energy usable by cells
Light reactions Dark
reactions/Calvin Cycle
6 CO2 + 6 H2O + light energy → C6H12O6 + 6O2
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Plant adaptations for acquiring CO2 from the environment C3 (most abundant)
CO2 converted to a 3C sugar, 3-phosphoglycerate RuBisCO (Ribulose-1,5-bisphosphate
carboxylase/oxygenase) enzyme catalyzes carbon fixation
prone to photorespiration, lessens efficiency of food production during hot and dry days
C4 store CO2 in specialized compartments convert CO2 into a 4C compound, oxaloacetate converted into the 3C sugar and CO2 used in the C3
pathway/Calvin cycle minimizes photorespiration and enhances sugar
production
CAM succulent plants f ix CO2 at night and store it as 4C organic acids minimizes water loss and enhances sugar production
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Gas exchange supplies oxygen for cellular respiration and removes CO2 Gas exchange – uptake of O2
from environment and discharge of CO2
Mitochondria need O2 to produce more ATP, CO2 is the by-product
C6H12O6 + 6O2 6CO2 + 6H2O + 36 ATP
Diffusion rate α SA large α 1/d2 thin
Moist so gases are dissolved first
DIFFUSION
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Respiratory surfaces and gas exchange Respiratory
surface Size of organism Habitat Metabolic demands
Unicellular organisms Entire surface area
for diffusion
Simple invertebrates Sponges,
cnidarians, flatworms, roundworms
diffusion
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Respiratory surfaces and gas exchange More complex
animals Thin, moist
epithelium Separates medium
from capillaries Entire outer skin Extensively folded
and branched respiratory organs
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Gills in aquatic animals Outfoldings of the
body surface suspended in water
Sea stars Segmented worms or
polychaetes Molluscs and
crustaceans Fishes Young amphibians Total surface area is
greater than the rest of the body
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Water as a respiratory medium Adv - Surfaces are
kept moist Disadv - O2
concentrations in water are low
Ventilation – increasing flow of respiratory medium over the surface
Countercurrent exchange – process in which two fluids flow in opposite directions, maximizing transfer rates
Why are gills impractical for land animals?
Just keep swimmin
g swimmin
g swimmin
g!
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Air as a respiratory medium Adv - Air has a
higher concentration of O2
Adv - O2 and CO2 diffuse much faster in the air less ventilation
Disadv - Difficulty of keeping surface moist
Solution: respiratory infolding inside the body
Tracheal system of insects – network of tubes that bring O2 to every cell
Spiracles
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Lungs Heavily vascularized
invaginations of the body surface restricted to one location
Found in spiders, terrestrial snails, vertebrates
Amphibians supplement lung breathing with skin
Turtles supplement lung breathing with moist surfaces in mouth and anus
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Mammalian respiration
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Lung ventilation through breathing
Positive pressure breathing in frogs
“Gulping in” air
Negative pressure breathing in reptiles and mammals
Rib muscles and diaphragm change lung volume and pressure
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Lung volumes Factors
Sex Height Smoking Physical activity Altitude
Tidal volume Volume of air inhaled
and exhaled with each breath
Vital capacity Maximum volume
inhaled and exhaled during forced breathing
Residual volume Air left in alveoli after
forced exhalation
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Avian breathing• Air sacs - bellows
to keep air flowing through the lungs
• Syrinx – vocal organ of birds
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Control centers in the brain regulate breathing
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Gases diffuse down pressure gradients
concentration and pressure drives the movement of gases into and out of blood
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Respiratory pigments Low solubility of O2 in
H2O Respiratory pigments
are proteins with metal atoms Hemoglobin – Fe Hemocyanin – Cu Allow reversible
binding of O2 Cooperativity Drop in pH results
in a lowered affinity of hemoglobin for O2
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Respiratory pigments
CO2 transport 7% in plasma 23% bound to
hemoglobin 70% as HCO3- *
*buffers resist pH changes
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Fetal hemoglobinHbF has greater affinity to O2 than Hb
low O2% by time blood reaches placenta fetal Hb must be able to bind O2 with
greater affinity than maternal Hb
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Deep-diving mammals Seals, whales, dolphins are capable of long underwater dives
Weddell seal 5% O2 in lungs, 70% in blood
Huge spleen stores huge volumes of blood
Large concentrations of myoglobin in muscles
Heart rate and O2 consumption rate decrease
Blood is redirected from muscles to brain, spinal cord, and eyes
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Respiratory disorders Asthma – chronic
inflammatory lung disease
Bronchitis – inflammation of bronchi (chronic/acute)
Emphysema – damage to alveoli
Cystic fibrosis – abnormality in mucus producing glands
Pneumonia – lung inflammation
Tuberculosis – airborne chronic bacterial infection
Lung cancer – normally begins in bronchi, usually carcinomas