respiration Flashcards
aerobic respiration
-the breakdown of food substances in the presence of oxygen, resulting in the release of a relatively large amount of energy. carbon dioxide and water are formed as waste products.
-the energy released is stored in the form of ATP molecules
-in eukaryotic cells, aerobic respiration occurs in the mitochondria
-C6H12O6 + O2 —> 6CO2 + 6H2O + relatively large amount of energy
anaerobic respiration
-the breakdown of food substances without oxygen, resulting in the release of a relatively small amount of energy
-anaerobic respiration occurs in the cytoplasm of cells
anaerobic respiration in yeasts
-C6H12O6 —> 2C2H5OH + 2CO2 + relatively small amount of energy
-production of wine and beer
anaerobic respiration in humans
-C6H12O6 —> 2C3H6O3 + relatively small amount of energy
-during exercise, the muscles contract vigorously to enable movement. this results in high energy demand.
-both the rate of breathing and heart rate increase to enable more oxygen to reach the muscles (so that rate of aerobic respiration can be increased to meet the high energy demand) and carbon dioxide to be removed effectively.
-if the increased oxygen intake is not able to meet the oxygen demand, anaerobic respiration takes place to provide the additional energy required.
-results in the accumulation of lactic acid in the muscle, causing fatigue and muscular pains
-in the liver, lactic acid is oxidised and converted to glucose. the oxygen required to oxidise the lactic acid is the oxygen debt.
nostrils
-air from external environment enters the nasal passage through the nostrils
nasal passages
-the fringe of hair and mucous layer on walls of nostrils trap dust and foreign particles
-as the air passes through the nasal passages, it is warmed and moistened
pharynx
-throat area containing openings to both the trachea and oesophagus
larynx
-cartilaginous structure, contains elastic vocal cords
trachea
-contains c-shaped rings of cartilage, prevents trachea from collapsing and keeps airways open
bronchi
-trachea divides into bronchi
inner walls of the trachea and bronchi
-gland/ goblet cells secrete mucus that trap dust particles and bacteria in the air that is inhaled
-ciliated cells have cilia that sweep the mucus containing dust particles and bacteria upwards and out of the airways
alveoli
-are the site of gaseous exchange
-numerous alveoli in the lungs increase the total surface area for gaseous exchange
-are well-supplied with blood capillaries to enable the efficient exchange of gases
-alveolar surface is coated with a thin film of water
-epithelium of an alveolus is only one cell thick
inspiration
-diaphragm contracts and flattens down
-external intercostal muscles contract and internal intercostal muscles relax
-the rib cage is raised upwards and outwards
-thoracic volume increases
-pressure in thoracic cavity decreases below atmospheric pressure, so air is drawn into the lungs
expiration
-diaphragm relaxes and arches up
-external intercostal muscles relax and internal intercostal muscles contract
-the rib cage moves downwards and inwards
-thoracic volume decreases
-pressure in thoracic cavity increases above atmospheric pressure, lungs are compressed and air is pushed out of the lungs
stimulus for breathing
-carbon dioxide
-oxygen concentration in blood has no effect on breathing rate
composition of inhaled air
-oxygen 21 %, carbon dioxide 0.03 %, nitrogen 78 %, water vapour variable, room temperature, dust particles variable
composition of exhaled air
-oxygen 17 %, carbon dioxide 4 %, nitrogen 78 %, water vapour saturated, body temperature, dust particles absent
adaptations of alveoli
-large numbers of alveoli increases the total surface area for quick diffusion of gases during gaseous exchange
-alveoli epithelium and blood capillary wall is one cell thick so short distance allows quick diffusion of gases between alveoli and blood capillary
-thin layer of moisture on the surface of alveoli allows gases to dissolve in and easily diffuse into the blood in the capillaries
-maintenance of a steep concentration gradient between alveoli and blood so that diffusion of substances can occur more quickly
transport of carbon dioxide
can be transported in 3 ways,
-majority transported in the form of bicarbonate ions dissolved in blood plasma to be transported to the lungs
-a small percentage dissolves directly in blood plasma
-a small percentage can bind to haemoglobin
-carbonic anhydrase catalyses the first reversible reaction CO2 + H2O —> H2CO3 (carbonic acid) —> HCO3- (bicarbonate ion) + H+
components of tobacco smoke
-nicotine stimulates release of adrenaline, increased heart rate and blood pressure. makes blood clot more easily, hence increased risk of coronary heart disease. highly addictive.
-tar has cancer causing chemical. usually lung cancer, paralysing cilia, hence dust particles trapped in mucus cannot be removed. increased risk of bronchitis and emphysema.
chronic bronchitis
-caused by prolonged exposure to dust particles in tobacco smoke
-cilia are paralysed, so mucus and dust particles cannot be removed
-persistent coughing to clear air passages in order to breathe
-excessive mucus is secreted by epithelium
-airways become inflamed
emphysema
-persistent and violent coughing due to bronchitis may lead to emphysema
-walls between alveoli break down due to persistent and violent coughing
-results in a decreased total surface area for gaseous exchange
-breathing becomes difficult, constantly breathless
