Respiration Flashcards
What is the human respiratory system’s function?
Functions in the gaseous exchange of oxygen and carbon dioxide between an organism and the environment
Pathway taken by the air during inhalation
Nostrils, nasal cavity, pharynx, larynx, trachea, bronchi, bronchiole, alveoli
Where does gaseous exchange occur?
In the alveoli (singular alvelolus) of the human respiratory system
What is the makeup of inspired air?
21% O2 0.03% CO2 78% N2 Variable H20 (g) Room temp Variable dust
What is the makeup of exhaled air?
17% O2 4% CO2 78% N2 Saturated water vapour 37° Absent dust particles
Function of nasal passage
Moisten and warm inhaled air
Lined with hairs to trap dirt in inhaled air
Function of the larynx
Cartilaginous structure
Contains elastic vocal cords
Function of the trachea
Contains C-shaped rings of cartilage
Prevents trachea from collapsing
Keeps airways open
Function of bronchi (singular bronchus)
Trachea divides into 2 branches known as the bronchi (into each lung)
Function of the bronchiole
Bronchiole form from the branching of the bronchi
Function of the alveoli
Found at the ends of the bronchiole
Site of gaseous exchange in the respiratory system
What do the inner surface of the airways contain, and what are their functions?
Mucus: sticky substance produced by goblet cells in respiratory system to trap inhaled dust
Cilia: hairs on inner surface of airways that sweep mucus containing dust out of the airways
Define ventilation
Ventilation (breathing) is the exchange of air between the lungs and the environment during inhalation (breathing in) and exhalation (breathing out)
Where are the lungs located?
Within the thoracic cavity
What is air moved in and out of the lungs by?
Internal and external intercoastal muscles
Diaphragm muscles
Rib cage
What happens during inhalation? (Intercoastal muscles, rib cage, diaphragm, volume of thoracic cavity, lung pressure, air movement)
External intercoastal muscle: contract Internal intercostal muscles: relax Movement of ribcage: upwards and outwards Diaphragm: muscle contracts, flattened Volume of thoracic cavity: increases Pressure of lungs: lower than atmosphere Movement of air: forced into lungs
What happens during exhalation? (Intercoastal muscles, rib cage, diaphragm, volume of thoracic cavity, lung pressure, air movement)
External intercoastal muscle: relax
Internal intercostal muscles: contract
Movement of ribcage: downwards and inwards
Diaphragm: muscle relaxes, curves up
Volume of thoracic cavity: decreases
Pressure of lungs: higher than atmosphere
Movement of air: forced out from lungs
What is tidal volume, vital capacity and residual volume?
The volume of air inhaled and exhaled in each breath (~500 cm^3)
Vital capacity: tidal volume during maximum inhalation and exhalation (~3.4-4.8 litres)
Residual volume: volume of air that remains in the lungs after forced exhalation
What is the stimulus for breathing? Does o2 concentration have any effect?
Carbon dioxide concentration
The higher the concentration of carbon dioxide in blood, the higher the breathing rate
Oxygen concentration in blood has no effect on breathing rate
Structural adaptations of alveoli
Large numbers: total large surface area for quick gas diffusion and exchange
Alveoli and capillary walls are one cell thick: short diffusion distance allows quick gas diffusion between alveoli and blood capillary
Thin layer of moisture of the surface of alveoli: allows gases like oxygen to dissolve in and easily diffuse into the blood in the capillaries
Maintenance of a steep concentration gradient between alveoli and blood: blood constantly flowing in alveoli capillaries due to heart pumping, keeps o2 low and CO2 high in blood capillaries. Breathing keeps concentration of o2 high and CO2 low in alveoli space
What is the difference in composition of blood in the pulmonary arteriole and venule?
The pulmonary arteriole (deoxygenated) contains a lower concentration of oxygen and a higher concentration of carbon dioxide as compared to the pulmonary venule (oxygenated)
What gaseous exchange occurs at the alveolus?
Simple diffusion, oxygen molecules out and carbon dioxide molecules into the alveolus
How is carbon dioxide transported in the body?
As bicarbonate ions dissolved in blood plasma
~7% of carbon dioxide dissolved directly
~5% of bicarbonate ions bind to haemoglobin and are transported inside the erythrocyte
What is the enzyme found in red blood cells and what is its function?
Carbonic anhydrase
It catalysed a reversible reaction, where the direction of the reaction depends on the relative concentration of CO2 and water with respect to carbonic acid
Overall reaction catalysed by carbonic anhydrase at the alveoli of the lungs
Low carbon dioxide concentration
H+ + HCO3- —> H2CO3
H2CO3 —(carbonic anhydrase)—> CO2 + H2O
What are the major components of tobacco smoke and its effects on health?
Nicotine: stimulates adrenaline release, makes blood clot more easily (increased risk of coronary heart disease), highly addictive
Tar: cancer-causing (usually lung), paralyses cilia lining air passages (dust particles trapped in mucus lining cannot be removed, increased bronchitis and emphysema risk)
Carbon monoxide: binds irreversibly with haemoglobin to form carboxyhemoglobin, less haemoglobin to transport O2
What are the symptoms of the diseases caused by tobacco smoke?
Bronchitis: Paralyses cilia in the airways, mucus and dust particles cannot be removed Persistent coughing to clear the airways Excessive mucus secretion Inflammation of airways
Emphysema:
Persistent and violent coughing due to bronchitis
Walls between alveoli sacs break down
Decreased total surface area of alveoli for gaseous exchange
Difficult breathing, constantly breathless
Define respiration
Respiration is a process that liberates chemical energy from the oxidation of organic molecules
What is the standard unit of energy released during respiration?
ATP is Adenosine triphosphate
What are potential substrates of respiration
Glucose, fatty acids, glycerol, protein
Why is glucose the preferred substrate of respiration and what is the least preferred?
Because stored glycogen is readily converted into glucose
Amino acids are the least preferred
Define aerobic respiration
Aerobic respiration is the process where large amounts of oxygen are released from glucose in the presence of oxygen
What is the word and chemical equation of aerobic respiration?
Glucose + oxygen —> carbon dioxide + water
C6H12O6 + 6O2 —> 6CO2 + 6 H2O
Where do aerobic and anaerobic respiration occur?
Aerobic: mitochondria of cells
Anaerobic: cytoplasm of cells
Define anaerobic respiration
Anaerobic respiration is the process where small amounts of energy are released from glucose in the absence of oxygen
Word equation of anaerobic respiration
Glucose —> lactic acid
When does anaerobic respiration occur?
During vigorous exercise, when muscle contractions result in a high energy demand, increasing the rate of aerobic respiration (rise in breathing rate, increased inhalation and exhalation, to obtain more O2 and CO2)
If the energy demand of exercise is higher than what aerobic respiration can release, anaerobic respiration will also occur
What is the effect of lactic acid on the muscles?
Lactic acid causes fatigue, cramps and discomfort in muscles
What happens to lactic acid after exercise?
Lactic acid is transported while dissolved in blood plasma from the muscle to the liver to be broken down
The additional oxygen taken in by the body after exercise used to break down lactic acid is known as oxygen debt
Word equation and use of anaerobic respiration in yeast
Glucose —> ethanol + carbon dioxide
Applications include the production of wine and beers (ethanol) or to help bread rise (CO2)
Pressure and volume change during inhalation and exhalation
Inhalation: pressure decreases, volume increases
Exhalation: pressure increases, volume decreases
Products of aerobic and anaerobic respiration
Aerobic: CO2, water
Anaerobic: lactic acid
