Respiration In Humans Flashcards
Why do we respire?
- need energy to live (move, grow, excrete, reproduce)
- oxidation is the process where food molecules as broken down to use energy available in food
- oxidation of food molecules to produce energy is called respiration
Aerobic respiration
- breakdown of food molecules in presence of oxygen
- produces large amts energy
- waste products: CO2, H2O
- chemical eqn: C6H1206 +602 to 6C02+6H2O+energy
ATP
- energy released during respiration is stored in a small molecule called adenosine triphosphate (ATP)
- main energy currency used in all cells
- energy released when a phosphate bond is broken
- ATP converted to ADP (Adenosine diphosphate)
- aerobic respiration occurs in mitochondria of cells
Anaerobic respiration
- breakdown of food molecules is absence of oxygen
- also know as incomplete oxidation of oxygen
- release less energy, produce lactic acid
- C6H12O6 to 2C3H6O3 (lactic acid) +energy
Anaerobic respiration in humans
- formation of lactic acid/ lactic acid fermentation
- glucose partially broken down
- lactic acid produced still contains energy, only small amt of energy is released
- energy released helps muscles to keep contracting
What happens during exercise and why?
- muscles contract vigorously to enable movement
- respiratory and heart rate increase to allow more oxygen to reach the muscles
- if increased oxygen intake is unable to meet oxygen demand, resulted in oxygen debt and anaerobic respiration to provide the energy required
- oxygen debt is the vol of oxygen required to remove lactic acid that has built up
- anaerobic respiration results in the accumulation of lactic acid
- accumulation of lactic acid can result in muscle fatigue
Recovery
- during period of rest, breathing rate remains fast to provide sufficient oxygen to muscle cells and repay oxygen debt
- lactic acid gradually removed from muscles and transported to liver
- in liver, some of the lactic acid is oxidized to release energy, energy used to convert rest of lactic acid to glucose
- once all lactic acid has been converted, oxygen debt is repaid
- glucose then transported back to muscles
Anaerobic respiration in plants
- yeast releases ethanol (alcohol) and carbon dioxide as waste products (irreversible)
- called alcoholic fermentation
- chemical eqn: C6H12O6 to C2H5OH +CO2+ small amts of energy
- glucose only partially broken down
- ethanol produced contains energy, small amt of energy released
Differences between alcoholic and lactic acid fermentation (where it occurs)
Alcoholic fermentation: plants and yeast
Lactic acid fermentation: mammals
Differences between alcoholic and lactic acid fermentation (Waste products)
Alcoholic fermentation: ethanol and carbon dioxide
Lactic acid fermentation: lactic acid, no carbon dioxide
Differences between alcoholic and lactic acid fermentation (oxidation/conversion to glucose)
Alcoholic fermentation: ethanol cannot be further oxidized or converted back to glucose
Lactic acid fermentation: can be oxidized and converted back to glucose
Difference between respiration and photosynthesis
energy
Respiration: energy released
Photosynthesis: energy stored in carbohydrate molecules
Difference between respiration and photosynthesis
uses and products
Respiration: oxygen used, CO2 and water given off
Photosynthesis: CO2 and water used, O2 given off
Difference between respiration and photosynthesis
catabolic/anabolic process
Respiration: catabolic process, breakdown of carbohydrate molecules
Photosynthesis: anabolic process, building up of carbohydrate molecules
Difference between respiration and photosynthesis
where it occurs
Respiration: occurs at all times in all cells, independent of chlorophyll and sunlight
Photosynthesis: occurs only in cells containing chlorophyll and in presence of sunlight
Difference between respiration and photosynthesis
dry mass
Respiration: results in loss of dry mass
photosynthesis: results in gain of dry mass
Why do we need a respiratory system?
- humans are large organisms, made up of millions of cells, small SA:V unlike unicellular organisms
- need a special system of organs for gaseous exchange between cells in body and environment
- mechanism of exchange is called external respiration, involves a process called breathing
Nasal passage
- fringe of hairs and mucous layer on walls of nasal passage
- trap dust, microorganisms
- as air passes thru the air passages it is warmed and moistened
Trachea
- supported by c-shaped rings of cartilage
- ensures trachea is always open and does not collapse
Gland cells
- in inner walls of trachea and bronchi
- gland cells secrete mucus, trap dust particles and bacteria in air that enters lungs
Ciliated cells
- in inner walls of trachea and bronchi
- have cilia that sweep trapped particles and bacteria up the bronchi and trachea, into pharynx
Bronchus and alveoli
- lungs lie in pleural cavity
- bronchial tubes divide repeatedly to form bronchioles
- bronchioles end in cluster of air sacs aka alveoli
Flow of air entering body
- nostrils
- nasal passages
- pharynx
- larynx
- trachea
- bronchi
- bronchioles
- alveoli
The alveoli
- site of gaseous exchange
- numerous alveoli increase SA:V for gaseous exchange
- rate of diffusion between alveoli and capillaries increase
Alveoli features and their uses
- well-supplied with blood capillaries, enable efficient gaseous exchange, maintains conc gradient
- alveolar surface coated with thin film of water, allow gases to dissolve in it (for diffusion)
- wall of each alveolus is 1 cell thick, supplied by 1 cell thick capillaries (decreases distance for diffusion)
Gaseous exchange in the alveolus
- blood entering lungs has lower conc of oxygen and high conc of CO2 than inhaled air in the alveolus
- CO2 from blood diffuses into the alveolus and is channeled out of lungs via expiration
- air in alveolus high conc of O2, lower conc of CO2 than blood entering lungs
- O2 in alveolus diffuses into blood in capillary vessels, transported to heart where it is pumped throughout the body
How oxygen is transported
-oxygen molecules bind to haemoglobin (Hb) in rbc to form oxyhaemoglobin
How O2 is absorbed in the lungs
- 1 cell thick alveolar wall that separates blood capillaries from alveolar air is permeable to O2 and CO2
- alveoli air contains high conc of O2 than blood, O2 dissolves in the moisture lining of the alveolar walls, diffuses into blood capillaries
- O2 combine with Hb to form oxyhaemog-lobin (reversible)
- direction depends on amt of O2 in surroundings
- lungs where O2 conc is high, O2 combine with Hb to form oxyhaemoglobin
- blood pass thru oxygen-poor tissues, oxyhaemoglobin releases oxygen which diffuses thru wall of blood capillaries into cell of tissues
How carbon dioxide is transported
- CO2 react with water to form carbonic acid
- reaction catalysed by carbonic anhydrase
- carbonic acid then converted into hydrogencarbonate ions which will diffuse out of rbc and into blood plasma
- in lungs, hydrogen carbonate ions are converted back into carbonic acid and then to carbon dioxide
- diffuses out of blood capillaries in cavity of the alveolus, expelled when breathe out
Diaphragm
-a dome-shaped sheet of muscle and elastic tissue that contracts and relaxes to change the vol of thoracic cavity
Inspiration (RICE)
- internal intercostal muscles relax, external contract)
- rib cage raised upwards and outwards
- thoracic vol increases
- diaphragm contracts and flattens down
Expiration (ERIC)
- external intercostal relax, internal contract
- rib cage downwards and inwards
- thoracic vol decreases
- diaphragm relaxes and arches upwards
Stimulus for breathing
- caused by high conc of CO2 in blood or alveolar air, not lack of O2
- when there is too little CO2 in lungs, breathing does not occur
Stimulus for breathing experiment
- number of breaths per minute taken by human subjects breathing in:
(i) Atmospheric air 21% O2, 0.03 CO2 (stable breathing)
(ii) 100% pure O2 (breathing decreases)
(iii) air with 90% O2, 10% CO2 (breathing increases)
Nicotine
- addictive drug that causes the release of adrenaline
- makes blood clot easily
- increases heartbeat rate and blood pressure
- increases risk of blood clots in the arteries, leads to increased risk of coronary heart disease
Carbon monoxide
- combines with haemoglobin to form carboxyhaemoglobin
- increase the rate of fatty deposits on inner arterial wall, lead to increased risk of coronary heart disease
- reduces ability of blood to carry oxygen
- narrows lumen of arteries, increase blood pressure
Tar
- cause uncontrolled cell division
- paralyses cilia lining in the air passages
- increases risk of cancer in lungs
- dust particles trapped in mucus lining air passages cannot be removed , increase risk chronic bronchitis and emphysema
Irritants (e.g. hydrogen cyanide, acrolein, formaldehyde)
- paralyses cilia lining air passages
- dust particles trapped in mucus lining air passages cannot be removed
- increased risk chronic bronchitis and emphysama
Chronic bronchitis
- the epithelium lining the airways is inflamed
- excessive mucus secretion
- cilia lining the airways are paralyzed
- air passages become blocked, difficult to breathe
- persistent coughing to clear air passages
- increase risk of lung infection
Symptoms of chronic bronchitis
- breathing difficulties due to blocked airways
- persistent cough (body’s response to clear blocked airways)
Emphysema
- partition walls of alveoli breaks down due to violent coughs
- reduces SA:V available for gaseous exchange
- lungs lose their elasticity, become inflated with air
Emphysema symptoms
- breathing difficulties (lungs no longer elastic)
- wheezing
Chronic obstructive lung disease
- a persons that suffers from both chronic bronchitis and emphysema
- chronic (recurrent, persistent)
- obstructive (due to blockage in airways)
Lung cancer
- risk of lung cancer increases when a person smokes tobacco
- cancer is the uncontrolled division of cells producing outgrowths or lumps of tissue
- also increases risk of cancers of mouth, throat, pancreas,, kidney, urinary bladder
