Respiration-metabolic process where energy rich food substances are oxidized, releasing energy in the form of ATP molecules (glucose-blood sugar, usually oxidized) (aerobic & anaerobic) Importance of energy: needed to maintain metabolic reactions of living organisms [human-protein synthesis, growth, excretion, locomotion, reproduction, etc. plants-active transport to absorb ions, glucose + other (in)organic substances] Aerobic Respiration
-food substances completely broken down in O2
-large amount of energy released (1 glucose molecule = 38 ATP molecules)
-products-CO2 + H2O
-takes place in the cytoplasm then mitochondria
C6H12O6+ 6O2 > (enzymes) > 6CO2 + 6H2O + 2830 kJ
Anaerobic Respiration
-food substances incompletely broken down in absence of O2
-small amount of energy released (1 glucose molecule = 2 ATP molecules)
-products;-(animals/plants)= (lactic acid/ethanol) + CO2 + H2O
-takes place in cytoplasm
C6H12O6 > (enzymes) > 2C2H5OH (ethanol) + 6CO2 + 118 kJ
In yeast (enzyme-zymase; sugar + zymase ethanol + CO2 + H2O) and bacteria, anaerobic respiration is called alcoholic fermentation. These organism are used in baking and brewing industries
Oxygen Debt
-strenuous muscular activities, O2 demands high, breathing rate faster [(due to CO2 conc.) nerve impulses from brain stimulates diaphragm + inter-costal muscles]
-Myoglobin (pigment in muscles)-oxygen reserve in muscles, release O2 when needed
oxygen debt =build up of lactic acid in muscle due to lack of O2 (lactic acid > liver > oxidised > CO2 +H2O)
-Result-anaerobic respiration in muscles > lactic acid formed, accumulates > muscle fatigue
Breathing/ Ventilation in Man
respiratory system=2 lungs (in thorax) + air passages (nasal passages, pharynx, larynx, trachea, bronchi, bronchioles)
+ rib cage (thoracic cavity), ribs, diaphragm, inter-costal muscles
advantages of air entering body through nostrils;-dust + foreign particles (bacteria) trapped by hairs
-air warmed + moistened before it enters lungs
-poisonous chemicals detectable by mucus membrane
nostrils > pharynx > larynx > trachea > bronchi > bronchioles > alveoli
larynx-a passage through the glottis, an opening, which is covered by lid-like epiglottis which prevents entry food particles into the trachea during swallowing
trachea-in front of oesophagus and supported by C-shaped cartilage rings which prevent trachea from collapsing during forced breathing and to keep it open. Lower end divided into 2 bronchi (bronchus) which divides into bronchioles ending in a cluster of air sacs, alveoli (1 alveolus-place where gaseous exchange takes place)
Adaptations of Alveoli for gaseous exchange
-large surface area (1000's of alveoli)
-thin walls (1-cell thick), fast diffusion
-wet walls (film of moisture), fast diffusion
-richly supplied w/ blood capillaries which are close to alveoli, fast diffusion
-large difference in conc. of gases in blood and in alveolar cavity, steep conc. gradient maintained, fast diffusion
-each lung found in a pleural cavity and is enclosed by pleura-elastic membrane
-the cavities contain pleural fluid; friction-free movements when lungs expand and contract during breathing
-thorax supported by ribs & joined to sternum. Between ribs: 2 sets of muscles, internal + external inter-costal muscles
-thorax separated from abdomen by diaphragm: dome-shaped sheet of elastic muscle
Inhalation
-external IC muscles contract, internal IC muscles relax
-ribs wing upwards and outwards
-diaphragm muscles contract:pulling down > forms an arch
-volume in chest cavity increases, pressure decreases
-air rushes into lungs as pressure outside is higher
Exhalation
-internal IC muscles contract, external IC muscles relax
-ribs wing downwards and inwards
-diaphragm muscles relax:return to dome-shaped structure
-volume in chest cavity decreases, pressure increases
-air rushes out of lungs as pressure outside is lower
Inspired air
Expired air
O2
~20
~16
CO2
~0.03
~4
N2
~79
~79
H2O vapour
variable (rarely saturated)
saturated
temp
variable
~ body temp (37°C)
dust partilces
variable (usually present)
little (nil)
Tidal Air-amount of air during normal (quiet) breathing (500cm3/0.5 dm3, approx. 450cm3) Complemental Air-extra volume of air taken in during a deep breathe (1500cm3) a.k.a. Inspiratory reserve volume Supplemental Air-extra volume of air possible to be exhaled during a forced exhalation (1500cm3) a.k.a. Expiratory reserve volume Residual Air-volume of air in lungs that can not be expelled (1500cm3) Vital Capacity =Tidal air + Complementary Air + Supplementary Air. amount of air exchanged after a force inspiration followed by a immediate expiration. Differs from person to person and can be improved by exercises (swimming)
Respiration
-energy liberated
-O2 used, CO2 + H2O given off
-catabolic reaction (destructive)
-breaking down of carbohydrate molecules
-occurs all the time
-results in loss in dry mass
Photosynthesis
-energy stored in carbohydrate molecules
-CO2 + H2O used, O2 given off
-anabolic reaction (constructive)
-building up of carbohydrate molecules
-occurs only in cells containing chlorophyll in the presence of light
-results in gain in dry mass
Smoke-Related Diseases
A cigarette is a drug, contains >4000 chemicals and some of which are harmful to the body. Contains: Nicotine-poisonous, addicted drug 1-causes addiction 2-increses secretion of adrenaline from adrenal gland, contributes
to high blood pressure and increase of heat beat Carbon Monoxide-combines w/ haemoglobin > stable carboxyhaemoglobin, O2 carrying capacity reduced Tar-brown sticky substance, accumulates in lungs during smoking, contains many carcinogens. Paralyses cilia, lining
air passages, prevents cilia from removing dust particles > large amount of mucus in air passages Irritants-substances (hydrogen cyanide) also paralyses cilia in air passages & may cause diseases
Emphysema:-break down of alveoli.
Alveoli walls (divides alveoli) weakened by substances in tobacco smoke.
Substances e.g. irritants cause smoker to cough unusually which bursts weakened alveoli. Thus surface area of lungs for gaseous exchange > reduced. Therefore smoker gets a lesser supply of oxygen > breathlessness and exhaustion
Bronchitis:- inflammation of walls of air passages + over production of mucus
Due to chemical substances found in tobacco smoke stop beating of cilia in air passages. People suffer from breathlessness + wheezing (consumes energy > O2 may not be sufficient available to tissues > fatigue + exhaustion)
Lung Cancer
Tar, nicotine and other carcinogenic substances in tobacco smoke (at least 17 substances cause cancer) increase chances of lung cancer. Cells in lungs divide uncontrollably > growth outgrowth (tumors). Mouth cancer, intestinal cancer also occur quite frequently in smokers
Heart Disease
Nicotine and CO from cigarette smoke increase tendency for to clot, blocking coronary arteries which are already blocked by fatty deposits. CO increases rate of fatty material depositing in arteries
Other Risks
Strokes due to arterial disease in brain, more frequent in smokers
Cancer of the bladder, ulcers in stomach + duodenum, tooth decay, gum disease and tuberculosis, more frequent
Babies born to women who smoke during pregnancy -smaller (low birth rate-result of reduced O2 supply caused by CO in blood), low IQ, physical deformed + still birth [miscarriage can also occur]
Short-term Effects
-constriction of bronchioles of lungs + cilia lining air passages stop beating (cleaning mechanism of lungs stopped > chemicals from tobacco smoke cause more damage to lung tissues)(thus, smokers suffer from diseases e.g. emphysema, bronchitis)
-nicotine, stimulant, increases nervous system's activities and relieves tension and fatigue
-blood vessels > narrow, heart rate increases, blood pressure increases, urine production decreases
1st time smoker often feels dizzy and may vomit
Long-term Effects(may take years to develop, but severe and causes death)
-nicotine increase fatty acids in bloodstream > lead to risk of heart disease, angina, high blood pressure, coronary thrombosis
-chronic smoker can get lung cancer, cancer of the mouth and throat and other harmful diseases
smoking addicts may develop withdrawal symptoms if try to stop smoking (become irritable, sleepless, numbness in arms and legs, inability to concentrate and coughing more than usual)
