Chapter 7: Respiration in Humans Flashcards
Define respiration.
Respiration refers to the oxidation of food molecules to release energy.
Define aerobic respiration.
Aerobic respiration refers to the breaking down of glucose in the presence of oxygen with the release of a large amount of energy.
Carbon dioxide and water are released as waste products.
Chemical equation for aerobic respiration?
C6H12O6 + 6O2 -> 6CO2 + 6H2O (+large amount of energy)
C6H12O6 is the chemical equation for all monosaccharide, incl. glucose
Word equation for aerobic respiration?
glucose + oxygen -> carbon dioxide + water (+large amount of energy)
Where does aerobic respiration occur (in the cell)?
Mitochondria
Can aerobic respiration be catalysed by enzymes?
(Yes / No)
Yes
Catalysts-catalyse CHEMICAL REACTIONS (e.g. respiration)
Examples of energy-consuming processes?
(6 pts.)
- Synthesis of new protoplasm for growth & repair
- Synthesis of proteins from amino acids
- Active transport in the absorption of food substances by the small intestine
- Muscular contractions (e.g. heartbeats, respiratory movements, etc.)
- Transmission of nerve impulses
- Cell division (growth)
How is energy also released?
As heat, heat energy is circulated around the body by blood to keep you warm (body temperature).
What are the differences between breathing and respiration?
-
Breathing-> Physical process of moving air in and out of lungs + gaseous exchange with the environment + intake of oxygen and removal of carbon dioxide
Respiration-> Chemical process of releasing energy from glucose -
Breathing-> occurs in the respiratory system
Respiration-> occurs within cells
Define anaerobic respiration.
Anaerobic respiration refers to the breaking down of glucose in the absence of oxygen.
It releases less energy than aerobic respiration, with lactic acid as a waste product.
Chemical equation for anaerobic respiration?
C6H1206 -> 2C3H6O3 (+small amount of energy)
Word equation for anaerobic respiration?
glucose -> lactic acid (+small amount of energy)
Differences between aerobic and anaerobic respiration?
(3 pts.)
- Aerobic respiration-> Occurs in the presence of oxygen
Anaerobic respiration-> Occurs in the absence of oxygen - Aerobic respiration-> A large amnt of energy is released
Anaerobic respiration-> A small amnt of energy is produced - Aerobic respiration-> Carbon dioxide and water are produced
Anaerobic respiration-> Only lactic acid is produced (in muscle and liver cells)
Define oxygen debt.
Oxygen debt refers to the volume of oxygen needed to convert lactic acid back into glucose.
What happens during exercise and why?
(15 pts.)
- During vigorous muscular contractions, muscle cells first respire aerobically.
- Panting occurs to remove carbon dioxide and take in oxygen at a faster rate.
- The heart begins to beat faster so that oxygen and glucose can be transported to muscles at a faster rate.
- There is a limit to the increase in the rate of breathing and heartbeat.
- When aerobic respiration alone is unable to release energy fast enough to meet the energy demands of muscle cells, muscle cells also carry out anaerobic respiration to release extra energy.
- Lactic acid is formed in the process.
- Energy released from anaerobic respiration and aerobic respiration together helps the muscles to keep contracting.
- Lactic acid concentrations build up slowly (accumulate) in the muscles, and may disrupt enzyme activity.
- The body then needs to rest and recover.
- During the period of rest, breathing rate and heart rate continues to be high for some time.
- This is to provide sufficient oxygen to muscle cells to repay the oxygen debt (that is incurred due to the need to oxidise lactic acid that is produced from anaerobic respiration).
- Lactic acid is removed from the muscles via blood and transported to the liver.
- In the liver, some of the lactic acid is oxidised to release energy, which is then used to convert the remaining lactic acid into glucose.
- ALL lactic acid is used up-> oxygen debt is repaid.
- Glucose is then transported back to muscles and the body is ready for another race.
note: all 15 pts are unlikely to come out in the same qn, but it is better to know all
4: phrasing
5: phrasing
Basis for studying aerobic respiration in experiments?
If it can be shown that an organism takes in oxygen and gives off carbon dioxide and heat energy, it can be said that it respires aerobically.
Basis for studying anaerobic respiration in experiments?
If it can be shown that a [micro]organism
(usually yeast) gives off carbon dioxide in the absence of oxygen, it can be said that it respires anaerobically.
State the flow of air in the respiratory system.
Nasal cavity->
Pharynx->
Larynx->
Trachea->
Bronchi->
Bronchioles->
Alveoli
State the features and functions of the nasal cavity.
(3 pts.)
-Fringe of hair and mucous layer on the walls of the nasal cavity-> traps dust and foreign particles
-Air is warmed and moistened as it passes through the air passages
-Sensory cells in mucous membrane-> detect harmful chemicals
State the features and functions of the trachea.
-Supported by C-shaped rings of cartilage-> ensure that the trachea is always open
-Epithelium of inner walls consist of 2 types of cells:
* Gland cells: secrete mucus-> trap dust particles and bacteria in the air that is channelled to the lungs
* Ciliated cells: have hair-like structures (cilia)-> sweep trapped particles and bacteria in mucus up the trachea and into the pharynx
State the features and functions of the bronchi and bronchioles
-Epithelium of inner walls (of bronchi) consist of 2 types of cells:
* Gland cells: secrete mucus-> trap dust particles and bacteria in the air that is channelled to the lungs
* Ciliated cells: have hair-like structures (cilia)-> sweep trapped particles and bacteria in mucus up the bronchi and trachea into the pharynx
-Each bronchus carries air into a lung (similar structure to trachea)
-Each bronchus branches repeatedly, giving rise to numerous bronchioles
-Each bronchiole ends in a cluster of alveoli
State the features and functions of the alveoli
(4 pts. for both parts)
Features:
-Inner alveolar surface coated with thin film of moisture-> allows oxygen to dissolve in it
-Alveolar wall and capillary wall only one-cell thick-> shorter diffusion distance for gases, for faster rate of diffusion
-Numerous alveoli in lungs-> increase surface area to volume ratio for gaseous exchange
-Surrounded by numerous blood capillaries-> maintain steep concentration gradient
Conc. gradients of gases between alveolar air and blood maintained by:
* Continuous flow of blood in blood capillaries surrounding alveolus
* Movement of air in and out of alveoli due to breathing
Functions:
-Site of gaseous exchange
1. Oxygen dissolves in thin film of moisture lining alveolar wall
2. Oxygen diffuses through one-cell thick wall of alveoli and blood capillaries into bloodstream
3. Oxygen combines reversibly with haemoglobin to form oxyhaemoglobin in red blood cells
4. Carbon dioxide diffuses from blood into alveolar cavity, which is removed during exhalation
-Conc. gradient of oxygen maintained such that conc. of oxygen in alveolar air > conc. of oxygen in blood
-Conc. gradient of carbon dioxide maintained such that conc. of carbon dioxide in alveolar air < conc. of carbon dioxide in blood
How is oxygen transported in red blood cells?
Oxygen molecules bind to haemoglobin reversibly in red blood cells to form oxyhaemoglobin.
State the features and functions of the intercostal muscles
Two sets of muscles found between ribs:
* External intercostal muscles
* Internal intercostal muscles
-Antagonistic muscles
-Move ribcage up and down during breathing
Describe the events that occur during inspiration (inhalation).
(8 pts.)
- Diaphragm muscles contract and diaphragm flattens
- Internal intercostal muscles relax, external intercostal muscles contract(R.I.C.E)
- Ribs move upwards and outwards
- Sternum moves up and forward
- Volume of thoracic cavity increases
- Lungs expand-> air pressure inside decreases as volume increases
- Atmospheric pressure is now higher than pressure within the lungs
- This forces atmospheric air into the lungs
Describe the events that occur during expiration (exhalation).
(8 pts.)
- Diaphragm muscles relax and diaphragm arches upwards
- External intercostal muscles relax, internal intercostal muscles contract (E.R.I.C)
- Ribs move downwards and inwards
- Sternum moves down to its original position
- Volume of thoracic cavity decreases
- Lungs are compressed-> air pressure inside increases as volume decreases
- Atmospheric pressure is now lower than pressure within the lungs
- This forces air out of lungs into the exterior environment
Differences between inspired and expired air?
(6 pts.)
OXYGEN:
Inspired air-> ab 21%
Expired air-> ab 16.4%
CARBON DIOXIDE:
Inspired air-> ab 0.03%
Expired air-> ab 4.0%
NITROGEN:
Inspired air-> ab 78%
Expired air-> ab 78%
WATER VAPOUR:
Inspired air-> Variable (rarely saturated)
Expired air-> Saturated (water evaporates from the surfaces of the alveoli)
TEMPERATURE:
Inspired air-> Variable
Expired air-> ab body temp., 36.9/37 ‘C
DUST PARTICLES:
Inspired air-> Variable, but usually present
Expired air-> Little, if any
What is the stimulus for breathing?
High concentration of carbon dioxide in blood or alveolar air (NOT lack of oxygen)
When there is too little carbon dioxide in lungs, breathing movements do not occur.
State the chemicals in tobacco smoke
Nicotine
Carbon monoxide
Tar
Irritants
Properties and effects on body of nicotine?
Properties:
* Addictive drug, causes release of adrenaline (hormone)
* Makes blood clot easily
Effects on body:
* Increases heartbeat rate and blood pressure
* Increases risk of blood clots in the arteries(incl. coronary artery)-> increased risk of coronary heart diseases-> stroke
Properties and effects on body of carbon monoxide?
Properties:
* Combines irreversibly with haemoglobin to form carboxyhaemoglobin
* Increases rate of fatty deposits on inner arterial wall
Effects on body:
* Reduces oxygen-carrying capability of red blood cells as there is less available haemoglobin to bind to oxygen
* Narrows lumen of arteries (incl. coronary artery)-> increased risk of coronary heart disease
Properties and effects on body of tar?
Properties:
*Causes uncontrolled cell division
* Paralyses cilia, which line the air passages
Effects on body:
* Increases risk of cancer in lungs
* Dust particles trapped in the mucus lining the air passages cannot be removed-> increased risks of chronic bronchitis and emphysema
Examples, properties and effects on body of irritants?
Examples:
- Hydrogen
- Cyanide
- Acrolein
- Formaldehyde
Properties:
* Paralyses cilia, which line the air passages
Effects on body:
* Dust particles trapped in the mucus lining the air passages cannot be removed-> increased risks of chronic bronchitis and emphysema
Description of chronic bronchitis?
(incl. cause & symptoms)
Cause:
Prolonged exposure to tar and irritants
Description:
- Epithelium lining the airways is inflamed
- There is excessive mucus secretion
- Cilia lining the airways are paralysed and unable to move mucus and dust up the bronchus and trachea and into the pharynx
Symptoms:
- Breathing difficulties (due to blocked airways)
- Persistent cough (as the body’s response to clear blocked airways and breathe)-> increased risk of lung infections
Description of emphysema?
(incl. cause & symptoms)
Cause:
Persistent and violent coughs from chronic bronchitis
Description:
- Partition walls of alveoli break down due to persistent and violent coughs from bronchitis
- This reduces the surface area to volume ratio for gaseous exchange
- Lungs lose their elasticity and become inflated with air
Symptoms:
- Breathing difficulties (due to inflated lungs)
- Wheezing and severe breathlessness
Description of cancers caused by smoking?
(incl. cause & examples)
Cause:
Uncontrolled division of cells caused by tar
Description:
- Uncontrolled division of cells produces outgrowths or lumps of tissues
Examples:
Cancers of:
- Mouth
- Throat
- Pancreas
- Kidneys
- Urinary bladder
