Chapter 7: respiration in humans

Question 1

Aerobic respiration

Answer 1

• the release of energy by the breakdown of glucose in the presence of oxygen. carbon dioxide and water are released as waste products
• releases a large amount of energy

Question 2

Overall equation for aerobic respiration

Answer 2

C6H12O6 + 6O2 ➡️ 6CO2 + 6H2O

Question 3

How aerobic respiration is carried out

Answer 3

• carried out in a series of steps that are catalysed by enzymes
• mitochondria in cells contain enzyme
• therefore mitochondria plays impt role in respiration

Question 4

What is aerobic respiration used for

Answer 4

• complex animals need it since they need large amounts of energy
  Ex:
• synthesis of new protoplasm for growth and repair
• synthesis of new proteins from amino acids
• active transport in absorption of food substances by small intestine
• muscular contractions
• transmission of nerve impluses
• cell division

Question 5

Anaerobic respiration

Answer 5

• release of energy by the breakdown of glucose in absence of oxygen.
• releases a relatively small amount of energy

Question 6

What causes anaerobic respiration

Answer 6

• aerobic respiration happens during muscular contractions in muscle cells
• may start panting to remove carbon dioxide and take in oxygen @ faster rate
• heart will beat faster to transport oxygen to muscles faster
• however, there is a limit to increase in rate of breathing and heart rate
• when vigorous activities continue, muscular contractions are so vigorous maximum aerobic respiration is unable to release energy fast enough to meet demand
• as muscular contractions continue, demand increases
• anaerobic respiration takes place to meet the increased demand for energy

Question 7

What happens during anaerobic respiration

Answer 7

• lactic acid is formed
• little energy is released
• energy from both types of respiration helps muscles keep contracting
• since there is insufficient oxygen, muscles incurs oxygen dept
• oxygen dept is amount of oxygen required to remove lactic acid

Question 8

How can oxygen dept be removed

Answer 8

1. continuation of fast heart rate: results in continued and fast transport of lactic acid from muscles to the liver and oxygen from lungs to liver
2. Continuation of deeper and faster breathing: results in continued and fast intake of oxygen by lungs. sufficient oxygen is required to remove lactic acid from blood

Question 9

Parts of the respiratory system

Answer 9

1. external nostril
2. nasal passage
3. pharynx
4. larynx
5. trachea
6. C-shaped ring of cartilage
7. bronchi
8. bronchioles
9. cluster of alveoli
10. diaphragm
11. lung
12. thorax
13. external intercoastal muscle
14. internal intercoastal muscle
15. rib

Question 10

Nose

Answer 10

• air enters via 2 nostrils
• walls of nostrils bears fringe of hairs
• nostrils leads to 2 nasal passages, which are lined with moist mucus membrane

Question 11

Advantages of breathing through nose

Answer 11

• dust & foreign particles, including bacteria in the air, are trapped by hairs in the nostrils as well as by mucus on muscus membrane
• as air passes through the nasal passage, it is warmed and moistered
• harmful chemicals may be detected by small sensory cells in mucus membrane

Question 12

From nose to trachea

Answer 12

• air in nasal passage enters via pharynx
• from pharynx, air passes into larynx & then into your trachea through an opening

Question 13

Trachea

Answer 13

• supported by c-shaped rings of cartilage
• cartilage keeps lumen of the trachea open
• membrane next to lumen is epithelium
• epithelium consists of gland cells and ciliated cells
• gland cells secret mucus to trap dust particles and bacteria
• ciliated cells have hair-like structures called cilia on their surfaces which sweep the dust-trapped mucus up trachea

Question 14

Bronchi & bronchioles

Answer 14

• trachea divides into 2 tubes called bronchi (singular:bronchus)
• each bronchus carry air into lung
• similar in structure to trachea
• each bronchus branches repeatedly, giving rise to numerous bronchioles
• bronchioles are very fine tubes
• each bronchioles end with cluster of alveoli

Question 15

Alveoli

Answer 15

• gas exchange takes place through walls of alveoli
• numerous alveoli are found in lungs, providing a very large surface area for gas exchange

Question 16

How are lungs adapted for efficient gas exchange

Answer 16

• numerous alveoli in lungs, providing larger surface area for gas exchange, hence quicker rate of absorption of oxygen
• wall of alveolus is 1 cell thick. Short diffusion distance ensures higher rate of diffusion of gases
• thin film of moisture covering inner wall of alveolus allows oxygen to dissolve in it & diffuse into the blood capillaries surrounding the alveolus quickly
• walls of alveoli are richly supplied with blood capillaries with continuous blood flow to maintain steep concentration gradient

Question 17

Gas exchange

Answer 17

• exchange of gas between an organism and its environment

Question 18

How does gas exchange happen in alveoli

Answer 18

• by diffusion
• blood entering lungs has lower concentration of oxygen & higher concentration of carbon dioxide
• concentration gradient of oxygen and carbon dioxide is set up between blood and air
• oxygen dissolve into thin film of moisture and then diffuse through wall of alveolus and capillary into red blood cells
• carbon dioxide diffuses from blood into air
• concentration gradient is maintained by continuous flow of blood in capillaries & continuous breathing, causing air in lungs to be constantly refreshed

Question 19

How is oxygen transported in body

Answer 19

• in lungs, where oxygen concentration is high, oxygen combine with haemoglobin in red blood cells to form oxyhaemoglobin
• oxygenated blood is then transported from lungs to other parts of body
• when blood passes through an organ/tissue where oxygen concentration is low, oxyhemoglobin will release its oxygen to respiring cells

Question 20

The Thoracic cavity

Answer 20

• chest wall is surrounded by ribs
• between ribs is the internal intercoastal muscle and the external intercoastal muscles
• they are antagonistic muscles
• thorax is separated from the abdomen by diaphragm
• diaphragm is made out of muscles and elastic tissue
• when diaphragm muscles contract, diaphragm flattens
• when diaphragm muscles, diaphragm arches upwards
• intercoastal muscles and diaphragm work together to change volume of the thoracic cavity

Question 21

Inspiration (inhalation)

Answer 21

• diaphragm muscles contract, diaphragm flattens
• internal intercoastal muscles relax, external intercoastal muscles contract (RICE)
• ribs move upwards and outwards.
• sternum moves up and forwards
• volume of thoracic cavity increases
• atmospheric pressure is higher than pressure in lungs
• aire moves into lungs

Question 22

Expiration (Exhalation)

Answer 22

• diaphragm relaxes and arches upwards
• external intercoastal muscles relax, which internal intercoastal muscles contract (ERIC)
• ribs move downwards and inwards
• sternum moves down and it original position
• volume of thoracic cavity decreases
• lungs are compressed & air pressure inside them increases as volume decreases
• pressure in lungs is higher than atmospheric pressure
• air is forced out of lungs into exterior envrionment

Question 23

Diff between inspired and expired air

Answer 23

• more oxygen in inspired air
• more carbon dioxide in expired air
• same amount of nitrogen
• water vapour is saturated in expired air, but is rarely saturated in inspired air
• more dust particles in inspired air
• temperature of expired air is always body temp, but can vary for inspired air

Question 24

Chemicals in tobacco smoke

Answer 24

1. nicotine
2. carbon monoxide
3. Tar

Question 25

Effects of nicotine

Answer 25

• increases heart rate and blood pressure
• increase risk of blood clots in arteries, increasing risk of coronary heart disease
• increases risk of arteries narrowing
• narrow arteries decrease amount of food substances reaching fetus, affecting fetus development

Question 26

Effects of carbon monoxide

Answer 26

• reduces ability of blood to transport oxygen as carbon monoxide binds permanently with haemoglobin
• there will be less haemoglobin available to transport oxygen
• can affect fetal development, since less oxygen reaches fetus
• increase risk of coronary heart disease

Question 27

Effects of tar

Answer 27

• increases risk of cancer in lungs as it can cause uncontrolled cell division
• increases risks of chronic bronchitis and emphysema
• tar paralyses the cillia lining the air passages
• dust particles trapped in mucus lining cannot be removed

Question 28

Diseases cause by tobacco smoke

Answer 28

1. Chronic bronchitis
2. Emphysema
3. Lung cancer

Question 29

Chronic bronchitis

Answer 29

• epithelium lining of air passages becomes inflamed
• excessive mucus is secreted by epithelium
• cilia on the epithelium are paralysed
• mucus & dust particles cannot be removed
• air passages becomes blocked, making breathing difficult
• in order to breathe, persistent coughing occurs to clear the air passages, increasing risk of lung infection

Question 30

Emphysema

Answer 30

• partition walls between alveoli break down due to persistent and violent coughing
• results a decreased surface area for gaseous exchange
• lungs lose their elasticity and become inflated with air
• breathing becomes difficult
• wheezing & severe breathlessness results
• when a person has chronic bronchitis & emphysema, they have chronic obstructive lung disease

Question 31

Lung cancer

Answer 31

• risk of lung cancer increases when a person smokes tobacco
• smoking also increases risk of cancers of mouth, throat, pancreas, kidneys and urinary bladder