respiration in humans

Question 1

define aerobic respiration

Answer 1

aerobic respiration is the breakdown of food substances in the presence of oxygen with the release of a large amount of energy with carbon dioxide and water as by-products

Question 2

aerobic respiration word equation

Answer 2

glucose + oxygen -> carbon dioxide + water + large amount of energy

Question 3

define anaerobic respiration

Answer 3

anaerobic respiration is the breakdown of food substances with the release of a comparatively small amount of energy in the absence of oxygen

Question 4

anaerobic word equation

Answer 4

glucose -> lactic acid + small amount of energy

Question 5

what occurs when humans do vigorous activities?

Answer 5

• Muscles normally respire aerobically. However, under vigorous muscular exertion, even the increased rate of breathing and cardiac cycles cannot provide sufficient oxygen to all the muscle tissue.
• Anaerobic respiration then occurs to produce lactic acid and some energy. The energy produced by anaerobic respiration supplements that produced by aerobic respiration to maximise the rate of muscular activity
• When lactic acid accumulates, the muscle tissue incurs an oxygen debt. A high concentration of lactic acid causes muscle fatigue.
• During rest, the lactic acid is removed from the muscle and transported to the liver where some of it is oxidised to provide energy and the rest converted back to glucose. The glucose is then transported back to the muscle tissue.

Question 6

pathway of air in the body

Answer 6

pharynx -> larynx -> trachea -> bronchus -> bronchioles -> alveoli

Question 7

gaseous exchange in the lungs (specifically the alveolus) occurs by?

Answer 7

diffusion
- when there is an intake of air, a diffusion gradient occurs with high O2 concentration in the alveoli and a comparatively high CO2 presence in the blood capillaries surrounding the alveoli

Question 8

how is the gradient maintained?

Answer 8

• the continuous action of inhaling and exhaling
• the continuous blood flow in the capillaries

Question 9

how is the structure of the alveoli adapted to its function?

Answer 9

• the one-cell thick membrane of the alveoli and capillaries allow for a rapid rate of diffusion
• large surface area of the alveoli: helps to increase the rate of exchange
• presence of a thin film of moisture in the alveolar cavity: provides a good medium for diffusion to take place as the gases will only diffuse in the dissolved state

Question 10

properties and effects of nicotine

Answer 10

• main cause of addiction to smoking
• results in the release of the hormone adrenaline which causes increased heartbeat and blood pressure
• increases the risk of blood clots forming internally and blocking important arteries, which leads to increased risk of coronary heart disease

Question 11

properties and effects of tar

Answer 11

• causes uncontrolled cell division
• paralyses cilia lining the air passages
  -increases risk of cancer in lungs
• dust particles trapped in mucus lining the air passages cannot be removed, increasing risks of chronic bronchitis and emphysema

Question 12

properties and effects of carbon monoxide

Answer 12

• decreases the ability of haemoglobin to carry oxygen in red blood cells
• increases the rate of fatty substances being deposited on the inner walls of arteries, thus increasing the risk of coronary heart disease
• damages the lining of blood vessels and increases the formation of clots

Question 13

advantages of breathing through the nose

Answer 13

• dust and foreign particles, including bacteria in the air, are trapped by the hairs in the nostrils as well as the mucus on the mucous membrane
• air that passes through the nasal passages are warmed and moistened
• harmful chemicals may be detected by small sensory cells in the mucous membrane

Question 14

what does the cillia do?

Answer 14

the cilia sweep the dust-trapped mucus up the trachea

Question 15

a high concentration of lactic acid causes?

Answer 15

muscle fatigue, pain or cramps