Chapter 7 part 1 : Respiration in humans

Question 1

What is aerobic respiration?

Answer 1

• Aerobic respiration is releasing energy by breaking down glucose in the presence of oxygen.
• Carbon dioxide and water are the waste products of aerobic respiration.

Question 2

What is the overall equation for aerobic respiration?

Answer 2

• Chemical equation: C6H12O6 + 6O2 + 6H2O
• Word equation: Glucose + oxygen –> Carbon dioxide + water

Question 3

Why does aerobic respiration release a large amount of energy?

Answer 3

• Aerobic respiration releases a large amount of energy because the amount of energy released is used for energy-consuming processes which include the synthesis of new organelles and macromolecules, active transport, the transmission of nerve impulses, muscular contraction, and others.

Question 4

What is anaerobic respiration?

Answer 4

• Anaerobic respiration is the release of energy by breaking down glucose in the absence of oxygen.
• This process releases relatively less energy than aerobic respiration because the glucose molecule is already partially broken down.

Question 5

What is the type of respiration that muscle cells carry out while doing vigorous exercises?

Answer 5

• During vigorous exercise, muscle cells carry out anaerobic respiration when there is insufficient oxygen.
• Muscle cells first respire aerobically.
• When muscular contractions become too vigorous for the maximum aerobic respiration to release energy fast enough to meet the demand, the muscle cells will carry out anaerobic respiration to release extra energy.
• Lactic acid is produced in the process.
• The small amount of energy released in anaerobic respiration, along with energy released in aerobic respiration helps the muscle cells to continue contracting.

My add-on:The heart rate also increases the heart needs to pump blood more vigorously to supply digested food, and oxygen to all parts of the body. It also has to pump quickly to release as much carbon dioxide (and waste materials) out of the body.

Question 6

What is the equation for anaerobic respiration in human muscles?

Answer 6

• Glucose –> lactic acid

Question 7

What is the term “Oxygen debt”?

Answer 7

• since there is insufficient oxygen for the vigorous muscle contractions, the muscles are said to incur (undergo) an oxygen debt.
• def: Oxygen debt is the amount of oxygen that is needed to remove lactic acid.

Question 8

What happens after the vigorous exercise?

Answer 8

• After the vigorous exercise, the oxygen debt is removed via:
  1. Breathing continues to be deep and fast to allow the lungs to take in insufficient oxygen.
  2. the heart rate continues to be fast to facilitate in the transport of lactic acid from the muscles to the liver, and oxygen from the lungs to the liver.
  3. The oxygen is used to convert lactic acid to glucose.
  4. Once the lactic acid is removed, the oxygen debt is said to be repaid.

Question 9

What is gas exchange?

Answer 9

• Gas change is the exchange of gases between an organism and the environment (surroundings).

Question 10

What are the organs that are involved in gas exchange in humans?

Answer 10

• Nasal cavity, nostril (2), pharynx, epiglottitis, larynx, trachea, c-shaped ring of cartilage, internal intercostal muscle, cut end of rib, bronchus (s)/bronchi (p), cluster of alveoli (air sacs), bronchiole, lung, external intercostal muscle, diaphragm, and the heart.

Question 11

What is the nasal passage?

Answer 11

• The nasal passage is where the air that enters the body through the nostrils will be led to.
• In the nose, dust, and foreign (dirt) particles are trapped in the nostril hairs and the mucus on the mucous (a slippery aqueous secretion produced by mucous membranes/mucous glands) membrane lining the nasal passages.
• Air is also warmed and moistened in the nose.

Question 12

What happens after air (oxygen) passes through the nostrils and nasal passages?

Answer 12

• Air then enters the pharynx, passes into the larynx, and makes its way to the trachea (windpipe).

Question 13

What is the trachea?

Answer 13

• the trachea is supported by c-shaped rings of cartilage, which keep the lumen of the trachea open.

Question 14

What are gland and ciliated epithelial cells?

Answer 14

• it is the cells that produce/secret mucus that are lined at the walls of the trachea.
• Gland cells produce/secrete mucus (sticky substances) to trap dust particles and bacteria.
• Cilia (hair-like structures) on the epithelial cells sweep dust-trapped mucus away up the trachea.

Question 15

What is a bronchi?

Answer 15

• A bronchi is the organ that the trachea branches out into.
• Each bronchus branches repeatedly, giving rise to numerous bronchioles.

Question 16

What are bronchioles?

Answer 16

• Bronchioles are very fine tubes that end in a cluster of air sacs called alveoli.

Question 17

What is alveoli?

Answer 17

• Alveoli is a cluster of air sacs.

Question 18

What is the method in which gas exchange takes place via?

Answer 18

• Gas exchange takes place through the walls of the alveoli by diffusion.

Question 19

What are the adaptations that the alveoli and lungs have for efficient gas exchange?

Answer 19

1. the great number of alveoli found in the lungs provide a very large surface area for gas exchange.
2. The wall of the alveolus is one-cell thick, which results in a short diffusion distance for gases and a faster rate of diffusion.
3. A thin film of moisture covering the surface of the alveolus allows oxygen to dissolve in it and enter the bloodstream.
   4.:
   - The extensive capillary network around the walls of the alveoli maintains the concentration gradient of gases.
   - blood entering the lungs has a lower concentration of oxygen and a higher concentration of carbon dioxide than the atmospheric air that is entering the alveoli in the lungs.
   5.:
   - Breathing ensures a higher oxygen concentration in the alveoli than in the blood capillaries.
   - This allows oxygen to diffuse from the alveolar cavity and into the blood capillaries and carbon dioxide to diffuse from the blood capillaries into the alveolar cavity.

Question 20

What is the process of gas exchange?

Answer 20

1. oxygen dissolves in the thin film of moisture on the wall of the alveolus.
2. The dissolved oxygen diffuses through the wall of the alveolus, and into the blood capillary.
3. Carbon dioxide diffuses from the blood in the capillary into the alveolus.
4. The oxygen combines with haemoglobin to form oxyhaemoglobin.

Question 21

What happens after oxygenated blood is being transported from the lungs to the other parts of the body?

Answer 21

• Oxygenated blood is transported from the lungs to the other parts of the body.
• The oxyhaemoglobin releases its oxygen in a region with low concentration.

Question 22

What is breathing?

Answer 22

• Breathing refers to the muscular contractions and movements of the ribs, this results in air moving in and out of the lungs.
• The muscles involved include external and internal intercostal muscles, together with the diaphragm.

Question 23

What is a diaphragm?

Answer 23

• The diaphragm is a sheet of muscle and elastic tissue that separates the thorax from the abdomen.

Question 24

What is the pathway of air into the lungs?

Answer 24

External nostrils –> nasal passages –> pharynx –> larynx –> trachea –> bronchi –> bronchioles –> alveoli (air sacs that are tiny)

Question 25

What are the 2 phases in breathing movements?

Answer 25

• It consists of:
  1. Inhalation/inspiration –> when air is taken in.
  2. Exhalation/expiration –> when air is given out.

Question 26

What are the sequence of events during inspiration and expiration?

Answer 26

Inspiration:
1. Diaphragm muscles contract and flatten.
2. External intercostal muscles contract and internal intercostal muscles relax.
3. Ribs move forward and outward, sternum moves up and forward.
4. Volume of the thoratic cavity increases.
5. Lungs expand, and as the volume increases, the air pressure inside the lungs decreases.
6. Atmospheric air pressure is higher than the air pressure inside the lungs.
7. Air moves into the lungs.

Expiration:
1. Diaphragm muscles relax and arch upwards.
2. External intercostal muscles relax, and internal intercostal muscles contract.
3. Ribs move forward and outward, and the sternum moves down to its original position.
4. Volume of the thoratic cavity decreases.
5. Lungs compress, and as the volume decreases, the air pressure inside the lungs increases.
6. Air pressure in the lungs is higher than the atmospheric pressure.
7. Air is forced out of the lungs.