chapter 11: gas exchange in humans

Question 1

describe the features of gas exchange surfaces

Answer 1

• large surface area for faster diffusion
• thin surface (one cell thick) to ensure shrot diffusion distance
• good blood supply to maintain high concentration for quicker diffusion
• good ventilation with air so diffusion gradients maintained

Question 2

describe the function of the ribs

Answer 2

• bone structure protecting internal organs

Question 3

describe the function of the intercostal muscle

Answer 3

• muscle between the ribs which control their movement causing inhalation and exhalation

Question 4

describe the function of the diaphragm

Answer 4

• sheet of connective tissue and muscle at the bottom of the thorax that helps change the volume of the thorax to allow inhalation and exhalation

Question 5

describe the function of the trachea

Answer 5

• windpipe that connects the mouth and nose to the lungs

Question 6

describe the function of the larynx

Answer 6

• voice box, air passes through it and sound is produced

Question 7

describe the function of the bronchi

Answer 7

• large tubes branching off the trachea with one bronchus for each lung

Question 8

describe the function of the bronchioles

Answer 8

• bronchi split to form smaller tubes called bronchioles in the lungs connected to alveoli

Question 9

describe the function of the alveoli

Answer 9

• tiny air sacs where gas exchange takes place

Question 10

describe the differences in the composition of inhaled and exhaled air

Answer 10

• oxygen: 21% inhaled, 16% exhaled; oxygen used up for aerobic respiration as oxygen diffused into thr blood in the lungs
• carbon dioxide: 0.04% inhaled, 4% exhaled; produed by respiration, diffuses from the blood into the alveoli
• water vapour: 0.04% inhaled, 4% exhaled; water evaporates from the moist lining of the alveoli into the expired air due to the warmth of the body

Question 11

describe the effect of physical activity on the rate and depth of breathing

Answer 11

• increases the rate and depth
• muscles working harder and aerobically respiring more, need more oxygen
• increased carbon dioxide concentration in blood causes blood to be acidic, brain detects this and sends nerve impulses to diaphragm and intercostal muscles to increase the rate and depth of muscle contraction
• if energy demand still not met, cells will respire anaerobically, producing lactic acid which accumulates in the muscle cells
• lactic acid must be removed unless it lowers cell pH and denatures enzymes
• continuatioj of fast heart rate and deep breathing transport lactic acid in the blood from the muscles to the liver to supply oxygen for aerobic respiration of lactic acid

Question 12

state the function of the cartilage in trachea

Answer 12

• supports the trachea
• keeps the trachea open

Question 13

explain the process of inhalation

Answer 13

• external intercostal musles contract
• ribcage moves up and out
• diaphragm contracts and flattens
• volume of thorax increases
• pressure inside thorax decreases
• air drawn in

Question 14

explain the process of exhalation

Answer 14

• internal intercostal muscles contract
• ribcage moves down and in
• diaphragm relaxes and becomes dome shaped
• volume of thorax decreases
• pressure in thorax increases
• air forced out

Question 15

how is the breathing system protected from pathogens and particles?

Answer 15

• goblet cells: produce mucus trap the pathogens and particles to be easily removed from the body
• ciliated cells: tiny hairs that best and push mucus up the passages towards the nose and throat

Question 16

state the uses of energy in living organisms

Answer 16

• muscle contraction
• protein synthesis
• active transport
• cell division
• growth
• passage of nerve impulses
• maintenance of constant body temperature