chapter 7 - respiration in humans

Question 1

larynx

Answer 1

protest respiratory tract from aspirating food into the trachea while breathing

Question 2

trachea

Answer 2

carries air in and out of lungs

Question 3

bronchi

Answer 3

delivers air from trachea to lungs

Question 4

alveoli

Answer 4

where lungs and blood exchange oxygen and carbon dioxide during the process of breathing in and out

Question 5

cilia

Answer 5

hair like structures that sweep dust trapped mucus towards the pharynx to be coughed out or swallowed

Question 6

inhalation

Answer 6

diaphragm muscle contracts and diaphragm flattens. external intercostal muscles contract while internal intercostal muscles relax. ribs moves upwards and outwards. sternum moves upwards and forwards. the volume of the thoracic cavity increases, the lungs expands and air pressure inside decreases. atmospheric pressure is higher than pressure in the lungs, and air is forced into the lungs

Question 7

exhalation

Answer 7

diaphragm muscle relaxes and arches upwards. external intercostal muscles relax while internal intercostal muscles contract. ribs move downwards and inwards. sternum moves down to original position. volume of thoracic cavity decreases, lungs compressed and air pressure inside increases. atmospheric pressure is lower than the pressure in the lungs. air is forced out of the lungs

Question 8

inspired air vs expired air

Answer 8

oxygen : higher in inspired air, lower in expired air

carbon dioxide : lower in inspired air, higher in expired air

nitrogen : about the same

water vapour : less saturated in inspired air, more saturated in expired air

dust particles : usually present in inspired air, rarely present in expired air

temperature : variable for inspired air, normally body temperature for expired air

Question 9

adaptations of alveoli

Answer 9

• numerous alveoli to increase surface area to volume ratio for faster rate of diffusion and gaseous exchange
• alveolar walls are one cell thick , allowing for faster diffusion of gasses due to the short diffusion distance
• thin film of moisture on the inner walls of alveoli allows for oxygen to dissolve in it
• walls of alveoli are richly supplied with blood capillaries, and the constant flow of blood maintains a steep concentration gradient between the blood and air in the alveoli for higher rate of diffusion

Question 10

describe the gaseous exchange of oxygen in the alveoli

Answer 10

molecule of oxygen dissolves in the layer of moisture on the surface of the alveolus and diffuses through the alveolar wall down a concentration gradient into the blood capillaries and into the red blood cell, binding with haemoglobin to form oxyhaemoglobin. it is the. carried by the blood from the blood capillaries through the pulmonary veins into the left atrium and into the left ventricle, thein into the aorta before entering the coronary arteries into a muscle cell in the wall of the left atrium

Question 11

effects of nicotine in tobacco smoke

Answer 11

it is addictive and causes increase in heartbeat and blood pressure, as well as increased risk of blood clots in blood vessels

Question 12

effects of carbon monoxide in tobacco smoke

Answer 12

it binds irreversibly with haemoglobin to form carboxyhemoglobin, reducing the oxygen carrying capacity of RBCs and reduces respiration by body tissues, reducing energy released. it can also caused increased fatty deposits on inner walls of arteries, which narrows the lumen and increases risk of blood clots

Question 13

effects of tar in tobacco smoke

Answer 13

it is a carcinogenic chemical that induces uncontrolled cell division of the epithelium. it also paralyses the villain lining air passages. this causes blockages in air sacs and reduces gas exchange efficiency, and the paralysis of cilia will cause dust particles to be trapped in the mucus lining and it can’t be removed

Question 14

chronic bronchitis

Answer 14

• epithelium lining of air passages become inflamed
• excessive mucus secreted by epithelium
• cilia on epithelium paralyzed. mucus and dust particles cannot be removed
• air passages become blocked, breathing becomes difficult
• persistent cough to clear air passages in order to breathe, increasing risk of getting lung cancer

Question 15

emphysema

Answer 15

• partition walls between alveoli break down due to persistent coughing
• decreases surface area too volume ratio of gaseous exchange
• lungs lose elasticity and become filled with air
• breathing becomes difficult and will result in breathlessness and wheezing

Question 16

respiration

Answer 16

break down of food molecules such as glucose to release energy

Question 17

aerobic respiration

Answer 17

breakdown of glucose that occurs in the mitochondria of human cells, in the presence of oxygen to release. large amount of energy

Question 18

chemical formula of respiration

Answer 18

C6H12O6 + 6O2 → 6CO2 + 6H2O (glucose + oxygen -> carbon dioxide + water + energy)

Question 19

anaerobic respiration

Answer 19

breakdown of glucose in the absence of oxygen, releasing a relatively small amount of energy. anaerobic respiration occurs in muscle cells during muscle cells. the break down of glucose forms lactic acid

Question 20

why does anaerobic respiration take place during vigorous exercise?

Answer 20

during exercise, muscle contractions increases, increasing the energy demand of the body. heartbeat rate and rate of respiration increases to supply more oxygen and glucose to his muscles for aerobic respiration, and to meet the energy demand. however, the energy from the maximum rate of aerobic respiration is insufficient due to increased muscular contractions, and anaerobic respiration will take place to meet the high energy demand. the production and accumulation of lactic acid results in oxygen debt (amount of oxygen needed to remove lactic acid)

Question 21

oxygen debt

Answer 21

volume of oxygen required to remove the latic acid that has been built up in the body

Question 22

how does the body address oxygen debt?

Answer 22

oxygen debt is addressed through deeper and faster breathing to obtain oxygen for supply to liver. in the liver, oxygen is used to oxidise some lactic acid to release energy. this energy is then used to convert the remaining lactic acid back to glucose to store inside the liver as glycogen. it can also be repaid by a continued fast heart rate to transport lactic acid to the liver via blood for removal and to transport more oxygen to the liver. oxygen debt is paid when lactic acid is removed from the body.

Question 23

why does oxygen uptake remain high after exercise?

Answer 23

to repay oxygen debt, lactic acid is removed from muscles and transported to the liver for detoxification. some of the lactic acid is oxidised to carbon dioxide and water, releasing energy that is used to covert the remaining lactic acid to glucose, which is then transported back to muscles. excess glucose is converted into glycogen to be stored in the liver and muscles.

Question 24

why does heart rate increase during exercise?

Answer 24

vigorous contraction of muscles require increasing energy demand. more blood is transported to the muscles to supply more oxygen and glucose for aerobic respiration to release more energy to meet oxygen demand

Question 25

what causes oxygen to diffuse from the alveoli into the blood

Answer 25

high concentration of oxygen in alveoli air space than blood, hence it diffuses down a concentration gradient

Question 26

what causes oxygen to diffuse from the alveoli into the blood

Answer 26

high concentration of oxygen in alveoli air space than blood, hence it diffuses down a concentration gradient