Chapter 07 - Respiration in Humans

Question 1

What is respiration?

Answer 1

A process by which energy is produced from oxidation of food

Question 2

What are the 2 types of respiration?

Answer 2

1) Aerobic
2) Anaerobic

Question 3

What is aerobic respiration?

Answer 3

Aerobic respiration is the release of energy by the break down of glucose in the presence of oxygen

Question 4

What is it known as when food molecules are combined with oxygen?

Answer 4

The food is said to be oxidised

Question 5

What is released during aerobic respiration?

Answer 5

Carbon dioxide and water as waste products and a lot of energy

Question 6

What atoms do all food molecules contain and what does oxidation do?

Answer 6

All food molecules contain carbon, hydrogen and oxygen atoms. Oxidation converts carbon atoms into carbon dioxide and hydrogen into water

Question 7

What is the chemical equation for aerobic respiration?

Answer 7

C6H12O6 + 6O2 –> 6CO2 + 6H2O

Question 8

What is the word equation for aerobic respiration?

Answer 8

glucose + oxygen –> carbon dioxide + water

Question 9

Respiration is catalysed by enzymes found in ____

Answer 9

Mitochondria, hence it plays an important role in aerobic respiration

Question 10

Energy is needed by many vital processes and activities. Name 2

Answer 10

1) Synthesis of new protoplasm for growth and repair
2) Synthesis of proteins from amino acids
3) Active transport of food substances in the small intestine
4) Muscular contraction
5) Transmission of nerve impulses
6) Cell division
Extra: In animals some energy is released as heat to maintain body temperature

Question 11

What is anaerobic respiration?

Answer 11

The release of energy by the breakdown of glucose in the absence of oxygen

Question 12

What is released from anaerobic respiration?

Answer 12

A small amount of energy

Question 13

How is lactic acid formed?

Answer 13

1) During vigorous muscular contractions, muscles will respire aerobically at a high rate
2) Panting occurs to remove carbon dioxide and take in oxygen faster
3) Heart beats faster, oxygen transported to muscles faster, however there is a limit to the breathing rate
4) Muscular contraction are so vigorous that max aerobic respiration is not enough to meet the demand
5) Muscles then carry out anaerobic respiration and lactic acid is formed

Question 14

What causes the fatigue in muscles and aching pain?

Answer 14

The build up of lactic acid

Question 15

What happens to the lactic acid in the liver?

Answer 15

It will be oxidised to carbon dioxide and water in the liver, using up oxygen in the process and producing energy at the same time

Question 16

What does the accumulation of lactic acid create?

Answer 16

An oxygen debt

Question 17

What are the 2 ways to remove lactic acid?

Answer 17

1) Continuation of fast heart rate resulting
- fast transport of lactic acid from the muscles to the liver
- fast transport of O2 from lungs to liver
2) Continuation of deeper/faster breathing resulting in fast intake of O2 by lungs

Question 18

What is gas exchange?

Answer 18

Gas exchange is the exchange of gases between organism and an environment

Question 19

Which gases exchange take place simultaneously and why?

Answer 19

Oxygen and carbon dioxide. Humans require a constant supply of oxygen for tissue respiration. At the same time, they must remove excess carbon dioxide takes places continously between the human body and atmosphere

Question 20

Describe the structures from the nose to the trachea

Answer 20

1) Air enters our body through the external nostrils mainly
2) Advantages of breathing through the nose
- Hairs on the wall of the nostrils and the mucus on the mucous membrane of the nasal passages trap dust and foreign particles
- Air is warmed and moistened
- Small, sensory cells in the mucous membrane detect harmful chemicals
3) From the nose, air flows through the nasal passage, passing through the pharynx, larynx, trachea

Question 21

Describe the structures in the trachea

Answer 21

1) It is the passage from the back of the mouth to the lungs
2) The presence of incomplete C-rings of cartilage prevents the trachea and bronchi from collapsing when we breathe in
3) Epithelium that lines the inside of the trachea, bronchi and bronchioles consist of gland cells and ciliated cells
- Gland cells secrete mucus to trap dust particles and bacteria
- Ciliated cells hair-like structures called cilia the surface to sweep the dust-trapped mucus up the trachea

Question 22

Describe the structures from the bronchi to bronchioles

Answer 22

Bronchi are 2 small tubes that branch out from the trachea and enter the lungs. They further divide into even smaller branches called bronchioles

Question 23

Describe the structure of alveoli

Answer 23

1) Each bronchioles ends in a cluster of air sacs called alveoli
2) Alveoli have characteristics to facilitate gas exchange more efficiently
- One cell thick epithelium for faster diffusion of gases
- Dense blood capillary network that can quickly bring oxygen away to the cells and maintains the diffusion gradient
- Thin layer of moisture on the surface that allows gases to dissolve into the lining of the alveoli
- Large number of alveoli that provides a large surface exchange of gases

Question 24

What gas exchange takes place in the lungs?

Answer 24

Gas exchange is the exchange of oxygen and carbon dioxide between air and the lungs. This exchange takes place across the surface of the alveoli and blood capillaries in the lungs

Question 25

How is gas exchange rake place in the lungs?

Answer 25

There is a concentration gradient for each gas between the spaces in the alveoli and blood, so gas exchange is carried out by diffusion
- Oxygen diffuses from alveolar air into the blood
- Carbon dioxide diffuses form the blood into the alveolar air

Question 26

How are concentration gradients of oxygen and carbon dioxide between the alveolar air and blood is maintained?

Answer 26

1) Continuous flow of blood through the blood capillaries
2) Continuous breathing, which refresh the air in the lungs constantly

Question 27

Describe the process of oxygen diffusing from the alveolar air to the blood

Answer 27

1) Inhaled air in the alveolus contains higher concentration of oxygen than in the blood capillaries surrounding the alveolus
2) This causes the oxygen to dissolve in the layer of moisture on the surface of the alveolus
3) It then diffuses through the wall of alveolus and the wall of the blood capillary into the red blood cells
4) Oxygen combines with haemoglobin in the red blood cells to form oxyhaemoglobin
5) The blood capillaries that carry oxygenated blood from the alveoli join to form pulmonary vein, which returns blood to the left atrium of the heart

Question 28

Describe the process of blood transported from the blood capillaries to the heart

Answer 28

6) Blood enters the left ventricle and is pumped all around the body, supplying the tissues which have lower concentration of oxygen
7) Oxyhaemoglobin is not stable. It dissociates easily to release oxygen in the surroundings that are low in oxygen concentration

Question 29

What is the thoraic cavity?

Answer 29

The hollow space inside the human body (aka chest cavity), protected by the chest wall

Question 30

What supports the chest wall?

Answer 30

The ribs

Question 31

What are between the ribs?

Answer 31

There are two sets of antagonistic muscles, the external and internal intercostal muscles

Question 32

What are antagonistic muscles?

Answer 32

When one relaxes, the other contracts

Question 33

What for the ribs form with the sternum?

Answer 33

The ribs form the rib cage with the sternum at the front

Question 34

What is the dome-shaped sheet called that separates the thoracic cavity from the abdomen?

Answer 34

Diaphragm, made up of muscle and elastic tissue.
- When the diaphragm muscles contract, the diaphragm flattens downwards
- When the diaphragm muscles relax, the diaphragm arches upwards

Question 35

How is the breathing mechanism in humans brought about?

Answer 35

By the collective actions of intercostal muscles and diaphragm muscles

Question 36

What are the 2 phases in the breathing movement?

Answer 36

1) Inspiration: Taking in of air
2) Expiration: Giving out of air

Question 37

Describe inhalation

Answer 37

1) Diaphragm muscles contract, the diaphragm flattens downwards
2) External intercostal muscles contract
3) Internal intercostal muscles relax
4) Ribs and sternum move up and forward
5) Lungs expand, volume of thoracic cavity increases, causing air pressure in the lungs to decrease
6) Atmospheric pressure is higher than the pressure within the lungs, forcing the atmospheric air into the lungs

Question 38

Describe exhalation

Answer 38

1) Diaphragm muscles relax, the diaphragm arches upward
2) External intercostal muscles relax
3) Internal intercostal muscles contract
4) Ribs and sternum move down to its original position
5) And the lungs are compressed, volume of thoracic cavity decreases, causing air pressure in the lungs to increase
6) Pressure in lungs is higher than atmospheric pressure, forcing alveolar air out of lungs