Chapter 8 - Respiratory System

Question 1

What is the respiratory system?

Answer 1

It is the body system specialised for the intake of oxygen and the removal of carbon dioxide to keep CO2 ( cell waste) and O2 in the tissues constant.

Question 2

What is the pleura?

Answer 2

The pleura is a membrane covering the surface lungs and lines the inside of the chest.

Question 3

What is pleural fluid?

Answer 3

Between the two layers of pleura membrane is a thin layer of pleura fluid.

This fluid holds the lungs against the inside of the chest wall and allows the lungs to slide along the wall when breathing.

Question 4

What is a bronchiole?

Answer 4

Found inside the lungs, are bronchi which branch off many times and eventually end in fine tubes called Bronchioles.

• a very small air tube in the lungs with walls of smooth muscle.

Question 5

What is the alveoli?

Answer 5

Making up most of the lungs are the smallest branches of bronchioles which open into clusters of tiny air sacs called alveoli.

They occur in clusters and have very thin walls that are well supplied with blood capillaries for the exchange or O2 and CO2.The alveoli are the exchange surface for respiratory gases.

Alveoli are tiny air sacs in the lungs; also the milk secreting part of the mammary gland. Sing. Alveolus.

Question 6

What is the nasal cavity?

Answer 6

The nasal cavity contains projections that increase the internal surface area.

It filters, warms and moistens air before it enters the lungs.

It contains smell receptors

Acts as a resonating chamber for speech sounds.

Hairs and mucus trap dust.

Question 7

What is the pharynx?

Answer 7

The pharynx is also known as the throat.

Air from the nasal cavity passes through here

Question 8

What is the epiglottis

Answer 8

The epiglottis is a flap of tissue that, during swallowing, closes off the trachea so food and liquid cannot enter the lungs.

Question 9

What is the larynx?

Answer 9

Larynx is an organ of voice.

Air passes through the larynx, going to and from the lungs.

It contains the vocal cords, which can vibrate and make sound.

Question 10

What is the trachea.

Answer 10

The trachea also known as the windpipe carries air to and from the lungs. It is lined with mucous membranes and cells with cilia.

The cilia beat to move the mucus and trapped particles upwards.

Question 11

What is the bronchi?

Answer 11

The bronchi are two primary pipes which branch off from the trachea, and each go into one lung.

They further divide and beach ti secondary and tertiary bronchi.

Question 12

What are the ribs?

Answer 12

The ribs form a framework for the chest.

Bones - protecting vital organs.

Question 13

What are intercostal muscles?

Answer 13

They are muscles between the ribs.
They move the rib cage upwards and outwards to increase the volume of the chest cavity and thus the lungs when breathing in.

Question 14

What are the lungs

Answer 14

The lungs are breathing organs occupying all the chest cavity, except the space taken up by the heart.

They are covered by pleural membrane that also lines the inside of the chest. And a pleural liquid can be found between the two layers holing the lungs against the chest and allows movement of lungs when breathing.

Question 15

What is the diaphragm?

Answer 15

The diaphragm is a muscle that separates the chest from the abdomen.

It contracts and flattens downwards, thereby increasing the volume of the chest cavity and lungs during breathing in.

Question 16

How are the lungs well suited for their gas exchange function?

Answer 16

• the small alveoli = larger surface area. The alveoli give the lungs a huge internal surface area so that large amount of gases can be exchanged in a relatively short time.
  Alveoli numbers in lungs varies form person to person but there are hundred of millions of them, TSA approx 50-80m^2 (1/3 area of a tennis court)
• blood vessels in alveolus; each alveolus is well supplied with blood vessels, so that as much blood as possible is close to the air in the alveolus. The continuous flow of blood helps to maintain a difference in concentrations of oxygen and carbon dioxide in the blood and in the air in the lungs.
• thing alveolus membrane. The membrane that forms the wall of the alveolus is very thin, so that gas molecules do not have far to travel when moving into or out of the blood. The wall has only one layer of cells and is only 1 micrometer thick.
• lung position. The lungs are positioned deep within the body to prevent excessive evaporation of the fluid that covers the respiratory surfaces. It is important that the membrane of the alveolus be covered by thin layer of the moisture because gases can diffuse into or out of the blood only when dissolved in fluid.
• changing lung volume. The lung volume can be changed by movements of the respiratory muscles, so that air is made to flow into and out of the lungs. Constant changing of the air in the alveoli helps to ensure that there is always a difference in the concentrations of oxygen and carbon dioxide in the air and in the blood.

Question 17

Define ventilation

Answer 17

For efficient exchange of gases between the blood and the air in the alveoli, the air in the lungs must continually change.

The process by which air is moved into and out of the lungs is called VENTILATION or breathing.

Question 18

Define inspiration

Answer 18

Breathing in or inhalation is the process of taking air into the lungs.

Question 19

What is the process of inspiration

Answer 19

For air to flow into lungs, the pressure of air in the lungs must be less than the atmospheric pressure outside the body.
Decreasing the pressure of air in the lungs is achieved by increasing the volume of the lungs.

To increase volume of lungs - external intercostal muscles and the diaphragm contracts.

The diaphragm becomes flatter and the rib cage moves upwards and outwards increasing volume of chest cavity.

Pleural adheres to the internal wall of chest cavity, the lungs expand with the expanding chest cavity.

Increased lung volume means that the air pressure inside of lungs is slightly lower than pressure outside.

Air flows in through nose and trachea until pressure becomes equal.

Question 20

Quiet breathing vs Loud breathing

Answer 20

Quiet breathing is a passive process.

• inspiration = the diaphragm is mainly responsible for the changes in chest volume.
• expiration = relaxation of muscles

Forced/ heavy/ loud breathing is an active process

• inspiration: the movement of rib cage become more important
• expiration : internal intercostal muscles contracts to actively lower rib cage Eg forcefully exhaling ad when blowing up a balloon.

Question 21

What is expiration?

Answer 21

Breathing out or exhalation is the process where air exists the lungs

Question 22

What are the stages of expiration?

Answer 22

The diaphragm and intercostal muscles relax making the diaphragm bulge more into the chest cavity and the rib cage moves downwards.

Reduces the volume of the chest cavity, hence lung volume decrease.
Air pressure in lungs is now far greater than pressure outside the body.

Air flows out through trachea and nose until pressure equalises.

Question 23

Explain the stages of gas exchange

Answer 23

1. Air flows into and out of the alveoli as we breathe
2. The blood in the capillaries surrounding the alveoli is brought to the lungs via the pulmonary artery. It is deoxygenated blood, with high concentration of CO2
3. The wall of alveolus is one cell thick, wall of capillaries is one cell thick, the inside of the alveolus is lined with a film of moisture. Theses characteristics make it easy for gas exchange; diffuse to and from the body
4. Carbon dioxide diffuses from higher concentration in blood to lower concentration in the air in the alveolus. The blood has low concentrations oxygen - lower than the concentration in the air in the alveolus. Oxygen therefore dissolves in the moisture on the inside of the alveolus and diffuses through the membrane, through the walls of capillaries and into the blood.
5. Oxygenated blood leaves the capillaries of the alveoli and is taken to the heart in the veins from the lungs.

Question 24

Define Concentration gradient

Answer 24

A difference in concentration of a solution, often between the inside and outside of a cell; also called diffusion gradient.

A difference in gas concentration between air in alveoli and the blood in the capillaries

Question 25

Oxygen and carbon dioxide concentrations in inspired and expired air

Answer 25

Inspired air

• Oxygen: 20.95%
• Carbon Dioxide: 0.04%

Expired air

• Oxygen: 15.80%
• Carbon dioxide: 4.30%

Question 26

What maintains the concentration gradient for oxygen and carbon dioxide?

Answer 26

• content flow of blood through the capillaries. As the blood flowing through the capillaries around each alveolus picks up oxygen and loses carbon dioxide, it is replaced by more blood pumped into the capillaries. This ‘new blood’ is low in oxygen and high in carbon dioxide, so the concentration gradient is maintained
• the movements of air into and out of the alveoli as we breathe in and out. The air that has picked up carbon dioxide from, and lost oxygen to, the blood is replaced by ‘new air’ with each breath.
  The new air is low in CO2 and high in O2

Question 27

What happens if particles enters the lungs?

Answer 27

A major complication of aspiration is harm to the lungs. When food, drink, or stomach contents make their way into your lungs, they can damage the tissues there. The damage can sometimes be severe. Aspiration also increases your risk of pneumonia - build up of fluid in the lungs.

Question 28

Why rate and depth of breathing change + heart rate increase when we exercise?

Answer 28

During exercise there is an increase in physical activity and muscle cells respire more than they do when the body is at rest. The heart rate increases during exercise. The rate and depth of breathing increases - this makes sure that more oxygen is absorbed into the blood, and more carbon dioxide is removed from it.

Question 29

how are the activities of the circulatory and respiratory systems coordinated

Answer 29

The circulatory and respiratory systems work together to circulate blood and oxygen throughout the body. Air moves in and out of the lungs through the trachea, bronchi, and bronchioles. Blood moves in and out of the lungs through the pulmonary arteries and veins that connect to the heart.

Question 30

Emphysema

Answer 30

Emphysema is a disease usually caused by long-term exposure to irritating particles in the air taken into the lungs.

People who smoke, live highly polluted cities and work with small chemical particles.

It cannot be cured, once lung damage begins, the progression of disease cannot be stoped

The irritating particles cause damage to the alveoli. They lose their elasticity, are often replaced with fibrous tissue, and may break down, reducing the internal surface area of the lung.

Because of loss of elasticity of lung tissue, the lungs are constantly inflated and breathing out no longer occurs passively but requires voluntary effort.

Sufferer has two problems ; 1. Inadequate surface area for gas exchange. 2. Difficulty in ventilating the lungs.

Question 31

Lung cancer

Answer 31

Lung cancer is the development of a tumour ( mass of cells dividing uncontrollably) links to smoking + other risk factors and chemical substances.

In order for lung cancer to occur it needs to be initiated or promoted for the growth of a tumour. Eg Tobacco = initiator

Most common form of lung cancer begins in the walls of the air passages ( usually bronchi).
The inhaled smoke particles constantly irritate the mucus membrane that lines air passages, resulting in excess mucus production.
The cells at the mucus membrane base divide more rapidly and the accumulating mucus cannot be removed. - resulting in smokers cough

Trapped mucus causes a rupture of the alveoli and emphysema develops
Ultimately cancerous growth develops in an air passage - May spread elsewhere in the body.

Question 32

Lung infections - Pneumonia

Answer 32

Pneumonia is an infection of the lungs caused by bacteria, viruses, fungi or other organisms

Inflammation resulting from infection causes secretion of fluid and mucus into alveoli thus reducing amount of air they may contain. S.A available for gas exchange is reduced, breathing difficulty is a symptom.

Question 33

Lung infections - Tuberculosis

Answer 33

TB is an infection by bacterium Mycobacterium Tuberculosis

It one of the top infectious diseases which spreads by droplets of moisture containing the bacteria.

Infected people cough, sneeze, spit droplets of moisture containing bacteria may be inhaled by other thus spreading infection.

Question 34

Asthma

Answer 34

Asthma is an allergic response to foreign substances that enter the body.

Trigger the attack - Eg anime fur, skin, feathers dust mites, pollen grains or food substances

During such an attack the muscles surrounding the bronchioles go into spasm - suddenly involuntary contraction
This causes a narrowing of air passages causing difficulty in Breathing

Usually the irrational of the membrane lining the air passages causes secretions of excessive mucus restricts movement of air.
The reduced volume of air going through in and out of lung = gas exchange is impaired and blood does not carry usually amount of O2.