Respiratory system

Question 1

Respiratory system

Answer 1

The respiratory system takes up oxygen from the air we breathe and expels the unwanted carbon dioxide. The main organ of the respiratory system is the lungs. Other respiratory organs include the nose, the trachea and the breathing muscles (the diaphragm and the intercostal muscles).

Question 2

Nose

Answer 2

Air enters the body through the mouth and nose. The lining of the nose and nasal cavity is lined by mucous membranes. As the air passes over the membranes, it is warmed and humidified. There are also hairs and mucus lining the nose. These trap debris, preventing it from reaching the lungs.

Question 3

Pharynx

Answer 3

region from the nasal cavity to the top of the trachea and oesophagus. Air travels through it before being diverted into the trachea by the epiglottis. During inhalation the epiglottis covers the oesophagus, guiding the air into the trachea; when swallowing, the epiglottis covers the larynx, preventing food from entering it.

Question 4

Larynx

Answer 4

The larynx (voice box) is a cartilage structure joining the pharynx and trachea. The larynx contains the vocal cords, which are mucous membranes that are able to vibrate as air passes over them.

Question 5

Trachea

Answer 5

(windpipe) carries the air into and out of the lungs. It is made up of C-shaped cartilage rings that hold the structure open

The epithelial lining of the trachea produces mucus, which is able to trap dust and debris and prevent it from entering the lungs.

The cilia that also line the trachea are able to move in a wave-like motion to take the mucus and debris up to the pharynx so that it can be swallowed and digested.

Question 6

Bronchi

Answer 6

At the end of the trachea, the structure splits into two primary bronchi, one for each lung. These then split further into secondary bronchi which take the air into each lobe of the lung. The secondary bronchi continue to divide, forming tertiary bronchi. The bronchi are made up of C-shaped cartilage rings.

Question 7

Bronchioles

Answer 7

made of smooth muscle and elastin which allows the them to control the flow of air in the lungs, expanding when the body needs more oxygen. Cilia + mucus are also in bronchioles protecting lungs from contaminates.

Question 8

Lungs

Answer 8

The left lung has two lobes; the right lung has three. A membrane, called the pleura, covers the surface of the lungs (the visceral pleura) and also lines the inside of the chest (the parietal pleura). Between these two layers of membrane is a thin layer of pleural fluid.

Question 9

Alveoli

Answer 9

Inside the lungs the smallest bronchioles open into clusters of tiny air sacs called alveoli. Each alveolus is surrounded by a network of blood capillaries. This is where gases move between the blood in the capillaries and the air in the alveoli. The alveoli are the functional units of the lungs. This makes it possible for the alveoli to be the surface for gaseous exchange, allowing a net flow of oxygen to pass from the airways into the blood and carbon dioxide to pass from the blood into the airways.

Question 10

Pleura and pleura fluid

Answer 10

Pleura – covers the surface of the lungs and lines the inside of the chest.

Pleural Fluid – Thin layer of fluid between the two layers of membrane. The fluid holds the lungs against the inside of the chest wall and allows the lungs to slide along the wall when breathing.

Question 11

Mechanics of breathing

Answer 11

Breathing is the process of moving air into and out of the lungs. Also called ventilation, Air flows from places of higher pressure to places of lower pressure, Pressure in the lungs constantly varies.

Question 12

Inspiration/inhalation

Answer 12

The process of taking air into the lungs, For air to go into the lungs the pressure inside the lungs must be less than the pressure outside the body (air flows high pressure to low pressure), To decrease pressure in the lungs we need to increase the volume of the lungs (thoracic cavity needs to get larger)

Question 13

Inspiration process

Answer 13

-Diaphragm contracts and flattens
- External Intercostal muscles contract and Rib cage moves upwards + outwards.
- This increases the volume of the chest cavity.
- Pleura adheres to the internal wall of the chest cavity, lungs expand with the expanding chest cavity.
- Increased lung volume means that the air pressure is higher than the lung pressure in the lungs. (lower)
- Air flows in through the nose and trachea from high pressure outside the body to lower pressure inside the lungs until the pressure becomes equal.

Question 14

Expiration/exhalation

Answer 14

The movement of air out of the lungs, For air to go out of the lungs the pressure inside the lungs must be more than the pressure outside the body, Moves with the concentration gradient of high to low pressure.

Question 15

Expiration process

Answer 15

• Diaphragm relaxes and bulges into chest cavity (dome shape)
• External Intercostal muscles relax and Rib cage moves downwards and inwards.
• This decreases the volume of the chest cavity and lungs.
• Decreased lung volume means that the air pressure outside the body is lower than the lung pressure in the lungs. (higher)
• Air flows from high pressure inside lungs to low pressure outside the body via the trachea and nose until the pressure equals.

Question 16

Function of the lungs during gas exchange

Answer 16

Oxygen to be passed from air to the blood, Carbon dioxide to be passed from the blood to the air, Gaseous exchange takes place between the alveoli and capillaries surrounding the alveoli.

Question 17

Lungs are well suited to gas exchange due to

Answer 17

1. Large surface area of alveoli- large amount of gases exchanged in short period of time.(1/3 area of tennis court)
2. High blood supply of alveolus - so that as much blood as possible is close to the air in the alveolus, continuous flow of blood helps maintain a concn difference in O2 and CO2 in blood + alveoli.
3. Thin membrane of alveoli- small distance to move in and out of the blood
4. Membrane of alveoli covered in thin layer of moisture - lungs deep inside body to prevent membrane drying out, gases can only diffuse when dissolved in moisture.

5.Ability to change lung volume - movements of respiratory muscles can alter the amount of air flowing in and out of the lungs ensuring always difference in O2 and CO2 concentration in air and blood.

Question 18

Process of gaseous exchange

Answer 18

Blood arriving at the alveoli is higher in carbon dioxide and lower in oxygen as it has come from the body circulation and has used some oxygen and picked up carbon dioxide.

Blood leaving the alveoli is higher in oxygen and lower in carbon dioxide as it has picked up the oxygen via diffusion from the alveoli and given off carbon dioxide into the alveoli via diffusion also.

Question 19

Concentration gradient for O2 and CO2 is maintained by

Answer 19

• constant flow of blood through capillaries surrounding the alveoli.
• movement of air in and out of the alveoli as we breathe in and out.

Question 20

Asthma

Answer 20

-Difficulty in breathing due to narrowing of airways due to, smooth muscles contracting, narrowing the airway, inflammation causing lining of airways to thicken, narrowing diameter, mucus filling the airway, narrowing the tube.

-Can be an allergic response to foreign substance or non allergic response.eg. respiratory infection, cigarette smoke, allergens such as dust, mites, mold, pollens, animals, foods. Other triggers: exercise, cold weather, smoke, some medications, stress and emotions.

-During attack muscles around bronchioles go into spasm causing narrowing of air passages (as no cartilage) and difficulty in breathing.

Question 21

Emphysema

Answer 21

-Caused by long term exposure to irritating particles ie dust, smoke, high pollution.

-Particles damage alveoli, lose elasticity and replaced with fibrous tissue. Alveoli break down reducing internal surface area of lung. Because of the loss of elasticity, the lungs are always inflated and expiration is not involuntary anymore. (effort required)

-2 problems – decrease in surface area for gas exchange, can’t ventilate the lungs

-Can’t be cured, once started progression can’t be stopped.

Question 22

Lung cancer

Answer 22

• tumour of mass of cells that divides in an uncontrolled manner, due to smoking, asbestos fibres, pollution.

-Some chemical substances initiate cancerous growths; others promote growth of tumour. Tobacco smoke contains initiators and promoters.

-Most common type begins in walls of bronchi, Constant irritation of mucus membrane by inhaled particles cause ↑ mucus, Cells at base of membrane divide and accumulating mucus can’t be removed because of damaged cilia (smokers cough)

-Trapped mucus ruptures alveoli, Emphysema then developed (cancer growth may spread to other parts of body)

Question 23

Lung infections, Pneumonia

Answer 23

infection of alveoli by Pneumococcus bacteria/other bacteria, fungi, viruses or other organisms, infection and accompanying inflammation cause fluid + mucus to accumulate in alveoli, reducing the effective volume of lungs.
surface area available for gas exchange is reduced. Symptom: breathing difficulty and is spread by droplets.

Question 24

Tuberculosis

Answer 24

infection of lungs caused by bacteria (mycobacterium tuberculosis), viruses, fungi or other microorganisms. In top 3 infectious diseases of world that causes death. But, low in Aust. Spread by droplets - cough, sneeze, spit. Good hygiene reduces its spread.