Respiratory System

objectives  You will find out about:  The structure and functions of the respiratory system  How we breathe  Gas exchange  The effect of exercise on breathing rate

Function of the Respiratory System Slide 13.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Passageways to the lungs purify, warm, and humidify the incoming air  To produce oxygenated blood  To remove carbon dioxide

Organs of the Respiratory system Slide 13.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Nose  Pharynx  Larynx  Trachea  Bronchi  Lungs – alveoli Figure 13.1

Slide 13.3b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 13.2 Upper Respiratory Tract

The Nasal Cavity Slide 13.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Hairs and mucous trap particles within the air to prevent it entering the lungs and causing damage or infection.  The air is warmed to within 1’C of body temperature as well as humidifying it to prevent drying and irritation.  Site of olfactory epithelium giving sense of smell.

 The throat has a dual function, one for the respiratory system and one for the digestive system.  The epiglottis separates the two systems at the top of the trachea and the oesophagus.

The Larynx Slide 13.9a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  This is made of cartilage.  Its function is to generate sound which can then be turned into speech by the mouth, tongue and oral cavity.  Vocal cords vibrate with expelled air.  The entrance is protected by the epiglottis to prevent food going down the wrong way.

Trachea  It is a tube like structure which has incomplete rings of cartilage around it to provide protection against crushing but also to allow food to pass through the oesophagus  It is approx 25mm in diameter and cm in length.  It opens out into the bronchi at the top of the lungs

Trachea (Windpipe) Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Connects larynx with bronchi  Lined with ciliated mucosa  Cilia beat continuously in the opposite direction of incoming air  They expel mucus loaded with dust and other debris away from lungs  Walls are reinforced with C-shaped hyaline cartilage

Primary Bronchi Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Formed by division of the trachea  These are large tubes that allow air into the lungs  Bronchi subdivide into smaller and smaller branches called bronchioles.  These end as tiny air sacs called alveoli.

Alveoli  Lastly, the alveoli are air filled sacs where gas exchange takes place. There are approx. 700 million in a pair of human lungs

Lungs Slide 13.12a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Occupy most of the thoracic cavity  Apex is near the clavicle (superior portion)  Base rests on the diaphragm (inferior portion)  Each lung is divided into lobes by fissures  Left lung – two lobes  Right lung – three lobes

Coverings of the Lungs Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Pleural membranes cover the lung surfaces  Pleura lines the walls of the thoracic cavity  Pleural fluid fills the area between layers of pleura to allow gliding  The thorax is an air-tight cavity

Breathing  Breathing movements draw air in and out of the lungs.  Due to pressure changes in the lungs brought about by movement of ribs and diaphragm

 The diaphragm is a sheet of skeletal muscle that encloses the bottom of the rib cage.  It is involved in the process of breathing

Inspiration Slide 13.22b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 13.7a

Inspiration Slide 13.22a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Diaphragm contracts, flattening diaphragm  external intercostal muscles contract moving ribs up and out.  Volume of thorax increases  External air is pulled into the lungs

Exhalation Slide 13.23b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 13.7b

Exhalation Slide 13.23a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Largely a passive process which depends on natural lung elasticity  Volume of thorax decreases  Pressure increases  Air moves out.

 The diaphragm relaxes and returns to it original position.  Elastic recoil of the lung and thoracic cavity tissue cause the volume to decrease, expelling air due to the pressure differential. This process is passive  If the internal intercostal and abdominal muscles are used the process becomes active and is known as forced expiration. This allows a greater volume of air to pass from the lungs.

Respiratory Capacities Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 13.9

 We can use a Spirometer to measure pulmonary ventilation  The spirometer measures the tidal volume (TV) as you breath in and out or vital capacity

Tidal volume  Normally only 0.5 litres of air move in and out with each breath.

Vital capacity  Measured using a spirometer  The maximum volume of air which can be breathed out following a forced inspiration.  Varies with age, sex and size

Residual volume  There is always some air left in the lungs following forced expiration.  This is Residual volume and is normally around 1.2 litres

 Inspiratory Reserve Volume is the volume of the lungs which the person fills when they take a deep breath.  It is normally in the region of 2.5 to 3.0 litres above the TV  Expiratory Reserve Volume is the volume exhaled by a person when they exhale as much air as possible from the lungs.  It is normally in the region of 1 litre above the TV

 As well as how much air you can get into and out of your lungs, how fast it enters and leaves is also important.  We use a Peak Flow Meter to measure the maximum rate of air flow per min  Rates will vary depending on your age, gender and height.  Maximum rates are normally around age 30 with the rate dropping gradually with age.  Males have higher rates than females

Gas Exchange  Oxygen moves by diffusion into the blood. Here it combines with Haemoglobin giving oxyhaemoglobin.  Carbon dioxide diffuses out of the blood and is breathed out,

Diffusion  Movement of atoms/molecules from an area of high concentration to one of lower concentration until they are evenly distributed.

Fick`s Law  Diffusion proportional to:  Surface area x concentration difference  diffusion distance

How are the alveoli adapted for gas exchange?

Respiratory Membrane (Air-Blood Barrier) Slide 13.18b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 13.6

The New Living Body-breathing video

Control of breathing Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Nerve centres that control rate and depth are located in the medulla of the brain  The pons (part of the brain) appears to smooth out respiratory rate  Normal breathing rate is 12–15 breaths per minute  Breathing rate and depth increases as we exercise

Factors Influencing Respiratory Rate and Depth Slide 13.39a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Chemical factors  Carbon dioxide levels  Level of carbon dioxide in the blood is the main regulatory chemical for respiration  Increased carbon dioxide increases respiration  Changes in carbon dioxide act directly on the medulla oblongata

Factors Influencing Respiratory Rate and Depth Slide 13.39b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Chemical factors (continued)  Oxygen levels  Changes in oxygen concentration in the blood are detected by chemoreceptors in the aorta and carotid artery  Information is sent to the medulla oblongata

Lung conditions  Emphysema  Bronchitis  Pneumonia  Asthma  Lung cancer

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Smokers Lung