health science sub-topics exercise physiology 2.1.1 list the principal structures of the ventilatory...

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2.1.1 List the principal structures of the ventilatory system

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Exercise Physiology

The principle structures of the respiratory system are: Nose/Mouth Pharynx Larynx: voice box Trachea Bronchi Bronchioles Lungs Alveoli: final branching of the respiratory tree

1. Structure & function of the ventilatory system

2. Structure & function of the cardiovascular system

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http://www.umm.edu/respiratory/images/respiratory_anatomy.jpg

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Smooth muscle tissue is found on the walls of some of our internal hollow organs. It produces smooth, rhythmical actions.

We can not consciously control the action of smooth muscle. It is subsequently termed involuntary.e.g. movement of blood and air in the lungs

DET PDHPE Distance Education Programme



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The trachea is a thin walled tube about the diameter of an average garden hose. It is composed of very thin, tough connective tissue and is strengthened at intervals by incomplete rings of cartilage.

The trachea muscle runs down the posterior wall of the trachea. This is an example of smooth muscle.

Solomon & Davis



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2.1.2 Outline the functions of the conducting airways

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The nostrils are fringed with coarse hair, which strains large particles out of the airstream and may also serve to protect the nasal cavity from invasion by insects.

Thanks to the structure of the nose, air entering the trachea is virtually 100% humidified.

Solomon & Davis



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Air passes through the 3 portions (nose (nasopharynx), mouth (oropharynx), base of esophagus (laryngopharynx) of the pharynx, which provides a low resistance path for airflow, to the trachea via the larynx.

In addition to its function as the voice box, the larynx protects the trachea from invasion by foods and fluids.

The cartilaginous trachea, branches into the two main bronchi.

The lining of the tracheobronchial system is designed to protect the lungs from dehydration and invasion by foreign particles, including micro-organisms.

Solomon & Davis



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The lungs themselves develop at the end of the bronchi. They are elastic spongy organs.

Gas exchange is carried out by a complex of structures at the end of each terminal bronchioles.

They are simple thin walled structures which also have numerous thin-walled outpocketings called alveoli, which are specialized for the function of gaseous exchange.

Solomon & Davis



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2.1.3 Define the terms pulmonary ventilation, total lung capacity, vital capacity, tidal volume, expiratory reserve volume, inspiratory reserve volume, and residual volume.

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Pulmonary ventilation: aka breathing. It is the process of air flowing into the lungs during inspiration (inhalation) and out of the lungs during expiration (exhalation). Air flows because of pressure differences between the atmosphere and gases inside the lungs.




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2.1.3 Define respiratory termsTopic 2

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Air, like other gases, flows from a region with higher pressure to a region with lower pressure. Muscular breathing movements and recoil of elastic tissues create the changes in pressure that result in ventilation. Pulmonary ventilation involves three different pressures:

• Atmospheric pressure • Intraalveolar (intrapulmonary) pressure • Intrapleural pressure

Atmospheric pressure is the pressure of the air outside the body. Intraalveolar pressure is the pressure inside the alveoli of the lungs. Intrapleural pressure is the pressure within the pleural cavity. These three pressures are responsible for pulmonary ventilation.

http://training.seer.cancer.gov/module_anatomy/unit9_2_resp_vent_mechanics.html



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It is important to understand the various volumes and capacities of the lungs in order to appreciate the effects of exercise on the respiratory system.

Total lung capacity (TLC) can be calculated by adding vital capacity to residual volume of the lungs.

During normal, quiet respiration, about 500mL of air is inspired. The same amount of air moves out with expiration. This volume of air is called the tidal volume (TV).

When we forcibly take a deep breath, we can take in up to 3100mL above the tidal volume. This additional air is the inspiratory reserve volume (IRV).

Browne et. al 2001



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We can also forcibly exhale. This is termed the expiratory reserve volume (ERV).

Even after the expiratory reserve volume is expelled, some air is still trapped in the lungs because of pressure. This is called the residual volume (RV).

Browne et al 2001




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2.1.4 Explain the mechanics of ventilation in the human lungs

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Diaphragm – a large, dome-shaped sheet of striated, musculofibrous tissue• Primary ventilatory muscle• Separates the abdominal, and thoracic (chest) cavities

Intercostal muscles – muscles that run between the rib cage.



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During inspiration (inhalation) – the chest cavity increases in size because the ribs raise and the diaphragm contracts and descends, causing air to flow into the lungs.

• As lung pressure decreases, air in the lungs increases

• External intercostal muscles become active• Internal intercostal muscles relax

Why do athletes bend forward from the waist to facilitate breathing following exhausting exercise?



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During exhalation –

• Thoracic (chest) cavity volume is reduced and air rushes out• The diaphragm moves up and relaxes, and the

ribs lower, which aids in bringing air out of the lungs• As air pressure in the lungs increases, air

decreases

• See figure 12.3

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This previous description is for quiet breathing. During strenuous exercise, internal intercostal AND

abdominal muscles act powerfully on the ribs and abdominal cavity to reduce thoracic dimensions, making exhalation rapid and more extensive.

In laboured inspiration (e.g. accompanying exercise), many of the muscles of the upper trunk are also recruited. They are only indirectly attached to the ribs, and are inefficient as respiratory muscles (e.g. Pectorals, Trapezius, Rhomboids).



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http://www.lib.mcg.edu/edu/eshuphysio/program/section4/4ch1/4ch1img/page17.jpg



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2.1.5 Describe nervous and chemical control of ventilation during exercise.

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Chemical control –• Ventilation increases as a direct result

of increases in blood acidity levels (low pH) due to increased carbon dioxide content of the blood detected by the respiratory center.

• Rate and depth of ventilation increases to try to rid the body of CO2



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2.1.5 Describe nervous and chemical control of ventilation during exercise.

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Nervous control – brain and nervous system• Chemoreceptors - send sensory input to

respiratory centers in the brain• Muscle proprioreceptors - receive

messages from chemoreceptors that control the force and frequency of respiratory muscle contraction

• Lung stretch receptors – monitor the amount of stretch in the lungs; they send signals to the respiratory centers to exhale and inhibit inspiration. Prevents damage to the lungs.



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2.1.6 Outline the role of hemoglobin in oxygen transportation

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Research task: Using a study of the effects of cardiovascular training at altitude, outline the role of hemoglobin in oxygen transportation. (1 A4 page – submit via Haiku in the dropbox – due December 6th)

www.runnersworld.com/races/latest-research-training-and-racing-altitude



http://www.runnersworld.com/races/latest-research-training-and-racing-altitude

http://www.runnersworld.com/races/latest-research-training-and-racing-altitude

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http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/19510.jpg

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Hemoglobin – iron-protein molecule containing oxygen within blood cells. It transports oxygen from the lungs to the rest of the body, such as the muscles, where it releases its load of oxygen.• Increases blood’s oxygen-carrying capacity

65 times. As a result, people who are physically active, should eat iron-rich foods.

• Most (98.5%) of oxygen in the blood is transported by hemoglobin as oxyhemoglobin (oxygen binding to red blood cells.

http://en.wikipedia.org/wiki/Hemoglobin



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2.1.7 Explain the process of gaseous exchange at the alveoli

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Gas exchanges between the air in the alveoli, and the blood capillaries occur across the respiratory membrane in a process known as pulmonary diffusion. The most critical factor for gas exchange between alveoli and the blood is the pressure gradient between the gases in the two areas.

According to Dalton’s law of partial pressures, the pressure of a mixture of gases equals the sum of the individual pressures (partial pressures) of each gas in the mixture.

Browne et.al



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If we take a normal breath of air (nitrogen, oxygen and carbon dioxide), the total pressure of the air is equal to the sum of the partial pressures of the individual gases in the blood, and the alveoli create a pressure gradient, so one into the other (from high partial pressure to low partial pressure)

The partial pressure of oxygen arriving at the alveoli is high, and the partial pressure of it in the capillaries is low. Therefore oxygen diffuses from the alveoli into the blood, and carbon dioxide will diffuse from the

blood into the alveolus.



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