✅Muscles & Mechanics Of Respiration Flashcards by Erinrose Doherty

What is the larynx associated with?

Muscles of neck and pharynx

2. Intrinsic muscles:
– Control vocal folds
– Open and close glottis

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What does the Trachealis muscle do?

Controls air going in and out

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What are the two pleural cavities separated by?

mediastinum

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What does each pleural cavity contain?

– Holds a lung
– Is lined with a serous membrane (the pleura)

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What are pleura?

Thin membranes between the lung & chest wall

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What are the inner and outer pleura called?

» Visceral pleura (inner)
» Parietal pleura (outer)

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Describe pleural space

» Contains a small amount of fluid
» Airtight, creating a negative pressure

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When does Pneumothorax occur?

Occurs when air enters the pleural space, due to spontaneous rupture or trauma

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What happens when Pneumothorax occurs?

Lung collapses while chest wall expands

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What lubricates space between two layers?

Pleural Fluid

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What does boyles law refine?

• Defines the relationship between gas pressure and volume
P = 1/V

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What happens in a contained gas?

– External pressure forces molecules closer together
– Movement of gas molecules exerts pressure on container

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What happens If you decrease the volume of the container

collisions occur more often per unit of time, increasing the pressure of the gas.

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What happens If you increase the volume?

fewer collisions occur per unit of time, because it takes longer for a gas molecule to travel from one wall to another. As a result, the gas pressure inside the container decreases.

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What happens in the body when breathing?

» Ribcage moves upward & outward during inspiration
» Ribcage moves downward & inward during expiration
» Inspiration creates a more –ve pressure in pleural space & lungs
» Air fills the lungs until the intrapulmonary gas pressure equals atmospheric

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What happens in inspiration?

Diaphragm, functioning like a piston

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What happens in expiration?

» “Elastic” recoil
» When ventilatory requirements increase (e.g. exercise), muscles of expiration are recruited.

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What direction does air flow?

from area of higher pressure to area of lower pressure

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What does A respiratory cycle consist of?

An inspiration (inhalation)
An expiration (exhalation)

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What are the components of the ventilatory pump?

chest wall, respiratory muscles, pleural space

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What is the chest wall made up of?

» Muscles of respiration (mostly intercostals)
» Bones (spine, ribs and sternum)

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What does the chest wall do?

It Enables outward expansion and inward recoil forces

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What are the respiratory muscles made up of?

» Diaphragm (major inspiratory muscle), separates the thorax from abdomen (bottom) & from the muscular chest wall (sides)
» Expiratory muscles used in “active breathing” (major: internal intercostals & abdominal muscles)

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What does pulmonary ventilation do?

Causes volume changes that create changes in pressure

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The volume of the thoracic cavity changes with expansion or contraction of....... or .......

Diaphragm | Rib cage

What does the diaphragm form?

The floor of the thoracic cavity

What is the diaphragm's shape when relaxed?

Dome shaped

What is the diaphragm made up of?

xiphoid process, internal surface of rib cage, costal cartilages of last 6 ribs and anterior surfaces of lumbar vertebra

What is inside the diaphragm?

The central tendon

What is always active?

Inhalation

What are the mechanics of breathing?

As the rib cage is elevated or the diaphragm is depressed, the volume of the thoracic cavity increases

What does Boyle's law define?

The relationship between gas pressure and volume

What does P =

1/V

What happens in a contained gas?

– External pressure forces molecules closer together – Movement of gas molecules exerts pressure on container

What are the four most common methods of reporting gas pressures?

Millimetres of mercury Torr Centimetres of water Pounds per square inch

What is the mechanics of inhalation? | P outside > P inside

Elevation of the rib cage and contraction of the diaphragm increase the size of the thoracic cavity. Pressure within the thoracic cavity decreases, and air flows into the lungs.

What is the mechanics of exhalation? P outside < P inside

When the rib cage returns to its original position and the diaphragm relaxes, the volume of the thoracic cavity decreases. Pressure increases, and air moves out of the lungs

What major factors does breathing depend on?

- the compliance of the lungs and chest wall - the resistance of the airways to the smooth flow of air

Describe wall compliance

The lung is elastic: constantly pulling inward & would collapse if not held open by the chest wall. The chest wall is also elastic, put constantly being pulled outward by muscles that are always under slight tension

Describe the airway resistance

The radius of the vessels of the airway establishes the resistance to airflow (inverse square law). Diameter of bronchi & bronchioles rarely restrict flow of air in healthy persons, but in some diseases (chronic obstructive pulmonary disease) airflow is restricted.

Compliance is an indicator of what?

Expandability

Low compliance requires what?

Greater force

High compliance requires what?

Less force

What 3 factors affect compliance?

1. Connective tissue structure of the lungs 2. Level of surfactant production 3. Mobility of the thoracic cage

Describe surfactant

• An oily secretion • Contains phospholipids and proteins • Coats alveolar surfaces and reduces surface tension

What is The intrapulmonary (also called intra-alveolar) pressure is relative to?

Atmospheric pressure

In relaxed breathing, the difference between atmospheric pressure and intrapulmonary pressure is what?

Small

Maximum intrapulmonary pressure: during maximum straining (dangerous activity) range can increase from what?

-30 mm Hg (inhalation) to +100 mm Hg (closed glottis)

What is intrapleural pressure?

The pressure in space between the parietal and visceral pleura

What does the intrapleural pressure remain below?

atmospheric pressure throughout respiratory cycle (due to relationship between lungs and body wall)

Describe 2 injuries to the chest wall

– Pneumothorax allows air into pleural cavity – Atelectasis (also called a collapsed lung) as a result of pneumothorax

What does Cyclical changes in intrapleural pressure operate?

the respiratory pump, aiding venous return to the heart

What is tidal volume (Vt)?

the amount of air moved in and out of lungs in a single respiratory cycle

What are the most important respiratory muscles? (Primary respiratory muscles)

• The diaphragm • External intercostal muscles of the ribs • Accessory respiratory muscles – activated only when respiration increases significantly

Why is the diaphragm important in inhalation?

– Contraction draws air into lungs – 75% of normal air movement

Why are External intercostal muscles important to inhalation?

– Assist inhalation – 25% of normal air movement

Why are accessory muscle important in inhalation?

Assist in elevating the ribs

What are the accessory muscles?

– Sternocleidomastoid – Serratus anterior – Pectoralis minor – Scalene muscles

When do the accessory respiratory muscles become active?

When the depth and frequency of respiration must be increased markedly

What do the Internal intercostal + transversus thoracis muscles in exhalation?

Depress the ribs

What do the abdominal muscles do in exhalation?

Compress the abdomen | Forces the diaphragm upward

What are the two modes of breathing?

Quiet | Forced

Describe quiet breathing

– Involves active inhalation and passive exhalation – Diaphragmatic breathing or deep breathing  dominated by diaphragm – Costal breathing or shallow breathing  dominated by rib cage movements

What is dyspnea?

Shortness of breath” – producing an accelerated pattern of shallow, ineffective breathing, and accompanies elevated arterial CO2 and [H+]

What is hyperventilation?

Overbreathing” so that the increase in pulmonary ventilation exceeds the oxygen needs of metabolism, it lowers the normal alveolar concentration of CO2, leading to excessive CO2 unloading