Anatomy of breathing Flashcards
What is the location of the lungs?
- located in the thorax
- separated by mediastinum and heart
- extend from neck to diaphragm
What are features of the lungs and where do the different surfaces lie?
- Conical shaped with a soft, spongy texture
- There are black speckles of carbon on the lungs
- The apex of the lung lies above the clavicle (in the neck)
- Diaphragmatic surface (base) sits on the diaphragm
- Costal surface – lies adjacent to the ribs (basically the entire middle section except the mediastinal surface)
- Mediastinal surface – faces the mediastinum
Describe the structure of the right lung
- Shorter and wider than the left lung (liver impedes up into it)
- Three lobes:
Superior (upper)
Middle
Inferior (lower) - Two fissures (separate lobes):
Oblique: separates middle and superior lobes from inferior lobe
Horizontal fissure: separates superior and middle lobes
Describe the structure of the left lung
- Narrower and longer than the right lung (heart projects to the left taking up some of the place in the thorax)
- Two lobes:
Superior
Inferior - One fissure:
Oblique
Where is the Hilum of the lung located and what is it?
- Located on the mediastinal surface
- Area where the pulmonary vessels, bronchi, bronchial vessels, lymphatics and nerves enter/ leave the lung (parasympathetic and sympathetic that go to the vessels to cause constriction and dilation)
- Usually lots of lymph nodes around the entrance to the lung
What are the two physical properties of the lungs?
- Compliance (distensibility)
- Elasticity
what is compliance and what is it affected by?
Th- e ability of the lungs to expand
Affected by:
- Connective tissue structure of the lungs
- Level of surfactant
- Mobility of the thoracic cage (if it can’t expand then the lungs can’t expand)
What is elasticity in the lungs
The fact that elastic tissue allows lung expansion during inspiration and recoil during expiration
Give features of the Pleura
- Double layered serous membrane
- Visceral pleura adheres to the lung
- Parietal pleura attaches to the thoracic wall and diaphragm
- The pleural cavity is a potential space between the parietal and visceral layers that contain a thin layer of serous fluid
- When lungs expand and visceral and parietal pleura don’t go with it, it creates a big pleural cavity which leads to a collapsed lung
What are the functions of the pleura?
- Reduces friction during breathing
- Creates a pressure gradient which assists in ventilation
- Compartmentalises each lung therefore reduces spread of infection
What is the Thoracic wall and what is it made up of?
The chest wall Made up of: - Bony thorax - sternum - Ribs - Thoracic vertebrae - intercostal muscles - intercostal nerves and vessels?
What does the bony thorax do and what does it consist of?
- Forms a skeleton of the chest wall
- Consists of
Sternum
Ribs (12 pair)
Thoracic vertebrae (12)
What is another name for the sternum and what does it consist of?
- Also called Breast bone
- Consists of
Manubrium – superior portion of sternum
Body
Xiphisternum (xiphoid process) – inferior portion of breast bone
Give features of the ribs
- Attached by the head and tubercule to the thoracic vertebrae
- Slope downwards and forwards
- Ribs 1-10 attached by costal cartilage to the sternum:
7 p airs true (costal cartilage directly attached to sternum)
3 pairs false (Cartilage attached to the cartilage above)
2 floating (Cartilage doesn’t attach at all at the front – just goes into the abdominal wall)
Give features of the thoracic vertebrae
- Part of the vertebrae column
- Have the ribs attach into them
- Have a body, transverse process and spinal process behind
- Head of rib articulates (attaches) to the body of the thoracic vertebrae
- Tubercule of rib articulates (attaches) with the transverse process of the thoracic vertebrae
- These attachments form small synovial joints allowing the movement of the ribs
What do the intercostal muscles do and what are the different types?
- Span the spaces between the ribs (intercostal spaces)
- External intercostal muscles – superficial layer
- Internal intercostal muscles – middle layer
- Innermost intercostal muscles – deep layer
- External intercostals: fibres run downwards and forwards
- Internal intercostals: fibres run downwards and backwards (start right from edge of sternum)
- Intercostal muscles running in different directions give strength
Where do the intercostal vessels and nerves run and what do they do?
- Run in intercostal spaces and are protected by the ribs
- Run in the intercostal spaces between the internal intercostal and innermost intercostal muscles
- Supply the muscles, adjacent skin and pleura
What does the diaphragm separate?
The thorax from the abdomen
What is the structure of the diaphragm, how is it placed, what does it do and what is it innervated by??
- Dome-shaped skeletal muscle with a central tendon
- Attached to the xiphisternum, costal margin, 11th and 12th ribs and the lumbar vertebrae (at the back)
- Domes upwards and forms a central tendon in the middle
- Openings for the inferior vena cava, oesophagus and aorta – in the central tendon in the middle
- Bottom of fibrous pericardium fused to central tendon (heart sits on top)
- When diaphragm contracts and moves downwards brings the heart with it
- Innervated by the phrenic nerve (somatic nervous system – it is skeletal)
What is breathing also called?
Pulmonary ventilation
What is inspiration/ inhalation?
Movement of air into the lungs
Occurs when intrapulmonary pressure is lower than atmospheric pressure
What is expiration/ exhalation?
Movement of air out of the lungs
Occurs when intrapulmonary pressure is greater than atmospheric pressure
What is interpulmonary pressure altered by and how does this work?
- interpulmonary pressure is altered by changes in thoracic volume
Decreased thoracic volume intrapulmonary pressure increases and air moves out of the lungs
Increase thoracic volume then intrapulmonary pressure decreases and air moves into the lungs
What can you change to alter the thoracic volume?
Vertical diameter (top of thorax down to diaphragm)
Anterior posterior (AP) diameter (distance between sternum at front and vertebrae column at back)
Transverse diameter (between right and left side of ribcage)
How is the vertical diameter altered?
- Contraction of diaphragm increases vertical diameter
- Relaxation of the diaphragm decreases vertical diameter
- Contraction responsible for 75% increase in thoracic capacity during inspiration
How do you increase AP and transverse diameters?
- Elevation of the ribs increases the AP and transverse diameters
- Responsible for 25% increase in thoracic diameter
How do you increase AP diameter?
Elevation of ribs at the sternal end makes them more horizontal and pushes sternum forward (pump handle movement)
How do you increase transverse diameter?
- Many of the ribs are lowest near their middle and rise at each end
- Like the handle of a bucket
- If the middle of the rib rises, it moves away from the midline of the body
- Makes the chest wider from left to right
What are the two different types of muscles of breathing?
- muscles of quiet breathing
- muscles of forced breathing
When does quiet inspiration and expiration take place?
Occurs at rest
What happens during quiet expiration?
- passive process
- the diaphragm and intercostal muscles relax
What are the muscles of quiet inspiration?
- The contracted diaphragm flattens to increase the vertical diameter of the thorax
- The external intercostals elevate the ribs and increase AP and transverse diameters
When does forced inspiration and expiration occur?
Occurs during exercise or respiratory illness
What do the extra muscles of forces inspiration (accessory muscles of inspiration) do?
In addition to diaphragm and external intercostals these muscles are recruited to assist in rib elevation, increase the speed and amount of movement
What are the muscles of forces inspiration?
Pectoralis minor (sit across chest)
Pectoralis major (sit across chest) - normally works to move the arm. However if the humours (arm muscle) is fixed so it can’t move it will move the ribs outwards
Scalenes
Serratus anterior
Sternocleidomastoid
(check notes for details about what they do)
What are the muscles of forced expiration?
- Internal and innermost
intercostals depress the ribs and reduce the size of the thoracic cavity
-Abdominal muscles compress the abdomen and force the diaphragm upwards (often located below abdomen):
Rectus abdominis (give six pack)
External oblique
Transverse abdominis
Internal oblique
What does the root of the lung have?
a meshwork of dense connective tissue – the entire array is anchored in it. It attached to the mediastinum and fixes the positions of the major nerves, blood vessels and lymphatic vessels
Where do the connective tissues of each lung extend into?
the lung’s parenchyma or functional cells
What do the interlobular septa divide the lung into?
pulmonary lobules
What supplies each lobule?
Branches of the pulmonary arteries, pulmonary veins and respiratory passageways
What are the connective tissues of the interlobular septa continuous with?
those of the visceral pleura of the serous membrane
What are the endothelial cells of the alveolar capillaries the primary source of which helps regulate blood volume and blood pressure?
the primary source of angiotensin-converting enzyme (ACE) which converts angiotensin I to angiotensin II
What happens to the venous blood in the lungs?
About 1/8 of the venous blood drains into bronchial veins, passes through the azygos, hemi-azygos or highest intercostal vein and enters the superior vena cava. The larger fraction of the venous blood enters anastomoses and drains into the pulmonary veins
Why can pulmonary blood vessels become easily blocked?
because of the low blood pressure in the pulmonary circuit
What do both the visceral and parietal pleura secrete?
secrete a small amount of pleural fluid: a moist, slippery coating that lubricates and reduces friction between the parietal and visceral surfaces as you breathe
What is pleurisy?
when the coating of pleural fluid does not prevent friction between the pleural surfaces. It causes pain and pleural inflammation. When pleurisy develops pleural fluid secretion may be excessive or the inflamed pleurae may adhere to one another, limiting movement. Breathing become difficult
