Lecture 17 - Anatomy of breathing Flashcards
What is the location of the lungs?
In the thorax, separated by the heart and mediastinum
Extend from neck to the diaphragm
What is the structure of the lungs?
Conical shaped
Soft spongy lungs
Apex = above clavicle
Diaphragmatic surface = adjacent to ribs
Costal surface = adjacent to ribs
Mediastinal surface = facing mediastinum
How is the right lung composed?
Wider and shorter
3 lobes, superior, middle, inferior
2 fissures, oblique, horizontal
How is the left lung composed?
Narrower and longer
2 lobes, superior, inferior
1 fissure, oblique
What is the hilum of the lung?
On the mediastinal surface
Is where pulmonary vessels, bronchi, bronchi vessels, lymphatics and nerves enter and leave the lung
What are some physical properties of the lungs?
Compliance
Elasticity
Why do the lungs have compliance?
Compliance is the ability to expand
Affected by:
Connective tissue structure
Level of surfactant
Mobility of thoracic cage
How do the lungs have elasticity?
They have elastic tissue
Allows for expansion during inspiration and recoil during expiration
What is the pleura?
Double layered serous membranes around the lungs
What is the visceral pleura?
Adheres directly to the lungs
What is the parietal pleura?
Layers on top of the parietal pleura
Attaches to thoracic wall and diaphragm
What is the pleural cavity?
Space between visceral pleura and parietal pleura containing a thin layer of serous fluid
What is the function of the pleura?
Reduces friction when breathing
Makes a pressure gradient to help ventilation
Compartmentalises each lung to stop infection
What is the bony thorax?
Forms skeleton around chest wall
Made up of 12 pairs of ribs, 12 thoracic vertebrae and the sternum
What is the sternum?
The breast bone, included in the bony thorax
Made up of manubrium, body and xiphisternum
What are the ribs?
Attaches by the head and tubercle to the thoracic vertebrae
Slope down and forwards
Ribs 1-10 are attached by costal cartilage to the sternum
What is the thoracic vertebrae?
A part of the rib
Head of the rib, articulates with the body of the thoracic vertebra
Tubercle of rib articulates with transverse process of thoracic vertebra
What are the intercostal muscles?
Span the spaces between the ribs
Made up of external intercostal muscles, internal, and innermost
What are the external intercostal muscles?
The superficial layer
Fibres run downwards and forwards
What are the internal intercostal muscles?
The middle layer
Fibres run downwards and backwards
What are the intercostal vessels and nerves?
They are in the spaces between the internal and innermost intercostal muscles
They supply the muscles, adjacent skin and pleura
What is the diaphragm?
Dome shaped skeletal muscle that separates the thorax from the abdomen
What is the diaphragm made up of?
Openings for inferior vena cava oesophagus and aorta
Fibrous pericardium which is fused to central tendon
Central tendon
Phrenic nerve
What occurs during inspiration?
Air goes into lungs
Happens when intrapulmonary pressure is lower than atmospheric pressure
What happens during expiration?
Air moves out of lungs
Happens when intrapulmonary pressure is higher than atmospheric pressure
How is the intrapulmonary pressure changed?
By changes in thoracic volume
What 3 things can alter the thoracic volume?
Vertical diameter
Anterior posterior diameter
Transverse diameter
How does is vertical diameter altered?
Contraction of diaphragm increases vertical diameter
Relaxation decreases vertical diameter
75% increase of thoracic capacity
How is the anterior posterior diameter changed?
Increased by the elevation of the ribs
25% of thoracic capacity
How is the transverse diameter altered?
Elevation of the ribs increases transverse diameter
25% increase in thoracic capacity
Which two types of muscles are involved in breathig?
Muscles of quiet inspiration and expiration
Muscles of forced inspiration and expiration
What is quiet inspiration and expiration?
Happens at rest, a passive process
Diaphragm relaxes and flattens, increasing vertical diameter of the thorax
External intercostals relax and elevate the ribs and increase AP and transverse diameters
What is forced inspiration and expiration?
Happens during exercise or respiratory illness
Other muscles are recruited
Internal and innermost intercostals depress ribs and decrease size of thoracic cavity
Abdominal muscles compress abdomen and force diaphragm upwards
Which other muscles are involved in forced expiration and inspiration?
Sternocleidomastoid
Pectoralis minor
Serratus anterior
Scalenes
Pectoralis major
