L15 Structure Of Respiratory System

Front 1

What is the nasal cavity?

Back 1

The nasal cavity is an irregularly shaped cavity lying between the bony plate of the floorwhich separates it from the oral cavity below and the cribriform plate which separates itfrom the cranial cavity above

Front 2

What are the features of the nasal cavity?

Back 2

The cavity is high, deep but narrow and divided into rightand left by the nasal septum. In life the anterior part of the nose is formed in cartilage.

Front 3

What does the nasal cavity communicate with posteriorly?

Back 3

the nasal part of the pharynx

Front 4

What does it communicate with anteriorly?

Back 4

theenvironment

Front 5

What does it communicate with superiorly?

Back 5

cranial cavity, the orbit and the paranasal air sinuses.

Front 6

What lines the nasal cavity?

Back 6

respiratory epithelium which is pseudostratified ciliated columnar withgoblet cells

Front 7

Why does the air in the nasal cavity swirl around?

Back 7

due to the irregular shape which causes the dust particles to be pushed to the walls

Front 8

How are the dust particles moved to the oropharynx where they are swallowed?

Back 8

they stick to the mucous on the walls andare moved by the cilia to the oropharynx

Front 9

What does the mucous membrane also do?

Back 9

The mucous moistens the air and the mucous membrane is very vascular and therefore warms the air.

Front 10

where does the air pass to after the nasal cavity?

Back 10

the pharynx, first the nasopharynx then the oropharynx.

Front 11

Why does the mouth feel very dry if you breath through it?

Back 11

It ispossible to breath through the mouth but the cleaning, moistening and warming of the airis less effective and can leave the mouth feeling very dry.

Front 12

What is the fuction of the larynx?

Back 12

The larynx acts as an air passageway linking the pharynx with the trachea. It also actsas a sphincter to prevent food from entering the trachea and is the organ of phonation.

Front 13

What does the larynx consist of?

Back 13

3 unpaired and 3 paired cartilages

Front 14

What do the intrinsic muscles of the larynx do?

Back 14

The vocal fold tension and thediameter of the glottis are adjusted by the intrinsic muscles of the larynx

Front 15

What does the pitch of sound depend on?

Back 15

The pitch of thesound depends on the length and tension of the vocal folds with increases in length andtension raising the pitch.

Front 16

What does the volume of sound depend on?

Back 16

The volume of sound depends on controlling the pressure of airpassing through the rima glottidis

Front 17

What lines the trachea?

Back 17

Respiratory epithelium lines the trachea with glands in the submucosa

Front 18

What prevents the trachea from collapse?

Back 18

‘C’ shapedcartilages which stiffen it preventing collapse and over expansion

Front 19

What makes up the posterior aspectof the trachea?

Back 19

soft tissue and contains smooth muscle

Front 20

Why may the posterior aspect be distorted?

Back 20

to allow forthe passage of food passing through the oesophagus

Front 21

How does the trachea end?

Back 21

The trachea ends by dividinginto the two principle bronchi.

Front 22

What forms the tracheal tree?

Back 22

The main bronchi and their branches

Front 23

What does each primary bronchi divide into?

Back 23

Each primary bronchidivides into secondary bronchi which enter the lobes of the lungs where further divisiontakes place finally into tertiary bronchi which supply a single segment of the lung(bronchopulmonary segment)

Front 24

What happens as the bronchi divide?

Back 24

As the bronchi divide their diameter decreases and the cartilage in their wall decreases and there is an increase in the quantity of smooth muscle. The terminal bronchi finally divide into multiple bronchioles which do not contain cartilage.

Front 25

What is the smallest and final part of the bronchial tree?

Back 25

respiratorybronchioles

Front 26

what do the respiratory bronchioles connect to?

Back 26

connect tothe alveoli where gaseousexchange takes place

Front 27

What separates the epithelium of the alveoli?

Back 27

The simple squamousepithelium of the alveoli(pneumocytes type I) areseparated by a basallamina from the simplesquamous epithelium ofthe blood vessels

Front 28

What happens at the lung alveoli?

Back 28

Site of gas exchange

Front 29

What lines the alveoli?

Back 29

lined by extremely flattened (squamous) type 1pneumocytes– about 40% of cells but cover >90% ofalveolar surface

Front 30

What secretes surfactant?

Back 30

more-rounded type 2 pneumocytes secretesurfactant

– about 60% of cells but cover <10% ofalveolar surface

– found esp. at the angles between adjacentsepta

– function as stem cells

Front 31

What are the features of the lung alveoli?

Back 31

• Contains an extensive capillaryplexus

• endothelial cells share acommon basal lamina with thetype 1 pneumocytes

– diffusion barrier is as little as0.2 m

Front 32

What are the 2 pleural cavities that surround the lungs?

Back 32

The pleuralmembranes consist of two layers; and outer one surrounding the inner aspect of thethoracic cavity, the parietal pleura and an inner one intimate with the lung tissue, thevisceral pleura.

Front 33

Why is there a small space inbetween the 2 membranes?

Back 33

There is a small space between them which contains a small amount offluid allowing the membranes to move over each other without causing friction

Front 34

What happens if air is introduced into this space?

Back 34

Airintroduced into this space causes the lung to collapse (pleurisy)

Front 35

What does the parietal pleura contain?

Back 35

The parietal pleura contains recesses into which the lungs expand during inspiration.Only in maximal inspiration are the recesses completely filled by lung tissue

Front 36

What is the main function of the lungs?

Back 36

The main function of the lungs is to oxygenate the blood by brining inspired air in closerelation to blood vessels and permitting gaseous exchange.

Front 37

What do the lungs occupy and what do healthy lungs look like?

Back 37

The lungs occupy thepleural cavity and in healthy lungs are light, soft, and spongy

Front 38

What separates the 2 lungs?

Back 38

The two lungs areseparated by the mediastinum

Front 39

How many lobes does each lung have?

Back 39

The right lung has three lobes and the left 2

Front 40

How does air flow into the lungs?

Back 40

Air flows into the lungs when the pressure inside the thoracic cavity is less than outside

Front 41

How is this lower pressure brought about?

Back 41

A decrease in pressure is caused by the movement of the thoracic cage and descent ofthe diaphragm. When the diaphragm relaxes and the cage is returns to its originalposition and air flows out.

Front 42

What encloses the lungs?

Back 42

The lungs are enclosed in a fluid filledpleural sac.

Front 43

What do cohesive forcesexerted by the fluid between thepleural membranes cause?

Back 43

Cohesive forcesexerted by the fluid between thepleural membranes cause thelung to adhere to the thoraciccage and thus when the thoraxchanges its shape the lungs movewith it.

Front 44

What happens to the elastic lungs during inspiration and expiration?

Back 44

The elastic lungs are forced tostretch during inspiration and recoilwhen the muscles relax returningthe thorax to its original volumeand expelling the air.

Front 45

How do rhythmic movements of repiration result in gaseous exchange?

Back 45

The rhythmic movements of respiration produce alterations in the capacity of the thoraciccavity resulting in the inflow and outflow of air to the lung alveoli resulting in gaseousexchange.

Front 46

In what dimensions may the thorax be expanded?

Back 46

The volume of the thorax may be increased in vertical, transverse andanteroposterior dimensions

Front 47

What do rib movements cause?

Back 47

Rib movements increase the transverse and anteroposterior dimensions of the thorax.

Front 48

What happens when the anterior ends of the ribs are elevated?

Back 48

When elevated the anterior ends of the ribs attached to the sternum are pushed forwardsand upwards increasing the anteroposterior diameter

Front 49

What happens at the same time?

Back 49

At the same time the ribs areeverted through rotation and thus increase the transverse diameter.

Front 50

What are the false ribs?

Back 50

The ‘false’ ribs i.e. those whose cartilages attached to the cartilage of the rib above andnot to the sternum, move outwards and backwards to increase the transverse diameter

Front 51

What increases the vertical dimension?

Back 51

The vertical dimension is increased by the descent of the diaphragm.

Front 52

What happens to the 500-750ml of inspired air in quiet respiration?

Back 52

In quiet respiration 500 -750ml of air is inspired one third of which fills the passagewaysof the respiratory system and is not therefore available for gaseous exchange.

Front 53

Which is the only muscle activated in quiet breathing?

Back 53

In quiet respiration the diaphragm is the only muscle activated and descends about1.5cm

Front 54

what do the scalene muscle of the neck and the upper intercostal muscle do?

Back 54

The scalene muscle of the neck contract to ‘fix’ the first rib in position and theupper intercostal muscle contracts to prevent sucking in or blowing out of the intercostalspaces

Front 55

What do the lower intercostals do?

Back 55

The lower intercostals may contract thereby increasing the transverse diameter

Front 56

What happens in expiration?

Back 56

Elastic recoil of the lungs and the relaxation of the respiratory muscles lead to expiration.

Front 57

What happens in deep inspiration?

Back 57

In deep inspiration other muscles are called into action with the intercostal musclesinvolved in the elevation of the ribs, the diaphragm descend further and accessarymuscles are activated.

Front 58

What is the structure of the diaphragm?

Back 58

The diaphragm is a musculotendinous dome-shaped structure which separatesthe thoracic and abdominal cavities. It is the chief muscle of respirationdescending during inspiration. The muscular part of the diaphragm lies at itperiphery with the fibres converging on a central ‘C’ shaped tendon whosesuperior part is fused with the pericardium of the heart.

Front 59

How are the heart vessels arranged in relation to the lungs?

Back 59

The aorta passes posterior to the diaphragm (T12). The inferior vena cavapass through the central tendon (T8). As it is attached to the margins of theopening contraction of the diaphragm widens the opening dilating the IVCfacilitating blood flow back to the heart.

Front 60

Where does the oesophagus pass through?

Back 60

The oesophagus passes through themuscular crura (T10) with the accompanying vagi.

Front 61

What happens to the diaphragm during inspiration?

Back 61

During inspiration the lowest ribs are fixed (Quadratus lumborum) and from thisposition the fibres of the diaphragm contract drawing the muscle downwardsand forwards. The abdominal wall is relaxed to allow for the descent of theviscera. The central tendon is then in contact with the viscera and can descendno further. From this point further contraction of the diaphragm elevates thelower ribs thus increasing the lateral diameter of the thorax having previouslydescended to increase the vertical diameter.