Lecture 16: Anatomy of the Thorax and Breathing

Question 1

What lines our body’s cavities?

Answer 1

serous membranes

Question 2

What are serous membranes?

Answer 2

double layer of secretory tissue with fluid between the layers

Question 3

What are the two layers of serous membranes and where are they?

Answer 3

• visceral layer on the organ

- parietal layer on the body wall

Question 4

What are the two serous membranes in the thoracic cavity?

Answer 4

pericardium

pleura

Question 5

What is the mediastinum?

Answer 5

where the heart, pericardium and major vessels are found

Question 6

Inside the pleural cavities there are the

Answer 6

lungs

Question 7

What bones indicate the boundaries of the thoracic cavity?

• anterior
• posterior
• inferior
• superior
• lateral

Answer 7

• anterior: sternum
• posterior: 12 thoracic vertebrae
• lateral: ribs
• superior: base of neck
• inferior: diaphragm

Question 8

What is inside the thoracic cavity?

Answer 8

the left and right pleural cavity

Question 9

What is inside the pleura?

Answer 9

pleural fluid

Question 10

Where does the visceral pleura sit?

Answer 10

On the lung itself

Question 11

Where does the parietal pleura sit?

Answer 11

against the ribs

Question 12

What is the purpose of the pleural fluid?

Answer 12

to create frictionless movement so the lungs don’t get damaged when they expand and rub against the ribs

Question 13

Breathing is driven by

Answer 13

pressure changes within the thoracic cavity

Question 14

Inspiration causes the volume to _____ and the pressure to ________

Answer 14

increase

decrease

Question 15

Expiration causes the volume to _____ and the pressure to ________

Answer 15

decrease

increase

Question 16

What is Boyle’s Law

Answer 16

P = 1/V

Question 17

Pressure is measured by

Answer 17

the number of collisions

Question 18

How does the number of collisions affect the pressure?

Answer 18

the increased number of collisions, the higher the pressure

Question 19

Air moves to the ____ pressure space

Answer 19

lower

Question 20

By changing the volume fo the thorax, we can change the

Answer 20

pressure

Question 21

In between breathing, there is no

Answer 21

pressure gradient

Question 22

Describe the flow of air when breathing in and why

Answer 22

When breathing in, the volume of the thoracic cavity increases so pressure decreases so air flows in

Question 23

Describe the flow of air when breathing out and why

Answer 23

When breathing out, the volume of the thoracic cavity decreases so pressure increases so air flows out

Question 24

How do the ribs attach to the costocartilage?

Answer 24

Via costochondral joints

Question 25

What type of joint are costochondral joints?

Answer 25

Cartilaginous joints

Question 26

What is the name of the joints attaching the sternum to the ribs?

Answer 26

sternocostal joints

Question 27

Are sternocostal joints cartilaginous or synovial?

Answer 27

The first one is cartilginous and the others are synovial

Question 28

What is the name of the joints that attach the cartilages of neighbouring ribs?

Answer 28

interchondral joints

Question 29

What type of joint are interchondral joints?

Answer 29

synovial

Question 30

How do the ribs articulate with the vertebrae?

Answer 30

through costotransverse and costovertebral joints

Question 31

Where are the costotransverse joints?

Answer 31

between the rib and the transverse process of vertebrae

Question 32

Where are the costovertebral joints?

Answer 32

between the ribs and the body of the vertebrae

Question 33

What sort of joints are costotransverse and costovertebral joints?

Answer 33

synovial joints

Question 34

What is used to change the volume of the ribcage?

Answer 34

respiratory muscles

Question 35

What are the primary inspiratory muscles?

Answer 35

disphragm | intercostals

Question 36

When are the accessory structures active?

Answer 36

Only when they are needed

Question 37

Where are the intercostal muscles?

Answer 37

In between the ribs

Question 38

What sort of muscle is the diagragm?

Answer 38

skeletal muscle

Question 39

What shape is the diaphragm when it is relaxed?

Answer 39

dome shaped

Question 40

What shape is the diaphragm when it is contracted?

Answer 40

it is flat

Question 41

How does the diaphragm affect the inflow of air?

Answer 41

Contraction of the diaphragm flattens it and expands the thoracic cavity. This means the pressure decreases so air flows in

Question 42

Where do the intercostal muscles attach?

Answer 42

diagonally between neighbouring ribs

Question 43

What are the two layers of the intercostal muscles?

Answer 43

1. external intercostals | 2. internal intercostals

Question 44

What happens when external intercostal muscles contract?

Answer 44

It pulls the ribcage upwards to increase the depth of the cavity

Question 45

External and internal intercostal muscles run in

Answer 45

opposite directions

Question 46

What happens when internal intercostal muscles contract?

Answer 46

it pulls the ribcage down and inwards

Question 47

Which intercostal muscles are used for inspiration?

Answer 47

external

Question 48

Which intercostal muscles are used for expiration?

Answer 48

internal

Question 49

What is quiet breathing?

Answer 49

everyday breathing without thinking about it

Question 50

What is forced breathing?

Answer 50

Doing exercise, needing more air in and out

Question 51

Which intercostals are only involved in forced expiration?

Answer 51

internal intercostals

Question 52

What are the functions of the accessory muscles?

Answer 52

- increase cavity volume for forced inspiration | - decrease cavity volume for forced expiration

Question 53

What happens during quiet inspiration with regards to the diaphragm and the intercostal ribs?

Answer 53

the diaphragm contracts and it flattens which enables air to enter the external intercostal ribs lift the ribs upwards

Question 54

What happens during forced inspiration with regards to the diaphragm and the intercostal ribs? Is there anything else that is used?

Answer 54

- the diaphragm contracts and it flattens which enables air to enter - the external intercostal ribs lift the ribs upwards - the accessory muscles contract to further expand the thoracic cavity

Question 55

What happens during quiet expiration with regards to the diaphragm and the intercostal ribs?

Answer 55

- it is a passive process - the diaphragm relaxes and becomes dome shaped - the external intercostals relax so the ribs are no longer raised

Question 56

What happens during forced expiration with regards to the diaphragm and the intercostal ribs? Is there anything else that is used?

Answer 56

- the diaphragm relaxes and becomes dome shaped - the external intercostals relax so the ribs are no longer raised - the internal intercostals contract to depress ribs - accessory structures contract to further decrease the cavity volume

Question 57

Lung tissue is very ______ and is always trying to _____

Answer 57

elastic | recoil to a smaller shape

Question 58

Why do we need the lungs to expand?

Answer 58

Because otherwise we would not get the pressure difference

Question 59

What is the role of the pleura with regards to expanding the lungs?

Answer 59

It makes the lungs stick to the thoracic wall so when walls do, the lungs do to

Question 60

Lungs expand during

Answer 60

inspiration

Question 61

Lungs decrease during

Answer 61

expiration

Question 62

The pleural fluid forms a

Answer 62

fluid bond with the lungs

Question 63

What is the significance of the fluid bond?

Answer 63

When the thoracic wall expands, the lungs is pulled with it

Question 64

How does airflow relate to the lungs?

Answer 64

When the ribcage expands, the lungs go with it which increases the volume which decreases the pressure and means that air flows in

Question 65

What are the anatomical features of the thoracic cavity?

Answer 65

Bones, joints and muscles form the thoracic wall | Inside the cavity there is the mediastinum, plus the lungs within a double layer of pleura

Question 66

How does the anatomical features change the thoracic volume?

Answer 66

Inspiration: diaphragm and external intercostals contract. Accessory muscles contract for forced breathing Expiration: diaphragm relaxes. Internal intercostals and accessory muscles contract for forced breathing

Question 67

How does our anatomy facilitate breathing?

Answer 67

Muscles move bones at joints to increase and decrease pressure for inspiration and to decrease volume and increase pressure for expiration. Pleural fluid adheres lungs to thoracic wall to ensure lungs expand and recoil as the cavity volume changes.