Overview of the Anatomy of the Respiratory System (Part 2)

Question 1

How can we change resistance in the upper airways?

Answer 1

Contraction decreases diameter which increases resistance, relaxation increases diameter which decreases resistance.

Question 2

What type of muscle do the bronchial airways have?

Answer 2

Smooth muscle

Question 3

How does the sympathetic nervous system act on bronchial smooth muscles?

Answer 3

Beta 2 receptors (because you’ve got two lungs) causes bronchial smooth muscle relaxation, when noradrenaline or adrenaline binds to a beta 2 receptor.

Question 4

What is special about the alveoli and the cardiovascular system?

Answer 4

The alveoli (the only place in the respiratory system that can take place in gas exchange) are in contact with the only part of the cardiovascular system that can take place in gas exchange (capillaries).

Question 5

What are alveoli surrounded by?

Answer 5

They are surrounded by a dense capillary network.

Question 6

Describe gas exchange at the alveoli.

Answer 6

Deoxygenated blood from the pulmonary artery (right side of heart) enters the capillaries around the alveoli, carbon dioxide enters the alveoli, oxygen leaves the alveoli and moves into the blood vessels in the capillaries. Oxygenated blood then enters the pulmonary vein, which goes to the left side of the heart.

Question 7

Why are alveoli covered in elastic fibres?

Answer 7

They are covered in elastic fibres because they allow expansion during inspiration and the energy that is stored is released during expiration to squeeze the alveoli and get air out of the alveoli.

Question 8

Does expiration use energy?

Answer 8

No

Question 9

Does inspiration use energy?

Answer 9

Yes

Question 10

How many cells make up the bulk of the wall of the alveoli?

Answer 10

1

Question 11

What cells make up the bulk of the alveolar wall?

Answer 11

Type one cells

Question 12

Are type one cells thick or thin?

Answer 12

Thin - very thin to allow gas exchange

Question 13

What are type one cells studded with?

Answer 13

type two alveolar cells

Question 14

what is the function of type two cells?

Answer 14

They secrete a substance called surfactant and they make the work of breathing easier.

Question 15

What are capillaries never sitting next to?

Answer 15

They are never sitting next to type two cells, they are always abutted to type one cells because gas exchange takes place in type one cells.

Question 16

What do alveoli also never sit next to?

Answer 16

They never sit next to type two cells, this helps minimise the distance that gas has to travel when diffusing from the alveoli to the capillary.

Question 17

Why are there macrophages in the respiratory system?

Answer 17

It is a point where the internal environment meets the external environment, and so they are needed to help boost the immune function around the lungs.

Question 18

Where do the lungs sit?

Answer 18

In the pleural cavity - 3ml of fluid each

Question 19

What is the function of the conducting airways?

Answer 19

The walls of the upper airways are too thick to allow gases to cross and their function is purely conduction of air to and from the alveoli (the air in these airways is known as anatomical dead space because it cannot participate in gas exchange).

Question 20

What lines the respiratory tract?

Answer 20

Epithelium (psuedo-stratified, ciliated, columnar) Glands Lymph nodes Blood vessels (nutritive) Ciliated Mucous

Question 21

What is the progression from the nose to the alveoli?

Answer 21

Epithelium becomes more squamous Mucous cells lost (before cilia) Goblet cells lost before cilia, cilia are the last thing to be lost

Question 22

What cells are associated with muscus?

Answer 22

Goblet cells

Subepithelial glands