W1 The respiratory system (not including anatomy overlap)

Question 1

What temperature does the conducting zone warm air to?

Answer 1

37 degrees

Question 2

What is the main function of the nasal cavity and nose within the conducting zone?

Answer 2

Major function is to condition inspired air.
Nose will filter, trap and clear particles greater than 10 micrometers
Nasal secretions contain important immunoglobulins, inflammatory cells and interferons. Is the first line in the host innate defence

Question 3

What might an increases nasal resistance indicate?

Answer 3

Viral infections
Increases air flow - such as during exercise

Question 4

What is meant by the mucociliary escalator?

Answer 4

Cilia propels mucus up towards the trachea at a rate of 1cm per minute.

Question 5

Where might white blood cells be found in the respiratory tract?

Answer 5

Throughout the tract, leave nearby capillaries to populate the surface of the airway and the alveoli,

Question 6

Roughly how many terminal bronchioles are there in the body?

Answer 6

150,000

Question 7

What is the deal with the development of lung function?

Answer 7

Lung function generally peaks at late teens/ early twenties.
After early twenties lung function declines at about 1% a year
In smokers it declines at about 2% a year.

Question 8

Why is PO2 /PCO2 important in the respiratory system?

Answer 8

Air moves down a pressure gradient, this gradient exists throughout the respiratory system.

Question 9

What is an acinus in relation to the respiratory system?

Answer 9

A basic functional unit in the lung, site of gas exchange.
Arises from one terminal bronchiole contains many alveolar ducts and more alveolar sacs.

Question 10

What are the different cell types in the alveoli epithelium?

Answer 10

Type 1: structural cells
Type 2: Secrete surfactant

Question 11

Give an overview of type 1 structural cells found in the alveoli?

Answer 11

Is an epithelial chief structural cell of the alveoli wall.
Provides mechanical support.
Rarely divides
Is not very metabolically active.
When injured is replaced by type 2 cells.

Question 12

What are type 2 secrete surfactant cells in the alveoli?

Answer 12

Are almost goblet cells, contains lamellated bodies (secretory organelles) that contain phospholipids which form surfactant.
Give very little structural support.

Question 13

Why are premature babies often connected to an incubator?

Answer 13

Have not yet developed surfactant in the alveoli.
Incubator helps filter and warm air.
Without surfactant the alveoli will collapse inwards on themselves.

Question 14

What type of epithelium is on the alveoli?

Answer 14

Simple sqaumous.

Question 15

What immune cells are commonly found inside the alveoli?

Answer 15

The alveolar macrophage, travels around the inside alveolar wall to engulf pathogens that have reached the end of the respiratory tract.

Question 16

What is the role of surfactant in the alveoli?

Answer 16

Also called surface acting agent, when added to the liquid present in the lungs it reduces the surface tension and increases its wetting and spreading abilities.
This reduces the extent to which water molecules from opposite sides of the alveolar walls are drawn together so prevent the alveoli from collapsing inwards on itself.

Question 17

What receptors are involved in lung and respiration control?

Answer 17

Central chemoreceptors
Peripheral chemoreceptors
Lung receptors

Question 18

Give an overview of the chemical control of respiration.

Answer 18

Controlled by chemoreceptors and lung receptors
Is an example of negative feedback
The control variables are the blood gas tensions, particularly carbon dioxide
Chemoreceptors sense the values of gas tensions.

Question 19

What are chemoreceptors?

Answer 19

Specialised tissue that responds to changes in the chemical composition of blood or other fluids.

Question 20

Explain how central chemoreceptors affect the rate of ventilation.

Answer 20

Chemoreceptors are situated close to the surface of the medulla, synapse directly with respiratory centres.
Detects changes in CO2 altering the pH in the cerebal spinal fluid and adjusting ventilation rate accordingly.
The chemoreceptor is not affected by H+ or PO2.
The CSF is separate from the blood by the blood brain barrier which is relatively impermeable to H+ and HCO3- but is highly permeable to CO2.

Question 21

How do peripheral chemoreceptors help regulate ventilation in the respiratory system?

Answer 21

Peripheral receptors in the arch of the aorta and common carotids.
Respond to decreased PO2, increased H+ and increased PCO2 to increase the rate of ventilation.
Send impulses up the vagus nerve and glossopharyngeal nerve to the medulla oblongata and pons.
Leads to a number of responses to increase PO2

Question 22

What chemoreceptor used in ventilation is most sensitive to PCO2?

Answer 22

Central chemoreceptors.

Question 23

Give an overview of glomus cells in the respiratory tract?
What are the five responses that they can bring about?

Answer 23

Glomus cells are a type of peripheral chemoreceptor found in the carotid or aortic bodies.
In response to decreased PO2 or increased PCO2 they bring about many responses to increase the rate of ventilation.
Calcium channels are inactivated
Cell depolarisation
Opens voltage gated calcium channels
Exocytosis of neurotransmitter onto sensory neurons
Signals to sensory neurons to increase ventilation.

Question 24

Label the diagram of the mediastinal lung surfaces

Answer 24

Missing label is the pulmonary ligament