Respiratory system

Question 1

What is partial pressure

Answer 1

The pressure exerted by an individual gas in a mixture is known as its partial pressure.

Question 2

Why is knowing partial pressures important

Answer 2

Because gases always diffuse from high partial pressure to low partial pressure

Question 3

What is gas exchange

Answer 3

It is also known as respiration, and involves the actions of taking O2 from the atmosphere and discharge of CO2 back into the environment from the body

Question 4

What is the atmospheric pressure

Answer 4

It is 760 mmHg

Question 5

How do you calculate specific pressures of gases given a certain pressure

Answer 5

Once we know the % composition of that gas in a certain environment, we can multiply that with the pressure known.

For example, O2 makes up 21% of the atmosphere. Thus the partial pressure of O2 (PO2) = 760 x 0.21 = 160 mmHg

Question 6

What is the nature of gas flow

Answer 6

Gas flows from higher pressure into lower pressure

Question 7

How does Oxygen come into the lungs

Answer 7

When we inhale, the diaphragm contracts and pulls downward, making our ribcages expand, thus allowing the lungs to expand. This creates a lower pressure in the lungs than outside. As a result from gas flow, the gas flows from high to low pressure thus bringing in the oxygen

Question 8

Explain the mechanisms of breathing out

Answer 8

When we breath out, our diaphragm relaxes, thus allowing ribcages to relax and shrink, allowing lungs to get smaller. This creates a higher pressure in the lungs than outside. This thus allows the gases from the lungs to flow out into the atmosphere

Question 9

Why do our lungs expand when our chest contracts

Answer 9

A double membrane surrounds the lungs. One side adheres to the outside of the lung, and the other to the wall of the thoracic cavity.

This membrane is filled with fluid that creates surface tension —> easily stuck together (physically) but not easily pulled apart

Question 10

Does expiration require contraction of muscles

Answer 10

No its a passive process. The relxation of diaphragm and rib cage reduces volume of thoracic cavity (relaxation involves diaphragm moving up), driving air out of lungs

Question 11

WHat is the minimal lung volume (residual volume)

Answer 11

Residual volume (RV) is the volume of air remaining in the lungs after maximum forceful expiration

Normal values are around 1000-1200 mL

Question 12

Why is minimal lung volume important

Answer 12

Because we need to ensure there is enough air for continual exchange of gases in the alveoli

Question 13

What is the total lung capacity

Answer 13

The maximum amount of air the body can have at max inhalation. Typically around 5700mL

Question 14

What is the normal volume of lungs at the end of normal inspiration

Answer 14

2700mL

Question 15

What is the normal volume of lungs at the end of normal expiration

Answer 15

2200mL

Question 16

What is the tidal volume

Answer 16

Difference between end expiratory and end inspiratory volume. It is around 500mL

Question 17

What is the function of alveoli

Answer 17

We have millions of them, and they allow O2 to rapidly diffuse across membrane into surrounding capillaries for dispersal around the body.

It also allows for CO2 to transfer back into the lungs

The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out. Oxygen breathed in from the air passes through the alveoli and into the blood and travels to the tissues throughout the body.

Question 18

WHat do type 2 alveolar cells do

Answer 18

Coats alveoli and stops hydrogen bonds forming in alveoli as it would cause it to collapse

Question 19

How is gas transported around the body

Answer 19

Oxygen is predominately transported around bound to haemoglobin within red blood cells (98% transported this way, 2% dissolved in plasma)

CO2 transported by 3 mechanisms:

7% dissolved in plasma
Remaining 93% within red blood cells, but via two separate mechanisms (23% bound to haemoglobin, 70% converted to bicarbonate)

Question 20

How many O2 molecules can a haemoglobin molecule carry

Answer 20

It can carry 4 molecules each

Question 21

What is the normal saturation of haemoglobin

Answer 21

Normally 98% saturated

Question 22

What happens if diffusion of gases between alveoli and blood is impaired

Answer 22

Hypoxia (typically goes with hypercapnia (too much co2))

Question 23

What are two general categories of dysfunction in the lungs

Answer 23

Obstructive lung disease
Restrictive lung disease

Question 24

WHat is the difference between obstructive and restrictive lung disease

Answer 24

Obstructive lung diseases include conditions that make it hard to exhale all the air in the lungs. People with restrictive lung disease have difficulty fully expanding their lungs with air.

Question 25

What are some more conditions which could affect respiratory function

Answer 25

Diseases affecting diffusion of O2 and CO2 across pulmonary membranes

Reduced ventilation due to mechanical failure

Failure of adequate pulmonary blood flow

Ventilation/perfusion abnormalities involving a poor matching of air and blood so that efficient gas exchange doesnt occur

Question 26

What are some involuntary responses

Answer 26

Sneezing
Coughing
Hiccups

Question 27

Why does sneezing occur

Answer 27

Receptors in nose sends signal to brain to close off mouth

Forces air out of lungs through nose to expel irritants

Question 28

Why does coughing occur

Answer 28

Receptors in respiratory tract send signal to brain to close off glottis and vocal cords

Builds pressure in lungs where it is then forced out when muscles contract

Question 29

Why do hiccups occur

Answer 29

Trigger leads to involuntary contraction of the diaphragm

This closes off vocal cord briefly causing air to bounce off them, creating the hic sound

Question 30

Describe flow of air into the body beginning at the nose and ending at the alveoli

Answer 30

Air enters the body through the mouth or nose and quickly moves to the pharynx, or throat. From there, it passes through the larynx, or voice box, and enters the trachea.

The trachea is a strong tube that contains rings of cartilage that prevent it from collapsing.

Within the lungs, the trachea branches into a left and right bronchus. These further divide into smaller and smaller branches called bronchioles.

The smallest bronchioles end in tiny air sacs. These are called alveoli. They inflate when a person inhales and deflate when a person exhales.

These alveoli then transfers gases to nearby capillaries

Question 31

How many lobes are there of the lung on the right and left side? WHy the difference?

Answer 31

Right side = 3 (superior, middle and inferior lobe)

Left side = 2 (superior, inferior lobe)

This is because left is missing the middle lobe, because of the cardiac notch that it has (allows for space for heart)