Lecture 14: Respiration

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Questions and Answers

What is the process of gas exchange also known as?

Oxygenation

Exhalation

Inhalation

Respiration (correct)

What determines the movement of gases?

Humidity

Temperature

Partial pressure (correct)

Atmospheric pressure

What happens to the chest when we take a deep breath?

It expands (correct)

It remains the same

It deflates

It contracts

Why do our lungs expand when our chest contracts?

Because of negative pressure breathing Signup and view all the answers

What happens to the abdomen when we take a deep breath?

It expands slightly Signup and view all the answers

What is the direction of gas diffusion?

From high to low partial pressure Signup and view all the answers

What is the function of the fluid between the double membrane surrounding the lungs?

To create surface tension, making it easy to stick but not pull apart Signup and view all the answers

What happens to the volume of the thoracic cavity during normal expiration?

It decreases Signup and view all the answers

What is the primary mechanism of oxygen transport in the blood?

Bound to haemoglobin within red blood cells Signup and view all the answers

What is the percentage of carbon dioxide transported by being dissolved in plasma?

7% Signup and view all the answers

How many molecules of oxygen can each haemoglobin molecule carry?

4 Signup and view all the answers

What is the percentage of oxygen that is transported dissolved in plasma?

2% Signup and view all the answers

What determines the blood's saturation?

The amount of oxygen bound to haemoglobin Signup and view all the answers

What is the percentage of haemoglobin saturation at normal PO2 levels?

98% Signup and view all the answers

Approximately how many breaths do humans take in their lifetime?

600 million Signup and view all the answers

If we could lay out the tiny tubes that make up our lungs, they would take up the size of:

A tennis court Signup and view all the answers

What is the main focus of the study of the mechanics of breathing and gas exchange?

Movement of oxygen from the environment into our lungs and then into the circulatory system Signup and view all the answers

What is the purpose of the respiratory membranes in the lungs?

To allow the movement of gases across the respiratory membranes Signup and view all the answers

What is unique about the experience of having lung disease?

Never having the capacity to breathe out Signup and view all the answers

What changes in our anatomy when we laugh, cry, yawn, or hiccup?

Our anatomy changes Signup and view all the answers

What happens when diffusion of gases between the alveoli and blood is impaired or oxygen transport in the blood is altered?

Hypoxia occurs, often accompanied by hypercapnia Signup and view all the answers

What is a common result of obstructive lung disease and restrictive lung disease?

Impaired gas exchange and hypoxia Signup and view all the answers

What can cause reduced ventilation in the respiratory system?

Mechanical failure Signup and view all the answers

What is the purpose of sneezing?

To expel irritants from the nose and lungs Signup and view all the answers

What happens when the receptors in the respiratory tract are stimulated?

The glottis and vocal cords close, building pressure in the lungs Signup and view all the answers

What is pneumothorax also known as?

Collapsed lung Signup and view all the answers

What causes the 'hic' sound in hiccups?

Air bouncing off the closed vocal cords Signup and view all the answers

What is a consequence of ventilation/perfusion abnormalities?

Poor matching of air and blood Signup and view all the answers

What is the role of receptors in the nose in relation to sneezing?

They detect irritants and send signals to the brain Signup and view all the answers

What is an important function of haemoglobin in the body?

A large store for O2 Signup and view all the answers

What is the purpose of the brain's response to receptor stimulation in the respiratory tract?

To remove irritants from the respiratory tract Signup and view all the answers

What is the result of the diaphragm's contraction in hiccups?

The vocal cords close, producing a 'hic' sound Signup and view all the answers

Study Notes

The Respiratory System

The human respiratory system allows us to take in oxygen and remove carbon dioxide from our bodies.
In a lifetime, we take around 600 million breaths, and if we laid out the 750 million little tubes that make up our lungs, they would cover the size of a tennis court.

Gas Exchange

Gas exchange, also known as respiration, is the uptake of oxygen from the atmosphere and the discharge of carbon dioxide back into the environment.
A particular gas within a mixture of gases exerts a pressure, known as partial pressure.
Gases always diffuse from a region of high partial pressure to a low partial pressure.

Breathing

When we take a deep breath, air rushes in through the nose or mouth, the chest expands, the abdomen expands slightly, and the shoulders may lift up.
This is due to negative pressure breathing, where the pressure must be lower in the lungs to pull air in.
The chest expands due to muscle contraction, which creates a lower pressure inside the lungs.

Lung Expansion

The lungs expand when the chest contracts due to a double membrane surrounding the lungs, which creates a surface tension that easily sticks together but doesn't easily pull apart.

Expiration

Breathing out, or expiration, is a passive process that does not require muscle contraction.
When the diaphragm and rib cage relax, the volume of the thoracic cavity reduces, driving air out of the lungs.

Lung Volumes and Capacities

We can alter the volume within our lungs.

Gas Exchange at the Alveoli

The human lungs contain millions of alveoli, creating a huge surface area for gas exchange.
Oxygen diffuses rapidly across the membrane into the surrounding capillaries for dispersal around the body.

Gas Transport in the Blood

Oxygen is predominantly transported around the body bound to haemoglobin within red blood cells (98%).
Carbon dioxide is transported by three different mechanisms: 7% dissolved in plasma, 23% bound to haemoglobin, and 70% converted to bicarbonate.

Oxygen Transport by Haemoglobin

Each haemoglobin molecule can carry four molecules of oxygen.
The blood's saturation depends on how much oxygen is bound, with 100% saturation occurring when all binding sites are occupied.

Oxyhaemoglobin Saturation Curves

At normal PO2 levels, haemoglobin is 98% saturated.
Minor changes in PO2 do not have a significant effect on the saturation.

When Things Go Wrong

Impaired diffusion of gases between the alveoli and blood or altered oxygen transport in the blood can result in hypoxia.
Two general categories of dysfunction: obstructive lung disease and restrictive lung disease.
Additional conditions affecting respiratory function include diseases affecting diffusion of oxygen and carbon dioxide, reduced ventilation, failure of adequate pulmonary blood flow, and ventilation/perfusion abnormalities.

Involuntary Responses

Sneezing: receptors in the nose send a signal to the brain to close off the mouth and force air out of the lungs through the nose to expel irritants.
Coughing: receptors in the respiratory tract send a signal to the brain to close off the glottis and vocal cords, building pressure in the lungs and forcing air out when muscles contract.
Hiccups: a trigger leads to involuntary contraction of the diaphragm, closing off vocal cords briefly, causing air to "bounce" off them, creating the "hic" sound.

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An interactive quiz exploring the basics of human respiration, covering breathing, lungs, and more. Take a breath and test your knowledge!