A.1.3.2 The Respiratory System

https://www.youtube.com/watch?v=9VdHhD1vcDU

Oxygen transport in the body

Step 1 - O₂ Transport

air enters the nose/mouth, and passes the pharynx and larynx, trachea carries air down the bronchi

Step 2 - O₂ Transport

bronchi is divided into bronchioles leading to clusters of alveoli

Step 3 - O₂ Transport

oxygen diffuses into bloodstream while CO₂ diffuses out into the alveoli

Step 4 - O₂ Transport

diaphragm relaxes, pushing air out of the lungs and travles backwards

Nose and nasal cavity

• entry point of air

  • filters incoming air

  • warms and humidifies air

Mouth and oral cavity

• alternate entry point for air

• speech and swallowing

Pharynx (throat)

• connects the cavities to the trachea

• epiglottis

Larynx (voice box)

• tough and flexible

• allows air to pass through it preventing food and drink blocking the airway

Trachea (windpipe)

• wide, hollow tube , C-shaped cartilage

• connects larynx to bronchi

• enable airflow to and from the lungs

Bronchi

• main airways to the lungs

• trachea branches into bronchus in each lung

• cilia

  • move mucus out of your lungs

Bronchioles

• small branching air passages in lungs

• connect larger bronchi to alveoli

Alveoli

• tiny air sacs, end of bronchioles

• cruical role of gas exchnage

How does gaseous exchange occur?

diffusion

Where do the gases move?

area of high partial pressure to area of lower partial pressure

What is partial pressure?

pressure exerted by a single gas (O₂₎ within a mixture (air, blood, tissue fluid)

What happens during inhalation?

• the volume of the thoracic cavity increases

  • so pressure decreases

• diaphragm contracts (flattens)

• external intercostal muscles contract

  • ribcage moves up and out

• air is drawn in

What happens during exhalation?

• the volume of the thoracic cavity decreases

  • so pressure increases

• diaphragm relaxes (dome-shape)

• external intercostal muscles relax

  • ribcage moves down

• air is forced out

What is Fick’s law?

describes how gases diffuse across membranes

What does it state?

rate of diffusion of a gas across a membrane depends on three main factors

What are the three factors?

1. Surface area

2. Concentration (PP) gradient

3. Thickness of the Membrane

Surface area - Ficks Law

the larger the surface area the greater the rate of diffusion

Concentration gradient (PP) - Ficks Law

the bigger the diff in concentration of the gas on either side of the membrane, the faster the diffusion

Thickness of the Membrane - Fick’s Law

thinner membrane = faster diffusion

What is minute ventilation (V_E)?

volume of air being exhaled per minute

Minute ventilation formula

What is tidal volume (V_T)?

amount of air inhaled and exhaled in a single breath during regular breathing

What is respiratory rate (B_T)?

number of breaths per minute

What is vital capacity?

maximum amount of air you can exhale after taking a deep breath

What is residual volume?

amount of air that remains in your lungs after exhaling as much as you can

What is total lung capacity?

total amount of air in your lungs can hold, sum of vital capacity and residual volume

What are the inspiratory/expiratory reserve volumes?

extra amount of air you can inhale/exhale after a normal inhalation/exhalation

How do trained and untrained individuals of the same size affect lung volumes and capacities?

Trained:

• larger capacites/volumes

• training improves respiratory muscle strength

• more efficient breathing

• larger tidal volumes

How does age affect lung volumes and capacities?

Young:

• larger capacities/volumes

• greater elasticity in lung tissue

Old:

• decline in vital capacity

• increase in residual volume

• reduce efficiency in gas exchange

How does fitness level affect lung volumes and capacities?

High fitness levels:

• accomodate more air with each breath

• higher capacites

• respiratory muscles are stronger

• greater expansion of lungs

How does body size affect lung volumes and capacities?

Larger/tall:

• larger volumes/capacities

• more space in the chest cavity

Shorter/small:

• smaller capacites/volumes

• lung size is small

How does gender affect lung volumes and capacities?

Males:

• larger volumes/capacites

• larger lung size

• larger thoracic dimensions

• a higher proportion of lung tissue