Lesson 5 - Respiratory System

Question 1

Why do we breathe?

Answer 1

Though it’s clear that we need to breathe to stay alive, the reason we do this is to supply our cells with oxygen!

Our cells use oxygen to obtain energy from food in a process called aerobic cellular respiration

Energy released in aerobic cellular respiration fulfills two (2) functions:
- 64% is released as thermal energy (to maintain body temperature)
- 34% is stored in a molecule called ATP

Question 2

What is ATP and What Does it do?

Answer 2

ATP powers almost all energy-requiring processes, such as growth, movement, and building new molecules.

ATP is formed when energy from the breakdown of glucose is used to attach a phosphate group (P) onto a molecule called
ADP. This process is called phosphorylation

Question 3

What is Gas Exchange? (How do we get Oxygen?)

Answer 3

Gas exchange: the process by which oxygen
diffuses into the body cells and carbon dioxide
diffuses out of the cells.

Occurs in:
- the lungs
- body cells

Ventilation: the process in more complex organisms that ensures a flow of oxygen- rich air to the lungs and carbon dioxide-rich air away from the lungs

Question 4

Respiratory Structures (What do we need to be able to breathe?

Answer 4

Mammalian respiratory systems have four key structural features that enable it to function properly
- A thin, permeable respiratory membrane through which diffusion can occur
- A large surface area for gas exchange (recall: atmosphere is only 21%
oxygen)
- A good supply of blood
- A breathing system for bringing oxygen-rich air to the respiratory membrane

Question 5

Nasal Passage and Mouth

Answer 5

Air enters the respiratory system

Air is filtered (tiny hairs and mucus
in the nasal passage trap dust and
other airborne particles)

Air is warmed and moistened (to
prevent damage to the delicate
tissue of the respiratory membrane
in the lungs)

Question 6

The Trachea

Answer 6

Air travels into the pharynx, past the
(open) epiglottis, and into the trachea

The Trachea: a semi-rigid tube of soft
tissue wrapped around a c-shaped
bands of cartilage (keep it open)

Mucus-producing cells - trap dust and other particles

Cilia (tiny hair-like structures)- sweep the trapped material upward through the trachea to be swallowed

Fun Fact: Cilia literally sweep! They move and do the wave!

Question 7

Bronchi

Answer 7

The trachea branches into two
bronchi, which each connect to a
lung

Inside the lungs, the bronchi branch
repeatedly into smaller and smaller
tubes called bronchioles

The airways end in clusters of tiny
sacs called alveoli

Question 8

Alveoli

Answer 8

Alveoli are tiny (0.1 micrometres!!), with ~150
million per lung to provide the necessary surface area for gas exchange.

Each cluster of alveoli is surrounded by a
network of capillaries. The respiratory
membrane is extremely thin (one cell layer thick), so oxygen and carbon dioxide can easily diffuse across the membrane.