Comprehensive Respiratory System: Structure, Function, and Control

What is the primary purpose of breathing?

To allow gas exchange (oxygen in, carbon dioxide out) for cellular respiration.

What is respiration?

The process of gas exchange in the body.

What is external respiration?

Air enters lungs and gases are exchanged between air and blood.

What is internal respiration?

Blood delivers oxygen to tissues and exchanges gases with cells.

Why do we need oxygen?

To produce ATP through cellular respiration.

What is ATP?

The energy molecule used to power cellular processes.

Where does cellular respiration occur?

In the mitochondria.

What are the main functions of the respiratory system?

Gas exchange, ATP production support, regulation of blood pH, sound production, sense of smell.

What organs are in the upper respiratory tract?

Nose, nasal cavity, sinuses, pharynx.

What organs are in the lower respiratory tract?

Larynx, trachea, bronchi, lungs.

Where are the lungs located?

In the pleural cavity.

What protects the lungs?

The visceral pleura membrane.

What is the function of serous fluid?

Lubricates lungs during breathing.

How many lobes does the right lung have?

3 lobes.

How many lobes does the left lung have?

2 lobes (due to cardiac notch).

What is the pathway of air through the lungs?

Primary bronchi → Secondary bronchi → Tertiary bronchi → Terminal bronchioles → Alveolar ducts → Alveolar sacs → Alveoli.

What are alveoli?

Tiny air sacs where gas exchange occurs.

Where does gas exchange occur?

In the alveoli.

What connects alveoli to the circulatory system?

Capillaries.

What gases are exchanged in alveoli?

Oxygen and carbon dioxide.

What makes up the respiratory membrane?

Alveolar epithelial cells, capillary endothelial cells, fused basement membranes.

What type of tissue is the respiratory membrane made of?

Simple squamous epithelial tissue.

What is diffusion?

Movement of particles from high to low concentration.

Why is diffusion important in respiration?

It allows gases to move across the respiratory membrane.

Why can breathalyzers detect alcohol?

Alcohol diffuses from blood into alveolar air.

What is the trachea?

A tube that carries air into the lungs (windpipe).

What are the functions of the trachea?

Air passageway, filters air with mucus, connects to bronchial tree.

What prevents the trachea from collapsing?

Cartilage rings.

What is the function of the nose?

Allows air to enter and filters large particles.

What do nose hairs do?

Trap large particles.

What is the nasal cavity?

Hollow space behind the nose.

What is the nasal septum?

Bone dividing the nose into two nostrils.

What is a deviated septum?

When the septum bends to one side.

What is the function of the mucus membrane?

Warms air, moistens air, traps particles.

What are nasal conchae?

Bones that increase surface area for air processing.

What are paranasal sinuses?

Air spaces that increase air volume and reduce skull weight.

What happens if sinuses are blocked?

Sinus infection can occur.

What is the pharynx?

A passageway connecting nasal/oral cavities to respiratory and digestive systems.

What is another name for the pharynx?

The throat.

Why don't most toxins enter the bloodstream through lungs?

The respiratory membrane filters substances via diffusion.

What happens to trapped particles in mucus?

They are swallowed and go to the stomach.

What does the septum do?

Bends to one side.

What is the function of nasal conchae?

Increase surface area for air.

What is the function of sinuses?

Increase air volume, reduce skull weight.

Is breathing voluntary or involuntary?

Both, but normally involuntary.

What does the respiratory center control?

Rate and depth of breathing.

Where is the rhythmicity center located?

Medulla oblongata.

What does the pneumotaxic area do?

Helps regulate breathing rate.

What does the dorsal respiratory group do?

Controls basic breathing rhythm.

What does the ventral respiratory group do?

Controls forceful breathing.

What affects breathing rate?

Chemicals, lung stretch, emotions.

What do central chemoreceptors detect?

CO₂ and hydrogen ion levels.

Where are central chemoreceptors located?

Medulla oblongata.

What do carotid and aortic bodies detect?

Low oxygen levels.

When do oxygen levels affect breathing?

Only when oxygen is very low.

What is the inflation reflex?

Prevents lungs from overexpanding.

What nerve is involved in the inflation reflex?

Vagus nerve.

What does hyperventilation do?

Lowers CO₂ in the blood.

What is the main driver of breathing rate?

CO₂ levels (not oxygen).

What type of tissue allows fast diffusion?

Simple squamous epithelium.

What is spirometry?

The measurement of different air volumes in the lungs.

What are the four respiratory volumes?

Inspiratory Reserve Volume (IRV), Expiratory Reserve Volume (ERV), Tidal Volume (TV), Residual Volume (RV).

What is a respiratory cycle?

One full inhalation followed by one exhalation.

What is tidal volume (TV)?

The amount of air inhaled or exhaled during normal breathing.

What is inspiratory reserve volume (IRV)?

The extra air that can be inhaled after a normal breath.

What is inspiratory capacity?

IRV + TV; the total air inhaled during a deep breath.

What is expiratory reserve volume (ERV)?

The extra air that can be forcefully exhaled after normal exhalation.

What is residual volume (RV)?

The air remaining in the lungs after maximal exhalation.

Why is residual volume important?

It prevents alveoli from collapsing.

What is functional residual capacity (FRC)?

ERV + RV; the amount of air left in lungs after normal exhalation.

What is vital capacity (VC)?

TV + IRV + ERV; the maximum air exhaled after a deep breath.

What is total lung capacity (TLC)?

VC + RV; the maximum amount of air lungs can hold.

What is anatomic dead space?

Air in the respiratory system that does not participate in gas exchange.

What is the function of anatomic dead space?

To warm, humidify, and filter incoming air.

How do diseases like asthma affect dead space?

They increase dead space and decrease gas exchange.

How does air move in the lungs?

From higher pressure to lower pressure.

What happens to pressure when volume decreases?

Pressure increases.

Do lungs use suction to pull in air?

No, suction does not exist; air moves due to pressure differences.

What muscle controls breathing?

The diaphragm.

What happens to the diaphragm during inhalation?

It contracts and moves downward.

What happens to the rib muscles during inhalation?

They contract, expanding the chest cavity.

What happens to thoracic cavity volume during inhalation?

It increases.

What happens to pressure during inhalation?

It decreases, causing air to flow in.

What causes air to enter the lungs?

Atmospheric pressure pushing air into lower-pressure lungs.

What happens during exhalation?

Muscles relax and elastic recoil pushes air out.

What happens to thoracic cavity volume during exhalation?

It decreases.

What happens to pressure during exhalation?

It increases, forcing air out.

What is atmospheric pressure?

The force exerted by air that helps move air into the lungs.

How does elevation affect breathing?

Higher elevation lowers oxygen availability and can cause hypoxia.

What is hypoxia?

Oxygen deprivation in the body.

How does the body adapt to high elevation?

Through acclimation (adjusting to lower oxygen levels).

What is the larynx?

The structure that produces sound (the human voice).

What is the glottis?

A triangular opening in the larynx between the vocal cords.

What does the glottis consist of?

The vocal cords and the opening between them.

What is the function of the epiglottis?

It closes during swallowing to prevent food from entering the airway.

What are false vocal folds?

Structures that help close the airway during swallowing but do not produce sound.

What are true vocal folds?

Structures that produce sound.

How is pitch controlled in the vocal cords?

By contracting and relaxing muscles; more tension = higher pitch.

What are vocal nodes?

Non-cancerous growths on the vocal cords.

What causes vocal nodes?

Overuse or misuse of the vocal cords.