my own notes for sciences

Respiratory system

Mnemonic to Remember the Order:

“Nice People Like Taking Big Big Apples” Nice – Nose

People – Pharynx

Like – Larynx

Taking – Trachea

Big – Bronchi

Big – Bronchioles

Apples – Alveoli

🫁

Air’s Journey Through the Respiratory System (Step-by-Step):

1. Nose/Nasal Cavity – Air enters here. It gets filtered, warmed, and moistened.

2. Pharynx (throat) – A shared tube for air and food.

3. Larynx (voice box) – Air passes through; helps with sound.

4. Trachea (windpipe) – Main airway going down the neck.

5. Primary Bronchi – Trachea splits into two main tubes:
   

   • Right Primary Bronchus → right lung

   • Left Primary Bronchus → left lung

7. Secondary Bronchi – Each primary bronchus divides into smaller branches going to each lobe of the lungs:
   

   • Right lung → 3 secondary bronchi

   • Left lung → 2 secondary bronchi

9. Bronchioles – Tiny tubes that branch from secondary bronchi like thin tree branches.

10. Terminal Bronchioles – The last part of the bronchioles.
    

    • They do NOT do gas exchange, but they lead into the next part that does.

Perfusion, ventilation, hyperventilation, hypoventilation

1. VentilatioN

Definition: The process of moving air in and out of the lungs (a.k.a. breathing).

✅ Brings in oxygen

✅ Removes carbon dioxide

Controlled by:

• Diaphragm & intercostal muscles

• Brainstem (medulla oblongata)

2. Perfusion

Definition: The flow of blood through the lungs, especially around the alveoli, where gas exchange occurs.

✅ Brings CO₂-rich blood to lungs

✅ Picks up O₂ to deliver to the body

Remember:

Ventilation = AIR

• Perfusion = BLOOD

🌬3. Hyperventilation

Definition: Fast, deep breathing beyond the body’s needs.

✅ CO₂ is blown off too quickly

🔻 Leads to low carbon dioxide (hypocapnia)

🔺 Blood becomes more alkaline (respiratory alkalosis)

Causes:

• Anxiety or panic attacks

• Pain

• Fever

• Brain injury

Symptoms:

• Dizziness

• Tingling in fingers/lips

• Lightheadedness

😮‍💨4. Hypoventilation

Definition: Slow or shallow breathing that doesn’t meet the body’s oxygen needs.

❌ Not enough CO₂ is exhaled

🔺 Leads to high carbon dioxide (hypercapnia)

🔻 Blood becomes more acidic (respiratory acidosis)

Causes:

• Drug overdose (like opioids)

• Brain injury

• Lung disease (e.g. COPD)

• Obesity-related hypoventilation

Symptoms:

• Confusion

• Sleepiness

• Headache

• Shortness of breath

Next

9. Respiratory Bronchioles – These start gas exchange.
   

   • Tiny openings allow oxygen in, and carbon dioxide out.

11. Alveolar Ducts – Short tubes that connect respiratory bronchioles to alveoli.

12. Alveoli (Air Sacs) – The final destination.

• Tiny balloon-like sacs

• Surrounded by capillaries

• This is where oxygen enters your blood, and carbon dioxide leaves your blood.

Function of the Respiratory Syste

• Main job: Bring in oxygen and remove carbon dioxide

• Works closely with the circulatory system (blood carries the gases)

Pathway of Air (From Nose to Alveoli)

Nose → Pharynx → Larynx → Trachea → Primary Bronchi → Secondary Bronchi → Bronchioles → Terminal Bronchioles → Respiratory Bronchioles → Alveolar Ducts → Alveoli

• Naughty = Nose

• People = Pharynx

• Love = Larynx

• To = Trachea

• Party = Primary Bronchi

• So = Secondary Bronchi

• Badly = Bronchioles

• They = Terminal Bronchioles

• Really = Respiratory Bronchioles

• Are = Alveolar Ducts

• Annoying = Alveoli

Zones of the Respiratory System

Conducting Zone

(Air passage only, NO gas exchange):

Nose/nasal cavity

• Pharynx

• Larynx

• Trachea

• Bronchi (primary & secondary)

• Bronchioles

• Terminal bronchioles (last part before gas exchange begins)

Respiratory Zone

(Gas exchange happens here):

• Respiratory bronchioles

• Alveolar ducts

• Alveoli (where oxygen enters blood, CO₂ exits)

4. Lungs & Structures

• Right lung = 3 lobes

• Left lung = 2 lobes (because of the heart)

• Pleura = double-layered membrane around the lungs

• Alveoli = tiny sacs for gas exchange (surrounded by capillaries)

• Diaphragm = dome-shaped muscle under the lungs that controls breathing

5 Breathing Mechanics (Ventilation)

Inhalation (Breathing in)

Diaphragm contracts (moves down)

• Chest expands

• Pressure in lungs decreases

• Air flows in

Exhalation (Breathing out)

Diaphragm relaxes (moves up)

• Chest gets smaller

• Pressure increases

• Air flows out

🧠 6.Gas Exchange & Transport

Happens in the alveoli

• Oxygen diffuses into blood

• Carbon dioxide diffuses out of blood

✅ Blood coming to the lungs = low in oxygen, high in CO₂

✅ Blood leaving the lungs = rich in oxygen

What muscle helps you breathe

Diaphragm – contracts to pull air in, relaxes to push air out.

What protects the lungs?

Rib cage and pleura (membrane