Mod 9: Block theory

Breathing involves what two cyclic phases? Describe

1. Inspiration (inhalation): Draws oxygen rich air into the lungs

2. Expiration (exhalation): Forces oxygen poor air out of the lungs

What does the respiratory system contribute to?

the functional mechanisms of

• respiration

• immunity

What is external respiration?

External respiration is the exchange of gases between the air and blood

Describe external respiration

• Oxygen (O₂) moves from the alveoli in the lungs into the blood

• Carbon dioxide moves from the blood into the alveoli

• Carbon dioxide is then removed from the body during expiration

What is internal respiration

Exchanges gases (oxygen + carbon dioxide) between the blood and cells of the body

What is gas conditioning?

Gas conditioning is the process of warming, humidifying, and cleansing air before it reaches the lungs

• prevents damage to lungs

Where does gas conditioning occur? Describe what hapens in each part

• Occurs in the nasal cavities and paranasal sinuses

  • Air is swirled to become warmed + humidified

• Particulate matter is removed by the mucosal lining of the respiratory epithelium

How does the production of sound occur?

occurs by forceful expiration of air through the vocal cords in the larynx causing them to vibrate

how do vocal cords produce different sounds?

• Different tensions

• Help from teeth, lips, and tongue

What does the olfactory epithelium cover?

the top of the nasal cavity

What is located within the olfactory epithelium?

receptors for the sense of smell

What happens to airborne molecules in the nasal cavity during inhalation?

Airborne molecules dissolve in the mucus lining the nasal cavity and stimulate sensory receptors

How are smell signals transmitted to the brain?

Signals from the receptors travel to the brain through the olfactory nerve (CNII), resulting in a sense of smell

Describe the respiratory systems line of defense (3) against airborne molecules + microbes that cause disease

• the coarse hairs of the nostrils

• ciliated cells of the respirtatory epithelium

• mucus lining help

all help to trap particles and microorgansims from entering the nose + respiratory system

What chamber of the heart does the deoxygnated blood exit from to enter the lungs?

Right ventricle

What chamber of the heart does oxygenated blood re-enter after exiting the lungs?

left atrium

What does the respiratory tract epithelum line?

lines most of the surfaces from the nasal cavity down to the terminal bronchi

• large role in defense

what type of epithelium is found in the respiratory tract?

Pseudostratified ciliated columnar epithelium

• apical surface: coveredi n cilia

• attached to basal lamina

What is the function of cilia in the respiratory tract

• Increase surface area for conditioning air (filtering, humidifying, moistening)

How do cilia help portect the respiratory system?

• They trap particles + microorganisms in mucus

• sweep them up the respiratory tract and out through the nose and mouth

What do goblet cells do? (4)

• produce mucus

• forms a protective layer over the epithelium

• traps PM / microorganisms that may be inhalated

• provides moisture to humidify the air before it reaches the lungs

Where are goblet cells found?

interspersed throught the pseudostratified epithetlium

Regions of the respiratory system

• Conducting portion

• Respiration portion

What is the function of the conducting portion of the respiratory system?

it carries air to and from the lungs without contributing to gas exchange

What processes occur in the conducting portion?

humidification of air and trapping of debris

Does gas exchange occur in the conducting portion?

No, oxygen is not absorbed because the walls are too thick

What structures are included in the conducting portion of the respiratory system?

• nose + nasal cavity

• paranasal sinuses

• pharynx

• larynx

• trachea

• primary/secondary/tertiary bronchi

• terminal brochioles

What does the respiratory region function to do?

transfer gases between the lungs + pulmonary capillaries

Describe pulmonary capilaries

• tiny blood vessels in the lungs that surround alveoli (air sacs)

• where gas exchange occurs

Structures that make up the respiratory portion

• Respiratory bronchioles

• Alveolar ducts

• Alveolar sacs

• Alveoli

What are the paranasal sinuses?

A collection of air-filled spaces within the bones of the skull that communicate with the nasal cavity

How do the paranasal sinuses contribute to defense?

They help protect against pathogens

What role do the paranasal sinuses play in speech?

They act as resonance chambers for speech

The (4) Sinuses:

• Frontal sinus (2)

• Maxillary sinus (2)

• Ethmoid sinus (2)

• Sphenoid sinus (2)

What lines paranasal sinuses

respiratory tract epithelium

What is the first line of defence against invading pathogens + debris? What does it do?

Nose + nasal cavity

• traps the in coarse hairs + mucus

air enters the nostril and is passed into the nasal cavity where it is conditioned

what are the 6 boundaires that make up the nasal cavity

1. roof

2. floor

3. medial wall

4. lateral wall

5. anterior

6. posterior

What is the roof of the nasal cavity?

ethmoid bone

what is the floor of the nasal cavity composed of?

hard palate

What does the medial wall of the nasal cavity make up?

Nasal septum

What is the nasal septum composed of? what does it do?

• vertical bones in the skull

  • seperates the two halves of the nasal cavity

What does the lateral walls of the nasal cavity contain?

nasal conchae

what does the nasal conchae do?

• create turbulence in the air

• allows for conditioning

• catches debris

what makes up the anterior boarder of the cavity?

Nares

• opening between the nose + nasal cavity

What is the posterior border of the nasal cavity?

the opening to the nasopharynx (choanae)

• where the nasal cavity connects to the pharynx

what is the nasal cavity covered in?

respiratory tract epithelium (RTE)

what lines the nasal cavity? what does it contain?

olfactory epithelium

• contains sensory receptors for smell

what is the oflactory epithelium composed of?

• pseudostratified ciliated columnar epithelium

• bipolar olfactory receptor neurons

what is the pharynx? what does it connect?

• muscular tube

• connects the nasal cavity + the larynx

• connects the oral cavity w/ esophagus

3 components that make up the pharynx? say which is superior, middle, inferior

• the nasopharynx

  • superior

• the oropharynx

  • middle

• the laryngopharynx

  • inferior

What systems is the oropharynx and laryngopharynx apart of?

both apart of respiratory + digestive systems

function of the oropharynx

• passes air from the nasopharynx

• passes food from the oral cavity into the laryngopharynx

laryngopharynx function

• passes food into digestive system

• passses air into respiratory system

what is the nasopharynx lined with?

respiratory tract epithelium (RTE)

what lines the oropharynx + laryngopharynx? why?

stratified squamous epithelium

• need for durability when swallowing food

what is the purpose of the larynx?

• produces sound

• prevents food from entering the trachea

3 main cartilages of the larynx

• epiglotties

• thyroid cartilage

• cricoid cartilage

purpose of the epiglottis

• prevents food from passing into the trachea

• during swallowing, the epiglotties flips downwards and covers the opening of the trachea

what are vocal cords?

small ligaments attahed to laryngeal cartilages that vibrate when air is forced out of the lungs

what are vocal cords protected by?

false vocal cords (membranous flap)

where does the trachea extend to? what happens once it reaches it?

extends from the larynx to T4/T5 where it splits at a junction called the carina

what is the main function of the trachea?

conduction of air to the lungs

what makes up the trachea

• 15-20 C shaped cartilaginous rings

what is the function of the rings in the trachea?

to keep the airway open

trachea can be identified by what 3 histological layers?

• Mucosa

• Submucosa

• Adventitia

what lines the trachea? why?

Respiratory tract epithelium

• clears any debris or pathogens that make it into the lower respiratory tract

What is the submucosa made up of?

• loose (areolar) connective tissue

what does the submucosa contain?

• larger vessels + nerves

• mucus secreting glands

What is the adventitia

• outer layer of connective tissue surrounding the trachea

What is the adventitia made up of?

• C-shaped cartilaginous rings

  • made of hyaline cartilage

Splitting of the treachea results in what?

2 primary bronchi

• left + right

• has the same functional + histological features as the trachea

Describe the primary bronchi’s

• Right primary bronchus is shorter + wider + more verticle

Where does the primary bonchi' enter the lung?

on the medial side of the hilus

What is the end of the conducting portion

• characterized by bronchi dividing into smaller and smaller tubes

What is the purpose of the conducting portion of the respiratory system

• moving air into and out of the lungs

the conducting portion of the respiratory ssytem leads into what?

the respiratory portion

Purpose of the respiratory portion

• allow for gas exchange between air and blood

Describe the walls at the respiratory portion

• one cell layer thick

  • gases are able to cross easily

WHere are the lungs located

either side of the heart

within the thoracic cavity

Which lung is bigger and why?

Left lung

• due to positioning of the heart

Describe the right lung features

• 3 lobes

  • superior, middle, and inferior lobes

• 2 fissures → seperate the lobes

  • horizontal + oblique fissures

Describe the left lung

• 2 lobes

  • superior + inferior lobes

• one fissure → seperates the lobes

  • oblique fissure

What’s special about the superior lobe on the left lung

• contains the cardiac notch

  • a depression

• lingula that covers the heart

  • small outward facing process

what is the apex of the lung

• most superior point

• sits above the first rib

what is the diaphragmatic surface

• the base of the lung

• surface that rests on the diaphragm

Where does the lung sit relative to the diaphragm

superiorly

What is the costal surface

Covers around the lateral aspect of the lung

What is the mediastinal surface of the lung

• the medial surface

• it contains the entry + exit points for all vessels and airways at a structure

What is the pleura?

A double-layered membrane that surrounds each lung

What are the two layers of the pleura?

• Visceral pleura (covers the lungs)

• parietal plerua 9lines the thoracic wall)

What is the pleural space

The space between the visceral and parietal pleura

What is found in the pleural space

Pleural fluid

What is the function of pleural fluid?

Acts as a lubricant to reduce friction during breathing

Why is pleural fluid important for lung movement?

It allows the lungs to slide smoothly against the thoracic wall during inflation and deflation

Where are the parietal + visceral pleura continuous?

at the hilus of the lung

What happens at the hilus?

Parietal pleura reflects inward to become visceral pleura

What do respiratory bronchioles branch from?

Terminal brochioles

What is significant about respiratory bronchioles?

They are the first structures where gas exchange begins

What is the alveolus?

The functional unit of the lung where gas exchange occurs

Why are alveoli surrounded by capillaries?

To maximize gas exchange