Body Systems topic 3

Respiratory System

basic functions of the respiratory system overall (7)

1. Olfactory epithelium (olfactory receptors) for sense of smell

2. Produces sounds

3. Protects respiratory surfaces from dehydration, temperature changes,

   and pathogens

4. surface area for gas exchange between air and

   circulating blood

5. Moves air to and from exchange surfaces of lungs

6. Acid-base balance

7. Regulates pH

define respiration

Respiration is the exchange of gases between the atmosphere, blood, and cells.

what are the three basic steps of respiration?

1. Ventilation (breathing)

2. External (pulmonary) respiration

3. Internal (tissue) respiration

what is contained within the upper and lower respiratory tract

Upper respiratory tract is:

• above vocal cords:

  • nose, nasal cavity

  • paranasal sinuses

  • pharynx

Lower respiratory tract is

• below vocal cords:

  • larynx

  • trachea

  • bronchi

  • bronchioles

  • alveoli

what componants are in the respiratory portion and which are in the conducting system

The conducting system consists of:

• a series of cavities and tubes

  • nose

  • pharynx

  • larynx

  • trachea

  • bronchi

  • bronchiole

  • terminal bronchioles

The respiratory portion consists of:

• the area where gas exchange occurs

  • respiratory bronchioles

  • alveolar ducts

  • alveolar sacs

  • alveoli.

define what anatomic dead space is?

It is the air in the conducting portion of the airways which does not take part in the process of gas exchange.

explain the role of the nose in the respiratory system (what are nasal hairs, pathway of air, functions)

Nasal hairs:

• in epithelium of vestibule - trap large particles in air (filters)

---

• Skin, nasal bones and cartilage lined with mucous membrane

• internal portion communicates with the paranasal sinuses and nasopharynx

  through the internal nares

---

Functions:

• warming, moistening, and filtering incoming air

• receiving olfactory stimuli

• serving as large, hollow resonating chambers to modify speech sounds

what are the paranasal siinuses

• Open into nasal cavity

• They lighten the skull and resonate voice

• There are ethmoid, sphenoid, frontal and maxillary sinuses

What are the tonsils (where and roles)

Where:

• at entrance of the respiratory tract

Roles:

• Are lymphatic tissues protect against infection.

• Lymph nodes monitor lymph drainage from lungs and provide specific defenses when infection occurs.

decribe the pathway of air through the noes

1. nose vestibule to choanae (internal openings of nasal cavity to pharynx)

2. through superior, middle, and inferior nasal meatuses

   • trap particles

   • warm and humidify

   • bring olfactory stimuli to receptors

Describe the structure of the nasal cavity

• divided into right and left by nasal septum (bones + cartilage)

• roof of ethmoid bone

• floor is hard plate

• superior, middle, and inferior nasal conchae on lateral walls

Describe the two palates in the nasal/oral cavity

Hard palate

• forms floor of nasal cavity separates nasal and oral cavities

Soft palate

• extends posterior to hard palate divides superior part of the pharynx (nasopharynx) from rest of pharynx

structure/location of pharynx + role

STRUCTURE

• skeletal muscular tube

• lined with mucous membrane

• comprised of three regions:

  • nasopharynx - respiration

  • oropharynx - digestion and respiration

  • laryngopharynx - digestion and respiration

LOCATION

• extends from internal nares to cricoid cartilage

ROLES

• resonating chamber for speech production

• Tonsils in the walls protect entry in body

What is the nasopharynx?

From choanae to soft palate

• openings of Eustachian (auditory) tubes from middle ear cavity

• adenoids or pharyngeal tonsil in roof

passage for airway only

What is the oropharynx

• between the soft plate and epiglottis

• common passageway for food and air

what is the laryngopharynx

Extends from epiglottis to cricoid cartilage, and ends as esophagus inferiorly

• Common passageway for food and air

What is the larynx

• Connects the pharynx with the trachea

• contains the:

  • thyroid cartilage

  • epiglottis

  • cricoid cartilage

• produces sound

• Opening and closing of the vocal folds occurs during breathing and speech

Explain what the thyroid cartilage is

adams apple

what is the epiglottis

a leaf-shaped piece of elastic cartilage which prevents food from entering the larynx.

• During swallowing, larynx moves upward, epiglottis bends to cover glottis

what is the cricoid cartilage

• a ring of cartilage connects larynx and trachea

explain the process of voice production in the larynx

Speech is a modified sound made by the larynx → requires pharynx, mouth, nasal cavity and sinuses to resonate sound

1. Vocal folds (true vocal cords) - produce sound

   • Taut vocal folds produce high pitches

   • Relaxed vocal folds produce low pitches

   • Vestibular folds (false vocal cords) found above vocal folds

explain how whispering occurs?

Whispering is forcing air through almost closed rima glottidis - oral cavity alone forms speech.

Tongue and lips movements form words

What is the true vocal cord?

• contains skeletal muscles

• contains elastic ligaments

• when muscles contract of the larynx contract → the cartilage moves and vocal chords are stretched tight.

  • when air is pushed past tight ligament = sound.

what is laryngitis

Is an inflammation of the larynx - usually caused by respiratory infection or irritants.

explain what the trachea is?

• From larynx → T5 anterior → oesophagus → splits into primary bronchii

  • composed of smooth muscle and c shaped rings of cartilage (keep airway open)

  • lined by pseudostratified epithelium

• cilia remove debris from lungs → throat to be swallowed.

what is a tracheostomy? and intubation

TRACHEOSTOMY

is incision in trachea below cricoid cartilage if larynx is obstructed

• Reestablished airflow past an airway obstruction

INSTUBATION:

• is passing a tube from mouth or nose through larynx and trachea

Explain the location of the lungs inside the thoracic cavity

1. Enclosed and protected by the pleural membrane:

   • Parietal pleura: outer layer attached to wall of thoracic cavity

   • Visceral pleura: inner layer covering lungs

   • Pleural cavity is potential space between the pleurae, contains a lubricating fluid secreted by the membranes

2. Lungs extend from the diaphragm to just slightly superior to the clavicles

3. lie against the ribs anteriorly and posteriorly

4. Lungs almost totally fill the thorax

What is visible from the costal surface of the lungs?

• apex

• base

• costal surface of right and left lung

• right lung = 3 lobes separated oblique and horizontal fissures.

• left lung = 2 lobes separated by oblique fissure and a cardiac notch (depression)

order of branching of the bronchial tree

trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, terminal bronchioles.

bronchioles → alveoli order

Branchings of single arteriole, venule and bronchiole are wrapped by elastic connective tissue - respiratory bronchioles are also wrapped by smooth muscles that can change diameter of these airways.

1. respiratory bronchiole → alveolar ducts → alveolar sacs → alveoli → alveolar pores

change in cartilage structure as bronchi branch

• When passing deeper into the lungs

  • Incomplete rings of cartilage replaced by rings of smooth muscle (bronchioles)

  • then replaced by connective tissue

Histology summary of respiratory system

CONDUCTION COMPONANT -

• Transports, cleans, warms, and humidifies air.

• Nose, pharynx, larynx, trachea, bronchi, terminal bronchioles

• ciliated pseudostratified columnar epithelium

RESPIRATORY PORTION

• Gas exchange (O2/CO2 diffusion)

• Respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli

• progresses from ciliated cuboidal epithelium to squamous epithelium.

histological composition of the respiratory system cells and functions

1. Epithelial cells - lined with basal cells that are attached to the basement membrane

2. Squamous epithelial cells - make up the beginning (nasal) and ends (alveoli) of the respiratory tract.

3. Ciliated and non-ciliated columnar epithelia - Upper tract and large bronchi

4. cuboidal epithelia - Small bronchi and bronchioles

5. Surface liquid - overlays the epithelial cells, is mucus, airway liquids, neutralising immunoglobulins, and antimicrobials

6. Resident leukocytes - line the mucosa, alveolar macrophages are found in lower airways and alveoli

7. Bronchiole smooth muscle cells - underlying the respiratory tract from the basal end provide structural support and elasticity to the airways.

4 layers of the trachea

1. mucosa - pseudostratified columnar epithelium with cilia and goblet cells

2. submucosa - loose connective tissue and seromucous glands

3. Hyaline cartilage - incomplete rings C-shaped structure closed by trachealis muscle

4. Adventitia - binds it to other organs

what is required for effective mucociliary drainage

• normal cilia

• optimum thickness and viscosity of mucous.

what causes increased and decreased mucocilary drainage

INCREASED:

• intense exercise

• postural drainage

• percussion

• nebulisation

DECREASED

• old age

• sleep

• disease

• dry cold air

explain what cystic fibrosis is?

The airways fill with thick sticky mucus, making it difficult to breathe.

• the thick mucus is an ideal breeding ground for bacteria

• affects mostly the lungs and digestive system

explain what asthma is?

Asthma is characterised by spasms of smooth muscle in bronchial tubes that result in partial or complete closure of air passageways

Can lead to:

• inflammation

• inflated alveoli

• excess mucus production.

Symptoms

• cough

• wheeze

• shortness of breath

• chest tightness

Can treat with nebulisation therapy

what is nebulisation therapy

Nebulisation therapy = inhale mist with chemicals that relax muscle and reduce thickness of mucus.

What are the types of alveolar cells?

Type 1 cells:

• simple squamous cells - gas exchange

Type 2 cells (septal cells):

• free surface has microvilli

• secrete alveolar fluid containing surfactant

Alveolar Macrophages:

• remove debris

Alveolar-capillary membrane

Respiratory membrane = 1/2 micron thick

• Vast surface area for gas exchange from alveoli to blood

This air-blood barrier is composed of:

• alveolar and capillary walls

• their fused basal laminas

Define respiration and the tree basic steps

Respiration: exchange of gases between atmosphere, blood, and cells.

Occurs in 3 basic steps:

1. Pulmonary ventilation (breathing)

2. External (pulmonary) respiration: all processes involved in exchange of O2 and CO2 with the external environment

3. Internal (tissue) respiration: uptake of O2 and release of CO2 by cells

Compare hypoxia to anoxia

Hypoxia

• Low tissue oxygen levels.

Anoxia

• Complete lack of oxygen in tissues.

Explain what pulmonary ventilation is

A mechanical process that depends on volume changes in the thoracic cavity.

• Volume changes lead to pressure changes, which lead to the flow of gases to equalise pressure.

Inspiration = Air in lungs < atmospheric pressure

Expiration = Air out Lung > Atmospheric pressure

What is Boyle’s Law?

Boyle’s law: the volume (V) of a gas varies inversely with pressure (P), assuming that temperature is constant.

• P = pressure of gas in mm Hg

• V = volume of a gas in cubic millimeters

P_InitialV_Initial = P_FinalV_Final

P = 1/V

Explain the role of a change in thoracic cavity size in respiration

1. when breathing in the thoracic cavity increases

   • contraction of the diaphragm, flattens, increases chest vertical dimenstions

   • contraction of the intercostal muscles, increases anterior-posterior dimension of the chest

2. When breathing out the thoracic cavity shrinks