BIOL 3320 - Respiratory chapter: part 1

What are the functions of the respiratory system?

• Gas exchange: O2 and CO2 exchanged between

blood and air

• Communication: speech and other vocalizations

• Olfaction: sense of smell

• Blood and lymph flow: breathing creates pressure

gradients between thorax and abdomen that

promote flow of lymph and blood

• Blood filtration: lungs filter small clots

• Expulsion of abdominal contents: breath-holding

assists in urination, defecation, and childbirth

(Valsalva maneuver)

What is the conducting division of the respiratory tract?

• Only air flow

• does NOT involve gas exchange

• from nostrils to bronchioles.

What is the respiratory division of the respiratory system?

• involves gas exchange

• Consists of alveoli and other gas exchange regions

Where is the upper respiratory tract located?

In the head and the neck

• Nose through larynx

Where is the lower respiratory tract located?

Organs of the thorax

• Trachea through lungs

What are the functions of the nose?

• warms, cleanses, humifies warmed air

• detects odor

• chamber that amplifies voice

What are the three regions of the pharynx?

• Nasopharynx

• Oropharynx

• Laryngopharynx

Characteristics of the Nasopharynx

• “nose part”

• Behind nose and above soft palate

• mainly an air passage

• Auditory (Eustachian) tubes open here → these connect to the ears and help equalize pressure

  Pharyngeal tonsil (adenoids) is here

Characteristics of the Oropharynx

• “mouth part”

• Behind the mouth

• Between the soft palate and the epiglottis

• Passageway for both air and food

• When you breathe through your mouth or swallow, things pass through here

• Palatine tonsils here

Characteristics of the Laryngopharynx

• “Bottom throat part”

• Epiglottis to cricoid cartilage

• Esophagus begins at that point

What is the function of the Larynx?

To keep food and liquid out of the airway

Epiglottic cartilage

• spoon-shaped supportive plate in

epiglottis

• most superior one

Thyroid cartilage

• largest, laryngeal prominence (Adam’s apple)

• shield-shaped

Cricoid cartilage

• connects larynx to trachea

• ring-like

Arytenoid cartilages

posterior to thyroid cartilage

Corniculate cartilages

attached to arytenoid cartilages like a pair of little horns

Cuneiform cartilages

support soft tissue between arytenoids and epiglottis

Superior vestibular folds

• Play no role in speech

• Close the larynx during swallowing

Inferior vocal cords

• Produce sound when air passes between them

• Contain vocal ligaments

• Covered with stratified squamous epithelium

  • Suited to endure vibration and contact

Glottis

the vocal cords and the opening between them

What are the functions of the vocal cords?

Loudness: determined by the force of air passing

between the vocal cords

Vocal cords produce crude sounds that are formed into

words by actions of pharynx, oral cavity, tongue, and lips

Where does the trachea start and end?

Starts: Cricoid cartilage

Ends: Carina

What is the function of the trachea?

It’s the windpipe

• transporting air

• conducting air

• maintaining airway

What are goblet cells and the function?

The secrete mucus to protect and lubricate mucosal surfaces.

Description of base of lungs

broad concave portion resting on diaphragm

Description of apex of lungs

tip that projects just above the clavicle

Description of costal surface of lungs

pressed against the ribcage

Description of mediastinal surface of lungs

faces medially toward the heart

What is the Hilum?

slit through which the lung receives the main bronchus, blood vessels, lymphatics, and nerves

Description of Right lung

• Shorter than left because liver rises higher on the right

• Has three lobes—superior, middle, and inferior

• separated by horizontal and oblique fissure

Description of left lung

• Tall and narrow because the heart tilts toward the left and occupies more space on this side of mediastinum

• Has indentation—cardiac impression

• Has two lobes—superior and inferior separated by a single oblique fissure

What is the Bronchial tree?

a branching system of air tubes in each lung

What things in the bronchi help keep pathogens from entering the bronchioles?

Secretes mucus and uses cilia to trap pathogens.

What is the path of the conducting division?

Starts at the nostrils and ends at the bronchi

Nose/nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → terminal bronchioles

What is the path of the respiratory division?

Respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli

What are the three types of cells in the alveoli?

• Squamous (type 1) alveolar cells

• Great (type 2) alveolar cells

• Alveolar macrophages (dust cells)

what is the function of Squamous (type 1) alveolar cells?

Allow for rapid gas diffusion between alveolus and blood stream

What is the function of Great (type 2) alveolar cells?

• Repair the alveolar epithelium when the squamous (type 1) cells are damaged

• secrete pulmonary surfactant (coats alveoli and prevents them from collapsing during exhalation

What is the function of Alveolar macrophages (dust cells)?

Keep the alveoli free from debris by phagocytizing dust particles

What is the function of the respiratory membrane?

It is the site of gas exchange between the air in the alveoli and the blood in the capillaries.

• thin barrier between the alveolar air and the blood

What does the respiratory membrane consist of?

• Squamous alveolar cells

• Endothelial cells of blood capillaries

• their shared basement membrane

How is fluid prevented from accumulating in the alveoli?

• blood capillaries absorbing excess liquid

• lymphatic drainage of the lungs

• low capillary blood pressure presents rupture of delicate respiratory membrane

What is the visceral pleura?

serous membrane that covers the lungs

What is the parietal pleura?

adheres to mediastinum, inner surface of the rib cage, and superior surface of the diaphragm.

What is the pleural cavity?

potential space between pleurae

• typically, no room between the membranes but contains a film of slippery pleural fluid.

What are the functions of the pleurae and pleural fluid?

• reduce friction

• create pressure gradient

  • lower pressure than atmospheric pressure; assists in lung inflation

• Compartmentalization

  • prevents spread of infection from one organ in mediastinum to others

why does the visceral pleura need to be attached the parietal pleura and why does negative pressure allow us to that?

When your chest expands, the parietal pleura moves outward.

Because the visceral pleura is “stuck” to it by the pleural fluid + negative pressure, the lungs are pulled outward too.

What is Boyle’s law?

at a constant temp, the pressure of a give quantity of gas is inversely proportional to its volume.

• in the lungs this means:

  • if the lungs contain a quantity of gas and the lung volume increases, the internal pressure falls

    • if pressure falls below atmospheric pressure, air moves into lungs

  • if lung volume decreases, pressure rises

    • if pressure rises above atmospheric pressure, air moves out of the lungs

What is the Valsalva maneuver?

Taking a deep breath, holding it by closing the glottis, then contracting abdominal muscles to raise abdominal pressure and push organ contents out.

• Happens during:

  • childbirth

  • urination

  • defecation

  • vomiting

What is the role of the diaphragm in the respiratory system?

• contraction flattens diaphragm, enlarging thoracic cavity and pulling air into the lungs

• relaxation allows diaphragm to bulge upward again, compressing the lungs and expelling air.

• two-thirds of airflow

What is the role of the internal and external intercostal muscles in the respiratory system?

• stiffens thoracic cage during respiration (breathing)

• prevents thoracic cage from caving inward when diaphragm descends

• contributes to enlargement and contraction of thoracic cage

• one-third of airflow

Should the pressure in the chest be greater or less than atmospheric pressure if you want to inhale?

less

Should the pressure in the chest be greater or less than atmospheric pressure if you want to exhale?

greater

What is interpleural pressure?

the slightly negative pressure that exists between the two pleural layers

What is Charles’s law?

volume of gas is directly proportional to its absolute temperature.

What is Pneumothorax?

the presence of air in the pleural cavity

• thoracic wall is punctured

• inspiration sucks air through the wound into the pleural cavity

• potential space becomes an air-filled cavity

• loss of negative intrapleural pressure allows lungs to recoil and collapse.

What is bronchodilation?

an increase in diameter of a bronchus or bronchiole

What causes bronchodilation?

Epinephrine and sympathetic stimulation to increase airflow

When do we want bronchodilation?

• when struggling to breath

  • asthma

  • COPD

  • Allergic reaction (EpiPen - epinephrine)

What is bronchoconstriction?

decrease in diameter of a bronchus or bronchiole

What causes bronchoconstriction?

• Histamine, parasympathetic nerves, cold air, chemical irritants decrease air flow

When do we want bronchoconstriction?

Never…unless you want to suffocate??

What is pulmonary compliance?

The ability for the lungs to stretch or recoil.

What is surfactant?

Secreted by the great alveoli type 2 cells

• disrupts hydrogen bonds between water molecules and reduces surfaces tension

When does surfactant begin to be secreted and what does it do for our lungs?

secreted during fetal development and it prevents alveoli from collapsing, makes the lungs easier to inflate, helps the lungs stay open after exhalation, reduces the work of breathing

What is anatomical dead space?

the conducting division of airway where there is no gas exchange

What is the alveolar ventilation rate? (concept)

The amount of air coming into the alveoli and the number of times you breathe per minute.

What is residual volume?

The amount of air that remains in the lungs after a maximal, forceful exhalation

What is tidal volume?

volume of air inhaled and exhaled in one cycle of breathing

What is inspiratory reserve volume?

amount you can take in above tidal volume that can be inhaled with maximum effort.

• amount after normal inhalation

What is expiratory reserve volume?

air in excess of tidal volume that can be exhaled with maximum effort.

• Amount after normal expiration

What is residual volume?

air remaining in lungs after maximum expiration.

What is vital capacity and how is it calculated?

the total amount of air that can be inhaled and then exhaled with maximum effort.

• Vital capacity = Expiratory reserve volume + Tidal volume + Inspiratory reserve volume

What is inspiratory capacity and how is it calculated?

It is the maximum amount of air that can be inhaled after a normal tidal expiration

• Inspiratory capacity = Tidal volume + inspiratory reserve volume

What is functional residual capacity and how is it calculated?

the amount of air remaining in lungs after a normal tidal expiration

• Functional residual capacity = Residual volume + expiratory reserve volume

What is total lung capacity and how is it calculated?

maximum amount of air the lungs can contain

• Total lung capacity = residual volume + vital capacity

What is Dalton’s law?

total atmospheric pressure is the sum of the contributions of the individual gases.

What is Henry’s law?

at the air-water interface, for a given temperature, the amount of gas that dissolves in the water is determined by its solubility in water and its partial pressure in air.

In order for the gases in the lungs to move, what two things must be present?

• pressure difference

• solubility in water

What direction does oxygen flow in the lungs and the tissue?

Lungs: out/loading

Tissues: in/unloading

What direction does CO2 flow in the lungs and the tissue?

Lungs: in/unloading

Tissue: out/loading

What hinders gas exchange in the membrane

• Solubility of gases

• Membrane surface area

• Membrane thickness

What is hemoglobin called when oxygen is bound to it?

Oxyhemoglobin

What is hemoglobin called when oxygen is NOT bound to it?

Deoxyhemoglobin

What is hemoglobin called when carbon monoxide is bound to it?

Carboxyhemoglobin

What is hemoglobin called when carbon dioxide is bound to it?

Carbaminohemoglobin

How is carbon dioxide transported in the blood?

• Carbonic acid

• as carbaminohemoglobin

• dissolved in plasma

What is carbonic acid?

hydrated carbon dioxide

What does carbonic acid dissociate into?

bicarbonate and hydrogen ions

What is systemic gas exchange?

the unloading of oxygen and loading of carbon dioxide at the systemic capillaries

What is the systemic gas exchange process?

CO2 loading from tissue into blood:

• carbon dioxide + water catalyzed by carbonic anhydrase

• creates carbonic acid

• dissociates into bicarbonate and hydrogen ions

!Chloride Shift!

• exchanges bicarbonate ion for chloride ion

• hydrogen binds to oxyhemoglobin

• oxyhemoglobin dissociates into oxygen (to be release) and deoxyhemoglobin

What is alveolar gas exchange?

the unloading of oxygen and loading of carbon dioxide in the lungs reversed from systemic gas exchange.

Is the pH higher or lower when there are more hydrogen ions?

lower

Is the pH higher or lower when there are less hydrogen ions?

higher

What predominantly monitors breathing (tells us when to respire faster or slower)?

pH level

When pH is lower, what is it called?

Acidosis

When the pH is higher what is it called?

Alkalosis

What is hypocapnia, what does it cause, and what corrective action do we take?

Low CO2 levels in the blood causing alkalosis

We need hypoventilation - allowing CO2 to accumulate in body fluids faster than it is exhaled

What is hypercapnia, what does it cause, and what corrective action do we take?

High levels of CO2 in the blood causing acidosis

Need to hyperventilate - blowing off CO2 faster than the body produces it

What does exercise do to the respiratory rate?

sends signals to brain to pick up respiratory rate