BIOL 320 - Lab 7: Respiratory Air Flow and Volume

What is the primary function of the respiratory system?

Release carbon dioxide from the body and to acquire oxygen for use by the body. Our bodies accomplish this through respiration.

What are the four steps of respiration?

1. Pulmonary ventilation

2. External respiration

3. Transport of respiratory gases

4. Internal respiration

Pulmonary Ventilation

The movement of air into (inspiration) and out of (expiration) the lungs so that the gases in the lung are constantly refreshed with infusions of new air and effusions of old air (the respiratory system does this).

External Respiration

Carbon dioxide diffuses to the lungs from the blood, and oxygen diffuses to the blood from the lungs (this also occurs in the respiratory system).

Transport of Respiratory Gases

Accomplished using the blood of the cardiovascular system. Carbon dioxide is transported from the cells of body tissues to the lungs, and oxygen is transported from the lungs to the cells of body tissues.

Internal Respiration

Occurs as oxygen diffuses from the cells of the body, and carbon dioxide diffuses from the cells of the body to the blood (this is more a function of the cardiovascular system).

What is produced during cellular respiration? Used?

Carbon dioxide is produced, and oxygen is used by cells for energy (in oxidative reactions).

Nose functions

1. Warms and moistens entering air

2. Provides a resonating chamber for vocalizations

3. Cleans and filters entering air

4. Houses the olfactory receptors

Olfactory mucosa epithelium

A small portion of the superior nasal cavity is lined with olfactory mucosa epithelium containing receptors for smell.

What is majority of the nasal cavity lined with?

The rest of the nasal cavity is lined with respiratory mucosa composed of pseudostratified ciliated columnar epithelium with goblet cells and seromucous nasal glands.

What are submucous nasal glands composed of? What do they do?

These seromucous nasal glands are composed of cells that secrete mucus (traps bacteria, dust, and debris) and cells that secrete a watery (to humidify incoming air), enzyme-rich (contains lysozyme which is antibacterial) fluid.

What do the respiratory mucosa epithelial cells secrete?

The respiratory mucosa epithelial cells secrete antibiotic defensins to assist in killing microbial invaders.

What do the cilia of the nasal cavity do?

The cilia of the nasal cavity sweep the contaminated mucus toward the throat to be swallowed and digested.

How does cold air affect the nasal cavity?

Cold air slows the cilia and thus allows some of the mucus to dribble out of the nostrils.

Cold air inspired also reflexively stimulates the plexuses of capillaries to engorge with blood, allowing for greater heat transfer.

Sneeze Reflex

A sneeze reflex is triggered when irritants (dust, pollen, etc.) contact the rich supply of sensory nerve endings in the nasal cavity. A sneeze forces these irritants out to protect the body from them.

What warms the air as it is inspired? Are they located superficially or deep?

Many thin-walled veins and plexuses of capillaries lie just beneath the nasal epithelium and warm the air as it is inspired.

The superficial location of these vessels does expose them and make them easy to damage leading to nose bleeds.

Nasal conchae

• Increase surface area

• Create turbulence to deflect non-gaseous particles onto the mucous coatings

How is the heat and moisture gradient in the nasal cavity constantly being flipped?

Inspired air is warmed, and in the process, cools the conchae to warm them. In this way, the heat and moisture gradient is constantly flipping each time we breathe out, and then when we breathe in, and so forth.

Where can paranasal sinuses be found?

Paranasal sinuses are located in the frontal, sphenoid, maxillary, and ethmoid bones.

What are the functions of paranasal sinuses?

These sinuses lighten the skill but are prone to inflammation, especially due to infection or allergies.

What happens when sinuses are inflammed?

When the sinuses are inflamed (sinusitis), additional mucus (and inflammatory products) are produced and can block the openings between the sinuses and nasal cavity. When this happens, the air in the sinus is absorbed and a partial vacuum is created which causes the pain associated with a sinus headache.

Inflammation of the nasal mucosa, such as due to viral or bacterial infection, or allergic reactions causes excessive mucus production leading to congestion and postnasal drip.

What happens when food is being swallowed?

Pharyngeal tonsil (adenoid)

What happens when the pharyngeal tonsils are swollen?

Pharyngotymapnic tubes

Conducting Zone

Consists of

• all of the tubes transporting air from the nose to the respiratory bronchioles

Function

• humidify, warm, and filter air

Respiratory Zone

Consists of

• respiratory bronchioles, alveolar ducts, alveoli (main site of exchange)

Function

• Site of external respiration (gas exchange)

Functional Divisions of Respiratory System

- Cartilage is least prominent the further the bronchial tree branches

• decreases

• Goblet cells decrease

• The number of cilia decreases

Boyle’s Law

At a constant temperature, the pressure of a gas is inversely related to volume

• P= P=1/V

• A given gas in a large volume will create a small pressure & vice versa

Breathing Mechanisms for Inspiration

Muscles of Inspiration

1. Diaphragm contracts (Flattens)

2. External Intercostal muscles contract

3. Pectoralis minor

4. Scalene muscles

→ Thoracic cavity enlarges (increase volume)

→ Decreased pressure inside thoracic cavity

→ Air moves in from area of high pressure to low pressure

Breathing Mechanisms of Expiration

Muscles of Expiration

1. Diaphragm relaxes (domes up)

2. External Intercostals relax

3. internal intercostal muscles

4. abdominal muscles

→ Thoracic cavity decreases in volume

→ Decreased volume causes increased pressure inside thoracic cavity

→ Air is forced out from an area of high pressure to low pressure

Tidal Volume (TV or VT)

• The amount of air moved in or out of the lungs during a single respiratory cycle

• Normal quiet breathing

• Averages 500 mL

Inspiratory Reserve Volume

• The amount of air you can breathe in beyond tidal volume

• Deep inhalation/inspired forcefully

Expiratory Reserve Volume (ERV)

• The amount of air you can exhale beyond tidal volume (after normal exhalation)

• Deep exhalation/expired forcefully

Residual Volume (RV)

• The volume of air left in the lungs after full exhalation (dead space)

• Prevents lung collapse

• Cannot be measured in spirometry

Inspiratory Capacity (IC)

• The amount of air a person can inspire maximally after a normal expiration

• IC= IRV+TV

Functional Residual Capacity (FRC)

The amount of air remaining in the lungs at the end of a normal expiration

• FRC = ERV+RV

Vital Capacity (VC)

The respiratory trace of i person inspeel tom

VC = IRV+TV+ERV

Total Lung Capacity (TLC)

• The maximum volume of air that can be inhaled into the lungs

• TLC = IRV+ERV+TV+RV

Dalton’s Law

All the partial pressures of gases added together equal the total pressure exerted by the gas mixture

Henry’s Law

Henry's Law states when a gas is in contact with a liquid, the gas will dissolve into the liquid in proportion to its partial pressure

- The higher the partial pressure of a gas above a liquid, the more of that gas will dissolve into the liquid until equilibrium is reached

Under f solutior

• Different gases in air have different solubilities in water (and in blood)

• carbon dioxide > water > nitrogen

Hemoglobin

• Made of four iron-containing heme groups

• One hemoglobin molecule can carry up to four 02 molecules

• 98.5% of oxygen is transported bound to hemoglobin

• Binding of oxygen is rapid and reversible

• The affinity of hemoglobin for oxygen increases with each oxygen molecule bound

• Hemoglobin affinity vs partial pressure

• high PO, → Hemoglobin has a high affinity for
  oxygen

Three ways CO2 is transported in blood:

1. Dissolved in plasma (10%)

2. Bound to hemoglobin (20%)

3. Transported in plasma as bicarbonate ion, HCO,
   (70%)

Breathing Regulation

• The reticular formation of the pons and the medulla oblongata controls respiration

• Medullary respiratory centers of the medulla oblongata set the rhythm

Ventral respiratory group → Initiates inspiration and expiration

Dorsal respiratory group → Alters breathing rate

Nasopharynx

• Nasopharynx: superior part of the throat (pharynx)

• Cilla propels mucus to the stomach

• pharyngeal tonsil: contains lymphatic tissue that traps and destroys pathogens

• pharyngotympanic tubes: connect the middle ear to the nasopharynx so that air in the middle ear can match pressure with atmospheric air

• important for sound conduction and proper hearing

Oropharynx (middle) and laryngopharynx (posterior)

receive both food AND air

• have more protective stratified squamous epithelium

Larynx

Houses the vocal cords for voice production

Thyroid cartilage

Stimulated by androgens

Laryngeal prominence → Adam’s Apple

Arytenoid cartilage

Anchors the vocal cords

Glottis

The vocal cords + the opening between them

Laryngeal muscles

Move cartilage of the larynx to change the length of the vocal folds

• Changes the size of the glottis to change pitch + produce vocalizations

• Tense vocal cords = more vibration + higher pitch

Valsalva maneuver

• abdominal muscles contract + glottis closes

• increases abdominal pressure to help empty the rectum

• increases pressure in thorax + decreases venous return by squeezing major BVs and presses on the vagus nerve to increase vagal tone - slows heart rate