Lab 7

Anatomy of the Respiratory System

In the conducting zone, the air is transported from the nose all the way to the respiratory  bronchioles. Beginning at the respiratory bronchioles, you have the exchange of oxygen and carbon dioxide.

Anatomy of the Respiratory System 2

• gas exchange occurs in the bronchioles and the alveoli

• intrapulmonary pressure: the pressure in the alveoli

Bronchioles

Bronchioles have cilia and goblet cells

• goblet cells make mucus which traps dust and germs

• cilia move mucus upward (ciliary escalator & resp. tract)

This helps keep the airways clean and prevent respiratory infections!

• as people age inactive cilia and decreased mucus secretion from goblet cells make then more prone

Airflow

as airflow moves from the trachea to the primary bronchi → secondary bronchi (gets closer to alveoli) → tertiary bronchi the cross-sectional area gets smaller and the flow gets less turbulent and more laminar or steady (gets slower & straighter)

Gas Exchange in the Lungs: Partial Pressure

• CO2 is the main drive of breathing under normal conditions

• the medulla oblongata monitors CO2 levels more than O2

• nitrogen is the most abundant gas in air and the highest partial pressure in the lungs

• nitrogen is most abundant because it is very stable and relatively unreactive

• because it does not readily participate in has exchange, it largely remains in the air spaces of the lungs

Respiratory System

• Pulmonary ventilation: Inspiration and expiration, the movement of air in and out of the lungs

  • what we think of as respiration (breathing)

  • movement of air and all of its products

• External respiration: breathing, occurs at the alveolar level

  • Carbon dioxide diffuses to the lungs from blood

  • Oxygen diffuses to the blood from lungs

  • CO2 out, O2 in

• Internal respiration: occurs at the cellular level

  • Oxygen diffuses from blood to cells

  • Carbon dioxide diffuses from cells to blood

  • O2 travels with Hb

Breathing Mechanisms

two muscles that assist in breathing: diaphragm and the external intercostal muscles

• inspiration increases available volume for lungs

Spirometry and Lung Function

• Process of measuring volumes of air that move into and out of the respiratory system using a spirometer

• Pulmonary volumes:

  1. Tidal volume

  2. Inspiratory reserve volume

  3. Expiratory reserve volume

  4. Residual volume

Pulmonary Capacities

Pulmonary Capacities 2

IC= IRV+TV 

(amount of air a person can inspire maximally after a normal expiration)

FRC= ERV+RV 

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

VC=IRV+TV+ERV 

(maximum volume of air a person can expel from the respiratory tract after a maximum inspiration)

TLC=IRV+ERV+TV+RV

Pulmonary Capacities 3

Lung Volume and Capacities

A: residual volume (RV)

B: vital capacity (VC)

C: inspiratory reserve volume (IRV)

D: tidal volume (TV)

E: total lung capacity (TLC)

F: expiratory capacity (EC)

G: inspiratory capacity (EC)

Where does the residual volume come from? Where does the tidal volume come from?

• Residual: extra space in lungs

  • D is at the level of primary and secondary volume

• Tidal volume comes from B

Physics of Gas Exchange

• When a gas is in contact with a liquid that gas will dissolve in the liquid in proportion to its partial pressure.

• For gas exchange to be efficient, there must be a close match, or coupling, between the amount of gas reaching the alveoli, known as ventilation, and the blood flow in pulmonary capillaries, known as perfusion.

• Oxygen and carbon dioxide move into and out of the body by diffusion down pressure gradients. (High to low pressure)

• Bohr Effect occurs when increasing partial pressures of carbon dioxide weakenend the hemoglobin-oxygen bond. The hemoglobin can then bind carbon dioxide and hydrogen ions to buffer carbon dioxide transport as bicarbonate. This is known as the Haldane effect. 

• At the body tissues, high carbon dioxide causes oxygen to dissociate from hemoglobin which allows more carbon dioxide to bind to the hemoglobin thus facilitating the exchange of gases. In the lungs, the gas gradients reverse, and the uptake of oxygen facilitates the release of carbon dioxide. As hemoglobin saturates, it releases the bound hydrogen ions which then combine with bicarbonate ions to generate carbonic acid which is subsequently converted to water and carbon dioxide. The carbon dioxide is then available to be removed from the body. 

Some Medical Terms

Hypoxia: not enough oxygen (in response to ischemia)

Ischemia: not enough blood flow (blood carries oxygen to body, obstruction of blood vessel)

• Ischemia often causes hypoxia, but hypoxia does not always mean ischemia

• Anemic Hypoxia: lack of oxygen delivery due to too few erythrocytes (RBCs)

Hypocapnia: low carbon dioxide (CO₂) in the blood (alkalosis, low Co2 in blood)

Emphysema: permanent enlargement of the alveoli due to destruction of the alveolar walls

Hyperpnea: increased respiratory rate in response to increased metabolic demand, like running a marathon

Hyperventilation

hyperventilation → kicks off lots of CO2 → blood pH goes up (alkalosis)

• high CO2 in blood, low blood pH, acidosis

• hyperventilation → alkalosis

Bohr Effect

• Hemoglobin binding curve shows how hemoglobin picks up and drops off oxygen

• In the lungs, hemoglobin binds oxygen; in the tissues, it releases oxygen

• Bohr effect: Increasing partial pressures of carbon dioxide weakening the hemoglobin-oxygen bond

• Haldane effect: when hemoglobin releases oxygen, it can carry more CO₂

• O2 and CO2 always reverse

Oxygen-Hemoglobin Dissociation Curve

Breathing Regulation

• Respiration is controlled in the pons and medulla oblongata

Medulla oblongata

• Ventral respiratory group

  • Initiates inspiration and expiration

• Dorsal respiratory group

  • Alters breathing rate 

Pons

• Pontine respiratory group

  • Modifies and fine tunes breathing rhythms

  • makes it more smooth… w/out, breathing would be choppy

The lungs role in the (Renin-Angiotensin-Aldosterone System) RAAS System

• ACE: Angiotensin Converting Enzyme

• The RAAS system regulates blood pressure!