Week 1: Respiratory System - Gas exchange & Hemoglobin

Identify the major structures of the respiratory tract

nose, pharynx, larynx, trachea, bronchi, bronchioles, alveoli

Distinguish the conducting zone

airways that move air

Distinguish the respiratory zone

alveoli, where gas exchange occurs

Describe the respiratory membrane

alveolar wall + capillary wall

Why is the respiratory membrane thin?

to allow gases to diffuse quickly and efficiently

State the pressure–volume relationship behind breathing

increasing volume lowers pressure, and air flows down the pressure gradient

Describe inspiration

diaphragm and intercostals contract → thoracic volume up → pressure down → air in

Describe expiration

muscles relax → volume down → pressure up → air out

Define tidal volume

the amount of air inhaled or exhaled during a normal breath

Define inspiratory reserve volume

the extra amount of air you can inhale after a normal inhalation

Define expiratory reserve volume

the extra amount of air you can exhale after a normal exhalation

Define residual volume

the amount of air remaining in the lungs after a forceful exhalation

Define vital capacity

the maximum amount of air you can exhale after taking the deepest possible breath

Define total lung capacity

the total amount of air the lungs can hold after the deepest possible inhalation

State what a spirometer measures

a device that measures the volume of air inhaled and exhaled by the lungs

Define partial pressure

the pressure of one specific gas in a mixture, which helps determine the direction it diffuses

In which direction does a gas diffuse based on its partial pressure?

high to where it is low

Define external respiration at the lungs in terms of partial pressures

O2 into blood, CO2 out

Explain internal respiration at the tissues in terms of partial pressures

O2 out to cells, CO2 into blood

How is most oxygen transported in the blood?

most oxygen is transported bound to hemoglobin inside red blood cells

How does hemoglobin load oxygen in the lungs and unload it in the body tissues?

hemoglobin binds oxygen in the lungs, where oxygen partial pressure is high, and releases it in body tissues, where oxygen partial pressure is lower

What is the oxygen–hemoglobin dissociation curve

percent saturation vs. PO2

Name the three ways CO₂ is carried in blood

dissolved, bound to hemoglobin, as bicarbonate

In what form is most carbon dioxide (CO₂) transported in the blood?

most CO2 travels as bicarbonate

Write the general bicarbonate reaction

CO2 + H2O ↔ H2CO3 ↔ H⁺ + HCO3⁻

Identify the control center that sets breathing rhythm

medulla and pons

Chemoreceptors monitor what?

carbon dioxide, oxygen, and pH.

What is the main stimulus that causes breathing to increase?

rising CO2 levels and falling blood pH are the main stimuli

How does exhaling CO₂ help regulate the body’s pH?

exhaling CO₂ reduces carbonic acid formation in the blood, lowering acidity and raising pH

How does changing the breathing rate affect blood pH?

faster breathing removes more CO₂, raising blood pH. Slower breathing keeps more CO2, lowering blood pH

Define respiratory acidosis

blood pH decreases because CO2 builds up in the blood

Define respiratory alkalosis

blood pH increases because too much CO2 is removed from the blood

How do breathing rate and depth change during exercise?

during exercise, breathing becomes faster and deeper to bring more oxygen into the body and remove more CO2

Define oxygen demand

the amount of oxygen the body needs to produce energy for its cells

Why do oxygen demand and CO₂ production rise during exercise

working muscles need more oxygen to produce ATP through cellular respiration and produce more CO2 as a waste product

Describe the central challenge of high altitude

lower atmospheric oxygen partial pressure

Distinguish obstructive lung disease in general terms

makes it difficult to move air out of the lungs because the airways are narrowed or blocked

Distinguish restrictive lung disease in general terms

lung tissue becomes stiff making it difficult for the lungs to expand fully, reducing the amount of air they can hold

Give an obstructive example

asthma or COPD

Give a restrictive example

pulmonary fibrosis