Lungs-Structure, Function & Acid-Base Balance

Flashcards covering lung anatomy, breathing mechanics, gas exchange mechanisms, and the respiratory system's role in maintaining acid-base balance.

Thoracic cavity

The location where the lungs are situated, on either side of the heart.

Right lung

The lung that is composed of $3$ lobes.

Left lung

The lung that is composed of $2$ lobes to accommodate space for the heart.

Pleura

The protective covering of the lungs that facilitates smooth movement during breathing.

Pathway of air

Nose/mouth $\rightarrow$ pharynx $\rightarrow$ larynx $\rightarrow$ trachea $\rightarrow$ bronchi $\rightarrow$ bronchioles $\rightarrow$ alveoli.

Alveoli

Tiny air sacs with thin walls surrounded by capillaries where gas exchange takes place.

Gas exchange

The main function of the lungs, involving bringing oxygen into the blood and removing carbon dioxide.

Oxygen transport at the alveoli

Oxygen diffuses from the alveoli into the blood and binds to haemoglobin in red blood cells.

Carbon dioxide removal at the alveoli

Carbon dioxide diffuses from the blood into the alveoli and is removed during exhalation.

Inhalation

The process where the diaphragm contracts and moves down, the external intercostal muscles contract, and thoracic volume increases, drawing air into the lungs.

Exhalation

The process where the diaphragm relaxes and moves up, reducing thoracic volume and causing air to leave the lungs.

Carbonic acid

A substance formed when $CO_2$ combines with water; it can release hydrogen ions and lower blood pH.

Blood pH acidity (increase in $CO_2$)

When $CO_2$ increases, more hydrogen ions are produced, causing blood pH to fall and become more acidic.

Lung control of blood pH

Regulation of blood pH by changing the rate and depth of breathing to adjust the amount of $CO_2$ removed.

Acidic blood response

Breathing rate increases to remove more $CO_2$, which helps raise the blood pH.

Alkaline blood response

Breathing slows down to allow $CO_2$ to increase, which helps lower the blood pH.

Kidney acid-base balance

Slower, longer-term control where the kidneys remove hydrogen ions and regulate bicarbonate ($HCO_3$) levels in the blood.

pH control speed

Lungs provide faster, rapid control of blood pH, while kidneys provide slower, long-term control.