Mechanics of Breathing
During inhalation, does the diaphragm contract or relax, and does it move up or down?
Contracts and moves down.
What is Boyle’s Law?
Gas volume is inversely proportional to pressure.
What muscle is the main one for breathing?
Diaphragm
Which disease is caused by Mycobacterium tuberculosis?
Tuberculosis
Two carrier parents: chance child has cystic fibrosis?
25% (1/4).
When the thoracic cavity expands, does lung volume increase or decrease?
Increase
If lung volume increases, does lung pressure increase or decrease? Why?
Decrease — because volume and pressure are inversely related.
What are the tiny air sacs where gas exchange occurs?
Alveoli.
Which disease damages alveoli, is often from smoking, and has no cure?
Emphysema.
Two carrier parents: chance child is a carrier?
50% (1/2).
During forced inhalation, are the ribs pulled up or pushed down?
Pulled up.
Why does air move into the lungs during inhalation?
Because outside pressure is higher than the lowered pressure inside the lungs.
What structures branch from the trachea into each lung?
Primary bronchi.
Name two asthma triggers and one short-term treatment.
Triggers: tobacco smoke, dust mites. Treatment: inhaler (bronchodilator).
One parent carrier (Ff), other FF: chance child has CF?
0% (child cannot have CF); 50% chance child is a carrier.
Name two things that happen to the lungs or chest during exhalation.
Thoracic cavity size decreases; lung volume decreases (pressure increases) causing air to leave.
If lung volume decreases, will air move in or out? Which has higher pressure?
Air moves out; inside lungs has higher pressure than outside.
Give the path of air from the nose to bronchioles in order (three or four steps).
Nasal cavity → pharynx/larynx → trachea → bronchi → bronchioles.
What does laryngitis affect and one symptom?
Affects the larynx; symptom: hoarseness or loss of voice.
In an Ff × Ff family with four kids shown, which genotype has CF?
ff has CF; FF not carrier; Ff are carriers.
List 4 short steps of inhalation (include main muscles).
Diaphragm contracts (moves down) and external intercostals lift ribs → chest volume increases → lung pressure decreases → air flows in to alveoli.
When the lungs expand during inhalation and lung volume increases, why does air flow in?
Increasing lung volume lowers internal lung pressure, so air flows in from the higher-pressure outside air.
How does chest expansion make the alveoli expand?
Chest expansion pulls the pleura, which pulls the lungs outward so alveoli volume increases.
Give two differences between influenza and tuberculosis (cause and treatment).
Influenza is viral and treated with supportive care/antivirals; TB is bacterial and treated with long-term antibiotics.
If two carriers already had a child with CF, does that change the chance their next child will have CF? Why or why not?
No — each pregnancy is independent; probability remains 25% per child.