refers to the movement of air into and out of the lungs

PULMONARY VENTILATION refers to the movement of air into and out of the lungs.

Explanation:

Pulmonary Ventilation is the movement of air into and out of the lungs. Breathing occurs due to the movement of the ribs, diaphragm and the intercostal muscles resulting in the increase and decrease in volume of the lungs. Breathing mechanism involves:

1.) Inspiration: when we breath in, the ribs are pulled upward and forward which enlarges the thoracic cavity thereby creating low air pressure in the lungs. As air is drawn in,the concentration of oxygen in the lungs is now higher than in the blood. Oxygen then diffuses from the lungs into the blood.

2.) Expiration: when we breath out,the muscle of the diaphragm relax. This reduces the volume of the thoracic cavity and increases its air pressure. At the same time the concentration of carbondioxide in the blood is higher than in the lungs and therefore diffuses from the blood onto the lungs which is expelled during expiration. I hope this helps, thanks.

they float because they are less dense than the water itself

something denser than water, like a rock, will sink to the bottom

there are 35 white marbles

step-by-step explanation:

y- yellow marbles

4y + 5 = 45

subtract 5 from both sides

4y = 40

divide for from both sides

y = 10

plug in 10 to get 40 yellow marbles then subtract by 5 to get 35 marbles

thus there are only 10 yellow marbles