Physiology Questions

At an atmospheric pressure of 870 mm Hg with 21 percent oxygen, the partial pressure of oxygen is _____.

182 mm Hg

Freshwater fish reside in hypotonic environments. They do not drink water, and they excrete large volumes of hypotonic urine in an effort to osmoregulate. How do they obtain an adequate supply of electrolytes?

Gill filaments take up additional electrolytes from freshwater.

Sharks live in seawater. Their tissues are isotonic to seawater, but their concentrations of sodium ions, potassium ions, and chloride ions in cells and extracellular fluids are similar to those of freshwater fishes. How is that possible?

High concentration of urea contribute to intra- and extracellular osmolarity in shark tissues.

What adaptations are observed in trachea and lungs to reduce water loss?

The location of the trachea and lungs (inside of the body) reduces water loss.

What role do chloride cells play in osmoregulation of marine fish with bony skeletons?

They are involved in excretion of excess salt.

If other factors are equal, which of the following environments would have the highest level of dissolved oxygen?

cool freshwater at low elevation

If, during protein starvation, the osmotic pressure on the venous side of capillary beds drops below the hydrostatic pressure, then _____.

fluids will tend to accumulate in tissues

A necropsy (postmortem analysis) of a marine sea star that died after it was mistakenly placed in fresh water would likely show that it died because ____

it was so hypertonic to the fresh water that it could not osmoregulate

Blood returning to the mammalian heart in a pulmonary vein drains first into the _____.

left atrium

The necropsy (postmortem analysis) of a freshwater fish that died after being placed accidentally in saltwater would likely show that _____.

loss of water by osmosis from cells in vital organs resulted in cell death and organ failure

Organisms categorized as osmoconformers are most likely _____

marine

Materials are returned to the blood from the filtrate by which of the following processes?

selective reabsorption

Which of the following develops the greatest pressure on the blood in the mammalian aorta? ​

systole of the left ventricle

The greatest difference in the concentration of respiratory gases is found in which of the following pairs of mammalian blood vessels?

the pulmonary vein and the superior vena cava

For filtration to take place through the fenestrated capillaries of the renal corpuscle, ____

there must be a greater pressure inside the glomerulus than in the renal tubules

The blood pressure is lowest in the ____

vena cava

Which of the following events would be predicted by the Bohr shift effect as the amount of carbon dioxide released from your tissues into the blood capillaries increases? The amount of oxygen in _____.

venous blood would decrease

Gas exchange is more difficult for aquatic animals with gills than for terrestrial animals with lungs because _____.

water contains much less oxygen per unit volume than air