Human Physiology
100

In the lungs, oxygen diffuses into the blood because the partial pressure of oxygen is higher in the alveoli than in this thing.

Pulmonary capillaries
200

Most nutrient absorption in humans takes place in this section of the digestive tract, which contains villi and microvilli to increase surface area.

Small intestine

300

Calcium ions stored in this organelle are released during muscle contraction.

Sarcoplasmic Reticulum

400
This part of the nephron is non-permeable to water but is permeable to NaCl. It does not have the capacity for active ion transportation.

Thin part of ascending loop of henle

500

Jason, a 19-year-old college student, is walking to class one day and slips on some notoriously slippery Bostonian ice, breaking his hip. Upon questioning by his doctor, he admits to feeling “slowed down” lately and experiencing frequent nausea, thirst, headaches, and muscle pain. Which organ is most likely malfunctioning?

Parathyroid

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