1-how does the osmolarity of the kidney interstitial fluid change from the cortex to the inner medulla? why is this important? 2-• in the medulla, the solute concentration is high which allows water to diffuse out of the loop of henle through osmosis. the vasa recta capillaries are also in the medulla. how does their solute and water concentration change along the loop?

Osmolarity of the kidney’s interstitial fluid increases from the cortex to inner medulla. This ensures that there is a concentration gradient that allows for osmosis to take place along the kidney tubules in a kind of countercurrent flow exchange system. This way most, amount of water can be reabsorbed.

The same occurs in the loop of Henle in a process called countercurrent multiplication. The descending loop actively takes up solutes hence making the blood plasma in the the vasa recta highly concentrated. In the ascending loop, therefore, water in the tubules is reabsorbed by osmosis hence making urine more concentrated as it gets to the bladder.

interphase

the period of cell growth when the cell synthesizes new molecules and organelles. the cell is not dividing and it constitutes the majority of the time spent in the cell cycle

prophase

changes occur in the nucleus and cytoplasm. the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still in tact

prometaphase

the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids

metaphase

all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle

anaphase

begins when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the cell

telophase

the daughter nuclei form at the two poles of a cell

cytokinesis

the division of a cytoplasm to form two separate daughter cells. usually occurs during telophase during mitosis. this and mitosis make up to mitotic (m) phase of the cell cycle