Osmosis, Concentration, and Diabetes Lecture

These flashcards review key concepts from the lecture on diffusion, osmosis, concentration, and how these principles apply to diabetes-related physiology.

What is diffusion in the context of cell biology?

The passive movement of molecules or ions from an area of higher concentration to an area of lower concentration.

Define osmosis in its simplest form.

The diffusion of water molecules across a semi-permeable membrane.

During osmosis, water moves toward the side with a _ molecular water concentration.

lower

During osmosis, water moves toward the side with a _ solute concentration.

higher

Why is a semi-permeable (selectively permeable) membrane essential for osmosis?

Because it allows water to pass but restricts solute movement, preventing solutes from equilibrating and driving net water flow.

What would happen if a membrane were freely permeable to the solute in an osmosis scenario?

The solute would diffuse until equal on both sides, eliminating the osmotic gradient and stopping net water movement.

State the three equivalent ways to define osmosis given in the lecture.

1) Diffusion of water across a semi-permeable membrane; 2) Movement of water from high to low molecular water concentration; 3) Movement of water toward higher solute concentration.

Is osmosis an active or passive process?

Passive.

Explain the phrase “solutes suck” in one sentence.

It reminds us that water is drawn toward the compartment containing more solute particles.

What is osmolarity?

A measure of solute concentration in a solution.

In the Ovaltine example, why is the glass with two scoops darker?

It has a higher concentration of Ovaltine solute particles in the same volume of milk.

When comparing two solutions, which two factors determine concentration?

The volume of solvent (water) and the amount of solute present.

Which pancreatic cells secrete insulin?

Beta cells in the islets of Langerhans.

What is the underlying cause of Type 1 diabetes?

Autoimmune destruction of pancreatic beta cells leading to insufficient insulin production.

What lifestyle factors commonly contribute to Type 2 diabetes?

Poor diet and lack of exercise, leading to chronically high blood glucose and insulin resistance.

Why does glucose appear in the urine of untreated diabetics?

Excess blood glucose is filtered by the kidneys and cannot be reabsorbed efficiently, so it remains in the filtrate and urine.

How does glucose in the filtrate lead to increased urination (polyuria) in diabetics?

Glucose acts as a solute that osmotically draws water into the filtrate, increasing urine volume.

Which renal structures initially filter blood to form filtrate containing excess glucose?

The nephrons of the kidneys.

Summarize the relationship between solute concentration, water movement, and diabetic polyuria in one sentence.

Excess glucose in the kidney filtrate raises solute concentration, so water follows by osmosis, producing large volumes of urine.

In one phrase, what is the key takeaway of the lecture regarding osmosis?

Water follows solutes across semi-permeable membranes.