Fluid Balance and Cellular Transport Lecture Notes

This set of vocabulary flashcards covers the mechanisms of fluid movement, types of IV solutions, cellular transport, and the physiological roles of water in temperature regulation and the CNS.

Osmosis

The movement of water from an area of lower osmolality (lower solute concentration) to an area of higher osmolality (higher solute concentration) until concentrations equalize.

Crystalloid

A solution of small molecules, such as normal saline ($0.9\%$ Sodium chloride), that can pass through capillary walls and is used for hydration or replacing electrolytes.

Colloid

A solution containing large particles like Albumin (protein found in blood) that are too big to pass through capillary walls and help draw water into blood vessels.

Active transport

A process requiring energy (ATP) to move substances against their concentration gradient from an area of low concentration to high concentration.

Diffusion

The movement of substances like $O_2$, $CO_2$, and $H_2O$ down a concentration gradient from high to low concentration without requiring energy (ATP).

Sodium-potassium pump

A cellular mechanism that actively pumps $3$ sodium ions out of the cell and $2$ potassium ions into the cell using ATP to maintain an electrochemical gradient.

Hypotonic solution

A solution with a lower solute concentration than the cell, causing water to rush into the cell and resulting in the cell swelling.

Hypertonic solution

A solution with a higher concentration than the cell, causing water to leave the cell and resulting in the cell shrinking.

Isotonic solution

A solution with a concentration equal to the inside of the cell, resulting in no net water movement and a stable cell volume.

Hydrostatic pressure

The pressure that decreases along a capillary; it is highest at the arterial end due to heart pressure and lowest at the venular end.

Edema

The swelling of tissues that occurs when fluid escapes into surrounding spaces due to increased capillary permeability or leaky capillary walls.

Lymph channels

Structures that collect excess fluid (lymph), including the $10\%$ of fluid leaked from capillaries not reabsorbed by veins, and return it to the bloodstream.

Specific heat capacity (of water)

The property of water that allows it to absorb and store heat to prevent sudden temperature changes, essential for maintaining body temperature.

Glymphatic system

A system in the Central Nervous System (CNS) that cleanses waste products and provides nutrient delivery and waste clearance from brain tissue.

Synovial fluid

A water-based fluid that acts as a lubricant between bones in the joints.

Cartilage

The cushion for joints that is kept plump by water to protect and strengthen muscles and reduce inflammation.

Hypothalamus

The part of the brain that controls the thirst mechanism and contains osmoreceptors to regulate water intake.

Osmoreceptors

Sensors in the hypothalamus that detect high osmolality in blood plasma, triggering thirst and the release of ADH.

ADH (Antidiuretic Hormone)

A hormone that increases during dehydration to signal the kidneys to reabsorb more fluid, thereby decreasing urine output.

Aldosterone

A hormone that helps raise blood pressure by increasing sodium and water reabsorption in the kidneys to increase blood volume.