Human Physiology: Body Fluids and Composition

Fluid inside cells, making up around 70% of total body water. It plays a crucial role in cell function and maintaining the internal environment.

Fluid outside cells, making up the remaining 30% of total body water. It includes blood plasma and interstitial fluid.

A person's overall weight is influenced by the amount of fluid they carry. This is because body fluids contribute a significant portion of our overall weight.

The percentage of body fluid is higher in younger people than in older adults.

Men have more body fluid than women because of differences in body composition, such as muscle mass.

Fat cells contain less water compared to lean muscle mass, so obese individuals tend to have lower overall body fluid percentages.

The skeleton is made up of bones and contains a lower percentage of water compared to other tissues like skin or muscle.

Blood, skin, and muscle tissue are known to have the highest water content in the body.

Movement of a substance across a membrane from an area of higher concentration to an area of lower concentration.

Movement of water across a semi-permeable membrane from an area of high water concentration to an area of low water concentration.

The movement of substances across a cell membrane against their concentration gradient (from low to high). Requires energy (ATP).

A specific type of active transport that pumps sodium ions (Na+) out of the cell and potassium ions (K+) into the cell. Important for maintaining cell potential and nerve impulse conduction.

A protein channel that opens in the cell membrane to allow glucose to enter the cell. Insulin is required for this to happen.

A solution that has a lower concentration of solutes compared to the cell. When a cell is placed in a hypotonic solution, water moves into the cell, causing it to swell.

A solution that has a higher concentration of solutes compared to the cell. When a cell is placed in a hypertonic solution, water moves out of the cell, causing it to shrink.

A solution that has the same concentration of solutes as the cell. When a cell is placed in an isotonic solution, there is no net movement of water.

The force exerted by blood pushing against the walls of blood vessels.

The pressure required to oppose the osmotic pull of proteins, mainly albumin, drawing fluid into the blood vessels.

The ability of a solution to change the volume of a cell due to water movement across the cell membrane.

The concentration of dissolved particles (solutes) per liter of solution.

The concentration of dissolved particles (solutes) per kilogram of solution.

Fluid in the space between cells, encompassing blood plasma and interstitial fluid.

Fluid inside cells, vital for cell function and maintaining internal balance.

An excessive accumulation of fluid in interstitial spaces or the extracellular compartment causing swelling.

A condition characterized by an abnormal increase in body fluid volume.

A condition where a person's body cannot retain adequate fluids, leading to dehydration.

A medical intervention aimed at replacing lost fluids, often through oral rehydration or intravenous solutions.

A common electrolyte imbalance characterized by low potassium levels in the blood (<3.5 mEq/L).

A condition characterized by high potassium levels in the blood (>5.5 mEq/L). It can be caused by various factors, including kidney dysfunction, excess intake, and certain medications.

A hormone released by the adrenal glands that helps regulate blood pressure and electrolyte balance. It enhances sodium reabsorption, contributing to fluid retention and potassium excretion.

Sodium (Na+) is a crucial electrolyte found primarily in the extracellular fluid. It plays a vital role in maintaining fluid balance, nerve impulse conduction, and muscle contraction.

Important electrolyte that helps regulate heart rhythm, nerve function, and muscle contraction. Low potassium levels (hypokalemia) can lead to heart problems, fatigue, muscle cramps, and weakness.

A hormone released by the heart's atria (upper chambers) in response to high blood pressure or excess blood volume. It helps lower blood pressure and regulate fluid balance by promoting sodium and water excretion, reducing thirst, and dilating blood vessels.

Specialized sensory receptors located in blood vessel walls that detect changes in blood pressure. They send signals to the brain, initiating adjustments to maintain blood pressure within a normal range.

Specialized sensors located in the brain that detect changes in the concentration of solutes (like salt) in the blood. They help regulate fluid balance by triggering thirst and influencing hormone release to control water reabsorption.

Substances that dissolve in solution and are capable of conducting an electrical current due to their ability to break into charged particles (ions). Electrolytes play vital roles in maintaining fluid balance, nerve function, and muscle contraction.

Positively charged ions.

Negatively charged ions.

A fluid volume deficit where both the volume (amount) and concentration (osmolality) of body fluids are decreased. This indicates a loss of both water and electrolytes.

A fluid volume deficit where the volume of body fluids is decreased, but the concentration remains normal. This indicates a loss of water, but electrolytes are relatively balanced.