Fluid Balance and Cellular Metabolism Lecture Review

Flashcards covering fluid compartments, electrolyte balance, kidney filtration mechanisms, cellular respiration stages, and hormonal regulation of pH and blood pressure.

Intracellular fluid (ICF)

The fluid found inside the cells, also known as the cytosol, which contains high concentrations of potassium and phosphate.

Extracellular fluid (ECF)

The fluid found outside the cells, including interstitial fluid between tissue cells and plasma within blood vessels.

Phospholipid bilayer

The structure of the plasma membrane where the outside is hydrophilic and the inside is hydrophobic.

Filtration

The movement of liquid and blood components through a membrane due to hydrostatic pressure.

Reabsorption

The process of returning water and electrolytes to the plasma, driven by blood colloid osmotic pressure exerted by proteins.

Osmosis

The primary means of water exchange between fluids, where water follows the concentration gradient of electrolytes and solutes.

Metabolism

The sum of all chemical reactions in the body, consisting of anabolism (building up) and catabolism (breaking down).

Cellular respiration

The process where cells break down glucose and oxygen to produce ATP, with byproducts of $CO_2$, water, and heat.

Glycolysis

The first step of cellular respiration occurring in the cytosol that breaks down glucose into pyruvate and yields $2$ ATP.

Electron transport chain

The stage of aerobic respiration in the inner mitochondrial membrane that produces the majority of ATP, approximately $32$ to $36$ units.

Anaerobic respiration

An oxygen-free energy production process occurring in the cytosol that produces lactic acid.

Creatine system

A rapid energy-production mechanism used by muscles for short, intense activities like a $100$-meter sprint.

Osmoreceptors

Sensory receptors found in the hypothalamus that detect increases in blood osmolarity and trigger the thirst center.

Antidiuretic hormone (ADH)

A hormone released by the posterior pituitary that promotes water reabsorption by inserting aquaporin channels into the collecting ducts.

Aldosterone

A hormone from the adrenal cortex that increases sodium ($Na^+$) reabsorption and potassium ($K^+$) secretion in the distal convoluted tubule (DCT).

Atrial natriuretic peptide (ANP)

A hormone secreted by the heart atria in response to high blood pressure that promotes the excretion of sodium and water in urine.

Hyperkalemia

An above-normal concentration of potassium in the blood that can be lethal due to its effect on heart rhythm and resting membrane potential.

Sodium-Potassium Pump

An active transport mechanism that constantly throws sodium ($Na^+$) out of the cell and brings potassium ($K^+$) in to maintain cell gradients.

Bicarbonate ($HCO_3^-$)

The principal buffer in the extracellular fluid that helps maintain the blood pH between $7.35$ and $7.45$.

Acidosis

A condition where blood pH falls below $7.35$, leading to depression of the central nervous system and possible coma.

Alkalosis

A condition where blood pH rises above $7.45$, leading to overexcitability of the nervous system and muscle spasms.

Volatile acid

Acid produced from carbon dioxide ($CO_2$) during metabolism that can be eliminated through the lungs via respiration.

Nonvolatile acid

Acids generated from the metabolism of nutrients like proteins and fats that must be buffered by bicarbonate and excreted by the kidneys.

Hemoglobin buffer

A protein buffer system in red blood cells that reversibly binds hydrogen ions to stabilize blood pH.

Water intoxication

A condition caused by drinking excessive plain water, leading to low sodium concentration and the swelling of body cells.