SPECIAL EXTRACELLULAR FLUIDS – Dr. Block Flashcards
What is the function and composition of synovial fluid?
Function: A lubricant found in joints.
Composition: Synovial fluid is normally clear-pale yellow fluid with specific gravity, glucose and electrolyte concentrations similar to plasma. It does not clot or contain fibrinogen. Contains very few cells and has a lower protein concentration than does plasma. Contains trace amounts of phosphlipids and cholesterol with NO triglycerides but some LDL and HDL.
How does synovial fluid change in a specific pathological case?
Inflammatory joint diseases lead to an increase in volume, increase in protein and globulin concentrations and a decrease in albumin. Also the fluid becomes cloudy, contains leukocytes and fibrinogen appears. After trauma, erythrocytes appear, but leukocyte concentrations are very low.
Describe the properties and function of aqueous humor.
Aqueous humor fills the anterior chamber of the eye and maintains intraocular pressure and nourishes the cornea, lens and iris. It is also the only supply of O2 to the cornea when the eye is closed and can function as a lens. In its composition, the Na, K, Mg, bicarbonate, glucose, citrate and urea concentrations are similar to that of plasma. Protein concentration is much lower (0.002), ascorbate concentration is much higher (20x), and lactate concentration is higher (1.5x) then that of plasma. Hormononally active compounds are also present. No enzymes are present.
Describe the properties and function of vitreous humor.
Vitreous humor is located in the posterior chamber. It is a clear, avascular, gelatinous material that functions to maintain intraocular pressure, offers mechanical support as a kind of shock absorber, acts as a source and sink of metabolites for the retina and acts as a lens. Very similar to plasma, with the exception that the protein concentrations are much lower (0.01 to 0.03) and the ascorbate concentrations are much higher (10x). Potassium is 1.7x that of plasma, has collagen II for structure and Hyaluronic acid for viscosity.
What is the function and composition of tears?
Most tears are secreted by the lacrimal gland and function to lubricate and oxygenate corneal tissues, wetting the optical surface and protecting the eye. Electrolyte concentration is greater in tears than in plasma, whereas the protein concentration is less than in plasma. Contains also all the enzymes necessary for glycolysis, TCA cycle, and PPP. Composition of tears are effected by rate of secretion. Isotonic = high rate. Hypertonic = slow rate (due to evaporation).
What are sensible and insensible sweat? Eccrine and apocrine sweat glands?
Types of Sweat:
Insensible sweat is when no visible perspiration is produced and consists of almost pure water.
Sensible sweat is when droplets are visible and its composition can vary depending on its rate of formation, evaporation, temperature, etc.
Glands:
Eccrine sweat glands are located on palms, soles of feet and the head and they produce dilute NaCl solution with some lactate and urea.
Apocrine sweat glands are located near the hair follicles of axilla and pubis and produce viscous sweat which contains pheromones.
What is the function and composition of cerebrospinal fluid?
Function: To protect the brain physically by forming a cushion and chemically via the blood-brain-barrier. It also helps in nutrifying the brain and meninges.
Composition:
Glucose, amino acid and protein levels are lower than that of plasma. Contains no cells or cholesterol.
What is the relationships between pathologies and sweat?
Pathological conditions can dramatically alter sweat composition.
- For Cystic Fibrosis, sweat is secreted that has a higher concentration of NaCl than normal.
- Schizophrenic patients have also been found to contain trans-3-methyl-2-hexenoic acid in their sweat which causes a peculiar body odor.
