Barrier between plasma and. ECF and ICF. Homeostasis: process of maintaining consistent composition of body s extracellular fluid

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1 : process of maintaining consistent composition of body s extracellular fluid Extracellular fluid (ECF) Fluid in which the cells live (fluid outside the cells) Major components: Plasma interstitial fluid Minor ECF components Lymph, transcellular fluid,cerebrospinal fluid, Intraocular fluid, synovial fluid, pericardial, intrapleural, and peritoneal fluids,digestive juices Intracellular fluid (ICF) Fluid contained within all body cells Fig. 1-5, p. 7 Barrier between plasma and interstitial fluid Blood vessel walls Barrier between ECF and ICF Cellular plasma membranes Barriers Separating Body Fluid Compartments 2 Blood= plasma + cells = capillary membrane separating plasma from interstitial fluid 2 = cell membrane separating ICF and ECF 3 = interstitial fluid 4 = intracellular fluid 5 = plasma, which is a part of blood; ECF trapped in capillary vessels

2 Barriers Separating Body Fluid Compartments Major differences between Extracellular Interstitial Fluid and Intracellular Fluid (ICF) Presence of cell proteins in ICF that cannot permeate the cell membrane to leave the cells Unequal distribution of Na + and K + and their attendant ions Overall electric (charge) balance between intracellular and extracellular fluid Overall osmotic balance between intracellular and extracellular fluid Milliequivalents per liter of H 2 O Plasma HCO 3 Capillary wall Interstitial fluid HCO 3 Na + Cl Na + Cl Intracellular fluid (skeletal muscle) Protein anions Protein K + anions Other Other Other K + Other Other Cations Anions Cations Anions Cations Anions Plasma membrane Na + K + PO 4 3 Fig. 14-2, p. 419 What is the expected volume of each compartment in a person weighing XXX pounds who is normally hydrated? Total Body Water (liters) = 60% of body weight kg Convert pounds to kilograms, multiply by.6 Liters/kg body weight to estimate Liters of Total Body Water ICF = 2/3 of TBW ECF = 1/3 of TBW Interstitial fluid = 75 80% of ECF Use 75% Plasma = 20-25% of ECF Use 25% 40% of body weight is intracellular fluid 20% of body weight is extracellular fluid

3 (Your body weight / 2) - 10% of answer = your weight in kg 160 lbs / 2 = 80 actual conversion160/2.2= (10% of 80) ~ 72 kg 160/ = Assume 1 kg weight = 1 liter fluid The primary extracellular fluid (ECF) cation is sodium The primary intracellular fluid (ICF) cation is potassium. This difference is maintained by the Na + /K + ATPase, which transport three Na + molecules out of the cell in exchange for two K + molecules transported into the cell. A balance of positive and negative charges is maintained in each compartment, but by different ions. 60% of 72kg, in liters 72 kg Maintain Body systems that make up Cells (consistency of ECF) Which is essential for function (1-6, + specialized) of Factors homeostatically regulated include Concentration of nutrient molecules Concentration of O 2 and CO 2 Concentration of waste products ph (concentration of free H+ or protons) Concentration of water, salt, and other electrolytes Blood volume and blood pressure Body Temperature Cell activity upsets (disorders) and restores (orders) ECF Fig. 1-6, p. 7

4 Circulatory system Carries materials from one part of the body to another Digestive system Breaks down dietary food into smaller molecules that can be distributed to body cells Transfers water and electrolytes from external to internal Eliminates undigested food residues to external in the feces Respiratory system Gets O 2 from and eliminates CO 2 to the external Important in maintenance of proper ph of internal Urinary system Removes excess water, salt, acid, and other electrolytes from plasma and eliminates them in urine; balances fluid and electrolytes Skeletal system Provides support and protection for soft tissues and organs Serves as storage reservoir for calcium Along with muscular system enables movement of body and its parts Bone marrow is ultimate source of blood cells Muscular system Moves the bones Integumentary system Serves as outer protective barrier Important in regulating body temperature Immune system Defends against foreign invaders and against body cells that have become cancerous Paves way for repairing or replacing injured or worn out cells

5 Nervous system Controls and coordinates bodily activities that require rapid responses Detects and initiates reactions to changes in external Endocrine system Secreting glands of endocrine regulate activities that require duration rather than speed Controls concentration of nutrients and, by adjusting kidney function, controls internal s volume and electrolyte composition Reproductive system Not essential for homeostasis (not essential for survival of individual) Is essential for perpetuating the species Homeostatic Control Systems In order to maintain homeostasis, control system must be able to Detect deviations from normal in the internal that need to be held within narrow limits Integrate this information with other relevant information Make appropriate adjustments in order to restore factor to its desired value Fig. 1-7, p. 12