Electrolytes Free moving ions in a solution that conduct electricity – Galvanic cell converts chemical energy into electrical – Electrolytic cell – converts electrical energy into chemical
Biological concepts related to ions Fluid balance Photosynthesis/ respiration – Electron transport system Membrane potential Oxidation reduction reactions
Terms Flow of electrons (ions) from one region to another is driven by a difference in potential energy Voltage: difference in electrochemical potential energy between two electrodes (V) – Does not depend on size of the electrodes or amount of materials. AAA, AA, A all have 1.54 V – All our cells have -90mV Current: the rate of electron flow (amps)
Major electrolytes Taken as minerals (along with vitamins) Several of them are needed for proper function of enzymes (cofactors) As for your body, the major electrolytes are as follows: – sodium (Na + ) - depolarization – potassium (K + ) - repolarization – chloride (Cl - ) – balancing the charges – calcium (Ca 2+ ) – trigger muscle contraction – magnesium (Mg 2+ ) - – bicarbonate (HCO 3 - ) – acid/base – phosphate (PO 4 2- ) - bones – sulfate (SO 4 2- ) - bones
Electrolytes and Water Balance Pure water vs electrolytes cells need to be bathed in fluids — inside and out. the current enables electrolytes to regulate how and where fluids are distributed throughout the body, which includes keeping water from floating freely across cell membranes. – Water follows the charged ions help maintain a state of fluid balance. transport nutrients into cells and wastes out of them. The difference in electrical balance inside and outside of cells also allows: – for transmission of nerve impulses, – contraction or relaxation of muscles, – blood pressure control, and – proper gland functioning.
Sodium levels 136 and 145 milliequivalents per liter (mEq/L) of sodium Sodium plays a key role in your body. It helps maintain normal blood pressure, supports the work of your nerves and muscles, and regulates your body's fluid balance. Hyponatremia: When the sodium levels in your blood become too low, excess water enters your cells and causes them to swell. Swelling in your brain is especially dangerous because the brain is confined by your skull and unable to expand. Hypernatremia, the body contains too little water for the amount of sodium. The sodium level in blood becomes abnormally high when water loss exceeds sodium loss, as typically occurs in dehydration, typically causes thirst. The most serious symptoms of hypernatremia result from brain dysfunction, confusion, muscle twitching, seizures, coma, and death.
8 Water and Mineral Availability Only minerals dissolved in water in spaces among soil particles are available -Organic soil particles tend to have negative charges, and so attract positive ions -Therefore, active transport is needed to move positive ions into root hairs
10 Plant Nutrients Plants require a number of inorganic nutrients -Macronutrients: Used in relatively large amounts -Nine = C, O, H, N, K, Ca, Mg, P & S -Micronutrients: Used in minute amounts -Seven = Cl, Fe, Mn, Zn, B, Cu & Mo A deficiency of any one can have severe effects on plant growth
12 Responses to Mechanical Stimuli http://plantsinmotion.bio.indiana.edu/plantmotion/m ovements/nastic/mimosa/mimosa.html (animation of plant response) Mimosa pudica leaves have swollen structures called pulvini at the base of their leaflets -When leaves are stimulated, an electrical signal is generated -Triggers movement of ions to outer side of pulvini -Water follows by osmosis -Decreased interior turgor pressure causes the leaf to fold
14 Carnivorous Plants Often grow in acidic soils that lack nitrogen -Trap and digest small animals, primarily insects, to extract additional nutrients -Have modified leaves adapted for luring and trapping prey -Prey is digested with enzymes secreted from specialized glands
16 The Rate of Transpiration Guard cells have thicker cell walls on the inside and thinner cell walls elsewhere -This allows them to bulge and bow outward when they become turgid -Causing the stomata to open Turgor in guard cells results from the active uptake of potassium (K + ), chloride (Cl – ), and malate
20 Water Stress Responses Plants, such as mangroves, that grow in salt water produce pneumatophores -Long, spongy, air-filled roots, that emerge above the mud -Have large lenticels through which oxygen enters -These plants also secrete large quantities of salt
22 Water Stress Responses Plants called halophytes live in saline soil -Produce high concentrations of organic molecules in their roots -This decreases the water potential enhancing water uptake from the soil
Humans and Electric shock 1mA – sense the shock 10-20mA “knocked across the room” or “can’t let go” effect – muscle contract and propelling them 100-300 mA – irregular uncoordinated heart beat disrupts overall pattern of the heart beat Defibrillator – 6A – continuous ventricular contraction and respiratory paralysis Everything stops – back to normal heart beat
Frequency effect 60 Hz – same as firing frequency of nerves Humans are most sensitive and is most dangerous frequency
Resting membrane potential Bioelectricity – Slight differences in ion concentrations – Inside more negative – Outside more positive – Difference -80mV – Concentration gradient - electrical potential – Coulombs force