pages 524-531. blood composition depends on: 1. diet 2. cellular metabolism 3. urine output how...
TRANSCRIPT
Pages 524-531
Blood composition depends on:1. Diet2. Cellular metabolism3. Urine output
How the kidneys manage blood composition:1. Excretion of nitrogenous wastes2. Water/electrolyte balance of the blood3. Ensuring proper blood pH
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The main fluid compartments that water occupies: 1. Intracellular Fluid (ICF) : fluid inside cells2. Extracellular Fluid (ICF) : fluid outside cells
1. interstitial fluid2. blood plasma, CSF, lymph, humors of the eye
Changes in electrolyte balance can influence blood volume/blood pressure, cellular activity
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Lungs Gastrointestinaltract
Kidneys
Bloodplasma
Interstitialfluid
Intracellularfluid in tissue cells
O2 CO2 Nutrients
O2 CO2 Nutrients
H2O,Ions
H2O
H2O,Ions
Ions
Nitrogenouswastes
Nitrogenouswastes
Electrolytes: charged particles (ions) that conduct an electrical current in aqueous solution allow reactions that require electrical charge to take
place Cell membrane stability Muscle contraction Nerve impulse
Body electrolytes include: Sodium (Na⁺) Potassium (K⁺) Calcium (Ca⁺⁺) Magnesium (Mg⁺⁺)
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Osmoreceptors: cells in the hypothalamus Activated by small changes in blood
composition Results in a dry mouth Reinforces the drive to drink water
What is a diuretic? A substance that causes your kidneys to eliminate more salt and water than it should
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Hormones regulate reabsorption of water and electrolytes by the kidneys Antidiuretic hormone (ADH)
Hypothalamus tells posterior pituitary to release ADH
prevents excessive water loss in the urine increases water reabsorption
Aldosterone (produced by adrenal cortex) increases sodium and water reabsorption; decreases potassium reabsorption
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Regulates blood pressure The juxtaglomerular (JG) apparatus of the
renal tubules sense drop in BP or solute concentration
Causes release of the enzyme renin into blood
Renin produces angiotensin II Acts directly on the blood vessels to
vasoconstrict Works to reduce filtrate volume
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Ideal blood pH: between 7.35 and 7.45 Kidneys : biggest impact in controlling
pH Other acid-base controlling systems
Blood buffers Respiration
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HCl H2CO3
H2CO3
H2CO3
H2CO3
H2CO3 HCO3−
HCO3−H+
H+
H+H+H+ H+
H+H+H+
Cl−
Cl− Cl−
Cl−
Cl− Cl−
Cl−
(a) A strong acidsuch as HCldissociatescompletelyinto its ions.
(b) A weak acid suchas H2CO3 doesnot dissociatecompletely.
The bicarbonate buffer system is a mixture of: sodium bicarbonate (NaHCO3)
carbonic acid (H2CO3)
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Bicarbonate ions (HCO3–):
react with strong acids to change them to weak acids
HCl + NaHCO3 H2CO3 + NaCl strong acid weak base weak acid salt
Carbonic acid :dissociates in the presence of a strong base to form a weak base and water
NaOH + H2CO3 NaHCO3 + H2O strong base weak acid weak base water
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As blood pH changes: respiratory rate can rise and fall to:
retain CO2 (decreasing the blood pH)
remove CO2 (increasing the blood pH)
CO2 + H2O H2CO3 H+ + HCO3−
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When blood pH rises: Bicarbonate ions are excreted Hydrogen ions are retained by kidney
tubules
When blood pH falls: Bicarbonate ions are reabsorbed Hydrogen ions are secreted
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