HUMAN RENAL PHYSIOLOGY: FLUID

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HUMAN RENAL PHYSIOLOGY FLUID ELECTROLYTE
BALANCE

• BIOLOGY 305 LABORATORY

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THIS WEEKS EXERCISE CARDIOVASCULAR PHYSIOLOGY

• Leopard Frog (Rana pipiens)
• Use of force transducer
• Measure force and frequency of contraction
• May observe both atrial ventricular contraction
  (systole)

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CHANGES IN HEART RATE

• Application of Neurotransmitters
• NE/Epi should increase HR
• A positive chronotropic agent
• Ach should decrease HR
• A negative chronotropic agent
• Application of Cold Saline
• Should decrease HR
• A negative chronotropic agent

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FORCE OF CONTRACTION

• Force of Contraction
• Measured by amplitude of periodic cycle
• Measured in Volts
• Influenced by
• Stretch (Starlings Law)
• Inotropy

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CARDIAC OUTPUT

• Cardiac Output (CO)
• Amount of blood pumped by ventricle per unit time
  
• CO HR x SV
• Units ml/min

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CHANGES IN FORCE OF CONTRACTION STROKE VOLUME

• Starlings Law of the Heart
• Amount of blood in ventricle when systole begins
  (EDV) influences force of contraction
• Heart muscle
• contracts with
• greater force if
• distended

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CHANGES IN FORCE OF CONTRACTION STROKE VOLUME

• Inotropy
• Intrinsic ability of myocardial cells to contract
  at a given length
• inotropic agents may increase force,
• despite increased HR ( less filling
• time)
• -- inotropic agents may decrease
• force, despite decreased HR ( greater
• filling time)

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IDENTIFICATION OF AN UNKNOWN

• Identify an unknown pharmacological agent
• after application to the amphibian heart
• Agent could work by either of the following
  mechanisms
• B1 adrenergic receptor agonist
• Muscarinic cholinergic antagonist

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AUTONOMIC PATHWAYS

• Sympathetic Pathway

B1 ADRENERGIC
THE HEART

Ach

NE
Parasympathetic Pathway
THE HEART

Ach

Ach
MUSCARINIC CHOLINERGIC
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NEXT WEEK HUMAN RENAL PHYSIOLOGY

• Osmoregulators
• Most Terrestrial Vertebrates
• Humans maintain fluid composition and
  concentration irrespective of surrounding
  environment

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HUMAN RENAL PHYSIOLOGY

• Renal Anatomy
• The Nephron
• Bowman's Capsule
• PCT
• Loop of Henley
• DCT
• Collecting duct

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HUMAN RENAL PHYSIOLOGY

• Functions of the Human Kidney
• Extracellular fluid volume
• Regulation of osmolarity
• Maintenance of ion balance
• Regulation of pH
• Excretion of wastes foreign substances
• Production of hormones

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HUMAN RENAL PHYSIOLOGY

• Four Main Processes
• Filtration
• Reabsorbtion
• Secretion
• Excretion

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HUMAN RENAL PHYSIOLOGY

• Functions of the Kidney
• Filtration
• First step in urine formation
• Bulk transport of fluid from blood to kidney
  tubule
• Isosmotic filtrate
• Blood cells and proteins dont filter
• Result of hydraulic pressure
• GFR 180 L/day

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HUMAN RENAL PHYSIOLOGY

• Functions of the Kidney
• Reabsorbtion
• Process of returning filtered material to
  bloodstream
• 99 of what is filtered
• May involve transport protein(s)
• Normally glucose is totally reabsorbed

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HUMAN RENAL PHYSIOLOGY

• Functions of the Kidney
• Secretion
• Material added to lumen of kidney from blood
• Active transport (usually) of toxins and foreign
  substances
• Saccharine
• Penicillin

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HUMAN RENAL PHYSIOLOGY

• Functions of the Kidney
• Excretion
• Loss of fluid from body in form of urine
• Amount Amount Amount --
  Amount
• of Solute Filtered Secreted
  Reabsorbed
• Excreted

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HUMAN RENAL PHYSIOLOGY

• Sources of Water Input
• Food drink
• 2 L/day
• Cellular respiration
• Glucose O2 ? CO2 H2O
• 0.3 L/day

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HUMAN RENAL PHYSIOLOGY

• Sources of Output
• Urine (1.5 L/day)
• Fecal matter (100 mL/day)
• Evaporative loss through skin respiration (900
  mL/day)

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HUMAN RENAL PHYSIOLOGY

• Conservation of Water
• Terrestrial animals often face dehydration
• Of all sources of water loss, excreted water (in
  urine) is the best regulated

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HUMAN RENAL PHYSIOLOGY

• Regulation of Fluid Volume
• Kidneys influence fluid volume by
• Altering water content of urine
• Removal of H2O in urine diuresis
• Substances that cause diuresis diuretics

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HUMAN RENAL PHYSIOLOGY

• Retention of Water is controlled by ADH
• Anti Diuretic Hormone
• ADH Release Is Controlled By
• Decrease in Blood Volume
• Decrease in Blood Pressure
• Increase in ECF Osmolarity

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HUMAN RENAL PHYSIOLOGY

• When Body Fluid Osmolarity
• Increases (280)
• Osmoreceptors (hypothalamus)?
• Trigger release of ADH?
• Increased permeability of CD to water?
• Water reabsorbion from tubule?
• Concentrated urine produced

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HUMAN RENAL PHYSIOLOGY

• Regulation of Sodium
• On average, an adult takes in 9 g/NaCl/day
• Addition of salt can raise body fluid osmolarity

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HUMAN RENAL PHYSIOLOGY

• Sodium Balance Is Controlled By Aldosterone
• Aldosterone
• Steroid hormone
• Synthesized in Adrenal Cortex
• Causes reabsorbtion of Na in DCT CD
• Also, K secretion

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HUMAN RENAL PHYSIOLOGY

• Sodium Balance Is Controlled By Aldosterone
• Aldosterone Release
• Triggered by increased ECF K ? Na reabsorbtion
• Inhibition of Aldosterone
• Triggered by increased extracellular osmolarity ?
  No Na reabsorbtion

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HUMAN RENAL PHYSIOLOGY

• A few Situations Encountered in Lab
• Increase Fluid Vol/Decrease Osmolarity
• Drink pure H2O
• Excrete dilute urine
• Norm Fluid Vol/Increase Osmolarity
• Salty popcorn (no drink)
• Highly concentrated urine of low volume

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HUMAN RENAL PHYSIOLOGY

• Urinalysis
• White Blood Cells
• Nitrites
• Proteins
• Glucose
• Ketones
• pH
• Urobilinogen
• Bilirubin