Electrolytes Flashcards
What do electrolytes do in regards to fluid?
Maintain fluid balance by causing an osmotic drag across biological membranes
In excessive dehydration what happens to cells? In hypotonic hydrations, what happens to cells?
Cells shrink ; cells expand
How do you figure out the mEq/l?
1 mEq/l is equal to 1mmol of the unit of electrical charge
Which electrolytes are found in high concentrations out side of cells?
Sodium and Chloride
Which electrolytes are found in high concentrations inside of the cell?
Potassium/phosphate
Where is Sodium found in the body?
30% on surface of bone crystals
70% in ECF, nerve and muscle tissue.
What is the most abundant cation in hte body?
Sodium
Where does most of our dietary sodium come from?
Processed foods
What are the main functions of Sodium?
Fluid Balance
Muscle contraction
Conduction of nerve impulses
What are the sodium-coupled cotransporters and where are they located?
Facilitate Glucose and amino acid movement with the gradient.
Located in the small intestine
Where is the electroneutral (no charge) Na/Cl transport system located and what is it?
It is located in the small intestine (proximal to colon) and it exchanges Na/H and Cl/HCO3
What is the electrogenic (has a charge) sodium absorption and where is it located?
Located in the colon and it is Na Channels
Mutations in SGLT1 causes what?
Glucose and galactose
- Watery osmotic diarrhea in newborns
- life threatening dehydration acidosis weight loss
What is nutritional management for newborns with a mutation in SLG1 protein?
Avoid sucrose and lactose
What is SLGT1?
A sodium coupled-transporter
What are the transporters in Electroneutral Na/Cl transport system?
Na/H exchanger and a Cl/HCO3 exchanger
What are the three ways Sodium can be absorbed into the intestine?
Sodium co-transporters
Electroneutral Na/Cl transport system
Electrogenic Sodium Absorption
How is sodium transported in the blood?
Freely
How are serum sodium concentrations maintained?
Antidiuretic hormone (vasopressin) Aldosterone Angiotensin II
How does ADH work?
Stimulus: Water component of the blood has gone down.
- Pituitary glan will release ADH and cause thirst at the same time
- Water consumption and water reabsorption occurs.
What happens during nerve transmission and muscle contraction?
Sodium/potassium exhange
-generates an electrochemic potential gradient where it mediates nerve and impulse conduction
How are nerve impulses transmitted?
- Neurotransmission: a neurotransmitter is released.
- Sodium channels open (membrane is depolarized)
- Calcium is released (contraction)
- Na channels close and K channels open (contraction ends, membrane re-polarizes)
High Sodium intake may cause an increase in what mineral excretion?
Calcium which could lead to osteoporosis
Where is sodium primarily excreted?
In urine and sweat
Renal excretion of Sodium is controlled by what?
Aldosterone
When is aldosterone released?
Released from adrenal gland in response to low Na or high K
What does aldosterone promote?
Promotes retention of Na and excretion of K
Sodium Deficiency
Rare
Could occur due to excessive sweating or weight loss
Symptoms include nausea, vomiting, dizziness, muscle cramps, shock, coma
What is used to measure blood sodium clinically?
Potentiometry
Na intake levels are reflected in a what?
24 hr urinary excretion test
What is major intracellular cation?
Potassium
What are the main food sources of potassium?
Fruits and vegetables
What are the functions of potassium?
Influences contractility of smooth, skeletal and cardiac muscle.
Effects excitability of nerve tissue
Maintaining electrolyte and fluid balance
What are the nutrient interaction of Potassium?
Decreases renal calcium excretion
What has homeostatis control of potassium levels?
Kidney
How does aldosterone effect potassium excretion?
It increases it
What does hyperkalemia causes and what causes it?
Cardiac arrythmias
Renal dysfunction is a possible cause
What causes hypokalemia?
Profound fluid loss, vomiting, diarrhea, diuretics, refeeding syndrome
What is the most abundant anion in ECF?
Chloride
Dietary sources of chloride?
Associated with dietary forms of Na and in eggs, fresh meats, seafood
Where is chloride absorbed?
All of it is absorbed in the small intestine
How can Chloride be absorbed?
Paracellularly (not sodium. unique to chloride)
Electroneutral Na/Cl system
Electrogenic Na system contributes to Cl absorption
How is chloride secreted?
Through GI tract
How is chloride absorbed from the blood?
via Na/K/Cl cotransport pathway
How does Cl exit cells?
Via apical Cl channels
Cl secretion is defective in what disease?
Cystic Fibrosis
The gene that is mutated in Cystic Fibrosis is
CFTR
DELTA F 508
What are the functions of Chloride?
Gastric acid production
-Cl secreted from parietal cells of stomach
Respose of neutrophils to invading microbes
-Cl released from white blood cells during phagocytosis
Acts as an exchange anion ffro HCO3 in blood cells (Chloride shift)
Neutrophils produce what and what are the involved in?
Produce hypochlorous acid and are involved in immunity.
What is the Chloride shift?
Cl acts as an exchange anion for HCO3 in blood cells
shifts from the blood into the cell and then from the cell back into the blood
What does the Chloride Shift do?
Transport tissue-derived CO2 back to the lungs in the form of HCO3
Waste CO2 enters RBCs and is converted to HCO3 by carbonic anyhydrase
Chloride bicarbonate exchange then transports HCO3 out of the cell as it simultaneously transports Cl into the cell
In the absence of chloride, HCO3 transport ceases
How is chlorine mainly excreted?
Mainly via the kidneys
Some via the GI tract and skin
How is Chlorine excretion regulated?
Regulated indirectly through sodium regulation
What are things that increase blood pressure?
Sodium, sucrose, alcohol
What are things that decrease blood pressure?
Potassium, calcium, magnesium
CHO lecture part 1 slide 3
.
