Chapter 32: Fluid and Electrolyte Balance Flashcards
Objective:
Explain the importance of fluid and electrolyte balance in the body.
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Amount of water & electrolytes entering body should = ?
amount of water & electrolytes leaving body
Total body water
Considered as a % of total body weight
It Differs due to a person’s what 3 things?
_ age, body fat and gender_
Total body water:
- Newborn=
- 10 years old=
- Adolescence=
- Adult=
Newborn= 75% of body weight
10 years old=percentage decreases rapidly
Adolescence= will vary due to gender & amount of fat tissue, differences which account for about 10% variation in total %
Adult=decrease to 45% of total body weight
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Total body water
infants will have the highest % of body weight, and decreases as we age.
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what are the Body Fluid Compartments (2)
- Extracellular fluid (ECF)
- Intracellular fluid (ICF)
- Total Body Fluid = ECF + ICF
- Anything outside of the cell
- Provides constant environment for cells
- Transports substances to and from cells
Includes- Interstitial fluid, plasma (2 main), lymph, & transcellular fluid like CSF/ joint fluid/ and humors of the eye.
Extracellular Fluid
what fluid Facilitates chemical reactions inside of cells?
Intracellular fluid
Chemical Content of Fluid
anything that will break up into charged particles or ions
Electrolytes
what are theses?
Ca2+
Na+
K+
Mg2+
Cl-
HCO3-
HPO4-
Anions and Cations that serve critical role in the body
cation will be atracted to the negative or positive electrodes?
negative
a cation is positvely charged
negeatilvely charged ions that attract positve electrodes ?
anions
Extracellular fluid
Blood Plasma and interstitial fluid (figure 32-3)
Almost identical
- The main difference between blood plasma and interstitial fluid is the amount of ______________, blood plasma has more proteins.
protein anions
Blood Plasma and interstitial fluid (figure 32-3)
Major cation is ?
sodium
Intracellular fluid
- Differs greatly from extracellular fluid
- Major cation is?
K+ = potassium
Chemical Structure of Body Fluids
the Function is to?
maintain homeostasis
differening charge or valence helps us move water.
WATER is added to the body through…
the digestive tract by ingesting food & fluids. It is also added to the bloodstream by cell catabolism.
WATER is lost from the body through…
Urine, feces, perspiration, exhaled air (water vapor)
Input (intake) vs Output
look at page 1008 (32-5)
all the ways it enters and exits the body.
look
The rules of fluid balance…
- Balance maintained only if intake equals output
- Mechanisms are available to adjust input & output (RAAS (activates aldosterone) system, ANH, ADH)
- The most rapid way to adjust fluid balance is by controlling water movement between fluid compartments (ICF and ECF) of the body. We will maintain normal blood volume at the expense of interstitial fluid volume.
Maintaining Fluid Balance (normally)
Primary mechanism
Adjust urine output via hormone systems
Maintaining Fluid Balance (normally)
Secondary mechanism
Adjust fluid intake
Maintaining Fluid Balance (normally)
what mechanism below
- Decreasing intake causes our “thirst center” to activate
- Receptors in the brain tell the hypothalamus to release ADH hormone which lets or cerebrum know our mouths are dry and we are thirsty
Secondary mechanism
2 Factors determine urine volume:
- Glomerular filtration rate generally is constant
- Rate of tubular reabsorption of water fluctuates and can be adjusted
- Under normal conditions it adjusts to intake
- It is influenced by the hormones ADH (from the pituitary), ANH(from the heart, and aldosterone (from the adrenal cortex) (feedback loops can be seen in figure 32-8)
- Rate of tubular reabsorption of water fluctuates and can be adjusted
- Rate of respiration and volume of sweat alter fluid output
- Hyperventilate- increases respiration rate and sweat production
- Dehydration- fluid output exceeds input
- Vomiting, diarrhea, or intestinal drainage can also produce fluid and electrolyte imbalances
Factors that alter fluid loss under abnormal conditions
Insufficient body fluid resulting from inadequate intake OR excessive loss OR both.
Dehydration
Dehydration
Symptoms vary
- Simple thirst
- Poor concentration
- Cannot regulate excess temperature
- Dizziness, weakness
- Muscle spasms
- Kidney failure
- Concentration of solutes in the extracellular fluid will increase
Starlings Law of capillaries= The control mechanism for water exchange between plasma and interstitial fluid consists of 4 types of pressure. Two directed in and 2 directed out.
- Blood colloid osmotic pressure ( pushes into capillaries)
- Blood hydrostatic pressure (push out of capillaries)
- Interstitial fluid hydrostatic pressure (push into capillaries)
- Interstitial fluid colloid osmotic pressure (push out of capillaries)
What law is this?
The control mechanism for water exchange between plasma and interstitial fluid consists of 4 types of pressure. Two directed in and 2 directed out.
Starlings Law of capillaries
Starlings Law of Capillaries
the rate and direction of movement of fluid electrolytes between plasma and interstitial fluid depends mainly on the_______________ inside and outside the vessel.
pressure differences
Starlings Law of Capillaries
the rate and direction of movement of fluid electrolytes between plasma and interstitial fluid hydrostactic** is the is highest inside the vessel at the arterial end of the capillaries and lowest inside the vessel at the ::::::::**
venous end of capillaries.
Fluid Shifts
Transfer of water:
There is fluid movement in and out of structures in order to deliver what the body needs, but no net transfer of water occurs between ……..?
blood and interstitial fluid.
- Large amounts of fluid in intercellular tissue spaces
- Lung
- Brain
- Subcutaneous space of dependent body areas
- An excessive amount of fluid in the interstitial space
Can be localized or generalized
Causes swelling/enlargement of the tissues
More visible in dependent areas of body
Edema
Some Things That Lead to Edema
pg 1016 32-13
-
Retention of electrolytes, especially sodium, in extracellular fluid (Pitting edema)
- can be caused by increased aldosterone secretion
- Increased blood volume or capillary blood pressure (such as in inflammation)
- Decrease in concentration of plasma proteins (albumin) normally retained in blood
- This can be the result of increased capillary permeability caused by infection, burn or shock.
ex) sweat —–> decreases H2O bloldd—->
Blood becomes more concentratd with electrolytes—> more fluid is sucked into blodd by BCOP—> lost fluid IF—–> more fluid is sucked into the IF by IFCOP form the intercellular fluid I C F
Mrs G wrote this on board
how we maintain blood pressure
- The plasma membrane plays a critical role in the regulation of ICF composition
- Transfers of fluid between IF (interstitial) and intracellular work very similarly to transfers between IF and plasma; again driven by hydrostatic and colloid osmotic pressures.
Regulation of Water and Electrolyte Levels in Intracellular Fluid (ICF)
Fluid levels in ICF
- Water movement is regulated
- Interstitial fluid and intracellular fluid hydrostatic and colloid osmotic pressure regulate water transfer
- Colloid osmotic pressure is chief regulator of water transfer
- Colliod osmotic pressure is associated with potassium and sodium levels
- Interstitial fluid and intracellular fluid electrolyte concentration are main determinants of colloid osmotic pressure
- Fluid balance depends on electrolyte balance
Fluid Balance
Regulation of Sodium and Potassium
Highly dependent on the amount of ADH and aldosterone secreted. The kidneys are the chief regulator of sodium levels
ADH: regulates amount of water reabsorbed into blood
Aldosterone: regulates sodium reabsorbed into blood
Na/K pump to maintain electrical properties of cell
Sodium: primary cation in ECF (therefore chloride is the primary anion in ECF)
Potassium: primary cation in ICF
If there is a drop in sodium or potassium, there can be a change in the fluid exchange (becomes unbalanced)
primary cation in ECF (therefore chloride is the primary anion in ECF)
Sodium:
primary cation in ICF
Potassium:
In Summary
Fluid balance depends on electrolyte balance and electrolyte balance depends on fluid balance.
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Fun Facts about electrolyte balance and exercise:
Posterior Pituitary Gland secretes antidiuretic hormone (ADH). Aka: Vassopressin
-it reduces water loss from the body to
maintain plasma volume
-stimulated by: high plasma osmolality &
low plasma volume due to seating (i.e. exercise
Fun Facts about electrolyte balance and exercise:
- How ADH Conserves Body water:
- Muscle activity promotes sweating
- Sweating causes loss of blood plasma, resulting in hemoconcentration & increased blood osmolarity.
- increased blood osmolarity stimulates the hypothalamus, which then stimulates the posterior pituitary gland
- Pituitary secretes ADH
- ADH acts on the kidneys increasing the water permiability of the renal tubules and collecting ducts, leading to increased reabsorption of water
- Plasma volume increases so blood osmolarity decreases after exercise and water ingestion
Fun Facts about electrolyte balance and exercise:
The Renin-Angiotensin Mechanism:
- Muscular Activity promotes Sweating & increases BP
- Sweating reduces plasma volume & blood flow to kidneys
- Reduced renal blood flow stimulates renin, released from kidneys. Renin then forms angiotensin 1, then to A2
- Angiotensin 2 stimulates release of aldosterone from adrenal cortex
- Aldosterone increases Na+ and H2O reabsorption from the renal tubules
- Plasma volume increases, urine production decreases with water and sodium intake, therefore electrolyte balance.
Chapter Review Questions
To help review this chapter, do the following review questions on pgs 1023-1024 #s 3, 4,6,7,10,12,14,15,17, 18
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adh is going to save water
aldosterone is going to save electrolytes
where sodium goes water goes.
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