Lecture 11 Flashcards
Water Balance
Medium for chemical reactions
Solvent
Thermoregulation
Blood pressure regulation
Electrolyte balance
Ion Gradient concentration
Muscle contraction
Nervous system impulses
Exocytosis of vesicles
pH balance
extracellular fluid - 7.35-7.45
Intracellular fluid/Blood 7
Important for enzymes to work
Flow of materials between fluid compartments.
Water In –> Digestive tract –> blood –> extracellular fluid –> intercellular fluid –> lymph nodes –> blood stream
Average Total Body Water (TBF)
Males 60%
Females 50%
Males are higher because more testosterone and muscle cells.
Females lower because more adipose tissue.
Easier to get off balance.
What is the largest fluid compartment?
Intracellular fluid
2/3 of TBW
What is the larges extracellular fluid compartment?
Intersticial Fluid- mostly your blood
What are the other compartments in extracellular fluid?
- Intersticial 25%
- Blood plasma and Lymphatic fluid 8%
- SF, synovial fluid, serous fluids, eye humors, inner ear fluids, bile, respiratory and digestive secretions
What is the main mechanism for water loss?
Urination 1500ml
Sensible
Sensible Water Loss and amounts
Urination 1500mL
Sweating 100mL
Deification 200 mL
Insensible water loss
Cutaneous transpiration 400mL
Expiration 300mL
What is obligatory water loss?
The minimal amount of fluid loss from the body that can occur is referred to as obligatory water loss. For example, at least 500mL of urine daily, or 100mL of sweat.
What is facultative water loss?
Facultative water loss is anything above and beyond the necessary loss to rid of waste. Examples: urine output above 500mL
List the three main ways that you gain body water over the course of the day.
Metabolic water, food, drink
Describe two ways that the body produces metabolic water.
Metabolic water can be made from aerobic respiration and dehydration synthesis
How does dehydration affect blood volume and osmolarity of extracellular fluid?
Dehydration lowers blood volume and pressure, and increases blood osmolarity.
List three groups of receptors (where they are located) that provide information about changes in extracellular fluid volumes and osmolarity.
Osmoreceptors in the hypothalamus
Baroreceptors in the carotid and aortic sinuses
Juxtaglomerular apparatus cells sense the changes of extracellular fluids
Describe the short-term regulation of the thirst reflex. In other words, what mechanisms are in place to prevent over-consumption of water when you are thirsty?
Cooling and moistening of the mouth from ingested water
Distention of the stomach are temporary mechanisms to shut down the thirst reflex.
Describe the hormonal mechanisms that help the body to maintain extracellular fluid volumes (and thus blood pressure) and osmolarity.
JGA will detect increases or decreases in BP, which alters the release of renin
–Increased renin release results in more angiotensin II, aldosterone, and ADH secretion
Heart- detect increases and decreases in BP
–When blood volume and pressure are high, there is increased secretion of natriuretic peptides (ANP and BNP) by cardiocytes–Blocks renin release (and therefore, aldosterone and ADH) so excess sodium and water are lost in urine
Volume Depletion
Hypovolemiais - when proportionate amount of water and sodium lost without replacement
–Isotonic fluid loss is greater than isotonic fluid gain
–Vomiting, diarrhea, third degree burns, hemorrhage, and aldosterone hyposecretion (Addison disease)
Volume Excess
Hypervolemia - is retention of excess isotonic ECF (water and sodium)
–Isotonic fluid loss is reduced due to a kidney problem, such as kidney failure or hypersecretion of aldosterone
Dehydration
More water lost than sodium
ECF osmolarity increases
•Water shifts from ICF to balance, and volume of both compartments is decreased from set point
- Primary cause is inadequate water consumption
- Other causes: excessive perspiration, all types of diabetes, use of diuretics, alcohol, along with hot and cold weather
•Infants more susceptible to dehydration than adults because of larger surface area to volume ratio and kidneys don’t concentrate urine as well
Hypotonic hydration
Occurs when more water than solute (relative to isotonic fluids) enters the ECF, and ECFs become hypotonic
•Fluid shifts from ECF to ICF
•Results in cellular swelling, cerebral edema, and loss of CNS function called water intoxication
•Primarily caused by sweating or urinating and replacing with drinking water
–Remember urine and sweat contain water and salt
–2007 radio contest
•ADH hypersecretion can also cause
Fluid sequestration
When total body water is normal, but fluid accumulates in a particular compartment
•Edema is sequestration of fluid in the IF compartment (usually lost from blood)
–May result in swelling and puffiness of a body part
–Can be caused by failure of a ventricle, hypertension, loss of plasma albumins, increase in capillary permeability to proteins, and/or blockage of lymphatic vessels
•Ascites is fluid sequestration in the abdominal cavity
