Water and pH Flashcards
What is homeostasis?
any process involved in the maintenance of an internal steady state of water.
What are the major solutes in extracellular fluid and tightly regular total body water content, circulating volume, and blood pH?
- Sodium (Na+)
2. Chloride (Cl-)
What are the important functions of sodium and chloride in the body?
tightly regular total water body content, circulating volume, and blood pH
What percentage of water is found in intracellular fluid?
55%-75%
What percentage of water is found in extracellular fluid?
25%-45%
The total body weight percentage is higher in (women, men)?
men
The water found in extracellular fluid is in intravascular and extravascular water. Name an example of where this fluid is found.
Intravascular- plasma
Extravascular- interstitial spaces
What is osmolality?
the solute or particular concentration of a fluid measured in osmoles or milliosmoles per kilogram of solvent
What is Osmolarity?
the solute concentration of a fluid measured in osmoles or milliosmoles per liter of fluid
What is an osmole?
the number of moles of solute that contribute to osmotic pressure
Ex. 1 mol of NaCl when dissolved results in 2 osmoles, Na+ and Cl-
What are the major rules of water homeostasis?
- Water intake must balance water loss
2. Osmotic equilibrium is required
What is osmotic pressure?
the process by which water or any solvent will cross a semipermeable membrane from an area of low concentration to high concentration until both sides of the semipermeable membrane are equal concentrations
In the human body, in what way does ECF osmolality = ICF osmolality?
- water ingestion
- hormonal control
- excretory system
When you ingest water, what happens to the osmolality as it goes through the bloodstream?
it decreases due to more water in the system
When the water goes through the bloodstream and gets filters by the kidneys, what happens to the osmolality?
it increases due to less water in the system
What is the normal fluid osmolality in the human body?
280 - 295 mOsm/kg
What organ is the key to mediate water homeostasis?
the kidneys
Which osmolality controls thirst and hormonal mechanisms?
plasma osmolality
What is the primary hormone that controls homeostasis?
arginine vasopressin (AVP) also called antidiuretic hormone (ADH)
AVP is stored and secreted where?
in the hypothalamus
AVP has axonal transport to the posterior pituitary gland where it is released where?
to the bloodstream
AVP has axonal transport where before it is released into the bloodstream?
posterior pituitary gland
AVP has two manifests. What are they?
- it increases the selective reabsorption of solute free water by aquaporins in the kidney that specifically takes place in the tubules of the nephron. Result: urine volume is decreased and concentration of urine increases
- at high enough levels of stimulation, it can cause constriction of the arterials, therefore raising arterial blood pressure
AVP has a very short half life of how long?
16-24 minutes
AVP is released when plasma osmolality exceeds what?
-285 mOSm/kg
AVP can also be released when baroceptors do what?
detect a drop in blood pressure.
Osmolality of extracellular fluid is directly dependent on what?
the modulation of water excretion in the distal tube and collecting duct of the kdieny
If the excretion is increased by the kidneys by producing urine with low osmolality, what is the urine like?
diluted urine
If the excretion of the kidneys is decreased by producing urine with a high osmolality, what kind of urine do you get?
concentrated urine.
What are the two main measures used for the excretory function of the kidney?
- Glomerular filtration rate (GF)
2. Filtration Fraction (FF)
What is GFR?
the volume of fluid that is filtered through the glomerular capillaries into the Bowman’s capsule per unit time
What is FF?
the GFR relative to the renal plasma flow (RPF)
How to calculate GFR?
(Urine Concentration x Urine Flow)/Plasma Concentration
How to calculate FF?
GFR/RPF
What does pH regulation do?
maintains balance between H+ ions and compounds that bind H+ ions in solution
Normal pH is between…….
7.2 and 7.5
Is blood slightly basic or slightly acidic?
slightly basic
What is the pH of blood?
7.35 to 7.45
What is acidosis?
abnormally low plasma pH
What is alkalosis?
abnormally high plasma pH
Is low pH acidic or basic?
acidic
Is high pH acidic or basic?
basic
What is the most significant buffer system in the human body?
Bicarbonate and carbon dioxide system
Other buffers in the human body utilize what?
hemoglobin and phosphatase
In the phosphate buffer system, is Na1H2PO4- the weak acid or base?
weak acid
In the phosphate buffer system, is Na2HPO4 2- the weak acid or base?
weak base
Explain the respiratory regulation of holding your breath?
blood CO2 increases, combines with H2O to form carbonic acid and lowers pH
Explain the respiratory regulation of hyperventilation.
blood CO2 decreases, carbonic acid levels decrease and blood pH rises
