Homeostasis: Volume And Composition Of Body Fluid Comparments Flashcards
The 💡maintenance of constant volume and composition of the body fluid compartments (and their temperature in warm-blooded animals and humans) is termed?
HOMEOSTASIS
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STEADY-STATE-BALANCE
Key concepts for steady state balance:
💡💡 SP ES EO SS
- SET POINT
- EFFECTOR SIGNALS
- EFFECTOR ORGANS
- SENSITIVITY OF THE SYSTEM
Key concept in the steady state balance of the human body 💡monitors deviation from baseline.
(e.g., the level of the lake in the preceding example, or setting the temperature in a room by adjusting the thermostat)
SET POINT
Key concept in the steady state balance of the human body that can 💡lead to changes in either input or output, or both, to 💡maintain the desired set point.
(e.g., electrical signals to adjust the spillway in the dam analogy, or electrical signals sent to either the furnace or air conditioner to maintain the proper room temperature).
EFFECTOR SIGNALS
Key concept in the steady state balance of the human body that 💡respond in an appropriate way to the effector signals generated by the set point monitor
(i.e., the spillway gates must operate, and the furnace or air conditioner must turn on).
EFFECTOR ORGANS
Key concept in the steady state balance of the human body that is 💡dependent on several factors, including the nature of the sensor the time necessary for generation of the effector signals, and how rapidly the effector organs respond to the effector signals.
SENSITIVITY OF THE SYSTEM
When input is greater than output, a state of __ exists.
Positive Balance
When input is less than output, a state of __ exists.
Negative Balance
A prolonged states of positive or negative balance are generally __ with life.
Incompatible
2 Major Compartments where total body water is distributed:
Intracellular Fluid (ICF) Compartment
Extracellular Fluid (ECF) Compartment
It is an 💡additional fluid may accumulate seen in some pathological conditions.
Example: accumulation of fluid in the peritoneal cavity (ascites) of individuals with liver disease.
THIRD SPACE
2 Division of ECF
- Interstitial Fluid
2. Plasma
It surrounds the cells in the various tissues of the body and makes up three fourths of the ECF volume
Interstitial Fluid
It is contained within the vascular compartment and represents the remaining fourth of the ECF
PLASMA
The driving force for this water movement is an __.
Osmotic Pressure Difference
The fact that cell volume remains (1)__ when ECF osmolality is (2)__ means that the osmotic pressure inside the cells is (3)__ to that of the ECF.
(1) Constant
(2) Constant
(3) Equal
Movement of water between the vascular (plasma) compartment and the interstitial fluid compartment occurs across the __.
CAPILLARY WALL
The driving forces for fluid (water) movement across the capillary wall are:
Hydrostatic Pressure
Oncotic Pressure
Collective term for hydrostatic pressure and oncotic pressure
Starling forces
__ within the capillary is a force that causes fluid to move out of the capillary.
Hydrostatic pressure
Hydrostatic pressure in the surrounding interstitial tissue __ the effect of the capillary hydrostatic pressure
Opposes
The (1)__ of the plasma in the capillary tends to draw fluid from the interstitium into the capillary. The oncotic pressure of the (2)__ opposes this.
(1) Oncotic Pressure
(2) Interstitial Fluid
Any change in the __ of one compartment quickly causes water to redistribute across all compartments, which brings them back into osmotic equilibrium
Osmolality
It is the major determinant of the osmolality of ECF compartment.
Na+ (and its attendant anions, primarily Cl− and HCO3−)
It 💡converts the energy in ATP into 💡ion and 💡electrical gradients, which can in turn be used to 💡drive the transport of other ions and molecules by means of ion channels and solute carriers (e.g., symporters and antiporters).
Na+,K+-adenosine triphosphatase (Na+,K+-ATPase)
__ 💡hyperpolarizes the Vm of cardiac myocytes and, in so doing, makes 💡initiating an action potential more difficult, because a larger depolarizing current is needed to reach threshold.
It can lead to cardiac arrhythmias, and eventually the heart can stop contracting (asystole).
A decrease in extracellular [K+] (hypokalemia)
__, the Vm is 💡depolarized, and it is 💡easier to initiate an action potential. However, once the action potential fires the channels become inactivated, and are unable to initiate another action potential, until they are reactivated by normal repolarization of the Vm.
Can lead to cardiac arrhythmias and loss of cardiac muscle contraction.
Increase in the extracellular [K+] (hyperkalemia)
It occurs when a 💡membrane separating two solutions can be permeated by some but not all of the molecules in solution.
It accounts for the 💡small differences in the ionic compositions of the plasma and the interstitial fluid.
The necessity for energy expenditure to maintain cell volume in an isotonic solution is the result of the effect of intracellular proteins on the distribution of ions across the plasma membrane
Gibbs-Donnan effect
For cells, the Gibbs-Donnan effect would (1)__ in the cell, and result in cell swelling. However, the activity of the(2)__ counteracts the Gibbs-Donnan effect by actively extruding cations. In addition, the(3)__ established by the Na+,K+-ATPase allows for the development of the Vm (in which the cell’s interior is electrically negative), that in turn drives Cl− and other anions out of the cell.
(1) increase the number of osmotically active particles
(2) Na+,K+-
(3) K+ gradient
With 💡cell swelling, a __ response transports osmotically active particles (osmolytes) out of the cell, reducing the intracellular osmotic pressure and thereby restoring cell volume to normal.
regulatory volume decrease
With 💡cell shrinking a __ response transports osmolytes into the cell, raising the intracellular osmotic pressure and thereby restoring cell volume to normal.
regulatory volume increase
The regulatory volume increase response results in the__ and a number of organic osmolytes.
rapid uptake of NaCl
The regulatory volume decrease response results in the__ from the cell.
loss of KCl and organic osmolytes
When cells are exposed to a 💡hypotonic medium, they 💡swell and then undergo a __.
volume-regulatory decrease (RVD)
When cells are exposed to a 💡hypertonic medium, they 💡shrink and then undergo a __.
volume-regulatory increase (RVI)
During the RVI, what will happen when NaCl and organic osmolytes enter the cell.
There will be increase in the activity of Na+,K+-ATPase (not depicted) enhances the exchange Na+ for K+ so that the K+ (and Cl−) content of the cell is increased.
During the RVD, what will happen when KCl and organic osmolytes from the cell is loss?
There will be a decrease in cellular KCl and organic osmolytes causes intracellular osmotic pressure to decrease, water leaves the cell, and the cell returns to nearly its original volume.
During RVI, what will happen to the cell when there’s an increase in cellular KCl and intracellular organic osmolytes?
There will be an increase in intracellular osmotic pressure, which brings water back into the cell, and the cell volume returns to nearly its original volume.
The free surface of the epithelial layer is referred to as the?
Apical membrane
It provide 💡low-resistance connections between cells.
Gap junctions
The 💡functional unit of the gap junction is the?
CONNEXON
The connexon is composed of 💡six integral membrane protein subunits called?
Connexins
2 main functions of the tight junction?
💡💡
➗
P
- It divides the cell into two membrane domains (apical and basolateral).
- It serve as a pathway for the movement of water, ions, and small molecules across the epithelium
It is called the pathway 💡between cells?
It is an important route for 💡transepithelial transport of solute and water
Paracellular Pathway
It is called the pathway 💡through the cells?
Transcellular Pathway
It is a 💡junctional protein important in determining the 💡permeability characteristics of the 💡tight junction, especially with regard to cations and anions.
CLAUDIN
Mutations in the gene that codes for 💡claudin 16 result in the autosomal recessive condition know as?
Familial Hypomagnesemia, Hypercalcuria, and Nephrocalcinosis (FHHNC)
It is a 💡junctional protein that is found in the 💡tight junction of the 💡thick ascending portion of Henle’s loop in the kidneys and serves as a route for the paracellular reabsorption of 💡Ca++ and Mg++ from the tubular fluid.
Claudin 16
It is the molecular motor that drives the 💡movement of the cilium.
Dynein
Nonmotile cilia serve as (1)__ and are involved in determining (2)__ during embryological development, as well as (3)__ in the nephron of the kidneys
💡💡
M
⬅️➡️
S
(1) mechanoreceptors
(2) left-right asymmetry of organs
(3) sensing the flow rate of fluid
The Na+ channel is present only in the (1)__, whereas the Na+,K+-ATPase and the K+ channels are confined to the (2)__.
(1) apical membrane
(2) basolateral membrane
Transport from the 💡apical side to the 💡basolateral side of an epithelium is termed either?
Absorption or Reabsorption
Transport from the 💡basolateral side of the epithelium to the 💡apical side is termed as?
Secretion
A type of transport where solutes and water can be transported 💡across an epithelium by 💡traversing both the apical and basolateral membranes
💡Active transport in nature.
Transcellular Transport
A type of transport where solutes and water can be transported 💡between the cells across the tight junction
💡Passive in nature.
Paracellular Transport
The two driving forces for paracellular transport:
💡💡
CG
V
- Transepithelial Concentration gradient
2. Transepithelial Voltage
It is important to recognize that __ set up the transepithelial chemical and voltage gradients, which in turn can drive paracellular transport.
transcellular transport processes
A process where the movement of water across the epithelium via the paracellular pathway can 💡drive the movement of additional solute.
SOLVENT DRAG
