Week 1 Flashcards
Describe ECF
where cells reside, take up O2 and nutrients, discharge waste. divided into interstitial fluid, blood plasma and lymph fluid. 20% body weight. Na+ is most abundant cation.
Describe ICF
cell membrane barrier. 40% body weight, K+ most abundant
Fluid compartment percentages for:
- total body weight
- ICF
- ECF
- Interstitial fluid
- PV
- total body weight = 60%
- ICF = 40%
- ECF = 20%
- Interstitial fluid = 15%
- PV = 5%
Improper compartmentalization of fluids
Edema
Homeostasis
balanced internal condition of cells
- maintained = physiology
- not maintained = pathophysiology
ex. maintenance of blood glucose and body temp
Dynamic constancy
always changing but helps maintain constant of our body (equilibrium)
Equilibrium
process of homeostasis; condition where variable is constant but no amount of energy input is required to maintain constancy (no net change)
Components of homeostatic system
- stressor = triggers mechanism
- sensor = detects stress
- control center = signals traveling from controlling gland to take action upon the stressor
- effector = takes action
- effect = result from effectors
Hyperthermia: Negative Feedback Loop
- stressor = hyperthermia / high body temp
- sensor = heat receptors in the skin
- control center = hypothalamus
- effector = increased activity of sweat glands
- effector = increased blood flow to the skin
- effect = perspiration evaporates thus colling the skin
Hyperglycemia : Negative Feedback Loop
- stressor = hyperglycemia/ high blood glucose
- sensor = pancreas beta cells
- control center = pancreas
- effector = insulin released in blood
- effector = liver and muscle cells uptake glucose from blood
- effect = decreased blood glucose
Afferent path
PNS to CNS
Efferent Pathway
CNS to PNS
Example of a Positive Feedback Loop within a Negative System
Coagulation - accelerating of clotting
Childbirth : Positive Feedback Loop
- stressor = pressure of fetus on uterine wall
- sensor = afferent nerve endings within the uterine wall
- control center = hypothalamus
- effector = production and release of oxytocin in the blood
- effector = increase in uterine contractions
- effect = intensification of contractions
Harmful effects of positive feedback system
-fever: continues to rise unless fever reducing medication is given
- chronic HTN: BV narrow causing increased pressure, further damaging BV
- decreased blood flow to brain: decrease in sympathetic nerve activity = decrease in BP = decreased blood flow
- anaphalaxis: overproduction of histamines
Most abundant cation in ICF
K+
Most abundant cation ECF
Na+
Plasma Membrane Functions
acts as “gatekeeper”
-binding sites for enzymes
Plasma Membrane
selective barrier to passage of molecules; impermeable to Na+
-phospholipid bilayer with hydrophilic heads (polar/outside) and hydrophobic tails (nonpolar/inside)
Phospholipid Bilayer
amphipathic:
hydrophilic heads - polar regions (outside)
hydrophobic tails - nonpolar regions (inside)
Hydrophobic molecules
pass easily through the membrane (attracted to middle of bilayer lacking H2O
ex. O2, CO2, H2O
Hydrophilic Molecules
do not pass easily through the membrane since they are attracted to the polar water molecules in the ECF and cytosol
ex. proteins
integral membrane proteins
cannot be extracted without disrupting the bilayer.
- amphipathic
- transmembrane
- loop through the membrane
- form channels to help with transmission of chemical signals
peripheral membrane proteins
bound to polar region of the integral proteins and on the cytosol surface