Introduction Flashcards
Total Body Water (TBW) in adults vs infants
60% in adult and 75% in infants
TBW in females and obese people
50% of weight
intracellular fluid % (water inside cells)
40% : 2/3 TBW
Extra cellular fluid %
20% : 1/3 TBW
Extra cellular fluid components
5% intravascular plasma (IVF)
15& extravascular intestinal fluid (ISF) (water outside vessels)
blood volume
8% of body weight
osmolality of ECF (concentration)
is equal to osmolality of ICF (300 mosmol/l)
main cation in ICF and EFC
ICF - K+
ECF - Na+
main anion in ICF and ECF
ICF - proteins, phosphate (50 mmol/L)
ECF - Cl- , HCo3-
fick’s principle
water volume = amount of indicator injected / concentration of indicator of plasma
in other words, AMOUNT = VOLUME X CONCENTRATION
application of indicator type for determination of total body water
heavy water, anti pyrine
application of indicator type for determination of ECF volume
inulin
radioactive Na, Cl, Br
application of indicator type for determination of plasma volume - IVF
evans blue
radioactive albumin
homeostasis
keeping conditions in internal environment (ISF surrounding cells) constant.
2 exchanges of homeostasis
- through cell membrane: between cells and ISF
2. through capillary membrane: between ISF & blood
total blood volume
8%
indicator in ricks principle must be
inert, non toxic, and not utilized by tissues
determination of ICF volume
TBW-ECF
determination of ISF volume
ECF-plasma volume
homeostasis- exchange through cell membrane
living cells take oxygen and food from interstitial fluid and cells give up CO2 and waste
homeostasis- exchange through capillary wall
oxygen and food move from blood to interstitial fluid and waste products go to blood
what happens to waste products
taken by blood and excreted by kidney
homeostasis is maintained by the control systems:
- stimulus
- receptor
- control center
- effector organ
- feed back mechanism
they detects and respond to changes.
negative feedback vs positive feedback in homeostasis
negative - almost all homeostasis mechanisms; change variable back to original state
positive- stimulus increases response in things that need to be finished quickly such as blood clotting.
cell membrane percentages
protein - 55% cholesterol - 13% phospholipid - 25% other lipids - 4% carbohydrates - 3%
lipid bilayer vs cholesterol
lipid bilayer is flexible & selective permeability
cholesterol is tough and affects permeability
functions of carbohydrates on cell membrane
receptors, cell identity, intercellular connections
diffusion transport
passive = no energy
types of diffusion transport
Simple, Facilitated, Osmosis
diffusion is
from high to low concentration
simple diffusion requires
no carrier, no energy, no enzymes
how to calculate diffusion rate
concentration gradient x surface area x temperature / square root of molecular weight x distance of diffusion
molecules in simple diffusion pass through:
- lipid bilayer
2. protein channels
what passes through lipid bilayer in simple diffusion
- lipid soluble substances
- water molecules
- lipid insoluble molecules
what passes through lipid bilayer in simple diffusion - lipid soluble substances
oxygen, nitrogen.
rate of diffusion = lipid solubility
what passes through lipid bilayer in simple diffusion - water molecules
through lipid bilayer and protein channels
very small & high kinetic energy so go through membrane like a bullet
what passes through lipid bilayer in simple diffusion - lipid insoluble molecules
same as water molecules IF they are small and uncharged such as urea
protein channels in simple diffusion has the ability to
have ability to change its shape to allow passage of ions and water
ions that are electrically charged can’t pass through and can pass through
can’t pass through lipid bilayer and can pass through protein channels
to pass through protein channels, ions are
bonded with water and form hydrated ions of bigger size.
hydrated ___ ions are bigger than hydrated ____ ions
Na+ bigger than K+
Protein channels have
selective permeability; each channel has its diameter, shape and electrical charges
gating of protein channels
non gated: open all the time
gated
gates can be
on inner or outer surface on membrane
how do you open a gated channel
by conformational (change in shape) of proteins
gates are controlled by:
voltage gating and ligand gating
gates are controlled by- voltage gating
respond to changes in electrical of membrane electrical potential
ex: Na+ channels
gates are controlled by- ligand binding
binding of ligand to receptor opens protein channel.
ligans are
acetyl choline and hormone (external) or G protein, cAMP, or Ca+ (internal)
channel junctions/gap junctions is
simple diffusion
gap junctions allow
rapid passage of ions and other light substances without entering intercellular space which permits rapid propagation of electrical activity from one cell membrane to another
what are formed at junction arrangement of proteins
a connexion unit surrounding the channel
diameter of the channel junctions/gap is regulated by
intracellular Ca++ , pH, hormones and drugs
facilitated transport
needs carrier
facilitated transport occurs
with concentration gradient
facilitated transport is for
large molecules such as glucose and amino acids
facilitated mechanism
carrier has large channel and specific receptor, closed from one side.
large molecules enter the channel and bind to the receptor and change the shape of protein which opens the closed side and releases the molecule
characters of facilitated diffusion
- specific to certain substances
- sensitive to temperature
- competition between similar substances for same carrier
- has a maximum rate of diffusion
osmosis
diffusion of water down its concentration gradient through a membrane permeable to H20 only
osmotic pressure
pressure to stop osmosis or prevent solvent migration
what does osmotic pressure depend on
number of molecules/unit volume of fluid
how is osmotic pressure measured
mmHg
osmole
number of particles in 1 gram of mole
osmolarity
number of osmoles per liter
osmolality
number of osmoles per kilogram
in the body
osmolarity=osmolality
tonicity
osmolarity of solution in relation to plasma
isotonic tonicity, hypotonic, hypertonic
iso- same as plasma
hypo- lower than plasma
hyper- higher
active transport
is against the concentration gradient so needs carrier and ATP
uniport and ex
transport of one substance in one direction (Ca++ pump_
symport and ex
transport of 2 substances in one direction (Na & glucose in intestinal lumen)
antiport and ex
transport of 2 substances in 2 opposite directions (Na/K pump)
cotransport
symport and antiport
primary active transport is present in
cell membrane - Na/K pump
alpha subunit for
beta subunit for
alpha- Na, K, ATP (binding)
beta- ATPase activity (breakdown of ATP)
Active transport ex
energy is released by breakdown of ATP to do the Na, K transport which brings 3 Na outside the cell and 2 K inside.
Na is high in ___ and K is
Na is high in ECF and K is high in ICF
Primary active transport helps in
- maintaining high Na in ECF and high K in ICF
- electronic pump (resting membrane potential)
- control cell volume and prevent cell rupture
secondary active transport
glucose transport is secondary to active Na transport.
secondary active transport mechanism
Na is transported by active pump outside the cell and Na and glucose bind to the same carrier and transported inside the cell with the concentration gradient. Glucose is then transported outside the cell by a carrier
Donnans effect
proteins are large diffusible anions (carry - charge) inside the cell and they inhibit the efflux of K and favor the efflux of Cl-
donnan states that
more ions are present within the cell
donnans effect: equilibrium
more osmotic particles in the cell switch up the Na/K pump which prevent rupture of cells
