Tags & Description
Characteristics of human cells (3)
O2 reacts w/ nutrients to release energy
deliver products of rxns into surrounding fluids
when cells die they are regenerated
Homeostasis
property of cells, tissues, and organisms that allows the maintenance and regulation of the stability and constancy needed to function properly
milieu exterieur
physically surrounds whole organism
milieu interieur
liquid that bathes structures in body, isolates structures from environment
For steady-state balance, there must be a _______ so that deviations from this baseline can be monitored
"set point"
For steady-state balance, sensors that monitor deviations from the set point must generate __________ that can lead to changes in either input or output, or both, to maintain the desired set point
"effector signals"
For steady-state balance, ________ must respond in an appropriate way to the effector signals generated by the set point monitor
"effector organs"
Sensitivity of a steady-state balance system depends on:
nature of sensor
time needed for effector signal generation
how fast effector organs respond to signals
Water balance determines __________ of body fluids
osmolality
Total body water correlates inversely with
body fat
ICF is ______ of total body water vs ECF is _________ of total body water
2/3, 1/3
Interstitial fluid
fluid that bathes cells, ultrafiltrate of plasma
______ is in constant motion throughout the body (by diffusion)
ECF
ECF contains
large amounts Na+ and Cl-
ICF contains
K+ and Mg2+, little Ca2+
Parameters of constants with narrow range
ph, Na+ conc, blood volume, arterial pressure, body temp, plasma glucose + O2, ions
Parameters of constants with large range
blood glucose level
Extracellular fluid is transported through the body in two stages
-movement of blood through the body in blood vessels -movement of fluid between capillaries and intercellular spaces between the tissue cells
Walls of capillaries permeable to most molecules in plasma blood except
plasma proteins
Blood pumped by heart also passes through walls of
GI tract
Endocrine hormones
released by glands or specialized cells into the circulating blood and influence the function of target cells at another location in the body
Neuroendocrine hormones
secreted by neurons into the circulating blood and influence the function of target cells at another location in the body
Paracrines
secreted by cells into the extracellular fluid and affect neighboring target cells of a different type
Autocrines
secreted by cells into the extracellular fluid and affect the function of the same cells that produced them
Nervous system regulates ________ activities while hormonal system regulates __________ activities
muscular + secretory, metabolic
Negative-feedback mechanism is responsible for
homeostasis, prevents deviations
4 elements of negative feedback mechanism
system sense parameters
system compares input signal with set-point
system multiplies error signal to make output signal
output signal activates effector mechanism that opposes source of input signal
Positive feedback loop leads to
instability
Advantageous instances of positive feedback loops
blood clot, childbirth, ovulation
O2 maintenance in ECF depends on
oxygen-buffering function of hemoglobin
System that regulates arterial blood pressure
baroreceptor system
Chemical rxns of cells take place
among dissolved chemicals or at surface of suspended particles/membranes
Ions
provide inorganic chemicals for rxns + for control mechanisms
Structural proteins
microtubules that make cytoskeleton
Functional proteins
enzymes
Plasma membrane - functions
selective transport
cell recognition
cell communication
tissue organization
membrane-dependent enzymatic activity
cell shape
Plasma membrane is made of
proteins and lipids
Phospholipids are
amphipatic
Proteins in cell membrane may be _____ or __________
integral, peripheral
Integral membrane proteins are in cell membrane by _________ interactions
hydrophobic
Transmembrane protein
span the lipid bilayer one or more times → in contact with both ECF and ICF
carrier proteins
bind with molecules or ions that are to be transported, and through conformational changes in the protein molecules, move the substances through the interstices of the protein to the other side of the membrane
channel proteins
free movement of water, as well as selected ions or molecules
Peripheral membrane proteins attached to cell membrane through
electrostatic interactions
Aquaporins/water channels
for water movement in/out cell
Regulation of the amount of H 2O that can enter or leave the cell via AQPs occurs primarily by
altering the number of AQPs in the membrane
Selectivity
nature of the ions that pass through the channel
Channel conductance
number of ions that pass through the channel and the range of conductance is considerable
Ion channels fluctuate between an open state or a closed state, a process called
gating
Factors that control gating
membrane voltage
extracell agonist/antagonists
intracell messenger
stretch of plasma membrane
Active transport
use the energy in ATP to drive the movement of molecules/ions across the membrane
With the hydrolysis of each ATP molecule, it transports ________ Na + ions out of the cell and _____ K + ions into the cell
3, 2
Primary active transport of H+ ions important at 2 places
gastric glands of stomach
distal tubules and cortical collecting ducts of kidneys
Uniporter/facilitated transporter
transports 1 molecule across membrane
symporters vs antiporters
moves 2+ molecules across membrane in same direction vs diff direction
Simple vs facilitated diffusion
facilitated requires carrier protein interaction
Osmosis
passive movement of water, from low to high solute conc
Osmotic pressure
amount of pressure to stop osmosis (of NaCl solution), determined by the number of solute molecules dissolved in the solution
Oncotic pressure
osmotic pressure generated by large molecules in solution
Tonicity
effect of the solution on the volume of a cell
Isotonic, hypotonic vs hypertonic
hypotonic - cell swells, osmolarity of ECF decreases hypertonic - cell shrinks, osmolarity of ECF increases
Specific gravity
total conc of all molecules in solution
Insensible water loss
respiratory tract and through skin
changes in excretion of water are mainly controlled by
ADH
Components extracellular fluid
interstitial fluid
plasma
transcellular fluid
Plasma - function
exchanges substances through capillary membranes
Donnan effect
uneven distribution across 2 sides of membrane, more cations in plasma than interstitial fluid
osmolality vs osmolarity
osmolality - conc expressed as osmoles per kg osmolarity - expressed as osmoles per L
Calculated osmolarity
2 (Na+) + 2 (K+) + Glucose + Urea
Hypoanetremia vs hyperanetremia
dependent on plasma Na conc, hypoanetremia cell swells, hyperanetremia cell shrinks
Hyperanetremia causes
dehydration, diabetes
Plasma - contents
electrolytes
organic compounds
metabolites
Colour differentiation of plasma
pink is hemolysis
brown/green is elevated bilirubin
cloudy is cryoglobulinemias
variations in plasma protein concentrations can be caused by
rate of protein synthesis
rate of removal
volume of distribution
Plasma protein conc aids in assessing
state of hydration
Albumin levels
low in hepatic cirrhosis high in low plasma colloid osmotic pressure
Starling forces
hydrostatic pressure of arterioles (37mmHg) and venules (17mmHg)
edema
if conc of plasma proteins diminished, accumulates in extravascular tissue
hypoalbuminaemic state
decreased plasma oncotic pressure, less movement of interstitial fluid back into blood in venules = edema
Edema is caused by
increase in capillary hydrostatic pressure
decrease in plasma oncotic pressure
increase in capillary permeability
Cytokines
control activity and growth of cells, coordinate immune responses
plasma contains __________ which is absent in serum
fibrinogen
Osmosis