L1 & L2: Homeostasis & Cell Signaling Flashcards
major types of fluid
intracellular and extracellular
extracellular fluid is composed of __
plasma and interstitial fluid
extracellular fluid serves as
buffer zone between cells and outside environment
what’s the percentage composition of three types of fluids out of overall volume?
plasma 7%
interstitial fluid 26%
intracellular fluid 67%
what’s the percentage composition of plasma and interstitial fluid out of extracellular fluid?
plasma 1/4
interstitial 3/4
homeostasis
dynamic stability of the internal environment of the body
in homeostasis, when the internal environment of the system is changed, ___
the system eventually returns to the set point
reflex
biological control system linking stimulus with response to maintain homeostasis
reflex arcs can be regulated by __
negative feedback
____ reinforce a stimulus
positive feedback
is positive feedback homeostatic?
no
paracrine signals
signals that affect nearby cells
autocrine signals
generated by the same cells upon which they act
when the target is close, cell communicate using
paracrine and autocrine signals
when the target is distant, cells communicate using
endocrine and neuronal signals
signaling molecules may trigger
a change in electrical potential, metabolism, gene expression, cellular motility
signal transduction
process by which cell converts one kind of signal into another
second messengers
molecules that direct, relay, and amplify signals
two classes of extracellular signal molecules
ones that go directly into the cell (small and hydrophobic), and ones that bind to surface receptors (hydrophilic)
what cells release NO?
endothelial cells
what enzyme does NO signal activate?
gyanylyl cyclase
where is gyanylyl cyclase located?
smooth muscle cell
what does gyanylyl cyclase synthesize?
cGMP
how does viagra affect the pathway?
by inhibiting PDE that normally breaks down cGMP, prolonging the NO signal and penile erection
do steroid hormones require cell surface receptors?
no, they easily diffuse into the cell
what are three major classes of cell surface receptors?
G-protein linked, ion-channel linked, enzyme linked
inactive G-proteins
are bound by GDP at the alpha subunit
binding of the G-protein to receptor triggers ___
the exchange of GDP with GTP by the alpha subunit, activating the G protein
what enzyme does GS activate?
adenylyl cyclase
what enzyme does GQ activate?
phospholipase C
what process does adenylyl cyclase catalyze?
cAMP formation
what does cAMP activate?
protein kinase A
what enzyme is involved in the degradation of cAMP?
phosphodiesterase
what is one of the physiological actions of caffeine?
PDE inhibitor
a rise in intracellular cAMP can ___
activate gene transcription
second messengers involved in GQ pathway
PIP2, IP3, and DAG
what protein is activated in EGFR pathway?
Ras protein
Ras activates __
MAP-kinase cascade
enzyme-linked receptors have __
intracellular enzymatic domains
largest class of enzyme-linked receptors
receptor tyrosine kinases (RTKs)
activated RTKs cause
the assembly of an intracellular signaling complex
what is Ras?
monomeric G-protein involved in EGFR pathway
enzyme-linked receptors have __
intracellular enzymatic domains
