Ch 6 Flashcards
electrical signals definition
changes in the membrane potential of a cell
physiological signals must be ______ or ______
electrical or chemical
chemical signals functions
-secreted by cells into ECF
-responsible for most communication within the body
four basic methods of cell communication
-gap junctions
-contact-dependent signals
-local communication
-long distance communication
gap junction properties
-direct constant and local cell-to-cell communication
-transfer both chemical and electrical signals
-form direct cytoplasmic connections between adjacent cells
contact-dependent signals require
interaction between membrane molecules on two cells
cell adhesion molecules transfer signals in ______ directions
both
autocrine signals act on
the same cell that secreted them
paracrine cells are
secreted by one cell and diffuse to adjacent cells
forms of local cell-to-cell communication
autocrine and paracrine
hormones function for what kind of communication
short and long distance
hormones are secreted by
endocrine glands or cells into the blood
most rapid type of cell to cell communication
neuro transmitters
What are NT
chemicals secreted by neurons that diffuse across a small gap to the target cell. they use electrical signals as well
what are neurohormones
chemicals released by neurons into the blood for action at distant targets
four categories of membrane receptors
-channel
-enzyme
-GPCR
-Integrin
signal transduction converts
one form of signal into a different form
transducers convert
extracellular signals into intracellular messages which create a response
examples of amplifier enzymes
-adenylyl cyclase
-guanylyl cyclase
-phospholipase C
biological signal transduction converts
chemical signals into cellular responses
tyrosine is a ______
receptor enzyme
GPCR properties
-membrane spanning proteins
-cytoplasmic tail linked to G protein, a three part transducer molecule
When G proteins are activated, they ______
-open ion channels in the membrane
-alter enzyme activity on the cytoplasmic side of the membrane
adenlylyl cyclase-cAMP pathway
-ligand binds to beta receptor
-beta receptor activates G protein
-G protein turns on adenylyl cyclase
-adenylyl cyclase converts ATP to cAMP
-cAMP activates protein kinase A
-protein kinase A phosphorylates other proteins
-cellular response
phospholipase C system pathway
-ligand activates beta receptor
-receptor activates G protein
-G protein activates PL-C
-PL-C converts phospholipids into DAG and IP3
-IP3 diffuses into cytoplasm and causes release of Ca2+ from organelles
-DAG remains in membrane and activates PK-C
calcium as an intracellular messenger can alter
-enzyme activity
-gating activity
-gating state
-movement
-exocytosis activity
-embryo development
functions of nitric oxide
-activates guanylyl cyclase
-acts as a neurotransmitter and neuro-modulator in brain
-produced by endothelial cells
-affects erectile dysfunction
carbon monoxide functions
-also activates guanylyl cyclase and cGMP
-targets smooth muscle and neural tissue
hydrogen sulfide functions
-targets cardiovascular system
-garlic is major source of precursors
agonist
activates the receptor and still achieves a response
antagonist functions by
blocking receptor activity resulting in no cellular response
can one ligand trigger multiple receptors
yeeeeeeeeeeeeees
forms of down-regulation
-by decreasing the number of receptors
-by decreasing the binding affinity
-one explanation for drug tolerance
diseases and drugs target
signal transduction protein
cannon’s postulates of homeostatic control systems
- nervous regulation “preserves the fitness” of the internal environment
- tonic control
- antagonistic control
- one chemical signal can have different effects in different tissues
