Slide set 3 Flashcards
Two basic types of physiological signals
Electrical signals (changes in membrane potential) Chemical signals (molecules in extracellular fluid)
4 basic methods of cell-to-cell communication
Gap junctions
Contract-dependent signals
Chemical that diffuse through the extracellular fluid to act on cells close by
Long-distance communication
Explain gap junctions
Allow direct cytoplasmic transfer of electrical and chemical signals between adjacent cells
When open, ions, amino acids, ATP, cAMP diffuse directly
from the cytoplasm of one cell to the cytoplasm of the next
- Larger molecules cannot pass through
- The only means by which electrical signals can pass directly
from cell to cell
Explain contact-dependent signals
When surface molecules on one cell membrane bind to surface molecules on another
Occurs in immune system and during growth
and development
Long-distance cell communication uses
A combination of chemical signals transported by the blood
Connexins are used ___
They form a union for gap junctions
What type of signaling includes cell-adhesion molecules
Contact-dependent signals
Also integrins are involved
Methods of chemical communication
Autocrine signals act on the same cell that secreted
them. Paracrine signals are secreted by one cell and
diffuse to adjacent cells
Characterize long distance communication
Hormones are secreted by endocrine
glands or cells into the blood. Only target
cells with receptors for the hormone will
respond to the signal.
Neurotransmitters are chemicals secreted
by neurons that diffuse across a small gap
to the target cell. Neurons use electrical
signals as well.
Neurotransmitters have ___ effect
rapid
What are neurohormones
Chemicals released by neurons onto the blood for action at distant targets
Cytokines may act as both
Local and long-distance signals
Where cytokines are synthesized, what are their roles, and how they are made
- Are synthesized and secreted by all nucleated
cells (not produced by specialized cells) - Control cell development, differentiation, and
immune responses - Act on a broader spectrum of target cells than
hormones - Made on demand (not stored)
Features shared by all signal pathways
- The signal molecule (ligand/first messenger)brings information to the
target cell - Ligand-receptor binding activates the receptor
- The receptor activates one or more intracellular signal molecules
- The last signal molecule initiates synthesis of target proteins or modifies
existing target proteins to create a response
Slide
The location of ligand/receptor binding is largely dependent
on whether a signal molecule is __________or ___________
Hydrophobic
Hydrophylic
________ signal molecules can diffuse through the
phospholipid bilayer binding to ___________ or __________
receptors
Hydrophobic
Nuclear
Cytoplasmic
Signaling through hydrophobic molecules is relatively ___
Slow process
Lipophobic molecules ___ diffuse through the plasma membrane, they bind to ___, this process is very ___
Cannot
Extracellular receptors
Rapid
Lipophylic signal can bound to
Receptor in cytoplasmic membrane
Receptor in cytosol
Receptor in nucleus
What is the scheme of signal transduction
Signal molecule->receptor->intracellular signal->target proteins->response
What is the role of second messenger
1. Alter the gating of ion channels 2. Increase intracellular calcium (which bind to proteins to change their function) 3. Change enzyme activity, especially of protein kinases and protein phosphatases
Steps of signal transduction pathway form a ___
Cascade
WHat is the role of tyrosine kinase
Transfers a phosphate group from ATP to a tyrosine of a protein
Tyrosine kinase is an example of
Receptor-enzyme (insulin receptor)