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Ch 6: Membrane Communication - Coggle Diagram
Ch 6: Membrane Communication
Physiological Signals
Electrical
changes in a cell membrane's "potential".
Chemical
molecules secreted by cells into the extracellular fluid
Target cells- cells that respond to both types
most chemical signals
Cell-Cell Communication
Long-Distance Cell Communication
combinations of electrical via nerve cells and chemical via blood to target systems; nervous and endocrine respectively
Ligand
Local Cell Communication
Gap Junction
cytoplasmic transfer of electrical and chemical signals between adjacent cells linked by membrane proteins
Direct Communication
Contact-dependent signals
surface molecules on one cell membrane binding to surface molecules of another cell membrane
Paracrine Signal
chemical secreted by a cell that acts on nearby cells
Autocrine Signal
local chemical signal that acts on the secreted cell
Ligand-ion or molecule stuck to a metal atom
Neurocrine Molecules- molecules secreted by a nerve cell
Neurotransmitter
chemical signal released by a neuron to affect its target cell
Neuromodulator
chemicals alter the response of a neuron; slower than neurotransmitter
Neurohormone-
hormone that is made and secreted by a neuron
bridge the gap between NS and ES, medium between the two
Cytokine
peptides that alter and make an immune response
associated with immune response (inflammation)
Cell Development and Differentiation
autocrine and paracrine signal
Stress and inflammation
act on relatively distant targets and transported via circulation like hormones
Made on demand; long or local distance signals
Ex) interferons, interleukins, colony-stimulating factors, growth factors, tumor necrosis factors, chemokines
Signal Pathways (Refer to drawing and steps)
Messengers are classified by chemical Properties
either be
Lipophilic
bind to cystolic or nuclear receptors
activates intracellular receptors to turn on a gene and make the nucleus craft mRNA
slow response
suppress/repress gene activity
Types
Steroids
hormone
Eicosanoids
paracrine
lipophobic
bind to cell membrane receptor since they can't enter the cell via simple diffustion
bind to receptor proteins;fast response time
Types
Amino Acids
functions as a neurotransmitter
Amines
Peptides/Proteins
Paracrine, neurotransmitter, hormones
Signal Transduction- sending info from one side of a membrane to another side using membrane proteins.
Transducer- device that converts a signal from one form into a different form
Change the function of a target cell
Messengers interact with the target cell by binding to receptors on or in the target cell (first messenger by bringing info to target cell).
receptors change enzyme activity or alter channel function/cell function.
ligand-receptor binding activates receptor
Receptor activates 1+ intracellular signal molecules
last signal molecule in the pathway modifies existing proteins or starts making new proteins
Properties of Receptors
specificity (Target Response)
Number of Interactions (Greater Responses) can be affected by
messenger concentration
Number of receptors present
Receptor affinity
Messenger Receptor Responses
Intracellular Mediated Responses
Receptors are either cytosol (cytoplasm) or nuclear (nucleus)
use of Lipophilic molecules and thyroid hormones
Responses includes gene inhibition or activation
Membrane-Bound Receptor-Mediated Responses
lipophobic messengers
receptors are from the cell membrane
Types
Receptor-Channels
Ion channels (simplest
Ligand binding opens/closes the channel and alters ion flow across the membrane (Ion movement)
Receptor-Enzyme
Membrane Proteins that binds ligands on the extracellular side and activates enzymes on the intracellular side
Inactive until a messenger molecule is attached
receptor enzymes results in intracellular enzymes to be activated
G-protein coupled receptors
large, complex family of membrane-spanning proteins
G-protein- cytoplasmic tail of the receptor protein
messenger molecule acts on the receptor and activates the G proteins which acts on another protein found in the cell membrane
Most signal transduction mechanisms
bonding ligands include hormones, growth factors, olfactory molecules, visual pigments, and neurotransmitters.
enzyme include adenyl cyclase and phospholipase C
Integrin Receptors
role in blood clotting, wound repair, cell adhesion, immune response recognition, and cell movement during development
aka enzyme receptors with additional properties
ligand
Second Messenger System
intracellular molecule produced by or entering into the target cell in response to an extracellular messenger
triggered by the first messenger (ligand) activating the G-protein-coupled receptor
Common 2nd messenger are calcium ions or Cyclic Amp
Signal Amplification
process by which a signal molecule can generate multiple intracellular effector molecules
exponentially increases number of molecules made: 1 -> multiple
Signal Molecules
Nitric Oxide
diffuses into target cells where it binds to intracelular proteins
made by endothelial cells that line blood vessels
causes muscles to relax and dilate blood vessels
neurotransmitter and neuromodulator in the brain
Hydrogen Sulfide
acts in the cardiovascular system to relax blood vessels
garlic has H2S
explains why eating foods with garlic has + heart effects
Calcium
Roles
alters enzyme/transporter activity or the gating of ion channels ex) binding to the protein calmodulin
Binding to regulatory proteins and alters movement of contractile or cytoskeletal proteins ex) calcium binding to troponin to make muscle contractions in a skeletal muscle cell
Binding to regulatory proteins to trigger exocytosis ex) release of insulin from pancreatic beta cells in response to calcium
Direct binding to ion channels to alter gating states example) Calcium and potassium channel in nerve cells