cell cell communication
DESCRIPTION
Human physiologyCell Cell CommunicationTRANSCRIPT
-
5/27/2018 Cell Cell Communication
1/14
Figure 6.19-7 ESSENTIALS Simple and Complex Reflex Pathways
E
S
T
KEY
Output PathwaysStimulus
Sensor
Sensory neuron(input pathway)
CNS integratingcenter
Endocrineintegrating center
Efferent neuron
Neurotransmitter
Neurohormone
Classic hormone
Target cell (effector)
Simple EndocrineReflex
Stimulus
Response
E
T
Example:Insulin releasewhen bloodglucose increases
-
5/27/2018 Cell Cell Communication
2/14
Figure 6.1-1 ESSENTIALS Communication in the BodyLOCAL COMMUNICATION
Gap junctionsformdirect cytoplasmicconnections betweenadjacent cells.
Contact-dependent signalsrequire interaction betweenmembrane molecules ontwo cells.
Autocrine signalsact on the same cellthat secreted them. Paracrine signalsare secreted by one cell and diffuse to
adjacent cells.
Receptor
-
5/27/2018 Cell Cell Communication
3/14
Figure 6.1-2 ESSENTIALS Communication in the BodyLONG-DISTANCE COMMUNICATION
Endocrine System Nervous System
Long-distance signaling may be electrical signals passingalong neurons or chemical signals that travel through thecirculatory system.
Endocrinecell
Cellwithoutreceptor
Cellwith
receptor Targetcell
No response
Response
Blood
Hormonesare secreted by endocrine glands or cells into theblood. Only target cells with receptors for the hormone respondto the signal.
Neurohormonesare chemicalsreleased by neurons into the bloodfor action at distant targets.
Neurotransmittersare chemicals secreted by neurons that diffuseacross a small gap to the target cell.
No response
Response
Response
Cellwithoutreceptor
Cellwith
receptor
Targetcell
Blood
Neuron
Neuron
Electricalsignal
-
5/27/2018 Cell Cell Communication
4/14
Figure 6.3 Target cell receptors may be located on the cell surface or inside the cellIntracellular Signal Receptors
Four Categories of Membrane Receptors
Cell Membrane Receptors
Extracellular signalmolecule binds to acell membranereceptor.
Bindingtriggers
Rapid cellularresponses
Receptorin nucleus
Receptor in cytosol
Lipophilic signalmolecules diffuse
through the cellmembrane.
Binding tocytosolicor nuclearreceptorstriggers
Slower responsesrelated to changes
in gene activity
Channel Receptor Receptor
ECF
Extracellularsignal
molecules
ICF
Enzyme G protein
Cell
membrane
Anchorprotein
Cytoskeleton
Ligand binding tointegrin receptorsalters the cytoskeleton.
Integrin receptorG proteincoupled receptorReceptor-enzyme
Ligand binding to a G proteincoupled receptor opens an ionchannel or alters enzyme activity.
Ligand binding to areceptor-enzyme activatesan intracellular enzyme.
Ligand bindingopens or closesthe channel.
Receptor-channel
-
5/27/2018 Cell Cell Communication
5/14
Figure 6.5a Biological signal transduction (1 of 2)
Basic Signal Transduction
Firstmessenger
Transducer
Secondmessengersystem
Targets
Signalmolecule
Membranereceptor protein
Intracellularsignal molecules
Targetproteins
binds to
activates
alter
create
Response Response
-
5/27/2018 Cell Cell Communication
6/14
Figure 6.6c ESSENTIALS Signal Transduction
Second messenger pathways
ATP
GTP
Membranephospholipids
Adenylyl cyclase(membrane)
Guanylyl cyclase(membrane)
Guanylyl cyclase(cytosol)
Phospholipase C(membrane)
GPCR*
GPCR
Receptor-enzyme
Nitric oxide (NO)
Activates proteinkinases, especially PKA.Binds to ion channels.
Activates proteinkinases, especially PKG.
Binds to ion channels.
Releases Ca2+fromintracellular stores.
Activates proteinkinase C.
Binds to calmodulin.Binds to other proteins.
Phosphorylatesproteins. Alterschannel opening.
Phosphorylatesproteins.
Alters channelopening.
See Ca2+effectsbelow.
Phosphorylatesproteins.
Alters enzyme activity.Exocytosis, musclecontraction, cyto-skeleton movement,channel opening.
*GPCR G proteincoupled receptor. IP3 Inositol trisphosphage. DAG idacylglycerol
Ca2+
IP3
DAG
cGMP
cAMP
Ions
Lipid-derived*
Nucleotides
SECONDMESSENGER MADE FROM
AMPLIFIERENZYME LINKED TO ACTION EFFECTS
-
5/27/2018 Cell Cell Communication
7/14
Figure 6.7
Tyrosine Kinase Receptor
Tyrosine kinase (TK) transfers a phosphate group fromATP to a tyrosine (an amino acid) of a protein.
Signal molecule bindsto surface receptor
Tyrosine kinase oncytoplasmic side
Phosphorylatedprotein
ADP
ATP
ICF
Protein Protein
Active binding site
Cellmembrane
ECF
TK
R
L
-
5/27/2018 Cell Cell Communication
8/14
Figure 6.8a (1 of 2)
GPCR-adenylyl Cyclase Signal Transduction and Amplification
One signalmolecule
GPCR
G protein
ATP
Adenylyl
cyclase
cAMP
Proteinkinase A
Phosphorylatedprotein
Cellresponse
Using the pattern shown in Fig. 6.6a,create a cascade that includes ATP, cAMP,adenylyl cyclase, a phosphorylatedprotein, and protein kinase A.
Protein kinase A phosphorylatesother proteins, leading ultimatelyto a cellular response.
cAMP activates protein kinase A.
Adenylyl cyclase converts ATP tocyclic AMP.
G protein turns on adenylyl cyclase,an amplifier enzyme.
Signal molecule binds to G proteincoupled receptor (GPCR), whichactivates the G protein.
FIGURE QUESTION
-
5/27/2018 Cell Cell Communication
9/14
!"#$% '()(*+,' -)./-+(0 1234512 3()'(.,2 6',7 *-2)'(-.)
8$)(5539 7():-2137 -20 ;54),3( 0(*(20(2)(
GLP-1 = glucagon-likepeptide 1
-
5/27/2018 Cell Cell Communication
10/14
Figure 6.8b (2 of 2)
GPCR-phospholipase C Signal Transduction
Signal
molecule
ReceptorG protein
ERCa2+ Ca2+stores
PLC
IP3
PKC
DAG
Membrane phospholipid
Cellularresponse
Phosphorylatedprotein
Protein Pi
KEY
PLC phospholipase C
DAG diacylglycerolPKC protein kinase C
IP3 inositol trisphosphate
ER endoplasmic reticulum
Cellmembrane
Intracellularfluid
Extracellular
fluid
IP3causes releaseof Ca2+fromorganelles, creatinga Ca2+signal.
DAG activates proteinkinase C (PKC), whichphosphorylatesproteins.
PLC converts membrane phospho-lipids into diacylglycerol (DAG), whichremains in the membrane, and IP3,which diffuses into the cytoplasm.
G protein activatesphospholipase C(PLC), an amplifierenzyme.
Signal moleculeactivates receptorand associatedG protein.
-
5/27/2018 Cell Cell Communication
11/14
Figure 6.10 ESSENTIALS Summary Map of Signal Transduction
-
5/27/2018 Cell Cell Communication
12/14
Figure 6.13
Target response depends on the target receptor.
-Receptor Response 2-Receptor Response
-Receptor 2-Receptor
Epinephrine -Receptor Epinephrine 2-Receptor
Vessel constricts.
Vessel dilates.
Intestinal
blood vessel Skeletal muscleblood vessel
Epinephrine can bind todifferent isoforms of theadrenergic receptor.
In this example, blood vesselsdilate or constrict dependingon their receptor type.
-
5/27/2018 Cell Cell Communication
13/14
Figure 6.15b Tonic and antagonist control of regulated variables (4 of 6)
ANTAGONISTIC CONTROL
Stimulation by sympathetic nerves increases heart rate.Antagonistic controluses different signalsto send a parameter in opposite directions. Inthis example, antagonistic neurons control heartrate: some speed it up, while others slow it down.
Sympatheticneuron
Parasympatheticneuron
Heartbeats
Heartbeats
Time (sec)
Time (sec)
0 1 2 3
Stimulation by parasympathetic nerves decreases heart rate.
What heart rates (in beats/min)are shown on the two ECGtracings?
FIGURE QUESTION
0 1 2 3
-
5/27/2018 Cell Cell Communication
14/14
Figure 6.19-1 ESSENTIALS Simple and Complex Reflex PathwaysComplex Neuroendocrine Reflexes Simple EndocrineReflexSimple NeuralReflex NeurohormoneReflexStimulus Stimulus Stimulus Stimulus Stimulus Stimulus
Sensor
Sensory
neuron
Efferentneuron
Neuro-transmitter
Targetcell
Example:The knee jerk reflex
Bloodvessel
Response
Response
Response
Response
Response
Neurotransmitter
Neurohormone
Endocrinecells
Hormone
Hormone #2
T
T
T
T
T
T
E
E
E
E1
E2
Example:Release of breastmilk in responseto suckling
Example:Insulin secretion inresponse to a signal
from the brain
Example:Secretion ofgrowth hormone
E
S
T
KEY
Output PathwaysStimulus
Sensor
Sensory neuron(input pathway)
CNS integratingcenter
Endocrineintegrating center
Efferent neuron
Neurotransmitter
Neurohormone
Classic hormone
Target cell (effector)
Example:This pattern occurswith hormonesreleased by theanterior pituitary.
Response
CNS CNS CNS CNS CNS