Cellular communication Flashcards
Examples of positive feedback control in the human body include (select 3):
a. generation of an action potential
b. PaCO2 regulation
c. coagulation cascade
d. core temperature
e. serum glucose concentration
f. childbirth
a. generation of an action potential
c. coagulation cascade
f. childbirth
________________ is a steady-state condition that comes with a price- it requires energy to maintain the system
Homeostasis
A control system must be able to do 4 things:
sense the vital parameter
compare the input signal with the set point
multiply the error signal
adjust the vital parameter
____________ reverse a disturbance in some factors and lead to stability
Negative feedback
______________ enhance or accelerate a disturbance in some factor and usually lead to instability
Positive feedback systems
Examples of beneficial positive feedback are
childbirth
the blood coagulation cascade
the generation and propagation of an action potential
Which method of cell signaling occurs when a cell responds to a chemical signaling molecule that the cell itself produced and secreted?
a. endocrine signaling
b. paracrine signaling
c. neurotransmitter signaling
d. autocrine signaling
d. autocrine signaling
The intracellular response to extracellular signals is called
cell signaling
Cell signaling allows cells to
communicate with one another
The conversion of information into a chemical change is called
signal transduction, a universal property of living cells
Information arrives at cells in these four forms:
purely physical (energy)
chemical
cellular
extracellular matrix molecules
Examples of purely physical forms include
light, sound, heat, pressure, electricity
Examples of chemical forms include
neurotransmitters
hormones
eicosanoids
drugs
toxins
Examples of cellular forms include:
gap junctions
Examples of extracellular matrix molecules include
collage (think of platelet adhesion), integrins, laminin
There are three main methods of intracellular communication:
endocrine
paracrine
autocrine
Describe endocrine cell signaling.
A signaling molecule (i.e. a hormone) is secreted by an endocrine cell and transported through the circulation where it acts on a distant target cell
________________ is a specific type of endocrine signaling where a neuron is the source of the hormone secreted into the blood
neuroendocrine cell signaling
Describe paracrine signaling.
a chemical signaling molecule is released by one cell and acts locally to regulate the behavior of a neighboring cell
Describe autocrine signaling.
A cell responds to a signaling molecule that is also produced
Think of _____ as talking to your friends and family around the country on a mobile phone, ______________ as talking directly to your neighbors, and ________________ signaling as talking to yourself
endocrine, paracrine, autocrine
Autocoid typically refers to
local hormones
Neurotransmitter signaling is a specific form of which type of cell communication method?
paracrine
A chemical molecule that binds to a receptors and initiates a cellular response is called a:
a. second messenger
b. transducer
c. ligand
d. kinase
c. ligand
Signal transduction has the following 6 characteristics:
specificity and sensitivity
amplification
integration
feedback
compartmentalization
desensitization
The flow of information in a signal transduction sequence follows
orderly pathways
There are six processes in signal transduction sequences (with occasional exceptions):
- recognition
- transduction
- transmission
- modulation
- response
- termination
What are the four categories or types of receptor-based signal transducers:
- transmembrane G protein coupled receptors
- transmembrane gated ion channels
- transmembrane enzyme linked receptors
- soluble nuclear (intracellular) receptors
Bonds ordered from weakest to strongest:
van der Waals< hydrophobic < hydrogen< ionic < covalent
Amplification is when
a small signal produces a disproportionately larger effect
The ability of a signal-transducing system to receive multiple signals and produce a unified response appropriate to the cell’s needs is
integration
___________ occurs when a signal is present continuously.
Desensitization
A general term for any chemical that binds to a receptor is
“ligand” or first messenger
Transduction is the generation of
a second messenger or the activation of a catalytic cascade
What chemical messengers are derived from arachidonic acid? (select 3)
a. prostaglandins
b. thyroxine
c. aldosterone
d. leukotrienes
e. dopamine
f. anandamide
a. prostaglandins
d. leukotrienes
f. anandamide
Most chemical signals fall into four categories of molecules:
- small hydrophilic molecules
- lipophilic molecules
- peptides and proteins
- others
The following messengers are not stored in vesicles:
lipophilic
purine
gas
endocannabinoid
Chemical messenger molecules bind to either
cell-surface receptors or intracellular receptors
Small hydrophilic chemical messengers can be broken up into 4 subclasses:
amino acids (glycine, glutamate, GABA, aspartate)
biogenic amines (dopamine, norepinephrine, epinephrine, serotonin, histamine)
choline esters (acetylcholine)
iodothyronines (Thyroxine T4, Triiodothyronine T3)
Characteristics of small, hydrophilic chemical messengers include:
polar molecules that are ionized
don’t cross plasma membranes
stored in vesicles in the cells that synthesized them
typically released by exocytosis (T4 & T3 are the exceptions)
The following are derived from tyrosine:
dopamine
NE
epi
iodothyronines
_________ & __________________- can be interconverted
GABE & glutamate
Subclasses of lipophilic chemical messengers include
steroids (aldosterone, cortisol, testosterone, progesterone, estrogens)
eicosanoids (prostaglandins, leukotrienes, thromboxanes)
miscellaneous (vitamin D3, retinoids)
Steroids are derived from
cholesterol & maintain the cholesterol rings structure
Steroids circulate in the
blood bound to a protein
Steroids ______________ through the lipid bilayer of plasma membranes
diffuse
Steroids are _____________ in the producing cells
not stored
Steroids bind to receptors in the
cytoplasm or nucleus of the target cells
