14 Cellular Signaling Flashcards
T or F: Cell to cell signaling is also called intracellular communication.
False. It should be intercellular communication.
What are the four main types of chemical messengers?
Endocrine, Paracrine, Autocrine, Neurocrine
T or F: Some of the chemical mediators act as more than one type of chemical messengers.
True.
Give one example of an endocrine messenger.
Insulin / Growth hormones
Endocrine messengers are also known as ___________.
Classical hormones
T or F: Paracrine messengers act on distant cells.
False. Paracrine messengers act locally to affect nearby, target cells, not distant ones.
Through what medium do paracrine messengers diffuse?
Interstitial fluid or ECF
Which messenger is typically involved in long-distance signaling?
Endocrine
What is the speed of transport for endcorine messengers: fast or slow?
Slow
What specialized structure allows direct communication between neighboring cells in juxtacrine signaling?
Gap junctions
What is another name for juxtacrine messengers?
Local hormones
T or F: Noradrenaline only functions as a neurotransmitter.
False. Noradrenaline functions both as a neurotransmitter and as a classical hormone.
What dual roles can dopamine play in the body?
Neurotransmitter and a hormone
What is another term for autocrine messengers?
Intracellular chemical mediators
How do endocrine messengers reach their target cells?
Bloodstream
Leukotrienes are an example of paracrine messengers.
False. Leukotrienes are an example of autocrine messengers.
What are neurocrine substances also known as?
Neural Messengers
An endogenous signaling molecule that carries information from one nerve cell to another nerve cell, muscle, or another tissue
Neurotransmiter
Name two examples of neurotransmitters.
- Acetylcholine
- Dopamine
Chemical substances released by nerve cells directly into the blood and transported to distant target cells.
Neurohormones
Give examples of neurohormones
- Oxytocin
- ADH
- Hypothalamic releasing hormones
What is the primary function of receptors in neurocrine signaling?
To sense and respond to changes in signals by activating biochemical pathways within the cell, leading to a defined response.
What are chemical mediators and receptors?
Protein molecules to which a chemical messenger binds to stimulate a cell response
Where are receptors located?
On the surface of the cell, within the cytoplasm, or in the nucleus.
Neurotransmitters are released at synaptic junctions from nerve cells and act across a narrow synoptic cleft on a post synaptic cell
Neural/Synaptic
How do hormones and growth factors reach their target cells in endocrine communication?
Through circulating blood or lymph.
What is the difference between paracrine and autocrine communication?
- In paracrine communication, the product of cells diffuses in the extracellular fluid (ECF) to affect neighboring cells
- in autocrine communication, the chemical
messenger binds to receptors on the same cell that secreted it.
Name types of chemical messengers that can function as neurotransmitters and paracrine mediators
Amines, amino acids, and steroids
What are the specialized junctions that allow intracellular signaling molecules to diffuse from the cytoplasm to one cell to an adjacent cells?
Gap Junctions
Where are gap junctions found?
Cardiac and smooth muscles
What are the specialized junctions that allows cells to be electrically coupled or permit rapid propagation of electrical activity, which is vitally important for the coordinated activity of cardiac and smooth muscles?
Gap Junctions
In neural communication, what are released at the synapse?
Neurotransmitters
What kind of communication utilizes neurotransmitters wherein the signal may travel long distances however the effect is limited to a very specific area?
Neural Communication
What kind of communication has a relatively slow due to time required for diffusion and the blood flow to reach the target cell?
Endocrine Communication
What does endocrine communication utilize to convey the signal?
Hormones
What kind of communication involves the secretion of chemicals into the interstitial fluid and primarily affects local areas or nearby cells?
Paracrine Communication
- In Paracrine communication, where are the chemicals secreted?
Interstitial fluid
What are specialized junctions allowing intracellular signaling molecules to diffuse from a cell’s cytoplasm to its adjacent cell.
Gap junctions
Why are gap junctions found in cardiac cells and smooth muscles?
Theey can rapidly propagate electrical activity from cell to cell which is important for coordinated activity of cardiac and smooth muscles
Gap junctions can be found in which cells?
Cardiac muscles and smooth muscles
T or F: As molecules go from one cell to another through gap junctions, they pass freely through the ECF.
False. They pass freely between cells WITHOUT entering the ECF.
Give some examples of substances that can pass via gap junctions.
-Ions
-Sugars
-Amino acid
-Other solutes within required molecular weight
In neural communication, at what site are neurotransmitters released?
Synapse
T or F:
1) Synaptic signaling is extremely fast or in milliseconds
2) Given its speed, the signal can travel only short distances.
1) True
2) False. It can travel LONG distances.
What characteristic of neural communication defines it as limited to a very specific area.
Discrete
In endocrine communication, the signaling molecules are released where?
Bloodstream, blood, lymph
Aside from signaling molecules, endocrine communication can also release?
Growth factors
Give an example of discrete or generalized hormone.
Antidiuretic hormone (ADH) or Vasopressin
T or F: The effect of endocrine communication is slow and short.
False. It is slow but prolonged
1) What is the type of communication if secreted chemicals affect local or nearby cells?
2) How about if it affects the same cell releasing it?
1) Paracrine communication
2) Autocrine communication
What are the 4 steps involved in cell signaling and signal transduction?
- Recognition
- Transduction
- Transmission
- Response
The receptor to which a signaling molecule binds to can be located in?
-Plasma membrane
-Cytoplasm
-Nucleus
In recognition, upon binding of a ligand to a receptor, what are activated? Cite some examples.
Intracellular proteins (i.e. kinases, phosphatases, GTP-binding proteins)
The signaling proteins interact with? What is their effect on them?
Target proteins; Regulate their activity
What are the functions of signaling molecules?
1) Regulate cell growth, division, and differentiation
2) Influence cellular metabolism
3) Modulate intracellular ionic composition
4) Control cytoskeleton-associated events (cell shape, division, migration)
5) Control adhesion (cell-to-cell and cell-to-matrix)
How do signaling molecules modulate the ionic composition intracellularly?
Regulating activity of ion channels and transport proteins
The recognition of chemical messengers or signal molecules or ligands by cells typically begins by _______
interaction or binding with a receptor at that cell
Which serve as cellular switches during recognition?
receptors
T or F. Receptors are static components of the cell.
False (receptors are not static components)
What do you call the type of regulation wherein there is an increase in the number of receptors when chemical messenger is deficient?
Up-regulation
What do you call the type of regulation wherein there is a decrease in the number/activity of receptors when chemical messenger is in excess.
Down-regulation
For receptors in the membrane, ______ is responsible for down regulation.
receptor-mediated endocytosis
In receptor-mediated endocytosis, when ligands bind to their receptors, what do they form?
ligand-receptor complexes
T or F. In receptor-mediated endocytosis, ligand-receptor complexes move internally in the membrane to coated bits
False (Ligand-receptor complexes move LATERALLY in the membrane to coated bits)
What do you call the process wherein the coated bits during receptor-mediated endocytosis are subjected to endocytosis to enter the cell?
Internalization
Some receptors are either ____ after internalization or ____ by de Novo synthesis in the cell.
recycled; replaced
When there is hormone or neurotransmitter in excess, number of active receptors increases or decreases?
decreases
When there is deficiency of chemical messengers, the number of active receptors increases or decreases?
increases
This is a type of down-regulation, wherein receptors are chemically modified to become less responsive.
Desensitization
What are the four major types of receptors according to their intracellular signaling pathways?
Ion Channel-Linked Receptors, G-Protein Coupled Receptors, Enzyme-Linked/Catalutic Receptors, Nuclear Receptors
Neurotransmitters directly gating ion channels.
Ionotropic receptors
Examples of neurotransmitters.
Acetylcholine and Norepinephrine
Examples of this receptor include Nicotinic cholinergic receptor.
Ligand-gated ion channels/Ion Channel-Linked Receptors
Examples of this receptor include K+ channel.
Ligand-gated ion channels/Ion Channel-Linked Receptors
Examples of this receptor include transient receptor potential cation channel vanilloid member 1 (TRPV1).
Ligand-gated ion channels/Ion Channel-Linked Receptors
This receptor mediate direct and rapid signaling between electrically excitable cells.
Ligand-gated ion channels/Ion Channel-Linked Receptors
What signaling molecules bind to receptors that cause the opening and closing of ion channels?
Neurotransmitters
True or False: Binding of neurotransmitters changes ionic permeability of plasma membrane as well as its membrane potential.
TRUE
True or False: The selectivity of Ion Channel-Linked receptor depends on diameter, shape, electrical charges, and chemical bonds along its inside surface.
TRUE
[From Book Guyton and Hall Textbook of Medical Physiology, 14th Ed., Ch. 146, Pgs. 574-575] A type of ion channels in the postsynaptic neuronal membrane which usually allow sodium ions to pass when opened (also sometimes allow K+ and/or Ca+).
Cation channel
[From Book Guyton and Hall Textbook of Medical Physiology, 14th Ed., Ch. 146, Pgs. 574-575] A type of ion channels in the postsynaptic neuronal membrane which mainly allow chloride ions to pass.
Anion channel
[From Book Guyton and Hall Textbook of Medical Physiology, 14th Ed., Ch. 146, Pgs. 574-575] A type of ion channels in the postsynaptic neuronal membrane which are lined with negative charges to attract the positively charged molecules.
Cation channel
[From Book Guyton and Hall Textbook of Medical Physiology, 14th Ed., Ch. 146, Pgs. 574-575] A neurotransmitter that opens cation channels (allow positively charges ions) and excite the neuron.
Excitatory transmitter
[From Book Guyton and Hall Textbook of Medical Physiology, 14th Ed., Ch. 146, Pgs. 574-575] A neurotransmitter that opens anion channels (allow negatively charges ions) and inhibit the neuron.
Inhibitory transmitter
GPCR downstream target proteins that regulate signaling pathways if the target protein is an?
Enzyme
GPCR change membrane ion permeability if target protein is an?
ion channel
What is the largest and most diverse group of membrane receptors?
G-Protein coupled receptors
other names of G-PCR
seven-transmembrane receptor, hepta-helical receptors, seven-helix receptore, serpentine receptors
type of receptor that is targeted in drug discovery
G-Protein coupled receptors ( because the cell surface receptors act like an inbox for messages in the form of light energy, peptides, lipids, sugars, and proteins making it diverse)
GPCR binds extracellular substances and transmits signals to an intracellular molecule called?
G-Protein (guanine nucleotide binding protein)
Name the subunits of G-proteins.
ɑ-subunit , β-subunit, 𝛾-subunit