Name: local cell signaling in blood and healing
Uploaded: 2026-08-26T08:20:53.277Z
Duration: 1 min 32 s
Channel: JoVE

Cells use paracrine signaling to communicate with nearby cells.In paracrine signaling, a cell releases signaling molecules that diffuse over short distances.As a result, these molecules trigger responses only in neighboring cells that possess the appropriate cell-surface receptors or intracellular target proteins.Signaling molecules that do not bind to receptors are rapidly degraded or inactivated, limiting the range of the signal.For example, physical activity, such as exercise, increases oxygen demand in skeletal muscles. To meet this increased demand, endothelial cells lining nearby blood vessels release nitric oxide gas, or NO, which acts as a paracrine mediator.NO diffuses through the extracellular matrix into neighboring smooth muscle cells, where it interacts with intracellular target proteins and triggers signaling pathways that cause the cells to relax.As a result, the blood vessels dilate, increasing blood flow to the active tissues.Like many other paracrine signaling molecules, NO is very short-lived outside endothelial cells and produces only a localized response.

paracrine signaling

Paracrine Signaling

Paracrine signaling allows cells to communicate with their immediate neighbors via secretion of signaling molecules. Such a signal can only trigger a response in nearby target cells because the signal molecules degrade quickly or are inactivated if not taken up. Prominent examples of paracrine signaling include nitric oxide signaling in blood vessels, synaptic signaling of neurons, the blood clotting system, tissue repair/wound healing, and local allergic skin reactions.Nitric oxide as a Paracrine Signaling MoleculeBlood vessels contain several layers of cells. The innermost layer of cells called the endothelium have nitric oxide synthase, which produces nitric oxide as a paracrine mediator. The nitric oxide that reaches the blood does not contribute to signaling but immediately reacts with biochemicals, such as hemoglobin. However, nitric oxide molecules that diffuse towards the smooth muscle cells surrounding the blood vessel facilitate their relaxation and vasodilation, and ultimately a decrease in blood pressure. At the molecular level, this signaling mechanism involves the binding of the nitric oxide molecules to guanylate cyclase receptors, which increases the levels of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells.Paracrine Signaling and Blood ClottingAnother example of paracrine signaling is blood clotting. When a blood vessel is damaged and begins to bleed, the endothelium has been broken. Broken endothelial tissue releases von Willebrand factors (vWF), which bind to platelet cells circulating in the blood via paracrine signaling. Meanwhile, collagen fibers under the endothelial cells also bind to the platelets. Several other platelet proteins are subsequently activated and released by the platelets. These proteins then activate more platelets via paracrine signaling. A complex series of reactions between many clotting factors forms a substance known as fibrin, which holds the blood clot together and patches the broken endothelium.

Paracrine signaling allows cells to communicate with their immediate neighbors via secretion of signaling molecules. Such a signal can only trigger a ...

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Cellular Processes

Cell Signaling

KEY TERMS AND CONCEPTS

local cell signaling in blood and healing

Local cell signaling helps cells communicate with nearby neighbors using released signaling molecules. These molecules act only over a short distance because they break down quickly or are inactivated if they are not taken up. This type of signaling supports processes such as nitric oxide signaling in blood vessels, neuron-to-neuron communication at synapses, blood clotting, tissue repair, and local allergic skin reactions.

A clear example is nitric oxide signaling in blood vessels. The endothelium, which is the innermost layer of cells, contains nitric oxide synthase and produces nitric oxide as a local signaling molecule. Nitric oxide that enters the blood does not continue the signal because it reacts right away with biochemicals such as hemoglobin. Nitric oxide that diffuses to nearby smooth muscle cells makes them relax, which causes vasodilation and can lower blood pressure. At the molecular level, nitric oxide binds to guanylate cyclase receptors and increases cyclic guanosine monophosphate, or cGMP, in the smooth muscle cells.

Blood clotting is another example of local signaling. When a blood vessel is damaged and bleeding starts, the endothelium is broken. Damaged endothelial tissue releases von Willebrand factor, or vWF, which binds to platelets in the blood. Collagen fibers under the endothelial cells also bind to the platelets. Activated platelets then release other proteins that activate more platelets through local signaling. A chain of clotting reactions finally forms fibrin, which holds the clot together and helps patch the broken endothelium.

Local Cell Signaling in Blood and Healing

local-cell-signaling-in-blood-and-healing

what is cell signaling?

How Cells Send and Receive Signals

Cell signaling lets cells send and receive messages from the environment and from other cells. Even with a protective membrane, cells need to detect changes and respond to them. Unicellular and multicellular organisms use signaling to stay coordinated and to react to outside cues. Cells often rely on receptor proteins in the membrane to sense information. Skin cells can respond to touch, and photoreceptors in the retina can detect light. Most cells respond to chemical signals such as hormones,...

internal receptors

Steroid Hormones and Intracellular Receptors

Steroid hormones and other small signaling molecules can pass through the cell membrane and bind to intracellular receptors inside the cell. These receptors are also called internal receptors. Many hydrophilic signals cannot cross the plasma membrane, so this pathway is used by signals that are small or hydrophobic. Nitric oxide, or NO, also uses this type of signaling. When a ligand, which is a signaling molecule, binds to a receptor in the cytoplasm or nucleus, the receptor changes shape.

contact-dependent cell communication

Cell-to-Cell Signaling via Channels

Cell-to-cell signaling can happen when neighboring cells are in direct contact. In this kind of communication, cells use receptor-ligand interactions or special cytoplasmic channels to move small molecules between them. In animal cells, these channels are called gap junctions. They form when six proteins called connexins assemble into a cylindrical structure in the plasma membrane called a connexon. When connexons from two adjacent cells line up, a channel opens between the cells. Enzymes help...

autocrine signaling

Self-Signaling Cells in Immunity and Cancer

Autocrine signaling is a cell communication method in which a cell sends a signal to itself. The same cell releases an extracellular signaling molecule and also has receptors that can bind to that molecule. This lets the cell respond to its own message. In the immune system, this process is important for homeostasis, or keeping body conditions stable. A well-studied example is the macrophage, an immune cell that secretes cytokines such as interleukin-1, or IL-1. Macrophages also have membrane...

Local cell signaling helps cells communicate with nearby neighbors using released signaling molecules. These molecules act only over a short distance because they break down quickly or are inactivated if they are not taken up. This type of signaling supports processes such as nitric oxide signaling in blood vessels, neuron-to-neuron communication at synapses, blood clotting, tissue repair, and local allergic skin reactions. A clear example is nitric oxide signaling in blood vessels. The...

synaptic signaling

Chemical and Electrical Synapses

Neurons send signals across synapses, which are junctions between cells. These signals can excite or inhibit other neurons or target cells such as muscles. Most synapses are chemical. Some are electrical. Chemical synapses use action potentials, which are electrical impulses, to trigger the release of neurotransmitters. The sending neuron is the presynaptic neuron, and the receiving neuron is the postsynaptic neuron. An action potential travels along the axon and reaches the axon terminal,...

endocrine signaling

Hormones Travel to Distant Target Cells

Endocrine signaling uses hormones to send messages to target cells in other organs. Endocrine cells release these hormones into the circulatory system, which carries the signal through the body. Because the hormone reaches the whole organism, only cells with the right receptors respond. This kind of signaling usually acts slowly, but its effects last longer. Endocrine cells can use cell surface receptors or intracellular receptors, depending on the hormone. Cell surface receptors are...

bacterial signaling

Quorum Sensing in Bacteria

Quorum sensing lets bacteria coordinate behavior by sensing how many cells are nearby. Bacteria can signal inside the cell or between cells. When many bacteria act together, they can behave like a community and change gene expression as a group. This signaling starts with autoinducers, or AIs. Individual bacteria make AIs and release them across the cell membrane into the surrounding space. Some AIs diffuse out passively along a concentration gradient, while others are moved out by active...

yeast signaling

Yeast Cell Communication in Mating

Yeast cell communication helps control mating, colony growth, and other cell responses. Yeasts are single-celled organisms, but unlike bacteria, they are eukaryotes with a nucleus. Their signaling works much like cell signaling in other eukaryotic cells. A signal often begins when a ligand, such as a protein or small molecule released from a yeast cell, binds to a receptor on the cell surface. This binding activates second-messenger kinases, which then switch transcription factors on or off.

g protein-coupled receptors

GPCR Signaling Through G Proteins

G-protein coupled receptors, or GPCRs, start cell signaling after a ligand binds to the receptor. The receptor is a single polypeptide that crosses the cell membrane seven times. These membrane loops create an outside pocket that fits a specific ligand, such as a neurotransmitter or hormone. The inside loops connect to a G-protein.

enzyme-linked receptors

Trk Receptors in Cell Signaling

Trk receptors are enzyme-linked receptors that help cells respond to growth factors and some hormones. They belong to the receptor tyrosine kinase, or RTK, family. These receptors can trigger several signals inside a cell after they are activated. Neurotrophin receptors are one RTK group and include TrkA, TrkB, and TrkC, which are tropomyosin-related kinase receptors. TrkA binds nerve growth factor, neurotrophin-6, and neurotrophin-7. TrkB binds brain-derived neurotrophic factor, or BDNF, and...

ion channels

Ion Channels in Cells and Membranes

Ion channels are membrane proteins that help cells move ions across the plasma membrane. Ions such as sodium, potassium, and calcium move into and out of cells to maintain the electrochemical gradient. This gradient supports cell size and volume, nerve signaling, and gas and nutrient exchange. Ion channels are specialized integral membrane proteins that let specific ions pass down their electrochemical gradient. Their main job is to help keep the membrane potential, which is needed for cell...

what are second messengers?

Cell Signals That Use Second Messengers

Cell signals often use second messengers to carry messages inside the cell. Many receptor-binding ligands are hydrophilic, so they do not cross the cell membrane. Instead, the signal is relayed to an internal messenger that can spread the message farther. G-protein coupled receptors can activate the phosphoinositol pathway and the cyclic AMP, or cAMP, pathway. In the phosphoinositol pathway, the receptor activates phospholipase C. This enzyme hydrolyzes phosphatidylinositol biphosphate, or...

intracellular signaling cascades

Cell-Surface Receptor Signal Cascades

Cell-surface receptor signal cascades move information from outside the cell into the cytoplasm. This process is called signal transduction. It happens only with cell-surface receptors, because they cannot interact with most cell parts, such as DNA. Internal receptors are different. They can interact directly with DNA in the nucleus and help start protein synthesis. When a ligand binds to a receptor, the receptor changes shape. That shape change affects the receptor’s intracellular domain or...

key terms and concepts

Explore how paracrine signaling helps nearby cells communicate, from nitric oxide in blood vessels to platelet activation and fibrin clot formation.

Local Cell Signaling in Blood and Healing | JoVE K12

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Local Cell Signaling in Blood and Healing

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