intercellular communication and signal transduction Flashcards
what types of cell communication is there?
indirect and direct
name the types of direct cell comunication
Gap junctions and linking of surface receptors
name the tyoes of indirect cell communication
paracrines
autocrines
neurotransmitters
hormones and neurohormones
what are Gap junctions
Gap junctions are specialized intercellular connections that allow direct communication between adjacent cells by forming minute tunnels, known as connexons, that bridge the cytoplasm of neighboring cells.
What are connexons, and what is their structure?
Connexons are tube-like structures made of six protein subunits arranged in a circular pattern. Two connexons from adjacent cell membranes align end-to-end to form a tunnel that allows the direct passage of small ions and molecules between cells.
What types of particles can pass through gap junctions?
Gap junctions allow the passage of small, water-soluble particles such as ions, glucose, and amino acids. These particles move directly between the cytoplasm of neighboring cells without entering the extracellular fluid
what tissues are gap junctions abundant
cardiac and smooth muscle
non muscle- pass nutrients like glucose and AA
What is the role of gap junctions in cardiac and smooth muscle tissues?
In cardiac and smooth muscle tissues, gap junctions allow the movement of ions between cells, transmitting electrical signals. This leads to synchronized contractions of the entire muscle, such as the coordinated pumping action of the heart chambers.
How do gap junctions contribute to the development of an egg in the ovary?
Gap junctions in the ovary allow the transfer of nutrients like glucose and amino acids between cells, helping the developing egg store essential nutrients necessary for its growth.
Why are gap junctions considered the most intimate means of intercellular communication?
allow the direct exchange of small ions and molecules between the cytoplasm of adjacent cells, bypassing the extracellular fluid
What happens when two connexons from adjacent cells join?
they form a tunnel that bridges the cytoplasm of both cells, allowing small, water-soluble molecules and ions to pass directly between them.
What is direct intercellular communication?
Direct intercellular communication is the process where cells communicate with each other through physical contact, allowing for the exchange of signals or molecules.
What mechanism allows direct linking
The transient linking of cell surface receptors allows direct linking between cells. Cells have specialized surface markers that can recognize and bind to compatible markers on other cells, enabling temporary interactions.
Which type of cells use direct communication, and why?
immune system to recognise and interact with cells- identify and respond to threats such as cancer or infected cells
what form of communication do phagocytes use and how?
transient linking of cell surface receptors to recognise undesirable cells like cancer. selectively interact with these cells enabling the immune system to destroy them while sparing healthy cells
What role do specialized surface markers play in immune system interactions?
specialized surface markers on immune cells help them identify and link with other cells that have compatible markers. This transient interaction allows immune cells to determine whether the target cell is healthy or should be destroyed.
What are surface markers, and how do they function in cell communication?
Surface markers are proteins or glycoproteins present on the cell membrane. They help in recognizing other cells by binding to compatible markers, facilitating direct and transient interactions essential for cellular recognition and communication
What is indirect intercellular communication?
cells releasing specific chemical messengers (signal molecules) into the extracellular fluid (ECF) to interact with target cells. These messengers bind to receptors on the target cells, allowing them to perform specific functions.
How do chemical messengers communicate with target cells?
Chemical messengers are released into the extracellular fluid by controlling cells and bind to receptors on target cells that are specific for those messengers. This triggers specific actions in the target cells.
What percentage of the human genome codes for the synthesis of membrane receptors, and why is this significant?
5% of the human genome codes for the synthesis of membrane receptors, highlighting the importance of this means of communication in regulating cellular functions.
What are paracrines, and how do they function?
local chemical messengers that exert their effects only on neighboring cells in the immediate environment of the secretion site. They diffuse through the interstitial fluid and act over short distances. An example is histamine, which dilates blood vessels during an inflammatory response.
How are paracrines different from other chemicals that influence neighboring cells?
Paracrines are specifically released for communication between neighboring cells, while other chemicals, like carbon dioxide (CO2) released during muscle activity, influence neighboring cells without being specifically released for that purpose. CO2 promotes blood vessel dilation in active muscle but is not classified as a paracrine.
What are neurotransmitters, and how do they communicate between neurons?
short-range chemical messengers released by neurons in response to electrical signals (action potentials). They diffuse across small gaps to act on adjacent target cells such as other neurons, muscles, or glands.
What distinguishes neurotransmitters from hormones?
: Neurotransmitters act over short distances, typically between adjacent cells, while hormones are long-range messengers secreted by endocrine glands and carried through the blood to distant target cells.
