What are Desmosomes and gap junctions and why are they important to heart function?
Intercalated discs are part of the sarcolemma and contain two structures important in cardiac muscle contraction: gap junctions and desmosomes. This joining is called electric coupling, and in cardiac muscle it allows the quick transmission of action potentials and the coordinated contraction of the entire heart.
What are gap junctions in heart?
Gap junctions are membrane channels that mediate the cell-to-cell movement of ions and small metabolites. In the heart, gap junctions play an important role in impulse conduction. Studies over the last decade have revealed that gap junctions are encoded by a multigene family known as the connexins.
How do gap junctions differ from Desmosomes quizlet?
How do gap junctions function? They provide a direct passageway for substances to travel between neighboring cells. A desmosome is a space that opens between two cells; intermediate filaments from each cytosol pass through the space to anchor the cells together.
Which type of junctions is prominent in cardiac muscles which allows for unified contraction of heart?
Explanation: Cardiac myocytes (muscle cells) need to be able to contract in unison in order to ensure proper pumping of blood. This is accomplished by specialized junctions called gap junctions that allow cells to communicate with one another very quickly.
What is the difference between tight and gap junctions?
Tight junction refers to a specialized connection of two adjacent animal cell membranes, such that, space usually lying between them is absent while a gap junction refers to a linkage of two adjacent cells consisting of a system of channels extending across a gap from one cell to the other, allowing the passage.
What is the function of gap junction?
Gap junctions allow the exchange of ions, second messengers, and small metabolites between adjacent cells and are formed by two unrelated protein families, the pannexins and connexins. Mutations in connexin genes cause a variety of genetic disorders, implicating a critical role in tissue homeostasis.
What is the main function of gap junctions?
What is the purpose of gap junctions?
Gap junctions are channels that physically connect adjacent cells, mediating the rapid exchange of small molecules, and playing an essential role in a wide range of physiological processes in nearly every system in the body, including the nervous system.
What is the difference between gap junctions and Desmosomes?
Plasmodesmata are channels between adjacent plant cells, while gap junctions are channels between adjacent animal cells. A tight junction is a watertight seal between two adjacent cells, while a desmosome acts like a spot weld.
What is an example of tight junction?
Examples of tight epithelia include the distal convoluted tubule, the collecting duct of the nephron in the kidney, and the bile ducts ramifying through liver tissue. Other examples are the blood-brain barrier and the blood cerebrospinal fluid barrier.
What is an example of a tight junction?
Tight epithelia have tight junctions that prevent most movement between cells. Examples of tight epithelia include the distal convoluted tubule, the collecting duct of the nephron in the kidney, and the bile ducts ramifying through liver tissue.
What is the structure of a tight junction?
Structure. Tight junctions are composed of a branching network of sealing strands, each strand acting independently from the others. Therefore, the efficiency of the junction in preventing ion passage increases exponentially with the number of strands. Each strand is formed from a row of transmembrane proteins embedded in both plasma membranes,…
Where are gap junctions found?
Gap junctions are found in many places throughout the body. This includes epithelia, which are the coverings of body surfaces, as well as nerves, cardiac (heart) muscle, and smooth muscle (such as that of the intestines). Their primary role is to coordinate the activity of adjacent cells.
What is a tight cell junction?
Tight junctions are areas where the membranes of two adjacent cells join together to form a barrier. The cell membranes are connected by strands of transmembrane proteins such as claudins and occludins. Tight junctions bind cells together, prevent molecules from passing in between the cells, and also help to maintain the polarity of cells.