Competitive Antagonism - Essay Example

Comments (0) Cite this document
Acetylcholine (ACh) stimulates the contraction of skeletal muscle via nicotinic receptors and the contraction of smooth muscle via muscarinic receptors. Muscarinic receptors belong to the 7TM superfamily (seven transmembrane spanning superfamily) of G-protein linked receptors…
Download full paperFile format: .doc, available for editing
GRAB THE BEST PAPER95.4% of users find it useful
Competitive Antagonism
Read TextPreview

Extract of sample "Competitive Antagonism"

Competitive Antagonism Discuss how ACh produces a contraction in smooth muscle, details of mechanism and second messenger involved. Acetylcholine(ACh) stimulates the contraction of skeletal muscle via nicotinic receptors and the contraction of smooth muscle via muscarinic receptors. Muscarinic receptors belong to the 7TM superfamily (seven transmembrane spanning superfamily) of G-protein linked receptors and are of the M1- M5 subtypes, depending on the type of smooth muscle they are located in. The ACh dependant response of the muscarinic receptors is mediated through GTP binding proteins. In the M1, M3 and M5 subtypes, the Gq family of G-proteins is involved in the activation of PLC (phospholipase C). Here, ACh is the agonist of muscarinic receptors.
Mechanism of smooth muscle contraction – When ACh stimulates the G-protein coupled muscarinic receptors, a conformational change occurs, leading to the activation of the G-protein. The activated G-protein activates the intracellular enzyme, PLC (phospholipase C). This enzyme in turn hydrolyses PI(4,5)P2 (phosphatidylinositol-4,5-bisphosphate). This hydrolysis results in the production of two compounds – DAG (diacylglycerol) and IP3 (inositol-1,4,5-triphosphate). IP3 is soluble and diffuses through the cytosol. It binds to receptors on the endoplasmic reticulum resulting in the release of calcium ions (Ca2+) from the intracellular stores. The rise in intracellular calcium ions results in contraction of the smooth muscle. This happens when the intracellular calcium ions bind to calmodulin and activate it. Activation of calmodulin results in activation of the myosin light-chain kinase (MLCK) enzyme by the calcium-calmodulin complex, which then catalyzes the transfer of phosphate group from ATP to myosin cross bridges. The phosphorylated myosin cross bridges then interact with actin, causing shortening of the fiber. This results in muscle contraction. The cross-bridge cycle is powered by ATP.
Second messenger involved - IP3 (inositol-1,4,5-triphosphate) is the second messenger, as it relays the signal from outside the cell to the inside, resulting in the release of calcium ions that cause muscle contraction.
(Gomperts, Kramer & Tatham 2009; Marieb & Hoehn 2010)
2. Discuss how Ad produces relaxation of pre-contracted smooth muscle, details of mechanism and second messenger involved.
Acetylcholine (ACh) and adrenaline (Ad) are two agonists whose actions are independent of one another and result in opposite effects. Ad brings about the relaxation of pre-contracted smooth muscle by acting via the G-protein coupled β-adrenergic receptors on the cells.
Mechanism of Ad induced relaxation of pre-contracted smooth muscle – Ad binds to the G-protein linked β-adrenergic receptor causing a conformational change in the G-protein. This activates the enzyme adenylate cyclase. Adenylate cyclase converts ATP to cAMP (cyclic AMP). cAMP in turn activates the enzyme PKA (protein kinase A). PKA is regulated by the amount of cAMP in the cell and so, it is also called cAMP dependant protein kinase. The activated enzyme PKA phosphorylates myosin light-chain kinase (MLCK) in the muscle cells. When MLCK is phosphorylated, it has low affinity for calcium-calmodulin complex (Ca2+–calmodulin).
During muscle contraction, calcium-calmodulin complex activates MLCK, which then catalyzes the transfer of phosphate group from ATP to myosin cross bridges that then interact with actin resulting in muscle contraction. However, when MLCK is phosphorylated and has low affinity for the calcium-calmodulin complex, it can no longer cause the phosphorylation of myosin cross bridges. This results in the relaxation of pre-contracted smooth muscles.
Second messenger involved - cAMP is the second messenger involved in this mechanism as it relays the signal from the outside of the cell to the inside, resulting in activation of PKA that causes smooth muscle relaxation.
(Baker, Murray & Baker 2001; Marieb & Hoehn 2010)
Baker, R, Murray, R, and Baker E 2001, PDQ biochemistry, Volume 1, BC Decker Inc, Ontario.
Gomperts, B, Kramer, I, and Tatham, P 2009, Signal transduction, Academic Press, London.
Marieb, E & Hoehn, K 2010, Human anatomy and physiology, Pearson Education, New Jersey. Read More
Cite this document
  • APA
  • MLA
(“Competitive Antagonism Essay Example | Topics and Well Written Essays - 500 words”, n.d.)
Competitive Antagonism Essay Example | Topics and Well Written Essays - 500 words. Retrieved from
(Competitive Antagonism Essay Example | Topics and Well Written Essays - 500 Words)
Competitive Antagonism Essay Example | Topics and Well Written Essays - 500 Words.
“Competitive Antagonism Essay Example | Topics and Well Written Essays - 500 Words”, n.d.
  • Cited: 0 times
Comments (0)
Click to create a comment or rate a document

CHECK THESE SAMPLES OF Competitive Antagonism

Competitive Strategies. Chaos Camera Company Competitive Advantages

...? s This paper analyses the performance of our team in the simulation of a camera company. The company, Chaos Camera Company, was run as a team. The analysis is broken down into various parts: our competitive strategies, competitive advantage and actions of our competitors, our offensive and defensive strategic options, regional strategic approach, decisions supporting strategy execution, improving value chain activities, corporate social responsibility and finally our decision making style. The analysis is made on all these accounts and keenly canvasses the company on the competitive advantage it gains over other companies in the industry and the strategies that the company undertakes to...
10 Pages(2500 words)Assignment

Competitive Analysis

...? The Samsung Galaxy Tab obviously is competing against the 900-pound gorilla of tablet computing: The IPad. There are numerous other tablet computers planned for release, like Dell's which was leaked unwittingly, but the problem is that the real competition aside from the IPad is the PC. “But every consumer who buys an iPad, Android tablet, or other tablet computer in the next year or two will be much less likely to buy a new Windows PC whenever Windows 8 comes out. The consumer PC cycle is being disrupted right now” (Rosoff, 2011). There are almost no weaknesses to Apple right now. Macintosh products are hip, edgy, associated with quality, and innovative. Smartphones are defined against the IPhone and tablet computing...
4 Pages(1000 words)Essay

Competitive Strategy

...?Competitive Strategy College: Competitive Strategy Samsung Company is one of the multinational companies that have successfully managed to push its business operations in the international market. Recently, the company expanded its electronic business operations in Turkey and has since then engaged in an extraneous competition that has threatened to undermine its survival in this new business environment. Microsoft and Arcelik are among the companies that Samsung has to compete with in order to overcome business challenges that are severe in a new market. Samsung has capitalized its investment in electronic sales, particularly in rolling out its mobile, computer and tablet hardware. On the other hand, Microsoft and Arcelik engage... from...
3 Pages(750 words)Research Paper

Competitive Anxiety

...Running head: ANXIETY EFFECTS ON PENALTY TAKING IN RUGBY Anxiety effects on penalty taking in rugby of the School Introduction Anxiety, a persistent and inherent feature of competitive sport, consists of time-limited and short-term events (e.g., making an error or receiving a penalty from the official during the contest) can unfavorably affect performance. Typical responses to stressful events include over-arousal, heightened anxiety, muscular tension, emotional turmoil, and slower, less accurate decision-making (Anshel, 1995). Long term consequences of ineffective coping with anxiety include psychological burnout and the athlete's withdrawal from competitive sport. Present paper is a research of...
10 Pages(2500 words)Essay

Physiology and Pharmacology

...for mydriatic and cycloplegic purposes. The drugs inactivate the action of acetylcholine at the choliergically activated muscles of the iris and the accommodative ciliary muscles of the lens. The inactivated muscles of the iris allow dilation of them pupils (mydriasis) and loss of accommodation (cycloplegia). The cycloplegic action is used for occlusion therapy as in the case of treating patients with mild amblyopia (PEDIG, 2002). Inclusion of drug dosage and dosable age and other criteria are eschewed here. 2. Research and Aim: This research experiment uses intact longitudinal muscle-myenteric plexus preparations of guinea pig ileum to determine competitive antagonism of the drug homatropine against...
6 Pages(1500 words)Essay

Competitive Strategy

...Introduction: In a highly globalised world an effective competitive strategy is essential for survival and growth of any organization. This paper is an assessment of competitive strategies of the multinational corporation SABMiller, a company that is engaged in the business of producing high quality beverages, especially beer. The focus will be on the following four areas. The first task will be to identify the corporate logics (strategic action) that SABMiller have adopted over the course of the case. The second one will be an explanation of strategic position that South African Breweries (SAB) finds itself in 2007. South African Breweries had acquired Miller Brewing Company in 2002 and had become...
8 Pages(2000 words)Essay

Competitive Environment

...Aide Memoire for UK Domestic Gas and Electri Markets of the of the Aide Memoire SCP Model =standing of industry sector = structure, conduct and performance of the firms that comprise it at a given point. Structure determinants= Number of Competing Firms; Homogeneity of Products, Cost of Entry and Exit. Conduct= strategies firm implements to gain competitive advantage over rivals. Performance= performance of individual firm + performance of economy (Creative Advantage Website, 2012, 1). Gas industry in Britain = imperfect competition. Market dominated by few large firms and smattering of local and regional entities. Bulk of supply lines/ consumers connected with British Gas or Transco- dominating both...
1 Pages(250 words)Essay

Competitive Review

...Introduction Vegetarian fast food cafes are becoming the trend of the latest years. The world is highly concerned with the issues of preserving the natural biosphere, obesity and related deceases, as well as healthy way of life. Vegetarian cafes and restaurants may become a perfect alternative for everyone concerned with the health and ecological issues. Therefore, the key aim of the paper is to study the competitive information associated with the vegetarian fast food concept promotion and development. Factor Veggies Wendy’s Pei Wei O’Naturals Product Line Vegetarian meals in fast food format Fresh an tasty meals, including traditional fast food, kids meals, dietary and vegetarian meals Traditional Asian meals, including...
3 Pages(750 words)Research Paper

Competitive Advantage

...Barnes & Noble is the industry leader in the book industry. The company generated $7.13 billion in sales in (Barnesandnobleinc, . The organization holds various competitive advantages over a small bookstore. As a public company whose stocks are traded in the New York Stock Exchange Barnes & Noble has greater access to capital than small bookstores. The firm has the ability to raise capital through the sale of stocks and bonds. The company also has a superior marketing and advertising budget which has enabled Barnes & Noble the ability to build brand value. Barnes & Noble has the greatest product variety in the industry in both books and e-books. Due to the size of the company the firm is in a better position to offer lower prices... & Noble...
1 Pages(250 words)Assignment

Competitive Benefits

...Competitive Benefits Research reveals that unionized workers benefit more from compensation benefits as comparedto the non-unionized employees. Some of the compensation components include retirement plans, sick leaves, educational assistance, health insurance, and paid holidays among others. Such benefits are imperative in helping attract, retain, and motivate workers. They also help in reducing turnover and absenteeism cases. Therefore, although unionization is costly, unionized organizations must continue cooperating and enhancing their relationship with their unions to ensure they remain competitive. Therefore, this discourse kicks off by analyzing the benefits that come with compensation components...
4 Pages(1000 words)Research Paper
sponsored ads
We use cookies to create the best experience for you. Keep on browsing if you are OK with that, or find out how to manage cookies.

Let us find you another Essay on topic Competitive Antagonism for FREE!

Contact Us