Name the three main types of membrane bound receptors. What is a ligand-gated io
ID: 53980 • Letter: N
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Name the three main types of membrane bound receptors. What is a ligand-gated ion channel? Compare and contrast Endocrine and Exocrine glands: Four Groups of Hormones (Fill in the blanks) Prostaglandin (5 carbon ring): present in small amounts but regulates multiple responses. Secreted continuously by almost all cells, they are present mostly in smooth muscle. If created in hypothalamus they cause fever. Aspirin and ibuprofen inhibit synthesis to reduce fever and inflammation Capable of diffusing across the cell membrane and travelling to the nucleus of the target cell. Adrenal Cortex (cortisol), testes (testosterone), ovaries (estrogen and progesterone), placenta all synthesize hormones from cholesterol. Simplest hormones. EX: Thyroid hormones, epinephrine (adrenaline), norepinephrine (noradrenaline) Largest group of hormones. Can't diffuse through cell membrane, must use receptor molecule. EX: Growth hormones, Thyroid-stimulating hormones, calcitonin, gonadotropic hormones, neuropeptides (ex: oxytocin and antidiurctic hormone ADH) Which hormones are released by the Anterior Pituitary? The Posterior Pituitary? Explain the difference between Autocrine, Paracrine, and Classical Endocrine signaling; Explain how the parathyroid gland is involved in regulation of calcium levels in the blood. Make sure to explain what ultimately inhibits the parathyroid gland from producing more hormones.Explanation / Answer
1. surface receptors are involved in most of the signaling in multicellular organisms. There are three general categories of cell-surface receptors: ion channel-linked receptors, G-protein-linked receptors, and enzyme-linked receptors.
2. Ligand-gated Ion Channels (LGICs) are a group of transmembrane ion channels that open when a signal molecule (ligand) binds to an extracellular receptor region of the channel protein. This binding changes the structural arrangements of the channel protein, which then causes the channels to open or close in response to the binding of a chemical messenger such as a neurotransmitter. This ligand-gated ion channel, a type of ionotropic receptor, allows specific ions (like Na+, K+, Ca2+, or Cl-) to flow in and out of the membrane. Examples of ligand-gated ion channels include acetylcholine receptors, serotonin receptor, GABAA, and Glutamate receptor.
3. Contrast:Exocrine glands are glands that produce enzymes into ducts that carry them to other organs or outside the body. These enzymes helps in the body metabolism (e.g. digestion of food in mouth). Endocrine glands secretes hormones directly into the bloodstreams. Hormones are chemical signals that aids in the communication of cells.
Comparison: Both of them produces proteins (hormones and enzymes) that are needed by the body in order to function normally. They are both composed of epithelial tissues.
Examples of exocrine glands are salivary glands, sebaceous gland, sweat glands, sublingual, mammary and the prostrate.
Examples of endocrine glands are ovaries which secrete sex hormones estrogen and progesterone directly into the bloodstream. Another example is the adrenal glands that secretes adrenaline hormones needed for a certain function.
4 a).Lipid group of hormones.
b)Steroid group of hormones.
c) Amino acid derivative group of hormones.
d)Peptide group of hormones.
5.Hormones secreted by anterior pituitary are:
Adrenocorticotrophic hormone (ACTH),Thyroid-stimulating hormone (TSH)
Luteinising hormone (LH),Follicle-stimulating hormone (FSH),Prolactin (PRL),Growth hormone (GH).
Hormones secreted by posterior pituitary are:
Hormones known classically as posterior pituitary hormones are synthesized by the hypothalamus; these include oxytocin and vasopressin.
6.The different signaling pathways in multicellular organisms are often divided into three categories: endocrine , paracrine, and autocrine signaling.
In endocrine signaling, a signaling molecule, called a hormone, acts on a cell located at a distance from where it was synthesized. An example of this is stimulation of glucose uptake by insulin. Insulin is a hormone produced by the cells in the pancreas and is secreted into the bloodstream, from where it can act on many different cells, even those located far from the pancreas.
Paracrine signaling refers to signaling between neighboring cells. Paracrine signaling is common during development, where a cell's fate is determined by interactions with its neighbors. In addition, the passing of nerve impulses between nerve cells is an example of paracrine signaling: neurotransmitters secreted by a nerve cell into a synapse (the space between two nerve cells) bind receptors located on the neighboring nerve cell, thus transmitting an impulse.
In autocrine signaling, a cell responds to stimulants it produces. An example of this occurs during the immune response. The T cells of the immune system help destroy harmful invaders, and upon detecting their presence they produce and secrete growth factors to which they themselves respond. The result is an increase in their numbers, and an ensuing increase in the magnitude of the defensive response. Whether a cell responds to a signal, and how it responds, is determined by the set of receptors it has and the transduction pathways it has in place when it receives the signal. Much of the development is based on using these differences in receptors and pathways.
7. Although the four parathyroid glands are quite small, they have a very rich blood supply. This suits them well since they are required to monitor the calcium level in the blood 24 hours a day. As the blood filters through the parathyroid glands, they detect the amount of calcium present in the blood and react by making more or less parathyroid hormone (PTH). When the calcium level in the blood is too low, the cells of the parathyroids sense it and make more parathyroid hormone. PTH raises the blood calcium level by:
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