Unit 2 Learning Objectives
Unit 2 Learning Objectives BIO 277-01
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This 6 page Class Notes was uploaded by Elizabeth Weathers on Tuesday August 30, 2016. The Class Notes belongs to BIO 277-01 at University of North Carolina - Greensboro taught by Elizabeth S. Tomlin in Fall 2016. Since its upload, it has received 196 views. For similar materials see Human Physiology in Biology at University of North Carolina - Greensboro.
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Date Created: 08/30/16
Bio 277 Unit 2 1. Define receptor and ligand. Receptors: proteins either embedded in the plasma membrane or inside the cell Ligands: signal molecules, when a ligand binds with the receptor there is a change in activity of the cell EX: activation of enzyme, opening/closing an ion channel, or changing gene expression 2. Distinguish between autocrine, paracrine and endocrine signaling and give examples of each. Autocrine – receptor on cell that produced signal; shortdistance signaling Paracrine – signal binds with receptor on nearby cell; passes through ISF; shortdistance signaling Endocrine – travel through blood before binding with receptor; longdistance signaling 3. Distinguish between steroid and nonsteroid hormones with respect to chemical nature of the signal, transport in the blood, location of receptors, mechanism of signal transduction and cellular response. Steroids – fatsoluble hormones (hydrophobic, lipophilic); need a protein carrier (steroidbinding globulins) because they are not water soluble; receptor located in cytosol or nucleus; can pass into cell by simple diffusion; steroids activate gene expression EX: estradiol (estrogen), testosterone, progesterone, cortisol, aldosterone NonSteroids – watersoluble hormones (lipophobic, hydrophilic); dissolved in blood, may need carrier proteins for protection from enzymes; receptors on plasma membrane, hormone does NOT ENTER CELL; activate enzymes, activate 2 messenger systems, open/close ion channels EX: Proteins insulin, antidiuretic hormone Catecholamines epinephrine 4. Distinguish between Gcoupled, enzymecoupled and ionchannel coupled receptors. Gcoupled When ligands bind with receptors, they can activate other proteins such as Gproteins (α adrenergic receptor) Enzymecoupled When ligands bind with receptors, they can activate an enzyme (insulin receptor) Bio 277 Ionchannel coupled When ligands bind with receptors, they can open or close an ion channel (eg. acetylcholine gated sodium channel on skeletal muscle membranes 5. Explain how one signal can cause difference effects in a target cell. The effect of a singular signal can potentially vary depending on what receptor it binds with. There can be more than one version of a receptor for the same signaling system in the body. EX: When norepinephrine (almost the same as EPI) binds with αadrenergic receptors, vascular smooth muscle contract. The part of the receptor on the outside of the cell is connected to a G protein on the inside of the cell When epinephrine or norepinephrine binds with βadrenergic receptors, vascular smooth muscle relaxes. The part of the receptor on the outside of the cell is connected to a different set of proteins on the inside of the cell 6. Define antagonistic control and explain how heart rate is controlled this way. Antagonistic Control: body systems can be signaled to do opposite tasks by different signals EX: Pacemaker cells in the heart one signal (EPI/NE) causes the heart to speed up, and a different signal (acetylcholine, Ach) causes the heart to slow down 7. Explain and draw the relationship between the hypothalamus, the anterior pituitary and the posterior pituitary. Bio 277 Neurons synthesizing trophic neurohormones release them into capillaries of the portal Portal veins carry the neurohormones directly to the anterior pituitary, where they act on Endocrine cells release peptide hormones into a second set of capillaries to be distributed throughout the body Bio 277 Neurohormones are made and packaged in the cell body of the neuron Vesicles are carried down the cell Vesicles containing neurohormones are stored in the posterior Neurohormones are released into the Oxytocin Vasopre ssin 8. Describe where the hormones oxytocin and antidiuretic hormone (vasopressin) are released from, the stimuli for release, target tissues (location of receptors), transduction mechanism, and functional response of tissues. Oxytocin Vasopressin Released from Hypothalamus Hypothalamus Bio 277 Stimuli for release neural reflex initiated by mechanical decreased blood pressure (MAP); stimulation of the nipples increased osmolarity (“saltiness”) of the cerebrospinal fluid (CSF) Target tissues Increased contraction of myoepithelial Kidney – water conservation cells in the mammary glands (prolactin Peripheral vascular circular from the APG is responsible form milk smooth muscle – causes blood production) vessels to squeeze blood from the periphery into the heart brain loop Transduction mechanism OxytocinR on the surface of the target ADHR on the surface of the target cells cell. ADH is a protein; R=receptor Tissue functional response Milk “let down” reflex Increased blood pressure and less urine formed 9. Explain what is meant by a tripartite axis for hormone control and release. The stress axis is an example of a “tripartite axis” because the signaling pathway involves 3 different endocrine glands – the hypothalamus (HT), anterior pituitary(APG) and the adrenal cortex. It also illustrates negative feedback 10. Draw and describe the stress axis in detail. Bio 277 hypothalamus CRH Cortisol receptors in the Hypothalamus & anterior pituitary repress the secretion of CRH & ACTH Anterior Pituitary ACTH Adrenal Cortex Cortisol Muscle Immune system cells Liver Adipose Tissue 11. Explain what negative feedback is, and include this in the above drawing. Negative feedback – the end product of a process will stop/slow down the previous steps in that process once enough end product has been produced or the desired effect has been completed
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