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BIOL 1080 (54)


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BIOL 1080
Jim Kirkland

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BIOL 1080 NOTE REVIEW  Biological systems are scaled in dimensions of size/ shape and time. Biomarkers Things to measure objectively so that you can track aging overtime. A steady, unbiased and narrow-ranged marker is better. Anatomy Normal structure Pathology Abnormal structure and harmful dysfunction Osteoporosis: - Height loss occurs due to bone degeneration in the vertebrae - Height is a biomarker for osteo, however has significant limitations Circadian Rhythms: Chronobiology The study of timescales and cycles in biology Biologic(al) Rhythms Cycles in all zones of biological rhythmicity - Ultradian (less than 24 hours i.e. appetite) - Circadian (24 hrs i.e. working shifts or sleeping) - Infradian (More than 24 hrs menstrual cycle)  The central “clock” is a brain region called the “suprachiasmatic nucleus”, which keeps time based on light signals from the retina  Nearly every cell in the body has a subsidiary clock, which coordinates its metabolism with the rest of the body Bones: - Filled with living cells, some which build the mineral structure and some that are breaking it down - This is called mineral turnover and allows the bone to serve as a functional calcium store for the body. When we need calcium we obtain it from the dissolution of the minerals in bone and when we have excess calcium we deposit it in bone or excrete in urine. - Mineral structure of bone is composed of hydroxyapatite. - What is calcium serving as a protective reservoir for then?  Serves as a buffer to assist in the maintenance of blood (plasma) calcium levels which is homeostatically controlled by the CCN Mechanisms of Intercellular Communication: 1) Direct Communication a) Gap Junctions - Pore size is very small for ions and small molecules. Two cells are very close - Composed of membrane protein structures called connexons that link the cytosols of two cells and action potential. b) Tunneling Nanotubes - Much longer then gap junc, larger pore sizes (proteins, small organelles) 2) Indirect Communication a) Chemical Messengers - Chemical leaves cell and goes to another “target cell”. Target cell responds to msger because it has certain proteins called receptors - Ligands= molecules that bind to proteins reversibly b) Mechanosignals - As cells move they tug on filamentous proteins of extracellular space. As cells move past surface filaments will be activated Communication via Chemical Messengers (Functional Classes of Second Messengers): a) Paracrines/autocrine - Signal doesn’t travel in blood - Chemicals that communicate with neighbouring cells. Include growth factors, clotting factors and cytokines - Autocrines are subclass that act on same cell that secreted them b) Neurotransmitters - 2 cells are very close, very few signal molecules escape from synaptic cleft - Chemicals released into interstitial fluid from nerv system called neurons. Released from axon terminal - Juncture between two cells is called synapse c) Hormones - Chemicals released from endocrine glands into interstitial fluid where they can diffuse into blood. - Hydrophilic Messenger: Water soluble, crossing membranes is difficult ( Insulin, Epinephrine). Can form thousands of cAMP. - Hydrophobic Messenger: “Water fearing”, diffuses across plasma membranes, requires a carrier in blood and ECF (Estrogen and testosterone) Lipophilic=Hydrophobic Lipophobic=Hydrophilic Short-Distance Communication: 1) Docking 2) Autocrine and paracrine signals Long-Distance Communicaton: 1) Nervous System - Consists of neurons and supporting cells called glial cells - Capable of long distances, because of cell to cell communication of chem signals at a synapse, the nervous system is often considered a “wire” system 2) Endocrine System - Lacks any direct link between secretory cell and target cell. Communicates through chem msgers called hormones which travel through bloodstream to all cells. 5 Major Cell Types of CNS: 1) Neurons 2) Astrocytes 3) Microglia 4) Ependymal Cells 5) Oligodendrocytes 1.) Types of Neurons: Myelinated  Faster (Up to 120) Unmyelinated  Fast - Built to signal specific target cells with a specific neurotransmitter - Built to be either excitatory or inhibitory - Built to diverge, converge and form networks  Divergence and convergence are required to form networks 2.) Oligodendrocytes/Schwann Cells: - In brain and spinal cord (CNS) and Peripheral Nervous System Astrocytic Super-Network Theory: 1) Coordinate overall function of the BBB and provide nutrients to neurons 2) Coordinate the function of the ventricle epithelium 3) Coordinate function at the nodes of Ranvier 4) Participate in the tripartite synapse 5) Serve as superhubs for neural networks via syncytium formation and calcium wave signaling The Brain: Traumatic Brain Injury: - Open Head: Bullet - Closed Head: Whiplash, concussion Acquired Brain Injury: - Strokes, tumors, aneurysm, etc How CNS Works… 1) Info flow crosses the longitudinal fissure 2) Personality is am emergent property, large iron rod through Gage’s skull and destroyed left frontal lobe. Frontal lobe controls goal directed behaviour he survived 12 more years but personality altered. Olfactory bulb is part of limbic system so one can connect smells with memories  RAS= Reticular Acti
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