Facts Sunday, December 30, 2018 4:34 PM Structural Proteins (Fibrous proteins) - Integrins - transmembrane proteins that modulate cell to extracellular matrix interactions ○ Often attached to cell to collagen and fibronectin fibers - Cadherins - transmembrane proteins which are for cell to cell adhesion ○ Forming adherens junction to bind cells within tissues together - Keratin - Skin, hair , and nails ○ It is hard according to the sulfur content. Cysteine residues ▪ So less sulfur then more flexible - Actin and myosin - Muscle tissue ○ Interact to form cross linkages which allow the sliding of the filaments over each other in muscle contraction ▪ Actin only region shrinks but the myosin region does not shrink - Collagen - found in tendons, connective ligaments, and gives extra support to the skin, cartilage and blood vessels ○ Triple helix formed by three proteins that wrap around one another Neural Pathways - Efferent nerves - instructions come from the CNS - Afferent nerves - Take info to the CNS Neurotransmitters - Glutamate - excitatory - GABA - inhibitory of CNS - hyperpolarize cells to reduce action potential firing ○ Alcohol binds to its receptors there alcohol intoxication - Glycine - inhibitory found in spinal cord and brainstem - Dopamine - used in reward and motor pathways - Endorphins - suppress pain and can produce euphoria - Serotonin - regulates mood, appetite and sleep - Acetylcholine - for activation of muscle contraction - in PNS - Epinephrine - flight or fight response - Norepinephrine - increases arousal and alertness and focuses attention Erythrocytes (also known as red blood cells or RBCs) are responsible for carrying oxygen to the different tissues of the body, and also aid in carrying carbon dioxide to the lungs, where it can be exhaled. Erythrocytes can do this because they are packed full of hemoglobin, a polymer of 4 proteins and iron that binds oxygen. Erythrocytes are created in the bone marrow in response to erythropoietin (EPO), a hormone that is released from the kidney whenever erythrocyte levels are low. During development in the bone marrow, erythrocytes lose their membrane-bound organelles, including their mitochondria and nucleus. As such, they only engage in anaerobic metabolism and have a limited lifespan of only about 100 days. Their lack of internal organelles contributes to their characteristic biconcave shape, which helps them travel more efficiently through capillaries and maximizes their surface area, which assists in gas exchange. Erythrocytes are degraded by the spleen, which is located in the left upper quadrant of the abdomen. MCAT 1 Page 1 spleen, which is located in the left upper quadrant of the abdomen. From <https://mcat.nextsteptestprep.com/mcattest/launch/37/e/139/4/x/22?aid=570114> Cyclic AMP stimulates PKA MCAT 1 Page 2
