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Biochem2 lecture 7 pt1 Organs2

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winniesmith1's version from 2017-03-21 20:09

Section 1

Question Answer
what is the structure of the brainHeterogenous structure: 1.5kg in weight (approx), Mainly nerve cells (grey matter + white matter), 100 billion (est) nerve cells, 900 billion (est) glial cells.
What is the blood supply to the brainCommon Carotid arteries (left and right). External Carotid. Internal jugular veins – superior vena cava. 50ml per min per 100g: Resting skeletal muscle – 2-5 ml per min per 100g, Exercising skeletal muscle – 50 ml per 100g
Describe metabolism of the brain120g (approx) of glucose per day (2MJ) 20% of daily energy expenditure. In total remains fairly constant with cognitive function BUT New techniques to show blood flow and local glucose utilisation show local changes
What is the blood brain barrierClosely packed layer of endothelial cells. Layer of periendothelial cells. Prevents lipid soluble molecules from crossing - Plasma non-esterified fatty acids. Continuous capillary, cleft 4nm wide, vesicles 70nm wide.
What fuels the brainLots of CHO metabolism. Starvation – ketone body. Glucose almost completely oxidised- small amount lactate. oxygen
How is glucose transported in the brainThrough GLUT3 (glucose transported) (look up GLUT1)
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Section 2

Question Answer
Describe (what is in) skeletal muscleStriated/smooth muscle. Contains myosin (thick)/actin (thin), Ca2+ and troponin-C (blocking sites), tropomyosin (strande), wrapped around nebulin. ATP---> ADP + Pi
Describe the steps that initiate a contraction1: ACh released, binding to receptors. 2: Action potential reaches T tubule. 3: Sarcoplasmic reticulum releases Ca2+. 4:Active site exposure cross-bridge formation. 5: Contraction begins
Describe the steps that end a contraction6: ACh removed by AChE. 7: Sarcoplasmic reticulum recaptures Ca2+. 8: Active sites covered no cross-bridge interaction. 9: Contraction ends. 10: Relaxation occurs, passive return to resting length.
What is oxidative capacityA measure of a muscle's maximal capacity to use oxygen in microlitres of oxygen consumed per gram of muscle per hour. Factors which affect the oxidative capacity of muscles include the activity of oxidative enzymes (e.g. succinic dehydrogenase).
*What is the oxidative capacity of skeletal muscle *look up
Why does skeletal muscle have red fibres due to good supply
How many mitochondria in a skeletal muscle celllots. needed to supply energy during contractions.
What is the glucose transporter in skeletal muscleGLUT4- major transport (insulin sensitive). GLUT1- uptake at basal rate (
How does GLUT1 facilitate glucose diffusion1. GLUT1 is a membrane protein shown with its binding site facing outside the cell. 2. Glucose binds to GLUT1 from outside the cell. 3: A conformational change results, transporting glucose to the interior. 4: Glucose is released inside of cell.
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