Biology unit 5

• Respiration


  1. Glycolysis

  2. Link reaction

  3. Krebs cycle

  4. Oxidative phosphorylation
• Aerobic respiration


  Respiration in the presence of oxygen
• Anaerobic respiration


  Respiration in the absence of oxygen
• Glycolysis


  Beginning of both aerobic and anaerobic respiration, takes place in the cytoplasm, 2 ATP used and 4 produced, produces 2 pyruvates from 1 glucose molecule
• Link reaction


  Takes place in the mitochondria, 3-carbon pyruvate is oxidised, NAD reduced to NADH, CO2 released, produces acetyl coenzyme A
• Krebs cycle


  Also known as the citric acid cycle, takes place in the mitochondria

  
• Oxidative phosphorylation


  Electrons transferred from NADH and FADH2 to protein complexes and electron carriers, used to create an electrochemical gradient, H+ travels to ATP synthase to make ATP
• Substrate-level phosphorylation involves direct transfer of a phosphate group from the substrate to ADP, while oxidative phosphorylation uses energy released from electron transfer in the transport chain to generate ATP
• Anaerobic respiration


  Pyruvate from glycolysis converted into lactic acid, produces 2 ATP per glucose molecule respired
• Respiratory quotient


  Volume of CO2 produced / volume of O2 used
• Tendons


  Inelastic, connect muscle to bone
• Ligaments


  Flexible, connect bone to bone
• Compact bones


  Dense and heavy, long bones, red blood cells made here
• Spongy bones


  Open structure
• Bones


  Made of collagen and calcium salts in a matrix
• Joints


  Allow movement and locomotion, produce synovial fluid to reduce friction
• Ball and socket joints


  Allow movement in 3 planes, e.g. shoulder and hip
• Hinge joints


  Allow movement up and down, e.g. knee and elbow
• Antagonistic muscle pairs


  Consist of a flexor and extensor working in opposite directions, when one contracts the other relaxes
• Cardiac muscle


  Electrical activity of myogenic impulses sent from cardiac control centre in medulla, sinoatrial node establishes wave of electrical excitation, atrioventricular node delays before depolarization passes to bundle of His and Purkyne fibres
• Cardiac output


  Volume of blood pumped in a single unit of time, calculated as stroke volume x heart rate
• Tidal volume


  Volume of air that enters and leaves the lungs at each natural resting breath
• Residual volume


  Volume of blood left in lungs after strongest possible exhalation
• Vital capacity


  Maximum volume of air that can be discharged from the lungs following maximum inhalation
• Stroke volume


  Volume of blood per beat
• Respiration minute ventilation


  Volume of gas inhaled or exhaled from lungs per minute
• Breathing rate


  Number of breaths taken in one minute
• Sliding filament theory


  Depolarisation triggers release of acetylcholine, Ca2+ binds to troponin, tropomyosin shifts to expose myosin-binding sites, myosin heads reorient to drag actin filaments and shorten sarcomere
• Adrenaline in fight or flight response

  Baroreceptors detect pressure changes, sympathetic nerves stimulate adrenal gland to release adrenaline, increases heart and breathing rate, vasodilation, blood flow, decreases insulin production
• Positive feedback


  Effectors work to increase the effect/change that triggered the stimulus
• Negative feedback


  Results in a decrease in the change of the variable that triggered the response, maintains systems within narrow limits
• Homeostasis


  The process of maintaining a stable internal environment despite changes in the external environment, e.g. insulin, glycogen, blood glucose
• Hormones


  Organic chemicals produced in endocrine glands and released into the blood, travel to target organs to cause changes
• Exocrine gland


  Group of cells that release a substance into a duct that carries it to where it is needed
• Endocrine gland


  Ductless, releases hormones directly into the blood
• Control of heart rate

  Chemoreceptors detect blood pH changes, baroreceptors detect blood pressure changes, impulses sent to cardiovascular control centre in medulla, centre increases/decreases frequency of impulses to sinoatrial node, parasympathetic system decreases rate if too high
• Control of breathing rate

  Chemoreceptors detect pH changes, impulses sent to ventilation centre in medulla, centre sends impulses to contract intercostal muscles and diaphragm, eventually inhibits breathing muscles to give resting rhythm
• Loop of Henle


  Consists of 3 sections: 1) freely permeable to water, not to NaCl, water moves out by osmosis, 2) permeable to NaCl, not water, NaCl moves out by facilitated diffusion, 3) impermeable to water, NaCl pumped out by active transport
• Control of mammalian plasma concentration and blood volume

  Osmoreceptors in hypothalamus detect changes, send impulses to pituitary to release ADH, ADH binds to receptors in distal convoluted tubule and collecting duct, increases water reabsorption

  
• Selective reabsorption


  Takes place in proximal convoluted tubule, 80% of filtrate reabsorbed, necessary substances reabsorbed by active transport, water and Cl- by facilitated diffusion and osmosis