Results for "Recycle"

Unité 3 : Je recycle donc je suis

về recycle

# Synaptic transmission and the vesicle cycle ILO: - the two fundamental synaptic mechanisms by which excitable cells and in particular neurones can affect one another's function: electrical or chemical synaptic communication - how a neurotransmitter supporting chemical synaptic communication is defined and the diversity of types of small molecules that can be defined as being a neurotransmitter - how these are stored in small membranous vesicles, what constitutes the classical vesicle cycle and full collapse vesicle fusion during release - the experimental evidence for this full collapse fusion release model and how the vesicle membrane is recycled - further experimental evidence for an alternative to this model: the "kiss and run" model of vesicle cycling - the proteins that make up the release machinery and how they are readied for release during "docking" and "priming" - what happens to these proteins during the release process and the subsequent retrieval of vesicle membrane following full collapse fusion # Types of synapse - **chemical synapse** - molecules stored in vesicles - molecules diffuse across a gap - relatively slow - unidirectional - majority of synaptic transmission in the nervous system - **electrical synapse** - holes in adjoining cell membranes - linked by channels - gap junctions or connexons - signalling is very fast - bidirectional - direct electrical coupling between cells - electrical synchronisation in the heart - relatively rare in the nervous system - inhibitory interneurons or local networks # Chemical synapse Key functional roles - Neural computation - integration of many input +/- - Exhibit plasticity - development, learning and memory - Act as targets for drug action - neurotransmitter synthesis, release, receptors, uptake, degradation to produce a broad range or complex series of effects - inc functional flexibility ## Neurotransmitter 6 criteria :  ### Types  - amino acids - amines - purines - peptides - **dales principle** - neurons release just one transmitter at all of its synapses - how is dales principle challenged? - challenged by co existence and co release of small molecule transmitter and peptides by interneurons eg GABA and enkephalins - and more than one small molecule transmitter in some projection pathways eg L glutamate and dopamine ## Vesicles - neurotransmitters are likely to be stored in one type of vesicle ### Types  For LDCVs - concentration is lower because of the relatively proximity to the voltage gated channels - only seen when there is sustained AP in a more global manner rather than restricted to synaptic active zone ### Cycling  1. vesicle is filled with neurotransmitter with appropriate transporter which uses ATP as an energy source to drive against conc gradient and fill the vesicle 2. vesicle collected in to reserve pool, mobilised to active zone for docking 1. atp dependent process 3. primed to be sensitive to calc conc to initiate membrane fusion 1. also atp dependent 4. exocytosis following inc in intracellular conc of calcium 5. vesicle membrane fully collapses into the membrane 6. loss of membrane recovered with endocytosis, calcium dependent with coated pits 1. uncoating requires atp 7. small vesicles become part of endosome, all recycled 8. then pinched off again to start the cycle ### Evidence for full fusion/collapse - slam freezing - rapidly cooling of the neuromuscular junction on a metal block after electrical stimulation of motor neurone axon fibres to initiate acetylcholine release - sections of the presynaptic membrane were visualised at different types after electrical stimulation to follow any changes in presynaptic membrane - activity led to increase in membrane surface area - therefore vesicle recycling ### Step 1 - docking - close association with plasma membrane - synaptic vesicles only dock at active zone - presynaptic area adjacent to signal transduction machinery - active zones differ between neurons by vesicle number ### Step 2 - priming - ready for release - maturation of synaptic vesicle - made competent to release transmitter - requires ATP - conformational change in proteins that drive release ### Step 3 fusion/exocytosis - full fusion of synaptic vesicle and presynaptic terminal membrane - requires calcium - calcium sensor protein - fusion induces exocytosis - takes 1ms ### Step 4 endocytosis - recovery of fused membrane - triggered by inc intracellular calcium - involves cytoskeletal protein lattice formation from clathrin monomers - this helps to pinch off membrane with clathrin coated pits - takes about 5 seconds - ATP dependent ### Step 5 - recycling - mechanism to conserve synaptic vesicle membrane via endosome - decoating of clathrin coated pits is also atp dependent - vesicles refill with transmitter - atp dependent ### Kiss and Run Model? - fast recycling and low capacity, favoured at low frequency stimulation - may be majority of glutamate release in hippocampus - whereas classical is slow, high capacity, favoured at high frequency stimulation - full vesicle fusion may not be required - neurotransmitter leaks out of small fusion pores - SSVs recycled intact - and not recycled as clathrin coated vesicles via the endosome Functional evidence - flickering capacitance changes instead of up stepping capacitance - capacitance dependent on surface area ### Targeting vesicles Vesicle associated proteins - synaptobrevins VAMP - synaptotagmins Plasma membrane associated proteins - SNAP-25 - syntaxins ### Snares for release - synaptobrevin - single transmembrane spanning - t snare - syntaxin - single transmembrane spanning - SNAP-25 - anchored to membrane by S-acylation ### Release machinery in the different steps     Syntaxin regulatory domain is important in maintaining a tight connection to the cell membrane Snares form a tighter complex during priming - atp dependent - Habc domains binding assisted by Munc18 - zippering - formation of the SNARE pins What is the Ca2+ sensor? - synaptotagmin - found on vesciles - binds to SNARE pins in absence of Ca2+ - during priming - binds to phospholipids in C region in presence of Ca2+ - Ca2+ binding may cause synaptotagmin to pull vesicle into membrane Why must SNAREs disassociate? - to allow internalisation of empty vesicles - re docking of another vesicle - involves NSF - ATPase which binds to the SNARE-pin complex to facilitate disassociation

Disposal and Recycle

Recycled words

Why is Oxygen gas so important for life on our planet? What specific process is it needed for? As well, what process makes it and what will it get recycled as? (4)

REDUCE - REUSE - RECYCLE

📘 Chapter 19: Blood – Full Simplified Study Notes (27 Slides) ⸻ Slide 1: Cardiovascular System • Cardiovascular system = heart, blood, blood vessels. • Blood’s job: • Delivers nutrients, hormones, oxygen, and chemical messages. • Carries immune cells to fight infections. • Why it matters: Without this transport system, cells would starve and toxins would build up. • Analogy: Like UPS + garbage service → delivers packages (nutrients, O₂) and removes trash (waste, CO₂). ⸻ Slide 2: Whole Blood • Whole blood = plasma + formed elements. • Hematocrit: percentage of blood volume made of cells. • Plasma: watery fluid. • Key properties of blood: • Temp: 38°C (100.4°F) → warmer than body surface. • Thickness: 5x thicker than water. • pH: ~7.4 (slightly alkaline). • Volume: Men = 5–6 L, Women = 4–5 L. • About 7% of body weight. • Example: If someone weighs 150 lbs, about 10 lbs of that is blood. ⸻ Slide 3: Blood Plasma • Plasma = liquid with proteins + solutes. • Proteins: • Albumins: keep water inside blood vessels (prevent swelling). • Globulins: antibodies → defense. • Fibrinogen: forms clots. • Other solutes: • Electrolytes: Na⁺, K⁺, Cl⁻, HCO₃⁻ (important for nerves/muscles). • Nutrients: glucose, fructose, amino acids. • Wastes: urea, uric acid. • Analogy: Plasma = soup broth carrying salt, sugar, proteins, and waste. ⸻ Slide 4: Formed Elements • Red Blood Cells (RBCs / erythrocytes): 99.9% of all blood cells. • RBC count: Men = 4.5–6.3 million/μL, Women = 4.2–5.5 million/μL. • Platelets: fragments needed for clotting. • White Blood Cells (WBCs / leukocytes): fight disease. • Think: Plasma is the liquid, formed elements are the “stuff floating inside.” ⸻ Slide 5: RBC Structure • RBCs lose their nucleus & organelles. • Consequences: • Can’t divide. • Can’t make proteins or repair. • Only use glycolysis (anaerobic metabolism) → no oxygen needed for energy. • Analogy: Like delivery trucks with no engine shop → they drive until they break down. ⸻ Slide 6: RBC Lifespan • RBCs have no nucleus, mitochondria, ribosomes → no repair. • Rely on glycolysis for energy. • Live about 120 days. • Must be recycled by spleen/liver. • Example: Like a disposable battery that runs until it dies. ⸻ Slide 7: RBC Shape & Function • Shape = biconcave disc (doughnut-like, thin middle). • Benefits: • High surface area → better oxygen exchange. • Can stack like coins → smooth flow. • Flexible → squeeze through tiny capillaries. • Analogy: Like a flexible frisbee that can bend and stack. ⸻ Slide 8: Hemoglobin • Main protein inside RBC. • Structure: • 2 alpha chains + 2 beta chains. • Each has heme group with iron atom (Fe). • Function: Iron binds oxygen → carries it around body. • Why recycle? Iron is valuable, so old RBCs get broken down to save it. • Analogy: Hemoglobin = oxygen backpack. ⸻ Slide 9: RBC Lifecycle • Starts from hemocytoblast (stem cell). • Branches into: • Myeloid stem cells: make RBCs + some WBCs. • Lymphoid stem cells: make lymphocytes. • Think: Hemocytoblast = tree trunk, RBCs and WBCs = branches. ⸻ Slide 10: RBC Production (Erythropoiesis) • Erythropoiesis = making RBCs. • Embryo: 1st 8 weeks = yolk sac → later liver, spleen, thymus, bone marrow. • Adult: red bone marrow only (vertebrae, sternum, ribs, skull, pelvis, ends of long bones). • Nutrients needed: amino acids, iron, vitamins B12, B6, folic acid. • Analogy: RBCs = cookies, bone marrow = kitchen, iron + vitamins = ingredients. ⸻ Slide 11: RBC Production Control • Controlled by erythropoietin (EPO). • Made by kidneys/liver when low oxygen (hypoxia). • Effects: • Increases stem cell division. • Speeds up hemoglobin production. • Blood doping: Athletes take EPO or reinfuse RBCs → more oxygen for muscles. • Risk: thicker blood → clots, strokes. • Analogy: EPO = coach yelling “make more RBCs!” ⸻ Slide 12: Blood Types • RBCs have antigens on membranes (A, B, AB, O). • Rh factor = + or –. • Plasma has antibodies (agglutinins): attack foreign antigens → cause clumping (agglutination). • Universal donor = O–. • Analogy: Blood type = ID card. If ID doesn’t match, antibodies attack. ⸻ Slide 13: RBC Summary • Know: • How typing works. • How RBCs are made. • What controls them. • Why they live 120 days. • How they’re broken down. • Analogy: RBCs = delivery trucks with expiration dates. ⸻ Slide 14: WBC Basics • WBCs = leukocytes. • Have nuclei, organelles, no Hb. • Functions: fight pathogens, remove wastes, destroy abnormal cells. • Only in blood briefly → then move into tissues. • Analogy: WBCs = body’s police force. ⸻ Slide 15: Neutrophils • 50–70% of WBCs. • Nucleus 2–5 lobes. • First responders → attack bacteria. • Use phagocytosis + enzymes. • Die quickly → pus = dead neutrophils + bacteria. • Analogy: Neutrophils = foot soldiers. ⸻ Slide 16: Basophils • <1% WBCs. • Release histamine (dilates vessels, causes swelling/redness). • Release heparin (prevents clots). • Trigger inflammation → work with mast cells. • Analogy: Basophils = fire alarms. ⸻ Slide 17: Eosinophils • 2–4% WBCs. • Stain red-orange. • Bi-lobed nucleus. • Kill parasites, respond to allergies. • Release toxic chemicals (nitric oxide, enzymes). • Help control inflammation. • Analogy: Eosinophils = exterminators. ⸻ Slide 18: Monocytes • 2–8% WBCs. • Largest WBC, kidney-shaped nucleus. • Become macrophages in tissue. • Eat large pathogens, dead cells. • Call fibrocytes → scar tissue. • Analogy: Monocytes = garbage trucks. ⸻ Slide 19: Lymphocytes • 20–30% WBCs. • Big nucleus, little cytoplasm. • Most live in lymph tissue. • Types: • T cells: attack infected cells. • B cells: make antibodies. • NK cells: kill cancer/virus cells. • Analogy: Lymphocytes = special forces. ⸻ Slide 20: WBC Production • From hemocytoblasts. • Myeloid stem cells: all except lymphocytes. • Lymphoid stem cells: lymphocytes. • Colony-Stimulating Factors (CSFs): • M-CSF = monocytes. • G-CSF = granulocytes. • GM-CSF = granulocytes + monocytes. • Multi-CSF = RBCs + WBCs + platelets. • Analogy: CSFs = managers assigning jobs. ⸻ Slide 21: Platelets • Fragments of cells, no nucleus. • Lifespan = 9–12 days. • Removed by spleen. • 2/3 stored for emergencies. • Analogy: Platelets = emergency patch kits. ⸻ Slide 22: Platelet Functions 1. Release clotting chemicals. 2. Form platelet plug at damage site. 3. Contract (actin + myosin) → shrink clot, close wound. • Analogy: Platelets = patch team pulling duct tape tight. ⸻ Slide 23: Hemostasis • Definition: stopping bleeding. • 3 phases: vascular, platelet, coagulation. • Analogy: Like fixing a leaking pipe step by step. ⸻ Slide 24: Vascular Phase • Vessel wall contracts (vascular spasm). • Endothelial cells: • Expose basement membrane. • Release endothelins → stimulate contraction/healing. • Become sticky → platelets attach. • Analogy: Pinch a hose to slow the leak. ⸻ Slide 25: Platelet Phase • Platelets stick to exposed collagen. • Form platelet plug (15 sec after injury). • Release chemicals: ADP, thromboxane A₂, serotonin, Ca²⁺, PDGF. • Feedback prevents over-clotting. • Analogy: Like putting your hand over a hole until repair arrives. ⸻ Slide 26: Coagulation Phase • Chain reaction of clotting factors. • Fibrinogen → fibrin (forms net). • Common pathway: 1. Factor X → prothrombinase. 2. Prothrombin → thrombin. 3. Fibrinogen → fibrin. • Clot retraction pulls vessel edges together. • Analogy: Casting a fishing net over the leak. ⸻ Slide 27: Fibrinolysis & Clotting Needs • Fibrinolysis: clot dissolves after healing. • t-PA → activates plasminogen → plasmin → digests fibrin. • Requirements for clotting: • Calcium (Ca²⁺): needed in all clotting steps. • Vitamin K: liver makes clotting factors; comes from food + gut bacteria. • Deficiency = bleeding problems. • Analogy: Once pipe is repaired, cut away the net (clot)

RECYCLE

CSS 1011 Final Review Recycled Questions

Reduce, reuse, and recycle

AP LANG MC Quiz 12 MASTER KEY RECYCLED

AP LANG MC Quiz 12 MASTER KEY RECYCLED

CSS 1011 Final Review Recycled Questions

recycle used paper

Insects as recyclers

Chemistry - 14 The Earth's Resources - 14.4 Extracting Metals From Ores & 14.5 Life Cycle Assessments & 14.6 Reduce, Reuse and Recycle

Recycled Text on Jem

The 6 Rs - AQA DT GCSE

Recycled Aggregates in Construction