JCCF CHS NAUTH LIBRARY 📚

👆👆👆 that's for Medical Biochemistry (2)..

That's For Metabolism of biomolecules of Life 🥰

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What's Knee Locking and Unlocking? Introduction: The ‘screw home mechanism’ is considered to be a key element to knee stability, is the rotation between the tibia and femur. It occurs at end of knee extension, between full extension (0 degrees) and 20 degrees of knee flexion. It includes locking and unlocking of knee joint. 🗒️ LOCKING OF KNEE JOINT Closed kinematic chain extension from 30 degree flexion- Larger medial femoral condyle continue rolling and gliding posteriorly when smaller lateral side stopped. These results in medial rotation of femur on tibia , seen in last 5 degree of extension .The medial rotation of femur at final stage of extension is not voluntary or produced by muscular force, which is referred as “Automatic” or “Terminal Rotation”. The rotation within the joint bring the joint in to a closed packed or locked position. The consequences of automatic rotation is also known as “locking mechanism” or “screw home mechanism.” Open kinematic chain: lateral rotation of tibia on femur. 🗒️ UNLOCKING OF KNEE JOINT To initiate flexion, knee must be unlocked. A flexion force will automatically result in lateral rotation of femur. Because the larger medial condyle will move before the shorter lateral condyle. Popliteus is the primary muscle to unlock the knee.

📝 *First week of development* • _FERTILIZATION_ Fertilization is simply the fusion of the male sex gamete and the female sex gamete resulting in the formation of a Zygote. • _CLEAVAGE_ Cleavage is the series of mitotic cell divisions of the zygote, resulting in the formation of early embryonic cells blastomeres. size of the cleaving zygote remains unchanged while blastomeres become smaller. Until the 8-cell stage, they form a loosely arranged clump. • *SITE OF CLEAVAGE* Division of zygote into blastomeres begins approximately 30 hours after fertilization. Cleavage normally occurs as the zygote passes along the uterine tube toward the uterus. During cleavage, zygote lies within the thick zona pellucida( *Take note: This prevents wrong implantation or ectopic pregnancy)* • _COMPACTION_ After the third cleavage, blastomeres maximize their contact with each other, forming a compact ball of cells held together by tight junctions. This process, compaction, segregates inner cells, which communicate extensively by gap junctions, from outer cells. • *MORULA* Latin., morus,- mulberry Approximately, 3 days after fertilization, cells of the compacted embryo divide again to form a 16-cell morula (mulberry). Inner cells of the morula constitute the inner cell mass, & surrounding cells compose the outer cell mass. • _BLASTOCYST FORMATION_ About the time the morula enters the uterine cavity, fluids begin to penetrate through the zona pellucida into the intercellular spaces of the inner cell mass. Gradually, the intercellular spaces become confluent, and finally, a single cavity, the blastocole forms. ‼️ Friends Let's Note: It is At this time the ZP-Zona Pellucida disappears allowing implantation to occur. 🌆 *Second week of development* 📝 💐 Day 8: -Blastocyst is partially embedded in the endometrial stroma. -Trophoblast differentiates into: Inner layer of mononucleated cells, the cytotrophoblast Outer multinucleated zone without boundaries, the syncytioblast Embryoblast differentiates into Layer of cuboidal cells, the hypobast layer appears. Layer of high columnar cells, the epiblast layer and the Amniotic cavity also appears.(I explained this in Class) 💐 Day 9: -Blastocyst is deeply buried in the endometrium and the penetration defect is closed by Fibrin Coagulum -Lacunae formed by the fusion of vacuoles which appear at the embryonic pole so called lacunar stage. -Exocoelomic membrane formed at the abembryonic pole, this membrane together with hypoblast forms primitive yolk sac (exocoelomic cavity) 💐Days 11 and 12 -Blastocyst completely embedded in endometrium and produces slight protusion. -Sinusoids formed by the penetration of syncytioblast into stroma eroding endothelial lining of maternal capillaries. -Uteroplacental circulation established. -Extraembryonic mesoderm formed by the cells derived from yolk sac cells. -Chorionic cavity developed by confluence of large cavities in the extraembryonic mesoderm. -Extraembryonic somatopleuric mesoderm and extraembryonic splanchopleuric mesoderm established. 💐Day 13 -Surface defect in endometrium heals (bleeding might occur due to greater blood flow into lacunar spaces-may be confused with normal menstrual bleeding) -Primary villi formed by proliferation and penetration of cytotrophoblast cells into syncytioblast. -Secondary yolk sac (definitive yolk sac) established. -Exocoelomic cysts are found in the chorionic cavity. 💐Day 14 -Appearance of the Prechordal Plate at the Cephalic region of the Bilaminar Germ Disc. Concise Note on the Second Week of Development 😊 Copy and paste into ur Note and Exam Paper 🥰 I will send Clinicals to the Group Later in the Day🤭 Share to your Friends ❤️ ©JCCF Unizik Nnewi Cares 🥰