BASIC STRUCTURE OF THE ENCEPHALON IN VERTEBRATES

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HUMAN EMBRYOGENESIS (STEP 1-4)

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Embryogenesis, the first eight weeks of development after fertilization, is an incredibly complicated process. It’s amazing that in eight weeks we’re transforming from a single cell to an organism with a multi-level body plan. The circulatory, excretory, and neurologic systems all begin to develop during this stage. Luckily, like with many complex biological concepts, fertilization can be broken down into smaller, simpler ideas. The big idea of embryogenesis is going from a single cell to a ball of cells to a set of tubes.  Starting from the very beginning Step 1 : a  zygote  is the single cell formed when an egg and a sperm cell fuse; the fusion is known as fertilization Step 2 : the first 12-to 24-hours after a zygote is formed are spent in  cleavage  – very rapid cell division The zygote’s first priority is dividing to make lots of new cells, so it’s first few days are spent in rapid mitotic division. With each round of division, it doubles in c...
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CENTRAL NERVOUS SYSTEM

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The Central Nervous System (CNS) The central nervous system is divided into two major parts: the brain and the spinal cord.   Firstly,we are going to talk about the brain. Parts of the Human Brain and their Subdivisions Human encephalon resembles, in structure and function, with that of the other vertebrates. The scientists reveal that parts of the human brain are Forebrain, Midbrain & Hindbrain and the related structures that collectively act as a single highly specialized unit. These parts work in coordination and perform  different functions of brain . More specifically, it is divided into five major regions, namely, telencephalon, diencephalon or inter-brain, myelencephalon (hindbrain/medulla oblongata), metencephalon and mesencephalon (midbrain). Here follows a precise but comprehensive description of each of the above given divisions. Telencephalon/Cerebrum—Anterior Part Of Forebrain Further composed of cerebral cortex, limbic and basal ganglia,...
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HUMAN EMBRYOGENESIS (STEP 5-7)

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Making Tubes Step 5 : During  gastrulation  the three germ layers form; the cell mass is now known as a gastrula Step 5a : The  primitive streak  forms Step 6 : The  notochord   is formed Week 3 of development is the week of  gastrulation . A germ layer is a layer of cells that will go on to form one of our organizational tubes. Our anatomy can really be boiled down to an inner tube (our digestive tract), and a series of tubes that wrap around it. The three germ layers that will translate into these tubes are the  ectoderm , the  mesoderm , and the  endoderm . Germ Layer What does the prefix mean? Goes on to form: Ectoderm Outer, external Epidermis (outer layer of skin), hair, nails, brain, spinal cord, peripheral nervous system Mesoderm Middle Muscle, bone, connective tissue, notochord, kidney, gonads, circulatory system Endoderm Within Epithelial lining of the digestive tract; Stomach, colon, liver, pancreas, bladd...
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SKELETAL SYSTEM (PHYSIOLOGY)

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Support and Protection The skeletal system’s primary function is to form a solid framework that supports and protects the body’s organs and anchors the skeletal muscles. The bones of the axial skeleton act as a hard shell to protect the internal organs— from damage caused by external forces. The bones of the appendicular skeleton provide support and flexibility at the joints and anchor the muscles that move the limbs. Movement The bones of the skeletal system act as attachment points for the skeletal muscles of the body. Almost every skeletal muscle works by pulling two or more bones either closer together or further apart. Joints act as pivot points for the movement of the bones.  Hematopoiesis Red bone marrow produces red and white blood cells in a process known as hematopoiesis. Red bone marrow is found in the hollow space inside of bones known as the   medullary cavity .  The amount of red bone marrow drops off at the end of puberty, replaced by yellow b...
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