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السلام عليكم بما إنه السنة راح تخلص وهمين صار اكو هواي قنوات فراح أحذف هاي القناة وأظل أنشر فقط ب @studybmc57 إن شاء الله ما قصرت وياكم وكدرت أفيد حضراتكم الله يوفقكم جميعاً 🌹

🟪 اساسيات الطب+مهارات التواصل 🔳 اساسيات الطب ❇️ شرح محاضرات 🛑 اسئلة فاينل 2020 🛑 اسئلة فاينل 2022 🛑 اسئلة امتحان تقييمي 2023 🛑 اسئلة فاينل 2023 🟡 اسئلة حول القصص مهمة ✳️ قناة الطالب زين العابدين حسين تحتوي على حلول بعض الاسئلة واماكن تواجدها في كتاب فن الحوار الطبي 🔳 اساسيات الطب 🟡 اسئلة السنوات السابقة تخص محاضرة الثانية + الثالثة 🛑 اسئلة المد 2024

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مراجعة النسيج العصبي nerve tissue is like epithelium derived from ectoderm composed of 1-- Neurons ((are the basic unit of nervous tissue)) 2-- glial cells ((serve to support nerve cells)) neurons : conduction, propagation, and reception of nervous impulses with axon and dendrites glial cells : No axons or dendrites. These cells are involved in nutrition, support, insulation, protection طبعاً الهن وظائف اخرى بمحاضرة neuroglia cell body : that called perikaryon or soma, It's basically a cell nucleus surrounded by cytoplasm. Their nuclei are large, round and euchromatic with single prominent nucleolus. The cytoplasm is abundantly supplied of rough endoplasmic reticulum, lots of smooth endoplasmic reticulum, numerous of Golgi bodies, mitochondria, cytoskeletal elements and different intermediate filaments (neurofibrils) /// contain pigments such as (lipofusion) or called ageing pigments. Under elecrtron microcope, the cell body contain highly developed rough endoplasmic reticulum organized into aggregation of parallel cisternae. Between these cisternae there are numerous polyribosomes suggestion that these cell synthesize both structural proteins and neurotransmitter proteins such as acetylcholine Nissl body ot tigroid : basophilic granular // RER + ribosome A--nissl body doesn't found in axon hillock B--Golgi apparatus is located only in the cell body C--mitochondria is located in the cell body and axon terminal Axon(nervefiber) : single thread-like extension from cell 1--mylien sheath is whitish, fatty layer surround the axon 2--neurilemma : cellular layer Outside the myelin sheath 3-- Schwann cells : support by increasing the speed of impulse propagation first segment of the axon == initial segment➡️high ionic area ---axon hillock is specialized pyramid area of the cell body that connects to the axon and is the last site of the soma ➡️action potential generation➡️ much higher density of voltage-gated ion channels dendrites : short, tapering and branched projections of a neuron that act to propagate the electrochemical stimulation Electrical stimulation is transmitted onto dendrites via synapses(( located at various points throughout the dendrites tree)) ☀️تحتوي كل أجزاء الخلية العصبية على العضيات الخلوية ما عدا جهاز كولجي موجود بس بجسم الخلية synapse : 1-Axodendritic // 2-Axosomatic // 3-Axoaxonic // 4-Dendrodendritic A--Structural classification : 1--Multipolar neurons : 3 or more processes+major neuron type in the CNS 2--Bipolar neurons : Sensory neurons that have 2 processes 1 axon 1 dendrite ⏺retina of the eye ⏺inner ear ⏺olfactory area of the brain 3--Pseudounipolar neurons: Sensory neurons that have one process that splits into two branches axon and dendrite 4--Unipolar brush cells : glutamateric have a single short dendrite terminating in a brush-like tuft of dendrioles. ⏺granular layer of the cerebellum 5--Anaxonic neurons : many dendrites//no axon,just regulate electrical changes of adjacent neurons ⏺brain ⏺retina B--Functional classification : 1--Motor (efferent) neurons : long axon➡️transmit nerve impulses from the CNS to a muscle or gland through a spinal or cranial nerve➡️multipolar 2--Sensory (afferent) neurons : transmit impulses from peripheral structure to the CNS➡️unipolar ☀️Interneurons (association neurons): Establish relationships among other neurons , forming complex functional networks. They are generally multipolar or anaxonic and are estimated to include 99% of the neurons in the human CNS. Mature neurons have little capacity for cell division and seldomform tumors. The majority of brain tumors in adults involve actively dividing neuroglia cells. Most brain tumors have to be treated with surgery or radiation therapy because of a blood-brain barrier

Genetic code (codon) : triplet sequence of mRNA that specifies certain amino acids 🔤🔤 translate the four–character codes (A, U, G, and C) into 20 amino acids of proteins IN DNA ADENINE THYMINE GUANINE CYTOSINE | | | | THYMINE ADENINE CYTOSINE GUANINE IN RNA ADENINE URACIL GUANINE CYTOSINE | | | | URACIL ADENINE CYTOSINE GUANINE AUG 1--amino acid methionine 2-- signal for the start of the polypeptide chain triplet codon is characterized by : 1--Unambiguous: Each codon specifies a particular amino acid, the codon ACG(only threonine) 2--None overlapping (ADJACENT) 3--not separated by punctuation

molecular genetic 1--Central Dogma : The flow of genetic information in a cell 2--Transcription : transfer of genetic information from DNA to RNA 3--Sense strand : acts as a template for the formation of an mRNA molecule it will be used to make protein transcription in 3 stages : a-Initiation / b-elongation / c-termination A--initiation stage ➡️ RNA polymerase and transcription factors➡️binds to nucleotide sequence in DNA (promoter region )marks the beginning of a gene(➡️ double-stranded DNA unwinds➡️Nucleotides that will make up the mRNA molecule form H- bonds with the complementary nucleotides in the template DNA strand B-- elongation stage➡️RNA polymerase joins the RNA nucleotides into a polynucleotide chain ☀️there is no T in RNA ☀️In humans,30-50 nucleotides per second are added to a mRNA molecule C--termination stage : RNA polymerase reaches to the end of the gene (terminator region),it detaches from the DNA template, the mRNA molecule is released ☀️(in human most of the transcripts are about 5000 nucleotides or may be reached up to 200000 nucleotides)

🌐 GENE MUTATION 1-Beneficial mutat 2-Neutral mutation 3-Harmful mutation A-- Base substitution (point mutation) 1-- Silent mutation 2--Missense mutation 3--Sense mutation 4--Nonsense mutation 5--splice site mutation B-- Base deletion | ------- frame-shift mutation | C-- Base insertion D--invesion

مراجعة النسيج العضلي contractile proteins : cells that have the special ability to shorten or contract in order to produce movement of the body parts Muscle tissues➡️mesodermal layer actin and myosin➡️protein filament Characteristics of all muscle tissues : 1--Specialized cells : high density of myofilaments of actin and myosin. 2-- Excitability : respond to stimuli. 3--Contractility : contract 4--Extensibility: stretched 5--Elasticity : ability to recoil endomycium, composed of basal lamina and reticular fibers (10-100) μm diameter of The Skeletal Muscle myofibrils : long cylindrical filamentous and Myofibril is composed of many sarcomeres running along its length myofilament : thin filaments (actin) and thick filaments (myosin) dark bands are A-bands /// light bands are I- bands Z disc : dark transverse line divid I band H zone : the presence of lighter zone in its center of A band sarcomere, extends from Z disc to Z disc and contains one entire A band and two halves of an I band sarcomeres units, which are the functional units of skeletal muscle ----------------------------------------------------------------------------------------------------- motor neurons : responsible for innervating muscle fibers axon terminals : the axon branches into several short ending At the site of junction with a muscle fiber the motor end plate, or the neuromuscular junction : axon terminals each occupying a shallow depression on the muscle cell surface 🔤🔤 neuromuscular junction, where it is the site of signal exchange between skeletal muscle and motor axon of nerve At this site, within the terminal axon are numerous mitochondria and synaptic vesicles that containing the neurotransmitter acetylcholine. That discharge these content during transmission of nerve impulse into narrow space (synaptic cleft) between the terminal axon and the sarcolemma of the muscle fiber.

🌐 Gene repair accumulated a large amount of DNA damage : 1-- senescence. 2--apoptosis or programmed cell death 3--cancerous -----metabolic processes inside the cell | DNA damage--- | -----environmental factors such as UV light and radiation اول شي يؤثر عليه ال DNA DAMAGE هو ال primary structure of the double helix A-- endogenous cellular processes : 1-- Oxidation of bases(generation of DNA strand interruptions from reactive oxygen species) 2-- Alkylation of bases (methylation) 3-- Hydrolysis of bases , such as deamination, depurination, and depyrimidination 4-- Mismatch of bases B-- exogenous agents (mutagens) 1--UV- B light -- pyrimidine dimer -- direct DNA damage 2--UV- A light -- free radicals -- indirect DNA damage 3--Ionizing radiation -- radioactive decay -- breaks in DNA strands 4--Thermal disruption -- depurination -- single-strand breaks 5-- Industrial chemicals such as vinyl chloride and hydrogen peroxide , and environmental chemicals such as hydrocarbons found in smoke, soot, and tar create oxidized bases, alkylated and crosslinking of DNA Direct reversal 1-- The formation of pyrimidine dimer 2--methylation of guanine bases Single-strand damage 1--Base excision repair: corrects errors that result from oxidation, alkylation,hydrolysis 2--Nucleotide excision repair:removes errors that result from exposure to chemical carcinogens, UVB in sunlight,and oxidative damage 3--Mismatch repair ☀️Enzyme photolyase,absorbs energy from visible light and detects and binds to pyrimidine dimers, then breaks the extra bonds ☀️protein methyl guanine methyltransferase (MGMT) removes the mutagenic methyl group from guanine bases ☀️Base excision repair : DNA glycosylase➡️➡️endonuclease➡️➡️ DNA polymerase➡️➡️DNA ligase ☀️ Nucleotide excision repair : endonuclease enzyme➡️Helicase enzyme➡️DNA polymerase➡️ DNA ligase ☀️Mismatch repair : DNA polymerase 📌Xeroderma Pigmentosum: defect in the human endonuclease that removes pyrimidine dimers 📌dry skin, freckling, corneal ulceration, and skin tumors

1--introns : non-coding sequences 2--exons : gene that are transcribed and translated into polypeptides 3--pre-mRNAs : large RNA precursor molecules produces by Transcription 4--mature mRNA : pre-mRNAs are processed and modified in the nucleus and are transported to the cytoplasm and bind to the ribosomes for translation ☀️cap of mature RNA 5' : addition of quinine (G) (aid in the binding of the mRNA to the ribosome during translation) ➡️adds methyl group (CH3)(recognition site for protein synthesis) ☀️At the 3' end : 30-100 (A) nucleotides, called poly–A tail is added 1--protein synthesis 2--stabilize the mRNA so that it stays intact pre-mRNA 5' 3' cup➡️intron➡️exon➡️intron➡️exon➡️tail ❌ ❌ cup➡️exon➡️exon➡️tail After processing and splicing, the mRNA moves from the nucleus to the cytoplasm, where the encoded information is translated into protein. β –thalassemia one or more mutations at the border between introns and exons lowe rthe efficiency of splicing, and result in a deficiency in the amount of the gene product (beta globin) synthesized.