Kapangidwe ndi Ntchito ya Myocardium
Myocardium, kapena minofu ya mtima, ndi gawo lofunika kwambiri la dongosolo la mtima la munthu. Ntchito yake yayikulu ndikupopera magazi m'thupi lonse, ntchito yomwe imafuna kugwira ntchito bwino komanso kupirira, chifukwa mtima umagwira ntchito mosalekeza m'moyo wonse wa munthu. Kuti timvetse zovuta zake, kuphunzira kapangidwe kake ndi ntchito yake ndikofunikira. Nkhaniyi ikambirana za kapangidwe kake, kapangidwe ka maselo, ndi histology ya myocardium, komanso ntchito zoyambira komanso zovuta za minofu ya mtima iyi.
Kapangidwe ndi Kapangidwe ka Myocardium
Mtima uli ndi zigawo zitatu zazikulu: endocardium (gawo lamkati), myocardium (gawo lapakati, lomwe ndi cholinga chathu chachikulu), ndi epicardium (gawo lakunja). Myocardium ndi gawo lokhuthala lomwe limalamulidwa ndi ulusi wa minofu ya mtima, kapena cardiomyocytes.
Matenda a mtima
Ma cardiomyocyte ndi mtundu wapadera wa maselo a minofu omwe ali ndi mawonekedwe apadera omwe amawalola kugwira ntchito bwino komanso mosalekeza popanda kutopa. Zina mwa makhalidwe apadera a cardiomyocyte ndi awa:
1. Mzere ndi nthambi: Maselo awa ali ndi mawonekedwe aatali komanso a nthambi, zomwe zimawalola kulumikizana wina ndi mnzake mu netiweki yovuta.
2. Chitoliro chimodzi kapena ziwiri: Nthawi zambiri chimakhala ndi chitoliro chimodzi kapena ziwiri pa selo lililonse.
3. Ma disc a intercalary: Mapangidwe awa amalola kulumikizana kwamphamvu pakati pa maselo komanso kusamutsa mwachangu kwa ma impulses amagetsi, zomwe ndizofunikira pogwirizanitsa kupsinjika kwa mtima.
4. Mitochondria yambiri: Imalola kupanga bwino ATP kuti ithandizire kugwira ntchito kosalekeza kwa minofu.
Ma Discs Osiyanasiyana ndi Mipata Yogawanika
Ma disc ophatikizana ndi mapangidwe apadera omwe amapezeka m'maselo a minofu ya mtima okha. Amapangidwa ndi:
1. Ma Desmosomu: Mapangidwe omwe amalumikiza maselo mwamakina, zomwe zimapatsa mphamvu ndi kukhazikika.
2. Mipata Yolumikizirana: Kupereka njira yosamutsira ma ayoni ndi mamolekyu ang'onoang'ono pakati pa ma cardiomyocytes, zomwe zimathandiza kuti zizindikiro zamagetsi zifalikire mofulumira ndikuwonetsetsa kuti minofu ya mtima ikulumikizana nthawi imodzi.
Kukhazikitsa Mitsempha ya Myocardial
Myocardium imalandira magazi okwanira kudzera m'mitsempha ya mtima. Netiweki ya mtima imeneyi imaonetsetsa kuti ma cardiomyocyte amalandira mpweya ndi michere yokwanira kuti igwire ntchito yawo mosalekeza. Kusokonezeka kwa kayendedwe ka magazi m'mitsempha ya mtima, monga matenda a mtima (myocardial infarction), kungayambitse kuwonongeka kwakukulu kwa mtima.
Ntchito ya Myocardium
Ntchito yaikulu ya myocardium ndi kufupika kwa mtima, komwe kumathandiza mtima kupopa magazi. Ntchitoyi imachitika kudzera mu njira yokhudza magawo angapo komanso zigawo zamakina ndi za biochemical.
Kupindika ndi Kupumula
Njira yochepetsera mtima imadziwika kuti systole, pomwe njira yopumula imadziwika kuti diastole. Panthawi ya systole, ma cardiomyocyte amafupika ndikutulutsa magazi m'zipinda zamtima. Kenako, panthawi ya diastole, amapumula ndikulola zipindazo kuti zidzaze ndi magazi.
Njira Yochepetsera Maselo
Kuchepa kwa mtima kumakhudza kuyanjana pakati pa mapuloteni a actin ndi myosin mu sarcomere, gawo laling'ono kwambiri la minofu. Masitepe akuluakulu omwe amachitika ndi awa:
1. Kuchotsa polarization ya Membrane: Mphamvu zamagetsi zomwe zimapangidwa ndi sinoatrial node (SA node) zimafalikira kudzera mu minofu ya mtima, zomwe zimapangitsa kuti cardiomyocyte nembanemba ichotse polarization.
2. Kutseguka kwa Njira za Calcium: Kuchepa kwa polarization kumeneku kumayambitsa kutseguka kwa njira za calcium zamtundu wa L mu nembanemba ya selo, zomwe zimapangitsa kuti ma calcium ions alowe mu selo.
3. Kutulutsidwa kwa Calcium kuchokera ku Sarcoplasmic Reticulum: Ma calcium ions omwe akubwera amayambitsa kutulutsidwa kwa calcium yowonjezera kuchokera ku sarcoplasmic reticulum, zomwe zimapangitsa kuti calcium yambiri ikhale m'maselo.
4. Kulumikizana kwa Calcium ndi Troponin: Calcium imagwirizana ndi puloteni ya troponin, zomwe zimapangitsa kusintha kwa mawonekedwe komwe kumatsegula malo olumikizirana a myosin pa actin.
5. Kusuntha kwa Actin ndi Myosin: Malo omangirira awa akatsegulidwa, mitu ya myosin imatha kumangirira ku actin ndikugwiritsa ntchito ATP kuti ipange kupindika pogwiritsa ntchito njira ya "power stroke".
Malamulo a Zachilengedwe
Myocardium sigwira ntchito yokha; ntchito yake imayendetsedwa bwino ndi njira zosiyanasiyana:
1. Dongosolo la Mitsempha Lodziyimira Payokha: Dongosolo la mitsempha la sympathetic ndi parasympathetic limakhudza mwachindunji kugunda kwa mtima ndi mphamvu ya kukomoka.
2. Mahomoni: Mahomoni monga epinephrine amatha kuwonjezera kuchuluka ndi mphamvu ya kupweteka kwa mtima.
Ntchito za Circadian Drive ndi Metabolic
Matenda a mtima ndi a arrhythmia nthawi zambiri zimachitika nthawi zina patsiku, zomwe zimasonyeza kuti mtima umakhudzidwa ndi ntchito ya mtima. Maselo a mtima amafunikanso kusunga kagayidwe kachakudya pakati pa kugwiritsa ntchito chakudya ndi mafuta acids ngati magwero a mphamvu.
Matenda a Mtima
Matenda omwe amakhudza mtima amatha kusokoneza ntchito yake ndikuyambitsa mavuto osiyanasiyana azaumoyo. Zina mwa matenda omwe amapezeka kwambiri ndi awa:
Kusakhazikika kwa Myocardial
Matenda a mtima otchedwa myocardial infarction, omwe amadziwikanso kuti matenda a mtima, amapezeka pamene magazi amayenda kupita ku gawo la myocardium mwadzidzidzi, nthawi zambiri chifukwa cha kupangika kwa atherosclerotic plaque kapena magazi kuundana m'mitsempha ya mtima. Popanda mpweya wokwanira, minofu ya mtima imafa ndipo imataya ntchito yake.
Matenda a mtima
Matenda a mtima otchedwa Cardiomyopathy ndi mawu ofala a matenda a mtima omwe amachititsa kuti minofu ya mtima ikule, kuuma, kapena kukhuthala, zomwe zimachepetsa mphamvu yake yopompa magazi. Pali mitundu ingapo ikuluikulu, kuphatikizapo matenda a mtima otchedwa dilated cardiomyopathy, hypertrophic cardiomyopathy, ndi matenda a mtima otchedwa restrictive cardiomyopathy.
Kulephera kwa mtima
Kulephera kwa mtima ndi vuto lomwe mtima sungapope magazi okwanira kuti ukwaniritse zosowa za thupi. Limachitika chifukwa cha matenda osiyanasiyana a mtima omwe amawononga kapena kufooketsa myocardium.
Kusakhazikika kwa mtima (arrhythmia)
Kusokonezeka kwa kugunda kwa mtima, kapena kuti arrhythmia, kungachitike pamene zizindikiro zamagetsi zomwe zimalamulira kupindika kwa mtima sizikuyenda bwino. Arrhythmia imatha kuyambira pa yosavulaza mpaka kupha ndipo ingachitike chifukwa cha zifukwa zosiyanasiyana, kuphatikizapo kuwonongeka kwa myocardium.
Matenda a mtima (Myocarditis)
Matenda a mtima otchedwa myocarditis ndi kutupa kwa minofu ya mtima komwe kungayambitsidwe ndi kachilombo ka HIV, mabakiteriya, kapena ngakhale autoimmune reaction. Matendawa amatha kuwononga ma cardiomyocytes ndikusokoneza magwiridwe antchito a mtima.
Mapeto
Myocardium ndi gawo la minofu ya mtima, gawo la minofu lomwe limagwira ntchito yofunika kwambiri popopera magazi m'thupi lonse. Kumvetsetsa kapangidwe ndi momwe myocardium imagwirira ntchito, kuyambira m'maselo mpaka m'thupi lonse, ndikofunikira kwambiri kuti timvetsetse thanzi la mtima ndi matenda. Kuzindikira kumeneku kumathandiza kupewa, kuzindikira, komanso kuchiza matenda omwe amakhudza minofu ya mtima, zomwe zimapangitsa kuti kuphunzira za myocardium kukhale gawo lofunika kwambiri pa matenda a mtima.
