Jini
Jini wani ruwa ne na jiki a cikin tsarin zagayar jini na mutane da sauran dabbobi masu kashin baya wadanda ke isar da abubuwan da jiki ke bukata kamar sinadaran  gina jiki da iskar oxygen zuwa sel, kuma yana jigilar abubuwan da jiki baya bukata daga wadannan kwayoyin halitta. Jini a cikin tsarin zagayar jini an san shi da peripheral blood, sannan kuma jinin da yake ɗauka, peripheral blood cells. 

Jini ya ƙunshi ƙwayoyin jini da ke watse a cikin wani abu da ake kira blood plasma. Plasma, wanda ya ƙunshi kaso 55% na ruwan jini, galibinsa ruwa ne (92% a yawa),  kuma ya ƙunshi sunadarai, glucose, mineral ions, hormones, carbon dioxide (plasma ya kasance muhimmin wajen jigilar fitar da abubuwan da jiki baya bukata), da kuma kwayoyin jinin da kan kansu. Albumin shine babban furotin a cikin plasma, kuma yana aiki don daidaita karfin osmotic colloidal na jini. Kwayoyin jinin mafi akasarinsu sunkasance jajayen kwayoyi jini ne - red blood cell (wanda kuma ake kira RBCs ko erythrocytes), fararen kwayoyin jini- white blood celles (wanda ake kira WBCs ko leukocytes), da kuma a tsakanin dabbobin mammals platelets (wanda ake kira thrombocytes).  Kwayoyin da suka fi yawa a cikin jinin dabbobi masu kashin baya sune jajayane kwayoyin jini.  Waɗannan sun ƙunshi haemoglobin, furotin da ke ɗauke da sinadaran iron, wanda ke sauƙaƙe jigilar iskar oxygen ta hanyar jujjuyawar iskar numfashi ta haka yana ƙara narkar da shi iskan a cikin jini. Sabanin haka, carbon dioxide galibi ana jigilarsata hanyar extracellularly a matsayin bibicarbonate ion wanda ake  jigilar su a cikin palasma.

Jinin dabbobi masu kashin baya (vertebrate) yana da launin ja mai haske idan yana dauke da sinadarn oxygen sannan kuma yana komawa launin ja mai duhu idan babu sinadaran oxeygen a tattare da shi.

Wasu dabbobin irinsu crustaceans da mollusks, suna amfani da  hemocyanin wajen sufurin jini a maimakon hemoglobin. Kwari irinsu mollusks suna amfani da wani ruwa mai suna Hemolymph a maimakon jini, bambanci shine shi hemolymph ba ya shiga tsarin zagayar jini - circulatory system. A cikin mafi yawancin wadannan kwari, mafi akasarinsu basu dauke da sinadaran da ke sufurin oxygen kamar hemoglobin, saboda jikinsu karami kuma ya wadatar wajen gudanar tsarin tracheal system don sufurin iskar oxygen.

Jini yana gudana ne acikin jiki ta hanyar tashohin jini ta hanyar bugun zuciya. A cikin dabbobin da ke da huhu, artery na cikin jini yana daukar iskar oxygen zuwa gabobin jiki sa'annan kuma veins yana daukar iskar carbondioxide, wani iska wanda jiki baya bukata da kyayoyin sel ke samarwa, daga wadannan gabobi zuwa huhu don fitar da su.

Kalmomin kiwon lafiya da ke da alaka da jini sukan fara ne da hemo-, hemato-, haemo- ko kuma haemato- daga kalmar Girkanci αἷμα (haima) wato "jini".

Amfanin jini 
Jini yana taka muhimman rawa acikin jiki, kamar:
 Jigilar oxygen zuwa gabobi (ta hanyar hemoglobin, wanda ake dauka acikin jajayen kwayoyin jini).
 Samar da sinadaran gina jiki irinsu glucose, amino acids, da fatty acids (wanda ke narke acikin plasma proteins, misali  blood lipids)
 Cire abubuwan da jiki baya bukata irinsu carbon dioxide, urea, da kuma lactic acid
 Kariyar jiki kamar watsa sindaran white blood cells da kuma gano abubuwan waje wanda basu cikin tsarin jiki daga antibodies.
 Coagulation, martani ga tashoshin jini da suka lalace, da kuma sauya jini daga ruwa zuwa daskararren jini - semisolid gel don tsayar da zubar jini
 Aika sakonni kamar jigilar  hormones da kuma nuna alamun lalacewar tsoka.
 Daidaita zafi da sanyin jiki
 Sauran amfanin ruwan jiki

Manazarta