Chapter  1.  The  study  of  Body  function

  1.  Homeostasis  and  Feedback  control

      ·  Claude  Bernard:  external  environment의  변화  →  internal  environment  유지

                                            (안  될  경우,  질병  발생)

      ·  Walter  Cannon:  homeostasis?  internal  constancy

                                          mechanism  of  physiological  regulation?  internal  constancy를

                                          유지하는  것이  목적

    1)  Negative  feedback  loops

        ①

 

negative  feedback  loops의  정의:  특정  effector  (muscle,  gland)에  의해  생산된                         

      어떤  물질이  sensor에  의해  감지된  후  integrating  center  (brain,  spinal  cord,                         

      gland)로  전달되어  다시  특정  effector의  활성을  negative  (=reverse)  direction으로                 

      조절

        ②  negative  feedback의  예

        ③  antagonistic  effectors

            ·

 

antagonistic  action을  나타내는  여러  가지  effector  (=antagonistic  effector)에                         

                의해  항상성  유지

            ·  37°C의  정상적인  체온:  sweat와  shiver의  antagonistic  effect에  의해  조절

                blood  glucose:  insulin과  glucagon

    2)  Positive  feedback

        ·  Effector의  작용이  effector를  촉진하는  변화를  증폭  (증가)시키는  기작

              ex)  temp↑  →  열  발생  (heat  production)의  증가

        ·  Blood  clotting:  clotting  factor들의  activation  →  다른  clotting  factor  activation 

                                          →  blood  clot

 

2.  The  primary  tissue

      ·  tissue  (비슷한  기능을  가진  세포들의  모임)  →  organ  →  system

      ·  4  primary  tissues:  muscle,  nervous,  epithelial  and  connective  tissues

    1)  Muscle  tissue

      (1)  skeletal  muscle

          ①  voluntary  muscle,  stripes

          ②  tendon이나  bone에  부착되어  있어  skeleton의  움직임을  생산

            (예외)  tongue,  esophagus의  윗부분,  anal  sphincter,  diaphragm

          ③  muscle  cell:  muscle  fiber  (=myofiber)                 

                                          long,  cylindrical,  multinucleated  cell

          ④  graded  contraction:  다발로  평행하게  배열  →  muscle  cell이  개별적으로  조절  →

                                                          각  muscle  cell의  수축의  합에  의해  점진적(완만한)  수축

      (2)  cardiac  muscle

          ①  stripes,  심장에만  존재

          ②  myocardial  cell:  short,  branched  cell

                                                  adjacent  cell과  연결되어  연속적  구조  형성

                                                  연결부위에  intercalated  disc  존재

          ③  contraction:  skeletal  muscle과  유사하나  1개의  muscle  cell의  수축  →  전체심장  수축 

      (3)  smooth  muscle

          ①  cross-  striation이  없다.

          ②  digestive  tract,  blood  vessel,  bronchiole,  urinary  system,  reproductive  system

    2)  Nervous  tissue

      ①  neuron과  neuroglia로  구성

      ②  neuron의  구조

            ·  cell  body:  nucleus  존재,  metabolic  center

            ·  dendrite:  external  stimulus  수용,  가지가  많은  cytoplasmic  process

            ·  axon:  cell  body의  long  process,  nerve  impulse를  전달

tendon(힘줄)  :  근육을  뼈에  연결

ligament(인대)  :  뼈와  뼈를  연결

가로  줄무늬 

      ③  neuroglial

            ·  여러  종류의  neuroglia  cell로  구성

            ·  function:  신경  충격의  전달  X

                                    neuron에  영양공급

                                    neuron의  electrical  activity  및  신경계의  외부환경  조절  (이온  농도)

            ·  number:  neuron의  5배

            ·  limited  mitosis

    3)  Epithelial  tissue

        ·  membrane,  gland  형성

                                exocrine:  chemical을  duct를  통해  body  surface  밖으로  분비

                                endocrine:  hormone을  blood로  분비

      (1)  epithelial  membrane

          ①  simple  epithelium  (single  layer  of  cells)                      (그림1-5)

              ·  squamous:  납작한  비늘  모양

                                        diffusion  and  filtration 

                                        ex)  blood  vessel의  endothelium

              ·  cuboidal:  주사위  모양

                                      excretion,  secretion  or  absorption

                                      ex)  exocrine  duct,  kidney  tubule의  lining

              ·  columnar:  원통  모양

                                        protection,  secretion,  absorption  or  movement

                                        ex)  digestive  tract의  lining  (goblet  cell  →  mucus  분비)

                                        uterine  tube의  lumen,  respiratory  passage  (cilia  →  movement)

        ②  striated  epithelium  (two  or  more  layers  of  cells)

            ·  squamous

                  keratinized:  keratin  함유,  dead  cell로  구성,  protection               

                                          ex)  skin의  epidermis  (계속  벗겨지며,  2주마다  재생)

                  nonkeratinized:  living  cell

                                                  ex)  oral  cavity,  nasal  cavity,  vagina,  anal  canal의  lining

water-resistant  protein

·  gland

      ＊Junctional  complex:  epithelial  cell들이  effective  barrier  기능을  담당하기  위해

                                                    서로  단단하게  결합되어  있는  구조

      ＊Epithelial  cell의  영양공급  방법:  junctional  complex  때문에  blood  vessel이나  nerve로부터     

                                                                      분리  →  이러한  구조로  해결  (그림1-7)

      (2)  exocrine  gland

          ①  epithelial  membrane으로부터  생성  →  duct를  통해  epithelial  membrane의  외부에  위치

          ②  secretory  unit:  simple  tube,  acinus-form

                                                                         

          ③  formation:  surface  epithelial  cell이  connective  cell  속으로  성장

                    (그림1-8)

epithelium  (tight)  :  epidermis 

basement  membrane    (protein  +  polysacharide)

connective  tissue  (loose)  :  dermis

loose  connective  tissue로서

extracellular  material  (collagen,  tissue  fluid)와 

blood  vessel  분포

epithelium과 

connective  tissue  연결

exocrine

connecting  cell의  계속  성장

가장  깊숙이  있는  세포가  분비세포

endocrine

connecting  cell의  소실

깊숙이  있는  세포가  분리되어

endocrine  cell  형성

berry-shaped  termination  of  exocrine  gland

(선방,  포도상선)

          ④  lacrimal  gland  (tear),  sebaceous  gland  (sebum),  sweat  gland

              liver  (소장으로  담즙),  pancreas  (소장으로  이자액,  소화  효소  분비)

    4)  Connective  tissue 

      ·  connective  tissue  cell  사이에  extracellular  material  존재

      ·  종류:  connective  tissue  proper,  cartilage,  bone,  blood

      (1)  connective  tissue  proper

        ①  loose  connective  tissue:  fibroblast,  collagen,  tissue  fluid로  구성

                                                                diffusion  기능

                                                                loose하기  때문에  blood  vessel,  nerve  fiber  들이  위치

                                                                ex)  dermis

        ②  dense  fibrous  connective  tissue:  collagen  fiber가  조밀하게  구성

                                                                                strong,  flexible  support

                                                                                ex)  tendon,  ligament   

        ③  adipose  connective  tissue:  adipose  cell로  구성

                                                                    protection,  fat  저장   

      (2)  cartilage 

        ①  chondrocyte  (연골세포)로  구성

        ②  supportive  and  protective  tissue

        ③  adult에서의  joint,  fetus에서  성장하는  뼈의  전구물질

    (3)  bone 

        ①  osteoblast  (bone-forming  cell,  골아세포)                                    osteocyte  (living  cell)               

                                                                                                                                           

        ②  haversian  system  (골원)

골세포의  cytoplasm이 

  blood  vessel에  연결

눈물의

    ③  dentin  (상아질):  loose  connective  tissue인  pulp  (연괴)속에  위치한  dental  bone

                                          cf)  enamel  :  dentin  바깥쪽의  고도로  석회화된  물질.  regeneration  X

  3.  Stem  cells

      ①  zygote  (접합자):  fertilized  egg  (수정란  :  난자  +  정자)

                                            totipotent  (전능  :  모든  종류의  세포로  분화  가능)

                                            완전한  생명체  생성

      ②  embryonic  stem  cell  (배아줄기세포)

          ·  수정  후  4~5일  된  세포.  50-150개의  cell로  구성

          ·  blastocyst:  배반포  상태의  embryo

          ·  pluripotent  (만능:  거의  모든  종류의  세포로  분화  가능)

      ③  adult  stem  cell  (성체줄기세포)

          ·  여러  기관에  존재.  소수이며  덜  분화된  세포

          ·  bone  marrow,  brain,  skeletal  muscle,  intestine,  hair  follicle

          ·  multipotent  (다능  :  특정  종류의  세포로만  분화)

          ·  ex  1)  bone  marrow의  조혈모세포  :  RBC,  WBC,  platelet

              ex  2)  hair  follicle의  bulge  region  (부풀어  오른  부분)에  있는  stem  cell 

                                  sebaceous  stem  cell  (피지줄기세포)

                                  melanocyte  stem  cell  (멜라닌세포줄기세포)  :  20-30대  최대