LECTURE 5

PLANT SKELETON

TURGOR PRESSURE

SCLERENCHYMA AND COLLENCHYMA

XYLEM IN WOOD




SYSTEM CONCERNED WITH MOTION

MUSCULAR SYSTEM

CONTRACTILE PROTEINS




STRIATED MUSCLE

    I-BAND = LIGHTER COLORED AREAS

    A-BAND = DARKER COLORED AREAS

    Z LINE IN THE I-BAND

    H ZONE IN THE A-BAND

    M LINE IN THE H ZONE





MYOSIN IS THICK

ACTIN IS THIN

SARCOMERE RUNS FROM ONE Z LINE TO THE NEXT




DURING CONTRACTION:
    LENGTH OF A-BAND IS CONSTANT

    I-BAND SHORTENS

    H ZONE SHORTENS

    ACTIN AND MYOSIN CROSSLINK
    AND FORM ACTOMYOSIN

    ACTOMYOSIN IS THE CONTRACTILE PROTEIN




SPINES ON MYOSIN REACT WITH ACTIN

REACTION TRIGGERED BY CALCIUM IONS

BUT DOES NOT REQUIRE ATP

SPINES CHANGE POSITION

AND USE ATP

SPINES DO NOT WORK IN UNISON

RELAXATION WHEN THE SPINES RELEASE

CAUSED BY REMOVAL OF CALCIUM IONS




ACTIN IN ALL EUKARYOTIC CELLS

PSEUDOPODIA ON AMOEBA

    ECTOPLASM AND ENDOPLASM




FLAGELLA AND CILIA

    MICROTUBULES

    9 + 2 ARRANGEMENT

    DYNEIN PROTEINS




MUSCLE CONTRACTION

    MOLECULAR

    MOTOR UNIT

    WHOLE MUSCLE




A GROUP OF MUSCLE CELLS ALL OF WHICH
CONTRACT DUE TO AN IMPULSE FROM ONE NERVE

A MUSCLE IS MADE OF MANY MOTOR UNITS




MUSCLES CONCERNED WITH FINE MOVEMENTS
HAVE SMALL MOTOR UNITS

MUSCLES CONCERNED WITH COARSE MOVEMENTS
HAVE LARGE MOTOR UNITS

A MOTOR UNIT CAN BE STIMULATED ELECTRICALLY

    THRESHOLD EFFECT

    ALL-OR-NONE EFFECT




STRENGTH OF CONTRACTION OF A MUSCLE IS
DETERMINED BY THE NUMBER OF MOTOR UNITS
THAT ARE ACTIVATED

ROTATION OF CONTRACTION OF MOTOR UNITS
DURING LONG, STRONG CONTRACTION




TWITCH

KYMOGRAPH

    LATENT PERIOD

    CONTRACTION PERIOD

    RELAXATION PERIOD

    SARCOPLASMIC RETICULUM

    ACTION POTENTIAL