Physiology 2130 Lecture Notes - Lecture 6: Endoplasmic Reticulum, T-Tubule, Globular Protein
30 Apr 2018
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Department
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Muscle Physiology
Intro to Muscles
-muscles are machines that use chemical energy from breakdown and metabolism of food to
perform useful work
-THREE kinds of muscles:
1)skeletal: for voluntary motion
2)smooth: found within walls of vessels, airways, digestive tracts, ducts
3)cardiac: found in heart
-are over 600 muscles in body
-FUNCTIONS: movement, heat production & support/posture
Structure of Muscle
Structure of Skeletal Muscle
-is striated (banding pattern comes from arrangement of thin & thick myofilaments)
-number of muscle cells in whole muscle depends on its size
-length of muscle can range from a few mm to 12 cm (sartorius)
-CONTAIN: many nuclei and mitochondria to make ATP
-sarcolemma
-is muscle cell membrane (where AP is transmitted)
-surround muscle cells
-cytoplasm inside is the sarcoplasm
-myofibrils
-long & cylindrical
-contain contractile proteins of muscle- the thin & thick myofilaments
-surrounded by sarcoplasmic reticulum
find more resources at oneclass.com
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-transverse tubules
-conduct AP deep into cell where contractile proteins are
-continuation of the sarcolemma
-sarcoplasmic reticulum (SR)
-mesh like network of tubes containing calcium ions (essential for contraction)
-located at the ends of SR are the lateral sacs (swelling part)
-lateral sac
-where Ca+ released to trigger muscle contraction
find more resources at oneclass.com
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Thin Myofilament
-composed of actin
-each actin molecule contains a special binding site for other contractile protein, myosin
-MADE UP OF 3 CONTRACTILE PROTEINS:
1) tropomyosin
-two protein strands wrapped together, lying lengthwise
-associated with 6-7 actin globular molecules
-when muscle at rest, tropomyosin cover binding sites for myosin
2)troponin
-when relaxed, troponin holds tropomyosin over myosin binding sites on action
-does this until Ca arrives (binds to troponin and pulls off binding site)
3) G- Actin
- a globular protein which, when liked to other G-actins, forms a alpha-helical chain
-each contains a myosin binding site
Thick Myofilament
-composed of myosin
-myosin is long, & has bendable tail & two heads that attach to actin
-MYOSIN heads have binding site for actin and ATPase (breaks down ATP to ADP+PI)
-the splitting of ATP releases energy to myosin that allows for contraction
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Muscles are machines that use chemical energy from breakdown and metabolism of food to perform useful work. 2)smooth: found within walls of vessels, airways, digestive tracts, ducts. Is striated (banding pattern comes from arrangement of thin & thick myofilaments) Number of muscle cells in whole muscle depends on its size. Length of muscle can range from a few mm to 12 cm (sartorius) Contain: many nuclei and mitochondria to make atp. Contain contractile proteins of muscle- the thin & thick myofilaments. Is muscle cell membrane (where ap is transmitted) Conduct ap deep into cell where contractile proteins are. Mesh like network of tubes containing calcium ions (essential for contraction) Located at the ends of sr are the lateral sacs (swelling part) Each actin molecule contains a special binding site for other contractile protein, myosin. Made up of 3 contractile proteins: tropomyosin. When muscle at rest, tropomyosin cover binding sites for myosin.
