Unit 4-muscle
myology study of muscle tissue
· -
-
muscle is 40-60% of body weight
convert chem energy (ATP) to mech
-
.
energy
types of muscle
·
Skeletal - stricted ; suncutial fibers (multinucleated cells)
-
> striated individual cells
cardiac - ; joined by intercalated disks (gapjxns)
-
smooth- unstricted
-
>
ofXn :
-
movement Skeletal mus contract to produce
:
.
movement/tension between bones
movement of tissue not anchored to bone (position of eyeball facial expressions)
·
,
reg containment vessels- smooth musc in blood vessels GI tract
-
.
, ,
bladder
reg inflow/outflow-sphincter-like muscles reg resistance
-
.
thermogenesis - heat
production (generate 85% of body heat;
shiveringinvol contractions
-
.
stabilizing joints > provide strengths support to joints
-
·
characteristics
excitability conductivity >
-
reg /triggered by NTs hormones
-
.
contractility -
> musc
generates force to do work
-
.
extensibility -
> musc Stretch who damage to the tissue
-
.
elasticity -
> musc returns to original shape after stretching/contracting
-
.
Skeletal muscle
·
muscle fibers - individual cells from which muscles develop form a
single fiber that is a suncitium (fxn unit)
-
intercellular plasma mem .
disappear
-
multiple nuclei
fiber represents contractile element
single one
-
Connective tissue
·
-
fibers bundled in
asicles surrounded by sheath
continuous with conn Tissue surrounds muscle
·
.
holds muscle to bone with tendon
·
·
Blood vessels -
> abundant
: remove Waste ; maintain ionic homeostasis
supply nutrients
-
·
Satellite cells (stem cells) - differenciate for growth or repair
·
Nerves
*motor unit : a motor neurons muscle fiber it stimulates
-
motor neurons
Acetylcholine NT released
·
:
·
axons branch into smaller axon terminals to extend onto surface of musc.
·
synaptic end bulbs : at end of axon terminals
-
motor end plate
·
directly across synaptic cleft from synaptic end bulbs
·
contain Ach receptors that open monovalent cation channels (favors Nat in out but electrochem +
, gradient favors
Nat early (depolarization) whileh+ moves later /repolarization)
, Building a skeletal muscle
·
myosin
-
one mol .
comprised of two identical subunits
-
ztails intertwined
ATPases Actin
Globular heads have two critical sites -
>
binding
-
-
mol Self-assemble tail to tail into thick filaments
.
·
actin
-
one mol . or monomer -
> G-actin
-
multiple form double helical structure >
- F-actin
tropomysin e thread-like protein lines edge of actin spiral ; can block myosin-actin inter
-
.
-
Troponin (Th) complex
Troponin T binds to tropomyosin
·
:
·
Troponin I : binds to actin; helps maintain inter .
·
Troponin C :
binds Calcium
Biochemistry myosin: actin -
1.
Resting Actin : myosin
:
ADP/P ; are close
together; "cocked" conform.
. Cabinds to troponin Ce conf out of inhibition
2 .
change moves tropomyosin
, position
. Myosin binds to actin
3 >
- Pi released myosin head moves 2 actin monomers (power-stroke wilnm)
. New ATP binds to myosin -
4
>
myosin dissociates actin
5
5 ATP is hydrolyzed - myosin Pi/ADP
> returns to resting "cocked" position
*
rigor :
no ATP present to allow for dissociation , muscles are stiff
structure
Sarcomere fxn composed of myosin , /Conn Tissue elastic proteins, tendons
·
>
- musc .
unit actin , connec .
elastic mol . .
,
-
z-line , A-band I-band ,
oT-tubules- run thru fiber perpendicular to mem at As I bands .
contiguous with plasma mem.
-
·
-
conducts AP
Sarcoplasmic reticulum (SR) - stores releases Ca
,
"and band
-
modified ER mesh surrounds each myofibril
not for each As I bands
contiguous (separate one
-
Excitation Contraction
coupling
-
·
Acetylcholine is released from somatic motor neuron
at motor end plate
binds to
cholinergic receptors
-
-
open cation channels (Natin/K
+
out ; but electro favors . Nat)
·
muscle Ap carried by Sarcolemmas down T-tubules
voltage-gated DHP receptor on T-tubule
triggers opening of Ryanodine receptors (RyR) on sarcoplasmic ret to release stored Cat
-
.
Rapid increase in sarcoplasm Cat combines with troponin to initiate contraction
·
Cat in sarcoplasm reduced
·
primarily via reuptake by sarcoplasmic/endoplasmic reticular Ca ATPase (SERCA)
myology study of muscle tissue
· -
-
muscle is 40-60% of body weight
convert chem energy (ATP) to mech
-
.
energy
types of muscle
·
Skeletal - stricted ; suncutial fibers (multinucleated cells)
-
> striated individual cells
cardiac - ; joined by intercalated disks (gapjxns)
-
smooth- unstricted
-
>
ofXn :
-
movement Skeletal mus contract to produce
:
.
movement/tension between bones
movement of tissue not anchored to bone (position of eyeball facial expressions)
·
,
reg containment vessels- smooth musc in blood vessels GI tract
-
.
, ,
bladder
reg inflow/outflow-sphincter-like muscles reg resistance
-
.
thermogenesis - heat
production (generate 85% of body heat;
shiveringinvol contractions
-
.
stabilizing joints > provide strengths support to joints
-
·
characteristics
excitability conductivity >
-
reg /triggered by NTs hormones
-
.
contractility -
> musc
generates force to do work
-
.
extensibility -
> musc Stretch who damage to the tissue
-
.
elasticity -
> musc returns to original shape after stretching/contracting
-
.
Skeletal muscle
·
muscle fibers - individual cells from which muscles develop form a
single fiber that is a suncitium (fxn unit)
-
intercellular plasma mem .
disappear
-
multiple nuclei
fiber represents contractile element
single one
-
Connective tissue
·
-
fibers bundled in
asicles surrounded by sheath
continuous with conn Tissue surrounds muscle
·
.
holds muscle to bone with tendon
·
·
Blood vessels -
> abundant
: remove Waste ; maintain ionic homeostasis
supply nutrients
-
·
Satellite cells (stem cells) - differenciate for growth or repair
·
Nerves
*motor unit : a motor neurons muscle fiber it stimulates
-
motor neurons
Acetylcholine NT released
·
:
·
axons branch into smaller axon terminals to extend onto surface of musc.
·
synaptic end bulbs : at end of axon terminals
-
motor end plate
·
directly across synaptic cleft from synaptic end bulbs
·
contain Ach receptors that open monovalent cation channels (favors Nat in out but electrochem +
, gradient favors
Nat early (depolarization) whileh+ moves later /repolarization)
, Building a skeletal muscle
·
myosin
-
one mol .
comprised of two identical subunits
-
ztails intertwined
ATPases Actin
Globular heads have two critical sites -
>
binding
-
-
mol Self-assemble tail to tail into thick filaments
.
·
actin
-
one mol . or monomer -
> G-actin
-
multiple form double helical structure >
- F-actin
tropomysin e thread-like protein lines edge of actin spiral ; can block myosin-actin inter
-
.
-
Troponin (Th) complex
Troponin T binds to tropomyosin
·
:
·
Troponin I : binds to actin; helps maintain inter .
·
Troponin C :
binds Calcium
Biochemistry myosin: actin -
1.
Resting Actin : myosin
:
ADP/P ; are close
together; "cocked" conform.
. Cabinds to troponin Ce conf out of inhibition
2 .
change moves tropomyosin
, position
. Myosin binds to actin
3 >
- Pi released myosin head moves 2 actin monomers (power-stroke wilnm)
. New ATP binds to myosin -
4
>
myosin dissociates actin
5
5 ATP is hydrolyzed - myosin Pi/ADP
> returns to resting "cocked" position
*
rigor :
no ATP present to allow for dissociation , muscles are stiff
structure
Sarcomere fxn composed of myosin , /Conn Tissue elastic proteins, tendons
·
>
- musc .
unit actin , connec .
elastic mol . .
,
-
z-line , A-band I-band ,
oT-tubules- run thru fiber perpendicular to mem at As I bands .
contiguous with plasma mem.
-
·
-
conducts AP
Sarcoplasmic reticulum (SR) - stores releases Ca
,
"and band
-
modified ER mesh surrounds each myofibril
not for each As I bands
contiguous (separate one
-
Excitation Contraction
coupling
-
·
Acetylcholine is released from somatic motor neuron
at motor end plate
binds to
cholinergic receptors
-
-
open cation channels (Natin/K
+
out ; but electro favors . Nat)
·
muscle Ap carried by Sarcolemmas down T-tubules
voltage-gated DHP receptor on T-tubule
triggers opening of Ryanodine receptors (RyR) on sarcoplasmic ret to release stored Cat
-
.
Rapid increase in sarcoplasm Cat combines with troponin to initiate contraction
·
Cat in sarcoplasm reduced
·
primarily via reuptake by sarcoplasmic/endoplasmic reticular Ca ATPase (SERCA)
