Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Muscular  Tissue  Notes
Three  types  of  muscle:  

•

Skeletal    

•
•
•
•
•
•

Longest  fibers  
Has  striations    
Voluntary  
Rapid  contractions,  but  tire  easily  

Cardiac  

•
•
•
•
•

Attaches  to  bone  

Only  in  the  heart  
Striated  
Involuntary  
Contracts  at  a  steady  rate  over  a  long  period  of  time  

Smooth  

•

Makes  up  walls  of  hollow  organs  

•
•
•
•
•

Stomach,  intestines,  arteries,  urinary  bladder,  respiratory  passages,  
uterus  

Contractions  force  stuff  through  these  passages  (peristalsis)    
No  striations  
Involuntary  
Slow,  sustained  contractions  

Functions  of  Muscle:  

•
•
•
•

Producing  body  movements  
Maintains  posture  
Storing  and  moving  substances  within  the  body  (urine,  blood,  food,  babies,  etc
...
 The  stimulus  
can  also  be  chemical,  such  as  neurotransmitters,  or  hormonal
...
   

•
•

Individual  muscles  are  separated  by  fascia,  which  also  forms  tendons
...
 (muscle  fiber  =  muscle  cell)
...
   

•

Perimysium  -­‐  surrounds  groups  of  ten  to  one  hundred  fibers
...
 (Dense  irregular  connective  tissue)
...
   

Muscle  Fiber:  

•
•

Sarcolemma:  Plasma  membrane  around  muscle  cell  
Sarcoplasm:  Cytoplasm  of  muscle  cell  

•
•
•
•

filled  with  rod-­‐like  myofibrils  

Sarcoplasmic  Reticulum:  Transport  system  in  muscle  cell  
Myofibrils:  Within  these,  smaller  structures  called  myofilaments  exist  
Myofilaments:  Two  types,  Actin  (thin)  and  Myosin  (thick)    

•

Myofilaments  form  dark  and  light  bands  (striations)
...
   

•

The  neurotransmitter  that  crosses  the  gap:  acetylcholine  

• Acetylcholine  is  broken  down  by  cholinesterase    
Sliding  Filament  Theory:  
•
•
•

The  theory  of  how  muscle  contracts  
Occurs  as  the  thin  filaments  slide  past  the  thick  filaments  
What  is  needed:    

•
•
•
•
•
Steps:  
1
...

3
...

5
...

7
...

9
...


ATP  
Calcium  
Myosin  &  Actin  
Acetylcholine  
Cholinesterase    

ACh  released,  binding  to  receptors  
Action  potential  reaches  T-­‐tubule  
Sarcoplasmic  reticulum  releases  Calcium  
Active-­‐site  exposure,  cross-­‐bridge  binding  
Contraction  begins  
ACh  removed  by  AChE  
Sarcoplasmic  reticulum  recaptures  Calcium    
Active  sites  covered,  no  cross-­‐bridged  interaction  
Contraction  ends  
Relaxation  occurs,  passive  return  to  resting  length  

Energy  Sources  for  Muscle  Contraction:  

•

Creatine  Phosphate  

•
•
•
•
•

Super  short  bursts  of  energy  (around  15  secs)    
Phosphate  joins  with  ADP  to  make  ATP    
Makes  one  ATP    

Glycolysis  

•
•
•
•

Anaerobic  

Anaerobic  
30-­‐40  secs  of  energy    
Makes  2  ATPs  &  lactic  acid  

Cellular  Respiration  

•
•
•
•

Aerobic  
Makes  36  ATPs  
Occurs  in  the  mitochondria  
Slower  process,  but  lasts  longer    

Terms  to  Know:  

•

Threshold  Stimulus  -­‐  stimulus  strength  increases  until  strong  enough  to  produce  action  
potential,  smallest  amount  needed  to  contract  

•

All-­‐or-­‐None  Response  -­‐  strength  by  which  muscle  fiber  responds  to  a  stimulus  is  
independent  of  stimulus  strength,  muscle  cannot  partially  contract  

•
•
•
•
•
•
•
•

Motor  Unit  -­‐  single  motor  neuron  and  all  muscle  fiber  innervated  by  it  
Recruitment  -­‐  increasing  number  of  muscle  fibers  contracting  
Muscle  Tone  -­‐  constant  tension  by  muscles  for  long  periods  of  time  
Muscular  Hypertrophy  -­‐  increased  in  muscle  size,  myofibrils,  and  nuclei  
Muscular  Atrophy  -­‐  decrease  in  muscle  size,  reversible  except  when  cells  die  
Muscle  Fatigue  -­‐  decreased  capacity  to  work  and  reduced  efficiency  of  muscle  
Muscle  Cramp  -­‐  sudden  and  involuntary  muscle  movement  
Oxygen  Debt  -­‐  insufficient  oxygen  consumption  relative  to  increased  activity  at  onset  of  
exercise    

 
Rigor  Mortis:  

•
•
•

Generally  occurs  around  six  hours  after  death  
Permanent  contraction  of  muscles  
Occurs  when  oxygen  supply  is  used  up  so  ATP  can  no  longer  be  made
...
   

Bacteria  that  causes  tetanus:  Clostridium  tetani    

•
•

 

Found  in:  soil,  rust,  and  animal  feces  

Tetanospasmin  causes  muscle  stiffness  and  spasms    



---