Muscles ILO's Flashcards
Myalgia
Muscle pain
Myasthenia
Muscle weakness
Myopathy
Disease of the muscles
Myoclonus
A sudden spasm of the muscles
Myocardium
Muscular component of the heart
Which of the 3 types of muscle are striated?
Cardiac and skeletal
In which of the 3 types of muscle tissue is myoglobin absent?
Smooth muscle
Which of the 3 types of muscle tissue are under involuntary control?
Cardiac and smooth
Type of nerve-muscle communication in skeletal muscle
Direct nerve-muscle communication
Which types of muscle cells have indirect nerve-muscle communication?
Cardiac and smooth
What is myoglobin?
A red protein that is structurally similar to a single subunit of haemaglobin
Function of myoglobin
Stores oxygen and provides O2 to working striated muscles
What are the 3 types of muscle fibre types?
Type 1 (slow oxidative fibres)
Type 2a (fast oxidative glycolytic fibres)
Type 2b (fast glycolytic fibres)
Differences between Hb and myoglobin
- myoglobin doesn’t bind to CO2
- myoglobin has a higher affinity for O2 (that’s why Hb gives up its O2 to myoglobin at the muscles at low pH)
What is Rhabdomyolysis?
What will be released into the blood stream?
Striated muscle damage
- Myoglobin released into bloodstream (myoglobinaemia)
- K ions will be released too - show lysis
Describe the significance of myoglobin in the blood stream
- Can cause renal damage so kidney remove it from blood into the urine (myoglobinuria)
- Tea- coloured urine
What are the different muscle contraction speeds? Describe the colours
What does each fascicle have?
- Slow twitch (red/dark)
- Intermediate (mix of slow twitch and fast twitch fibres)
- Fast twitch (white/light)
- Each fascicle has at least one of each
What does continued contraction depend on?
- Amounts of ATP
AND - Ca2+ ions
Compare and contrast fast and slow twitch fibres
In addition to diagram:
Type 1: Fatty acids
Type 2a: Fatty acids and glycogen
Type 2b: Glycogen
Type 1: Lots of ATP/Co2
Type 2a: Initially lots of CO2 then lots of lactate
Type 2b: Lots of lactate, little ATP
Contrast the histology of slow and fast twitch muscle fibres (3)
Where is an example of where fast twitch fibres can be found?
Eye muscles
Where is an example of where slow twitch fibres can be found?
Soleus in the lower leg
Describe the reparation of skeletal muscle (3)
- Cannot divide but can regenerate by mitotic activity of satellite cells (they divide to produce another satellite cell and a muscle cell)
- So hyperplasia follows muscle injury.
- Satellite cells can also fuse with existing muscle cells to increase mass (skeletal muscle hypertrophy)
Reparation of cardiac muscle
- Regeneration is impossible so following muscle injury fibroblasts invade, divide and lay down scar tissue
Reparation of smooth muscle
- Retain mitotic activity and can form new smooth muscle cells
- Very good at repairing themselves
Give an example of smooth muscle cell hypertrophy and hyperplasia
- Pregnant uterus where the muscle wall (myometrium) becomes thicker by hypertrophy (cell enlargement)
- hyperplasia (cell division/mitosis) of individual cells, thus to increase muscle mass
Describe the order from skeletal muscle to sarcomere
- Skeletal muscles surrounded by epimysium
- Fasicles surrounded by perimisum
- Muscle fibres/cells surrounded by endomysium
- Each muscle fibre contains myofibrils
- Sarcomeres are small contraction units from z line to z line
Muscle cell component terminology (5)
Sarcolemma - outer membrane
Sarcoplasm - cytoplasm
Sarcoplasmic reticulum - smooth endoplasmic reticulum
Sarcosome - mitochondria
Sarcomere - contraction unit ONLY IN STRIATED
a striated muscle cell is called a … it’s plasma membrane is called the …
muscle fibre; sarcolemma
each striated muscle cell fibre is made up of many … which contain many …
myofibrils; sarcomeres
What length is a sarcomere?
Z line/disc to z line/disc
actin filament is … and found in the … … band and … disc, whereas myosin filament is … and found in the … … band and … zone
actin filament is thin and found in the light I-band and Z-disc, whereas myosin filament is thick and found in the dark A-band and H-zone
Is actin thick or thin?
Is myosin thick or thin?
Describe the bands present in a muscle fibre and their staining, if applicable
Actin - thin
Myosin - thick
I band - just actin so stains lighter
H zone - just myosin (stains darker)
A band is overlap of myosin and actin so stains DARK
What is the M line and what does it act as?
- In the centre of the A band
- Marks the centre of the sarcomere
- Attachment site for myosin filaments
Features of skeletal muscle fibres/cells(2)
Abundant mitochondria between myofibrils
Nuclei are peripheral
3 connective tissue layers in muscle
Where are they found?
Epimysium - around whole muscle
Perimysium - around fascicles
Endomysium - between muscle fibres/cells
Continuous to tendon
What is the epimysium, perimysium and endomysium ?
Fibrous connective tissue
surrounding muscle, fascicle and between muscle fibres/cells, respectively
What does the epimysium, perimysium and endomysium do? (5)
- Lubricate (mainly perimysium)
- Protect
- Strengthen
- Separate
- Bind
What do the epimysium, perimysium and endomysium contain ?
- Blood vessels
- Lymphatic vessels
- Nerves
… Supplying the muscles
a bundle of muscle fibres is called a … and is surrounded by …
fascicle; perimysium
What’s the difference between epimysium and endomysium and perimysium?
epimysium covers the whole muscle body
endomysium covers individual muscle fibres
(perimysium covers fascicles)
How do different fibres require different amounts of blood?
Thin fibres need less blood, thick fibres need more blood
Which band contains actin only?
What colour is it?
I band
It is light
Which band contains myosin only?
H zone (It is part of the dark A band)
Which band contains actin and myosin?
What colour is it?
A band
It is dark
What is a sarcomere?
The contractile unit of striated muscle
What are the similarities between cardiac and smooth muscle cells histology?
