BL 8 Flashcards
Whats myalgia?
Muscle Pain
Myoclonus?
Sudden spasm of the muscle
Explain the 3 muscle types morphology
Skel: Long parallel cyclinders
Card: Short branched cyclinders
Sm: Spindle shaped
Explain the 3 muscle types innervation/control
Skel: Somatic motor control
Card: Intrinsic, involuntary modification
Sm: Involuntary, autonomic intrinsic activity
Skeletal Muscle has 3 types of fibres? Which is the sprinters or marathon runner?
Red - Marathon runner
Intermediate
White - Sprinter
Explain the structure of a muscle from the actin-myosin fibres up
Muscle Fibre (Endomysium)
Fascicle (perimysium)
Muscle, bundle of fascicles (epimysium)
Muscle structure sheaths. 3 types
Endo
Peri
Epi
myseum
How would you identify skeletal muscle? Nuclei
Striations
Multi-nucleaic
Arranged in fascicles
Striated Muscle. What are the dark strands?
what are the light strands?
A bands = Dark
H band = light
How do you remember the sarcomere lines and zones
Z is the end of the alphabet and Z is the end of the sarcomere.
M is the middle of the alphabet and M is in the middle of the sarcomere.
Attached to the M line are your Mighty Myosin (Mighty = thick filaments)
“My tits” (Sorry for the vulgar language) is for remembering that myosin is attached by titin to the Z line.
Actin (acthin) is the thin filament attached to the Z line.
H is a thick letter so only thick filaments are found in the H band.
I is a thin letter so I band has only thin filaments!
Myosin doesn’t like to change and is very bossy. So it not only took the middle M letter for the M line, but also took the A alphabet to represent
What happens in hypertrophy?
Increase contractile proteins so increased fibre diameter
What does stretching do?
Adds sarcomeres
Whats the name of the curve associated with sliding filament mechanism. And use for heart output?
Frank-starling curve
What can a troponin Assay detect?
Cardiac Ischaemia (1hr-20hrs)
Creatin Kinase detection?
Ck can be used to diagnose MIs and the proportion of its conc indicates size of MI
What does tropomysosin do when IC calcium is increased?
Ca binds to TropC and tropomyosin confirmationally changes revealing actin bind sites
4 steps in sliding filament theory
1) Myosin head attaches to actin binding site
2) POWER STROKE (pulls actin and ADP+Pi dissociates)
3) ATP attaches to myosin head and it detaches
4) ATP split which cocks the myosin head
Explain the events leading to a skeletal muscle contraction. 9
- Initiation: nerve impulse along motor neuron
axon arrives at neuromuscular junction. - Impulse prompts release of acetylcholine
(Ach) into synaptic cleft causing local
depolarization of sarcolemma. - Voltage-gated Na+channels open; Na+
enters cell. - General depolarization spreads over
sarcolemma and into T tubules. - Voltage sensor proteins of T tubule
membrane change their conformation. - Gated Ca2+-release channels of adjacent
terminal cisternae are activated by 5.
7.Ca2+is rapidly released from the terminal
cisternae into the sarcoplasm. - Ca2+binds to the TnC subunit of troponin.
- The contraction cycle is initiated and Ca2+
is returned to the terminal cisternae of
sarcoplasmic reticulum.
Cardiac Muscle structural characteristics? 4
Striations
Centrally positioned Nuclei (1or2)
Intercalated discs
Branching
Whats hypertropy and hyperplasia?
cellular hypertrophy = increased cell size
cellular hyperplasia = increased cell number
Whats ANP?
Whens it released?
Whats its effect?
Atrial Naturetic Peptide
Released in atrium due to stretch
Decreased blood volume
Whats BNP?
Whens it released?
Whats its effect?
Brain natriuretic peptide
Ventricles (10X lower affinity but double half life compared to ANP)
Reduces BP by naturesis and decreases in systematic vascular resistance
How does ANP/BNP relate to RAASystem
natriuretic peptides serve as a counter-regulatory system for the renin-angiotensin-aldosterone system
Myopathy?
Any disease of the muscles
Myasthenia
Weakness of the muscles
What does sarkos mean?
Flesh
What is the function of myoglobin?
Like Haemoglobin storage and transport of O2
What is in the I band?
Just Actin
What is in the A band
Actin and myosin.
It is the length of the myosin filament
On a histology slide what is the darker band?
A band
What is atropy?
Destruction of muscle
Hypertrophy?
Increasing the size of the cell or increased cell diameter
Hyperplasia?
Increasing the number of cells
What does calcium bind to in the SF theory?
Troponin Complex (TnI, TnC, TnT)
What is tropomyosin?
Ca binds to Troponin complex and pulls on the tropomysosin (sitting on the actin fibres) releasing actin binding sides
Whats a marker for cardiac ischaemia?
Troponin
What does a rise in plasma creatin kinase suggest? 3
Heart attack muscular dystrophy vigorous physical exercise intramuscular injection acute kidney injury
Are there myofibrils in cardaic muscle?
No. Actin and myosin filaments form a continuous mass in cytoplasm
Which type of muscle has intercalated discs
Cardiac muscle
What are two main effects of Naturetic peptides?
Reduces Blood Volume (stops renin releases)
Reduces Vascular resistance (vasodilation)
What may be high in the plasma during heart disease?
Naturetic Peptides
How are myosin and actin filaments arranged in a smooth muscle cell?
Diagonally
Can skeletal muscle cells divide?
No. They can fuse and repair themselves better than Cardiac cells
Can cardiac muscle cells divide?
No. Apon damage fibrobasts invade and lay down scar tissue
Can smooth muscle cells divide?
Yes
Functions of Circulation system? 4 main
Transportation (Nutrients in Waste out) Body defence Temperature Regulation Maintains pH and homeostasis
How much blood does an average adult have?
5 litres
Where does the majority of our blood lie?
Periphery 65%
Heart and Lungs 20%
Whats an End Artery?
An artery that supplies a part of the body without a significant collateral circulation
Name the three sections of the arteries?
Tunica Adventitia Tunica Media (40 layers of smooth muscle +CT) Tunica Intima (epithelial)
Metarterioles?
Arteries that supply blood to capillary beds are called
metarterioles
Where is the mitral valve?
Left side of the heart
