Muscle Tisue (Structure & Function) Flashcards
What is Myalgia?
Muscle pain
What s Myasthenia?
Weakness of the muscles
What is a myocardium?
Any muscular component of the heart
What is myopathy?
Any disease of the muscles
What is myoclonus?
A sudden spasm of the muscles
List the two types of striated muscles.
Skeletal
Cardiac
State the type of non-striated muscle.
Smooth muscle
List some features of skeletal muscle.
Myoglobin present
Striated
Voluntary control
Direct nerve-muscle communication
List some features of cardiac muscle.
Myoglboin present
Involuntary control
Indirect nerve-muscle communication
Striated
List some features of smooth muscle.
Myoglobin is absent
Involuntary control
No direct nerve-muscle communication
What is myoglobin and what its role in a muscle?
It’s a red protein that is structurally similar to a single subunit of heamoglobin
It stores O2 giving it up to working striated muscles
Heamoglobin gives O2 up to myoglobin, esp at low pH
What happens when striated muscle dies (in terms of myoglobin) and what damage can this cause?
When the muscle dies (muscle necrosis) myoglobin is released into the bloodstream (myoglobinuria)
Kidneys remove it from the blood into the urine, the urge becomes tea-coloured.
May damage the kidneys if it builds up
What is the outer membrane of a muscle cell called?
The sarcolemma
What is the cytoplasm of a muscle cell called?
The sarcoplasm
What is a sarcosome?
Another word for a muscle cells mitochondrion.
What is the smooth endoplasmic reticulum called in a muscle cell and what does it hold?
It’s called the sarcoplasmic reticulum and it holds Ca2+ ions
What does movement depend on in skeletal muscle?
Movement depends on the direction of muscle fibres contraction .
What is a muscle origin?
Usual proximal to the insertion point (closer to the body than insertion point)
Doesn’t move during contraction
Tension is created here
Usually into bone or something sturdy
What is a muscle insertion point?
Usually distal to origin (further from the body than origin)
May move during contraction (elbow moves = insertion, shoulder still = origin)
Where movement is created in contraction
Can be into bone, tendon or connective tissue
What are extrinsic muscle attached to?
They attach to bone or cartilage
Eg(allow tongue to stick out, In and move side to side,)
What is unusual about intrinsic muscles?
They are not attached to bone
Eg( allow tongue to Shante shape not position, aid swallowing)
What are skeletal muscle fascicles surrounded by?
Each separate fascicles surrounded by perimysium (a form of connective tissue carrying nerves and blood vessels)
Hw does blood supply to muscles correlate to muscle thickness?
Thick fibres require more blood.
Thin fibres require less blood.
Describe the relative thickness of ACtin and MYosin and how they’d appear in microscopy.
Actin is the thinner filament so appears as the lighter section in microscopy.
The opposite is true for myosin
What are the 3 types of striated muscle cells?
Slow twitch, fast twitch and intermediate
Why is slow twitch fibres darker on a stain?
As they contain more myoglobin and mitochondria (to maintain energy for longer)
Look at fibres twitch types table in PowerPoint
Y
Describe the structure of cardiac muscle fibres.
Striated
Centrally positioned nuclei (1/2 per cell), with glycogen around them
Intercalated discs
Branching fibres
What are ANP and BNP?
Peptides released by ANP=atria, BNP=ventricles during heart failure.
They reduce arterial pressure by decreasing blood volume and systemic vascular resistance
ANP released in congestive heart failure
BNP released in left ventricular hypertrophy and mitral valve disease
What is cell hypertrophy?
When the number of cells remain the same but they all grow in size individually - tissue grows
What is cel hyperplasia?
When the cells remain the same in size but they multiply in number - tissue grows
What is the role of purkinje fibres and describe their cellular make-up.
They conduct action potentials rapidly eneabling ventricles to contract in synchronous manner.
Have abundant glycogen (good conduction), sparse microfibrils and extensive gap junction sites.
Describe the structure of smooth muscle cells
Spindle shaped (fusiform)
Single central large nucleus
No striations, sarcomeres or T tubules
Can be stretched substantially
Form sheets, bundles or layers of thousands of cells Numerous caseload (cavelike invagination that sample external environ)
What does smooth muscle contraction rely upon? And describe it compared to other muscular contraction.
Depends upon actin-myosin interactions
Contraction is slower, more sustained and requires less ATP than other muscles
May remain contracted for hours or days
Due to smooth muscles involuntary nature it ca contribute to a number of conditions list some..
High BP (primary hypertension) Dysmenorrhea (painful menstruation) Asthma Abnormal gut mobility (IBS) Incontinence
How do smooth muscle initiate contraction?
Innervated by autonomic nervous system fibres. They release neurotransmitters from varicosities into a wide synaptic cleft
How do skeletal muscles repair?
The regenerate by the mitotic activity of satellite cells, so hyperplasia follows muscle injury. Satellite cells can also fuse with existing muscle cells to increase mass. (Hypertrophy)
Can cardiac muscle regenerate?
Adult cardiac muscles are incapable of regeneration.
After damage fibroblasts invade, divide and lay scar tissue
How do smooth muscle cells regenerate? Give a prevalent example,
They retain their mitotic activity so can form new muscle cells
Evident in pregnant uterus where muscle wall becomes thicker by hypertrophy and hyperplasia.
