4. Connective Tissues 2 Flashcards
What are the 3 types of muscles and their characteristics?
Where are they each found?
2 types of skeletal muscle?
Muscle Types
-
Skeletal - bone attachments, skeletal multicellular fibres
- Fast (white) contracting
- Slow (red) and continuously contracting
-
Smooth - organ contraction
- Veins & Arteries
- Lungs
- Gut
- Gall & Urinary Bladders
- Uterus
- Ureter & Fallopian Tube
- Fibromuscular stroma of the Prostate
- Cardiac - heart myocytes
What is the structure of a skeletal muscle?
Skeletal Muscle
- Multicellular Fibre - Group of skeletal muscle cells
- All cell nuclei located at periphery of fibre
- Arranged in bundles surrounded by CT
- Endomysium (smallest bundle)
- Perimysium - Of type I collagen & fibroblasts = Makes it into FASCICLES
- Epimysium surrounds the entire muscle
-
Sarcolemma = cell membrane over whole fibre!
- Invaginations of sarcolemma
- T tubules bring in action potential into the fibre
- Create triads at each end of sarcomere with sarcoplasmic reticulum
-
Sarcomere = Individual contractile unit of myofibrils
- Myofibrils linked in series by aligned sarcomeres of myofibrils
- Sarcoplasmic reticulum = Myocyte endoplasmic reticulum
What is the basic contractile unit of skeletal muscle?
Basic Contractile Unit of Skeletal Muscle - Sarcomere
- Sarcomere composed of 2 main proteins = Actin & Myosin
- Sarcomeres linked to each other in each myofibril
- Z band actin anchor
- I band fibrils of actin
- A band myosin bundle (M line), overlaps actin
- M band linkage of myosin bundles
- Myofibrils linked in series
- Aligned laterally at the Z disk
What are the 2 types of skeletal muscle?
- What colour are they each?
- Which fast type fatigues?
- Blood supply and metabolism type of each?
What are the 2 types of skeletal muscle innervation?
Motor = Neuromuscular junction
- Each skeletal muscle cell in a fibre is enervated by a peripheral motor neuron.
- The axon looses myelin sheath and branches into telodendria as it approach to muscle
- Telodendria (telodendrion - singular) lie in shallow grooves (primary cleft) on the myocyte surface
Sensory = Muscle spindle
- Small group of thin muscle fibres
- Known as intrafusal fibres
- Separated from extrafusal fibres (rest of muscle) by connective tissue capsule
What is the structure of smooth muscle?
- Where do the nuclei lie?
*
Smooth Muscle
- Individual cells with central nuclei
- Small size
- Non-striated, but contain actin & myosin which criss-cross the cytoplasm (not around the nucleus)
- Sparsely enervated by autonomic system - Both PNSN & SNS
- Retain regenerative capacity - So can proliferate & regenerate lost smooth muscle
What is the structure of cardiac muscle?
*
Cardiac Muscle
- Single, Branched cell
- Synchronizes contraction with other cardiac myocytes to which it connects (heart beat)
- Central nucleus
- Intercellular junctions (between individual cells) = intercalated discs
- Striated - (NEVER called striated muscle! This reserved for skeletal muscle fibres!)
- CANNOT regenerate
- Compensatory Hypertrophy
– Increased work load
– Loss of surrounding muscle cells
What type of muscle is this?
What type of muscle is this?
What type of muscle is this?
What muscle is this?
What is M? S? Sr?
What are the red arrows pointing to in this EM of Skeletal muscle?
= rows of mitochondria
What are the arrows pointing to in this EM of skeletal muscle?
What does the red triangle indicate?
What is crossed out in black?
Red arrow = rows of mitochondria
red triangle = BM
Nucleus
Label the bands of skeletal muscle. Where is Actin/Myosin?
What muscle is this in cross section?
How can you tell?
skeletal muscle - peripheral nuclei for each fibre
What accounts for the different shading between skeletal muscle fibres seen here in cross section?
What are the red arrows pointing at?
variable amounts of mitochondria = different shading of fibres
arrow = capillaries
What is labelled in this EM of a skeletal muscle fibre?
#
*
arrows
= portion of neuromuscular junction
*= peripheral nucleus
Arrows = mitochondria
What is labelled in this image of a skeletal muscle spindle?
What muscle type is this?
What muscle type is this?
= smooth muscle
What is labelled in this cross-section of the GIT?
What is labelled in this cross-section of the GIT?
What does the red crown label?
What are the arrows pointing at?
What is labelled in this cross-section of a muscular artery?
What muscle type is this?
Blue arrow?
Label the layers of cardiac muscle making up the wall of the heart.
What muscle type is this a picture of in cross-section?
How can you tell?
What features of cardiac muscle are labelled here?
Yellow arrow, Red, Purple, orange, pink?
Yellow = branching of myocytes
Red = striations
Purple = striations
orange = rich mitochondria
pink = nucleus
What features of cardiac muscle are labelled here?
Orange, Blue, Red, Pink?
Orange = Nucleus
Blue = Intercalated disk
Red = Striations
Pink = rows of mitochondria
