9808 Lecture Notes - Lecture 5: Endoplasmic Reticulum, Skeletal Muscle, Cardiac Muscle
19 Jun 2018
School
Department
Course
Professor
Muscles lecture
Words & Terminology
• My-, Myo-, mys-, and sarco- = muscle/flesh
• -mysium = sheath
• Sarcolemma –=is muscles plamsa membrane
Sarcoplasm = is the muscles cells cytoplasm
Sarcoplasmic reticulum = releases calcium ions during muscle contraction and absorbs them
durng relaxation
Sarcomere = smallest contractile unti within muscle
Myoblasts = are the embryonic cells in which me originate. Its an embryonic cells that
becomes a muscle cell or muscle fibre
Myocyte = muscle cells but don’t tend to see much
Endomysium = surrounds individual muscle cells
A muscle is there to
transform atp to a
directed mechanical
energy therefore we
can make movement
, exert force
depending on the
muscle type .
Universal Characteristics of Muscle
Responsiveness (excitability/irritability ) – To chemical signals, stretch, and electrical
changes across the plasma membrane .
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Conductivity – Local electrical change triggers a wave of excitation that travels along
the muscle fibre. a local stimulation can trigger a wave that will travel along the muscle
fibre
Contractility – Shortens when stimulated.
Extensibility – Capable of being stretched between contractions.
Elasticity – Returns to its original resting length after being stretched
Functions
Produce movement – they work to move bones over a joint. Muscles cannot push. muscles
never act by themselves (in isolation )
Maintaining posture – they maintain posture
Stabilising joints – particulary at joojts that are highly mobile
Generating Heat- eg when shiver muscles contract
Help to portect organs
Conform valves
Form sphincters
Control pupil size
Can cause Goosebumps
Have
mesenchymal cells and differentiate into myoblast- can mature and fuse and become a
muscle fibre. Early development (childhood) we replicate myoblast.
find more resources at oneclass.com
find more resources at oneclass.com
Mature myocyte – the satellite cells hang on outside and they can jump back into cycle
of skeletal muscle production, repair damaged repair tissue and therefore allow muscle
growth.
Types of Muscle Tissue
• Skeletal muscle – really long muscle fibres
Cardiac muscle – only found in heart
Smooth muscle – is found in walls of hallow organs eg. Intestines.
Skeletal muscle
Unique features:
- Elongated cells called muscle fibres
- Each have a connection with a neuron (how they get their info)
- They are voluntary – you can control them
- Contract rapidly but tired easily – response is quite powerful
- Are extremely adaptable
Functions - must have neuronal connection
- Moves the skeleton
- Produces heat
- Stabilises joints
Cardiac muscle
Unique features:
- Branching cells connected to each other via intercalated disks ( contract like a wave , so not
all at once )
- Is not voluntary – can’t control it
- Its contraction is quite rapid
- It does not tire
- Has neuron control – controlled by nerves and hormones
- Allows use to change the rate of contraction in regard to the body’s needs
- Has 1 or 2 nucleus in each cells
Function:
- Pump blood
Smooth muscle
• Unique features
– Spindle shaped cells
- Only have 1 nucleus in each cells
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Words & terminology: my-, myo-, mys-, and sarco- = muscle/flesh, -mysium = sheath, sarcolemma =is muscles plamsa membrane. Sarcoplasmic reticulum = releases calcium ions during muscle contraction and absorbs them durng relaxation. Myoblasts = are the embryonic cells in which me originate. Its an embryonic cells that becomes a muscle cell or muscle fibre. Myocyte = muscle cells but don"t tend to see much. A muscle is there to transform atp to a directed mechanical energy therefore we can make movement. , exert force depending on the muscle type . Responsiveness (excitability/irritability ) to chemical signals, stretch, and electrical changes across the plasma membrane . Conductivity local electrical change triggers a wave of excitation that travels along the muscle fibre. a local stimulation can trigger a wave that will travel along the muscle fibre. Extensibility capable of being stretched between contractions. Elasticity returns to its original resting length after being stretched.
