skeletal muscle structure and function (lecture 8)

Question 1

name the three types of muscle in the human body, and which ones are involuntary

Answer 1

smooth, cardiac (involuntary)
skeletal (mostly voluntary)

Question 2

describe the musculoskeletal structure at the cellular level

Answer 2

a singular muscle fibre contains bundles of myofibrils, repeating units of sacromeres, which are made of myofilaments (actin/thin & myosin/thick), strucurally organised in a striated appearance

Question 3

describe electrical skeletal muscle structure at the cellular level

Answer 3

external to each singular muscle fibre is the sarcoplasmic reticulum, which is important for the storage and release of calcium to the muscles via the cytoplasm upon contraction. transverse tubules are also present at regular intervals to conduct electrical signals to the core of the fibre.

Question 4

name skeletal muscles primary functions

Answer 4

for voluntary movement,
develop force by contracting, not solely movement but also posture.

Question 5

name the secondary functions of skeletal muscle

Answer 5

support and protection for soft internal organs, provides voluntary control over major openings,
converts energy too heat (shivering)

Question 6

outline the general whole muscle structure

Answer 6

individual muscle cells are called muscle fibres, they run parallel to one another and bundled together in fascicles, and fascicles are bundled together to create the muscle itself. while connective tissue within the muscle presents blood vessels and nerves, externally it gathers together to create tendons to connect the muscle to bone.

Question 7

what are the three main components of the excitation process within excitation-contraction coupling?

Answer 7

the voltage gated sensor (DHPR),
the ryanodine receptor (RyR),
the sacro(endo)plasmic reticulum calcium+ATPase (SERCA)

Question 8

how does an electrical signal perform the movement of calcium during excitation of excitation-contraction coupling?

Answer 8

the signal travels down the sarcolema, down the transverse tubule, engaging the voltage gated sensor (DHPR) to interact with the ryanodine receptor (RyR) to release the stored calcium from within the sarcoplasmic reticulum out and and to the contractile apparatus, then in order to get the calcium back into the SR the sacro(endo)plasmic reticulum calcium-ATPase (SERCA) burns ATP to push the calcium against its concentration gradient ending excitation and relaxing the muscle.