Muscle Anatomy Flashcards
What are 5 reasons why SKELETAL MUSCLE contracts?
1) Move BONES for locomotion
2) Maintain HOMEOSTASIS e.g. shivering, respiration
3) Maintain posture and balance
4) Support soft tissue e.g. abdominal wall
5) Guards entrances and exits e.g. voluntary control of urination and defecation
Each MUSCLE is surrounded by________?
EPIMYSIUM
S & F of EPIMYSIUM
S - CT surrounding each whole MUSCLE, dense collagen fibers
F - Separates MUSCLE from other organs, continuous with TENDON and PERIOSTEUM
A MUSCLE is made up of many __________
FASCICLES
S & F of PARALLEL MUSCLE
Give an example
S - FASCICLES run side by side along length of MUSCLE
F - Can shorten the most
Example = Most MUSCLES, BICEPS BRACHII
S & F of CONVERGENT MUSCLE
Give an example
S - FASCICLES converge like a fan
F - Can vary direction of pull
Example = PECTORALIS MAJOR
S & F of PENNATE MUSCLE
What are the 3 different types?
Give an example
S - Short FASCICLES attach to central TENDON like a feather, has many FASCICLES = many FIBERS F - Can produce most tension 1) UNIPENNATE e.g. EXTENSOR DIGITORUM 2) BIPENNATE e.g. RECTUS FEMORIS 3) MULTIPENNATE e.g. DELTOID
S & F of CIRCULAR MUSCLE
Give an example
S - FASCICLES arranged in concentric rings around an opening aka sphincter
F - Allows control of opening/closing
Example = Mouth, anus
Each MUSCLE FASCICLE is surrounded by _________
PERIMYSIUM
S & F of PERIMYSIUM
S - Made of COLLAGEN and ELASTIC FIBERS
F - Supports larger blood vessels/branching nerves, continuous with ENDOMYSIUM and EPIMYSIUM
PERIMYSIUM is made up of many ______ ____ = ______ ____
MUSCLE FIBERS = MUSCLE CELLS
Each MUSCLE FIBER is surrounded by _________
ENDOMYSIUM
S & F of ENDOMYSIUM
S - Made of loose CT
F - Supports CAPILLARIES to nourish FIBERS, Supports nerve endings to stim. FIBERS, continuous with PERIMYSIUM
What is each MUSCLE FIBER composed of?
1) SARCOLEMMA
2) TRANSVERSE TUBULES
3) SARCOPLASMIC RETICULUM
4) MULTIPLE NULCEI
5) MITOCHONDRIA
6) MYOFIBRILS
What is the SARCOLEMMA?
A MUSCLE CELL MEMBRANE
What are the TRANSVERSE TUBULES?
- Parts of SARCOLEMMA that dive deep into the cell
- Wrap around each SARCOMERE
- Quickly bring signal to contract to each SARCOMERE
- Allow all SARCOMERES to contract together
What is the SARCOPLASMIC RETICULUM?
- ER of MUSCLE CELLS
- Has Ca2+ pumps to take up and store Ca2+
- Has voltage gated Ca2+ channels to release Ca2+ in response to AP
Where are the MULTIPLE NUCLEI pushed to?
The edge of the cell
What is the role of the MITOCHONDRIA?
Provide ATP required for contraction and relaxation
What are MYOFIBRILS?
- ACTIN and MYOSIN proteins packed and organized into bundles (visible as striations)
- fills 80% of MUSCLE FIBER volume
- responsible for contraction and relaxation
Which protein in a MYOFIBRIL is a thick filament?
MYOSIN (includes MYOSIN HEADS)
Which protein in a MYOFIBRIL is a thin filament?
ACTIN (includes TROPONIN and TROPOMYOSIN
1 SACROMERE =
From Z-DISC to Z-DISC
Z-DISC =
Connects thin filaments
M-LINE =
Connects thick filaments
TITAN PROTEIN =
Elastic, connects thick filaments to Z-DISC
H-ZONE =
During contraction, thin filaments slide into H-ZONE = H-ZONE dec.
A-BAND =
Dark striations
I-BAND =
Light striations
How many SARCOMERE end to end make a MYOFIBRIL?
1000’s
