Skeletal & Muscular Systems Flashcards
2 components of the skeleton:
cartilage and bone
cartilage
- type of CT that is softer and more flexible than bone
- chondrocytes are cells responsible for synthesizing cartilage
bone
-mineralized CT that can withstand physical stress
compact bone
-dense bone composed of structural units called osteons
structure of an osteon
-central microscopic channel called a Haversian Haversian canal surrounded by a number of concentric circles called lamellae
spongy bone
- less dense, consists of bony spicules (trabeculae)
- cavities b/w spicules filled with red (blood cell formation) or yellow bone marrow (infiltrated by adipose tissue)
osteoblasts
- synthesize new bone
- mature into osteocytes
osteoclasts
-bone is broken down and released into the blood
endochondral ossification
- existing cartilage is replaced by bone
- typically long bones
intramembranous ossification
-CT is transformed into and replaced by bone
pyramidal system
-provides rapid motor commands (voluntary) to skeletal muscle and other organs
extrapyramidal system
-somatic motor commands as a result of processing performed at the involuntary level
skeletal muscle
- responsible for voluntary movement and is innervated by the somatic nervous system
- striated
myofibrils
-embedded in the fibers, further divided into contractile units called sarcomeres
sarcoplasmic reticulum
-modified ER that envelopes myofibrils and stores calcium ions
sarcolemma
- cell membrane of a muscle fiber
- propagates an action potential and is connected to a system of transverse tubules
T system
-provides a channel for ion flow throughout the muscle fibers
sarcomeres
-composed of thin (actin) and thick (myosin) filaments
Z line
defines boundaries of a single sarcomere
M line
runs down the center of the sarcomere
I band
contains thin filaments only
H zone
contains thick filaments only
A band
spans the entire length of the thick filaments and any overlapping portions of thin filaments
neuromuscular junction
link b/w the nerve terminal and the sarcolemma of the muscle fiber