Chapter 11- The Musculoskeletal System Flashcards
3 types of muscle
- skeletal (supporting body/ voluntary movement)
- smooth (involuntary movement/ peristalsis)
- cardiac (maintain rhythmic contraction of heart w/o NS input)
sarcomeres
basic contractile unit of skeletal muscle. made of thick and thin filaments. thick are bundles of myosin. thin are made of actin (troponin and tropomyosin help regulate interaction b/w thin and thick)
different fibers in skeletal muscle
red fibers (aka. slow-twitch fibers)- high myoglobin content white fibers (aka. fast-twitch fibers)- contain less myoglobin
smooth vs skeletal muscle nuclei
skeletal- multinucleated
smooth- single nucleus
tonus
constant state of low-level contraction by smooth muscle
myogenic activity
smooth muscle can contract without NS input. muscle cells contract directly in response to stretch or other stimuli. both smooth and cardiac exhibit myogenic activity.
cardiac muscle characteristics
autonomic NS. appears striated. may contain two nuclei, usually only one. each cell is connected by intercalated discs which contain gap junctions (cytoplasm is shared b/w those cells)
what is required for muscle contraction?
Ca2+ and ATP
I-band
only thin filaments
H-zone
only thick filaments
which band always remains constant with respect to size
A-band
which structure separates each sarcomere
Z-line
sarcoplasmic reticulum (SR)
cover myofibrils. modified endoplasmic reticulum with high Ca2+ concentration.
sarcolemma
cell membrane of myocyte. capable of propagating and distributing action potential.
myocyte
muscle cell
where does Acetylcholine bind during an action potential
receptors on the sarcolemma, causing depolarization
what is responsible for the powerstroke in muscle movement
the dissociation of ADP and P from myosin. the binding of ATP is required for releasing the myosin head from the actin filament.
without Ca2+…
myosin-binding sites will be covered by tropomyosin and contraction will be prevented
tetanus
very frequent contractions so that the muscle is unable to relax. this can cause muscle fatigue
creatine phosphate
created by transferring phosphate from ATP to creatine during times of rest (1 way to reserve energy b/c it can be reversed quickly to generate ATP quickly)
axial skeleton
skull, vertebral column, ribcage, hyoid bone (small bone in anterior of neck used for swallowing.
appendicular skeleton
bones of limbs, pectoral girdle, and pelvis
skeleton is created from 2 major components
bone and cartilage
3 major segments of bone
- epiphysis (ends)
- metaphysis(near the end)
- diaphysis (middle long part)
epiphysis
epiphyseal plate (growth plate, site of longitudinal growth), spongy bone, periosteum (muscle attachment here/ fibrous sheet that surrounds long bones)
diaphysis
periosteum, compact bone, marrow cavity
compact bone vs. spongy/cancellous bone
compact- strong and dense, outermost bone
s/c- lattice structure with trabeculae filled with bone marrow, internal core of bone
bone marrow
red marrow- hematopoietic stem cells (generate all cells in blood)
yellow marrow- made of fat and is relatively inactive
tendons
attach muscle to bone
ligaments
pieces of fibrous tissue that connect bones together at joints. strengthen movable joints.
bone matrix
organic (collagen, glycoproteins, peptides) and inorganic (Ca, phosphate, hydroxide ions all together form hydroxyapatite crystals) components
osteons/ Haversian systems
structural units of bony matrix.
lamellae
each osteon contains concentric circles of bony matrix.
Haversian canals
longitudinal channels (those with axis parallel to the bone)
Volkmann’s canals
transverse channels (those with an axis perpendicular to the bone)
lacunae
between lamellar rings are these small spaces. these house mature bone cells known as osteocytes.
canaliculi
lacunae are interconnected by tiny channels which allow for the exchange of nutrients and wastes between osteocytes and the Haversian and Volkmann’s canals
osteoblast vs. osteoclast
blast- builds bone (uses Ca and phosphate from bone)
clast- chew bone, macrophages of bone and resorb it.
parathyroid hormone
peptide hormone released by the parathyroid glands in response to low blood Ca, promotes resorption of bone, increasing the concentration of Ca and phosphate in the blood
Vitamin D
activated by parathyroid hormone also promotes the resorption of bone.
calcitonin
a peptide hormone released by the parafollicular cells of the thyroid in response to high blood calcium, promotes bone formation, lowering blood calcium levels
cartilage
chondrin (secreted by cells called chondrocytes)- softer and more flexible than bone
endochondral ossification
hardening of cartilage into bone. responsible for formation of most long bones in body.
intramembranous ossification
undifferentiated embryonic connective tissue (mesenchymal tissue) is transformed into and replaced by bone— this occurs in the skull
immovable joints
bones fused together to form sutures or similar fibrous joints (found in head, anchor bones of skull together)
movable joints
joints (elbow/ knee), ball-and-socket joints (shoulder/ hip)
what do ligaments consist of
synovial capsule (encloses actual joint cavity-articular cavity)
synovium
layer of soft tissue that secretes synovial fluid (lubricates movement of structures in the joint space)
articular cartilage
contributes to the joint by coating the articular surfaces of the bones so that impact is restricted to the lubricated joint cartilage
synergistic
working together to accomplish the same function
flexor and extensor
antagonistic pairs. flexor- decreases angle across joint. extensor- increases this angle.
abductor
moves part of body away from midline
adductor
moves part of body toward the midline
medial vs. lateral rotation
m- rotating axis toward midline
l- rotating axis away from midline
what causes Ca2+ release from bones
parathyroid
