Skeletal and Muscular System Flashcards
Endoskeleton
-serves as the framework with in all vertebrate organisms
-provides protection by surrounding internal organs with bone
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what does the rib cage protect?
protects the thoracic organs (lungs and heart)
What does the skull protect?
the brain
What does the vertebral column protect?
spinal chord
what are the two main components of the endoskeleton?
cartilage and bone
Cartilage
a type of connective tissue that is softer and more flexible than bone
-retained in adults in places where firmness and flexibility are needed
What contains cartilage on humans?
external ear, nose, walls of the larynx and trachea, and skeletal joints
Chrondocytes
cells responsible for synthesizing cartilage
Bone
specialized type of mineralized connect tissue that has the ability to withstand physical stress
- bone is adapted for body support
- bone tissue is hard and strong while lightweight and elastic
What are the two basic types of bones?
compact and spongy
compact bones
- is dense bone that does not appear to have any cavities when observed with the naked eye
- the bony matrix is deposited into structural units called OSTEONS
Osteons
-consists of a central microscopic channel called Hervesian canal, surrounded by a number of concentric circles of boney matrix called LAMALLE
Spongy Bone
-much less dense and consist of an interconnecting lattice of bony spicules
Yellow marrow of spongy bone
is inactive and infiltrated by adipose tissue
Red Marrow of spongy bone
is involved in blood cell formation
what are Osteocytes and the two kinds
osteocytes are a type of cell found in bone tissue
- Osteoblasts
- osteoclasts
osteoblasts
synthesize and secrete the organic material of the bone matrix
-once they have become surrounded by their matrix they mature into osterocytes
Osteoclasts
large, multinucleate cells involved in bone reabsorption
-where bone is broken down and minerals are released into the blood
Bone Formation
occurs by either endochondral ossification or intramembranous ossification
endochondral ossification
- existing cartilage is replaced by bone
- large bones primarily form
Intramembranous Ossification
-messenchymal (embryonic or undifferentiated) connective tissue is transformed into and replaced by bone
Axial Skeleton
basic framework of the body
-consists of the skull, vertebral column, and rib cage
Appendicular Skeleton
point of attachment
-includes the bonds of the appendages (limbs) and the pectoral and pelvic girdles
Ligaments
bone to bone connectors
Tendons
attach skeletal muscles to bones
-bend the skeleton at moveable joints
What holds the bones of the skull together?
sutures or immovable joints
Origin
the point of attachment to a stationary bone
-ex: proximal end and limb muscles
insertion
the point of attachment of a muscle to a bone that moves
extension
indicates the straightening of a joint
Flexion
refers to the bending of a joint
What does muscle tissue consist of?
consists of bundles of specialized contractive fibers held together by connective tissue
What are the different types of muscles?
skeletal muscle
smooth muscle
cardia muscles
Skeletal muscles
responsible for voluntary movements and is innervated by the somatic nervous system
-has striations of light and dark bands reffered to as STRIATED BANDS
What is embedded in the muscle fibers?
filaments called MYOFIBRILS
What are myofibrils further divided into?
contractile vacuoles called SACROMERES
Sacroplasmic Reticulum
envelope the myofibrils
-is a modified endoplasmic reticulum that stores calcium ions
Sarcoplasm
the cytoplasm of a muscle fiber
Sarcolemma
cell membrane of a muscle fiber
- capable of making an action potential
- is connectd to a system of transverse tubules (T-system)
T-systems
provides channels for ion flow throughout the muscle fibers
-can make an action potential
Sacromeres
composed of thin and thick filaments
- the thin filaments are chains of actin molecules
- the thick filaments are organized bundles of myosin molecules
Z lines
- defines the boundaries of a signal sacromere
- anchor the thin filaments
-during contraction the Z lines move toward each other
M line
runs down the center of the sacromere
I Band
region containing the thin filaments ONLY of the sacromere
-Reduced in size when contraction occurs
H zone
region containing thick filaments only of the sacromere
-reduced in size when contraction occurs
A band
spans the entire length of the thick filament and any overlapping portions of the thin filaments
-DOES NOT reduce in size when contraction occurs
Contraction
stimulated by a message from the somatic nervous system sent via a motor neuron
Neuromuscular junction
link between the nerve terminal and the sacrollema of the muscle fiber
Synapse/Synaptic Cleft
is in-between the neuromuscular junction and sacrollema
Rigor Mortis
after death our muscles go into this state
-our muscles contract and become rigid, even without action potentials
What are the 5 major types of muscle contractions?
- isotonic
- dynamic
- concentric
- eccentric
- Isometric
Isotonic muscle contractions
contraction occurs when a muscle shortens against a fixed load while the tension on that muscle remains constant
Dynamic Muscle contraction
includes both concentric and eccentric types of contraction
-results in the change in length of the muscle with a corresponding change of tension on the mucles
concentric muscle contraction
a type of dynamic contraction
-the muscle fibers shortens and the tension on the muscle increases
Eccentric muscle contraction
contraction is a type of dynamic contraction of the muscles -the muscle fibers lengthen and then tension of the muscles increases
Isometric muscle contraction
contraction occurs when both ends o the muscle are fixed and no change in length occurs during contraction, BUT THE TENSION INCREASES
What elicits a contraction?
muscles exhibit an all or none response
-ONLY a stimulus above a minimum (THRESHOLD VALUE) can elicit a contraction
How can you increase the strength of contraction of a single muscle fiber?
CANT regardless of the strength of the stimuli
HOw can you increase the strength of contraction of entire muscle?
can be done
-can increase strength by recruiting more muscle fibers
Simple twitch
muscle response
- response of a single muscle fiber to a brief stimulus at or above the threshold value
- consists of a latent period, contraction period, and relaxation period
what is the latent period of simple twitch
is the time between stimulation and the onset of contraction
-the action potential spreads along the sacrollema and Ca2+ ions are released
Absolute refractory period
after the contraction period there is a brief relaxation period during which the muscle is unresponsive to a stimulus
Temporal stimulation
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