muscles and skeleton Flashcards
what are the shapes of muscle
what are the functions of bones
- support
- protection
- movement
- blood formation
- mineral storage
what makes up the axial skeleton
- cranium
- hyoid
- verterbral collumn
- ribs
- sternum
what makes up the appendicular skeleton
upper and lower limbs
what are the features of long bones
- tubular
- long axis
- 2 ends that articulate with other bones
what are the features of short bones
cuboidal
what are the features of flat bones
flat
thin
possibly curved
protect internal organs
what are the features of sesamoid bones
lie within tendons
what are the features of irregular bones
complex shapes
what is a notch
depression
an indentation
what is a fossa
a shallower depression
what is a formen
opening that gives passage to nerves and vessels
what is a head
a head fits into a fossa forming a joint
what is a condyle
in pairs and rounded
what is A facet
smooth surface that is flat or slightly curved
what is a joint
junction point between two or more bones
what are the uniaxial joints
plane
pivot
hinge
what are the biaxial joints
saddle
condyloid
what is the multiaxial joint
ball-and-socket
what do ligaments do
strenghten, stablise and limit joints
what is ossification
producing new bone
how do bones fracture
Any bone can be fractures if it is loaded enough
Systematically weakened bone has a lower breaking point
how do bone fractures heal
Bone heals quickly due to its plentiful bone supply
The blood clot, encourages the growth of a cartilage bridge*
Followed by osteoblasts laying down new rough or ‘woven’ bone
This is then remodeled into organised lamellar bone
what are the types of bone fractures
what is skeletal muscle
attaches bone to skin
does skeletal muscle do
It is mostly voluntary, maintains posture, stabilises joints and generates heat.
what is the connective tissue in the skeletal muscles
epimysium wraps around muscle, perimysium wraps around fascicles in the muscle and endomysium wraps around muscle fibres.
what is at the end of skeletal muscles
they combine at the end to form tendons
what is a myocyte
skeletal muslce cell
what are the features of myocytes
- The cell membrane is the sarcolemma and the cytoplasm is the sarcoplasm
- It contains the sarcoplasmic reticulum which stores calcium
- It has T tubules which project to the sarcolemma to the center of the muscle
- myofibrils which contain thin actin and thick myosin arragned into sarcomeres
what is the mechanism for skeletal muscle contraction
- motor neurons release ACh receptors onto sarcolemma
- Ions shift across the sarcolemma down t tubules
- Sarcoplasmic reticulum releases calcium into the sarcoplasm
- Actin myosin binds and the sarcomeres contract
- Sarcoplasmic reticulum retrieve calcium in the muscle relaxes
what is the location of skeletal muscle
attached to bones
what is the location of smooth muscle
forms walls of hollow organs
lines blood vessels,glands
what is the location of cardiac muslce
heart
what is the neurological control of skeletal muscle
is mainly voluntary
has some involuntary reactions i.e. shivvering
what is the innervation of the skeletal muscles
somatic nervous system
what is the neurotransmitters of all muslces
ACh
what is the neurological control of smooth muscle
involuntary
what is the innervation of smooth muscle
autonomic nervous system
what is the innervation of the cardiac muscle
autonomic
what is the neurological control of cardiac muscle
involuntary
what is the functions of skeletal muscle
movement, posture, stabilisation of body
shivering
voluntary control of sphincter
what is the function of smooth muscle
movement of food
bladder emptying
vessel diameter
pupil size
contraction of glands
what is the function of cardiac muslce
propulsion of blood
what are the skeletal cell characteristics
long
cyndrical
striated
what are the smooth cell characteristics
spindle-shaped
what are the cardiac cell characteristics
cyndrical
striated
branched
how are the skeletal cells nucleated
multiple
how are the smooth cells nucleated
one
how are the cardiac cells nucleated
one
what is an agonist muscle
the prime mover
what is an antagonist muscle
opposes the agonist
what is the synergist muscle
prevents unwanted movements
what is a fixer muscle
increases agnosit but does not move on its own
how do cardiac muscles regenerate
In cardiac muscle there are no stem cells so damage to cardiac muscle leads to ca collagenous scar
how do skeletal muscles regenerate
Skeletal muscles have satellite cells which can divide from new muscle cells after tissue damage
what are the heart wall layers
epicardium-covers the surface of the heart
myocardium-middle muscular layer
endocardium- innermost layer
pericardium- double layer sac
what is in the myocardium
- cardiac muscle cells that are stirated with many mitochondria
- cardiac myocytes that are striated cells with fibourous cardiac skeleton- coronary vessles penetrate into the myocardium
what is in the endocardium
made of thin epithelial layer
lines heart chamber and valves
what is in the pericardium
fibrous pericardium is the outer layer, tough which anchors heart within the mediastinum
what is the serous pericardium
simple squamous epitherlium layer
what is the pariteal pericardium
lines fibrous pericardium
what are neuromuscular junctions
Specialized intercellular connections between a neuron and a muscle cell (myocyte)
what is the excitation-contraction coupling (ECC)
stimulation causes myocyte to contract
where is ACh found
The skeletal neuromuscular junctions
The synapse of the vagus nerve
The cardiac muscle fibers
Synapses in the ganglia of the visceral motor system
A range of sites in the central nervous system
what is the Ach functional antagonist used for
increasae muscle relaxation
what is the Ach functional agonist used for
treat diseases such as myasthenia gravs
what is the muscle structure
msucle fibre
fasciculus
endomysium
perimysium
fascia
label this
what are the ionic events in muscle contraction
ACh binds to the receptor, Na+ influx
Depolarisation and stimulation of Ca2+ channels of sarcoplasmic reticulum that now open
Calcium flows into the sarcoplasm increasing Ca2+ levels, moving troponin/tropomyosin out of the groove, and allowing myosin to interact with actin
ATP cleaved and sarcomere contracts
Ca2+ returned to sarcoplasmic reticulum by Ca2+ pumps
Muscle fibre relaxes
how is calcium regulated in cross bridges
the groove in the thin filament needs to be exposed since the actin with binding sites is blocked by tropomyosin and troponin
troponin complex binds to calcium
troponin complex changes
actin and myosin able to interact and form cross bridge
what is tension
how much force is generated by muscle contraction
what is twitch
a single contraction of a muscle fiber
what is tetany
abnormal excitability of myoctye
what is rigor mortis
Breathing ceases after death so cells rapidly deplete ATP
In muscles this means Ca2+ cannot be pumped back to the sarcoplasmic reticulum
Ca2+ remains high in the sarcoplasm allowing crossbridge cycle contraction
The cross bridge cycle stops just after the power stroke with myosin still bound to actin (and the muscle contracted)
Rigor mortis ends when muscle tissue degrades
what is myasthenia gravis
Rare long-term condition causing weakness in the skeletal muscles
Condition normally worsens after periods of activity and improves after periods of rest
Caused by antibody driven auto-immune reaction against the acetylcholine receptors at the neuromuscular junction
what is synarthrosis (fibrous joint)
bones united by fibrous tissue
little to no movement
what is a cartilaginous joint
Two bones linked by cartilage (slightly movable joints)
what are 2 types of cartilaginous joints
Synchondrosis
symphysis
what are Synchondrosis
bones are bound by hyaline cartilage, may ossify to synostosis (bony joint)
what is symphysis
two bones joined by fibrocartilage, generally located in the midline of the body.
what are synovial joints (diarthroses)
Synovial joints (diarthrosis) provide free movement between the bones they join.
what are the parts of synovial joints
Joint (articular) cavity – separates articular surfaces, contains synovial fluid
Synovial fluid – joint lubricating fluid, removes wastes, absorbs shock, distributes stress across articular surfaces
Articular cartilage – hyaline cartilage that covers the articulating surfaces
Reinforced by ligaments – extrinsic and intrinsic to the joint capsule
what is cortical (compact bone)
outer shell of the bone
what is trabecular/cancellous (spongy) bone
underneath joint surfaces
what is the medullary (marrow) cavity
space in the diaphysis of a long bone that contains bone marrow
what happens in endochondral ossification
hyaline cartilaginous template continuously grows and is progressively replaced by bone
different ossification centres emerge
primary in diaphysis and secondary in the epiphysis
Epiphyseal plate (growth plate) emerges between diaphysis and epiphysis
what is the growth plate - bone
Where epiphyseal cartilage converts to bone
Results in bone elongation
what is intramembranous ossificaton
Direct mineralisation of connective tissue (mesenchyme) – NO cartilage
Grows radially from a primary ossification centre
what do osteoblasts do
Deposit collagen and bone matrix called osteoid
what do osteocytes do?
Former osteoblasts trapped in formed bone communicate through small channels called canaliculi
Sense bone loading and trigger differentiation and activity of osteoblasts and osteoclasts
what do osteoclasts do
Secretes organic acids to dissolve mineral component of bone; enzymes to destroy organic osteoid matrix
Resorb bone tissue for remodeling and to free calcium to the blood stream
Found in Howship lacuna (resorption bay)
what is bone remodelling
cycle of resorption and formation that optimizes bone structure = maintenance
what is bone modelling
bone formation without prior resorption – results in an increase in bone mass, bone growth and maintenance of bone strength
what is osteoporosis
osteoporotic bone has few plates and thin struts
Caused by lower than normal bone mass growth or abnormal bone loss
Can lead to collapse of vertebral bodies
what is Imbalances in bone remodeling caused by
Lack of Exercise
Hormonal changes: e.g. Menopause or Acromegaly
Lack of proper dietary intake:
Vitamin A is essential for bone remodeling
Vitamin C is essential for connective tissue
Vitamin D is essential for calcium absorption
