Week 1- MSK science Flashcards
Are skeletal muscles myogenic or neurogenic?
Neurogenic
What makes up a motor unit?
A single alpha motor neuron and all the skeletal muscle that it innervates.
If a motor unit has a large number of muscle fibres which purpose is more likely? Precision or power?
Power
Rank in order of size the following (smallest to largest): muscle myofibril muscle fibre (cell) sarcomere
sarcomere
myofibril
muscle fibre
muscle
Between which lines is a sarcomere measured?
Z lines
What is excitation contraction coupling?
Where the surface action potential triggers calcium ion release from the sarcoplasmic reticulum.
What complex is removed by Ca2+ ions in muscle contraction?
Troponin-tropomyosin complex
______ is necessary to transport Ca2+ ions back into the __________ __________.
ATP
Sarcoplasmic Reticulum
Why does rigor mortis occur?
If there is no ATP then Calcium ions cannot be returned to the sarcoplasmic reticulum and the muscles remain in a state of contraction.
identify what each of the following bands consist of: I band A band H zone M line Z line
I- actin alone A- Myosin and actin H zone- myosin alone M line- centre of myosin Z line- centre of actin
____________ muscle unit ___________ during submaximal contraction helps prevent muscle fatigue.
asynchronous
recruitment
Stronger muscle contraction is brought about by stimulation of more motor units. What is this known as?
Motor Unit recruitment
What is tetanus?
A maximal sustained contraction of a motor unit. This occurs when the muscle fibre is stimulated so rapidly that it does not have time to relax between stimuli
What type of muscle cannot be tetanised?
Cardiac muscle
If skeletal muscle receives a second stimulation before it had time to completely relax, the second response add to the first and a greater muscle ________ is developed
Tension
The ________ developed by skeletal muscle _________ with increasing _________ of stimulation.
Sustained contraction occurs when the muscle is stimulated _______ with no opportunity to ______ in between stimuli.
Tension increases frequency rapidly relax
Skeletal muscle tension is conveyed to bone via the stretching of _______/________ _____ of muscle.
tendon
connective tissue
Name the two types of skeletal muscle contraction
Isotonic
Isometric
What is the difference between isotonic/isometric contraction?
isotonic- tension remains constant, muscle length changes
isometric-tension develops at constant muscle length
Give two examples of isotonic and isometric contraction
isotonic- lifting objects, body movements
isometric- supporting objects in fixed positions, maintaining posture
the greater the velocity of shortening the _______ the load
lighter
Name the three types of skeletal muscle
Slow oxidative fibres (type I) for prolonged/low work aerobic activities
Fast oxidative fibres (type IIa) for relatively prolonged moderate work activities
Fast glycolytic fibres (type IIx) anaerobic activity- short term high work activity
Define a reflex action
A stereotyped response to a specific stimulus
stretch reflexes resist passive change in ________ _______ and so they maintain optimum muscle length
muscle length
Muscle spindles are known as _________ fibres rather than _________. They are specialised sensory muscle fibres.
intrafusal
extrafusal
The efferent neurones that supply muscle spindles are called ________ ______ _______.
Gamma Motor neurones
Give another name of a fibrous joint
Synarthrosis
Little-no movement occurs at fibrous joints. the bones are joined together by fibrous tissue. Give an example of a fibrous joint in the adult skeleton
Skull sutures
fibrocatilaginous joints are joined together by cartilage. Give 4 examples of such joints
pubic symphysis
sacroiliac joints
costochondral joints
intervertebral joints
Give another name for a cartilaginous joint
Amphiarthrosis
Bones separated by a ________ cavity (containing _______ _____) and united by a fibrous ________ (and other extra-articular structures e.g. ligaments, tendons, and bursae)
The inner aspect of fibrous _______ is lined with ________ membrane
synovial synovial fluid capsule capsule synovial
The synovial membrane is ________ _________ _____ with capillary networks and lymphatics
The synovial membrane contains ________ cells (fibroblasts) which produces the synovial fluid
The _________ ________ of bones are covered with hyaline cartilage
vascular connective tissue
synovial cells
articular surfaces
What is the difference between simple and compound synovial joints?
Simple synovial joints consist of only one pair of articular surfaces whereas compound joints consist of more than one pair.
identify three extra-articular structures
Bursa
tendon
ligament
Synovial fluid consists of ___________ ____ and _______.
Hyaluronic acid
lubricin
The articular cartilage is __________ and instead derives its nourishment from _________ ______.
avascular
synovial fluid
Synovial fluid is continuously replenished and absorbed by the __________ __________.
Synovial membrane
___ acid in the synovial fluid is derived from the _______ of blood plasma.
Uric acid
dialysis
The elasticity and viscosity of synovial fluid varies between different joints. Rapid movement is associated with ___________ viscosity and _________ elasticity.
decreased viscosity
increased elasticity
Synovial fluid is usually _________ and the WBC is _____m3.
colourless
<200m3
Red synovial fluid is a sign of what two conditions?
Haemorrhagic arthritis
traumatic synovial tap
Identify the four zones of articular cartilage
superficial
middle
deep
calcified
Identify the three components of articular cartilage ECM. Each degrades with age. Relative concentrations of each can vary thus changing the mechanical properties of the matrix
water
collagen (mainly type 2)
proteoglycans
Chondrocytes both degrade and synthesize the ECM. the rate of both processes varies and this is known as what?
Cartilage ECM turnover
Identify two catabolic and two anabolic factors of Matrix turnover
catabolic- TNF-alpha and Interleukin 1
anabolic- TGF-beta and IGF 1
Skeletal muscle is innervated by myelinated ______ _______ __________. Near the muscle it divides into ___________ branches which innervate each individual muscle fibre.
alpha motor neurones
unmyelinated
Give another name for the presynaptic heads at a neuromuscular junction
Terminal Bouton
Name the cavity across which ACh travels at an NMJ
synaptic cleft
Upon which ion is the release of ACh into the synaptic cleft dependant?
Ca2+
_______ enters the terminal bouton via a Na+ symporter. It combines with _______ _______ __ to form acetylcholine. this reaction is catalysed by ______ ________________. ACh is concentrated in the synaptic vesicles by __________ ____ __________.
choline
acetyl coenzyme A
choline acetyltransferase
vesicular ACh transporter
Arrival of an action potential at the terminal bouton causes the opening of voltage activated ____ ion channels.
Ca2+
On the end plate the ACh binds to _________ ACh receptors allowing _____ influx and ____ efflux leading to an _____ ______ potential.
Nicotinic
Na+
K+
End Plate
Each vesicle of ACh contains a ________ of neurotransmitter which creates a __________ end plate potential. A number of these combined produces an ____ _______ __________ which triggers an action potential when the threshold is reached.
Quantum
Miniature
end plate potential
The presence of voltage gated ____ channels across the muscle fibre facilitates the propagation of the action potential across the whole muscle fibre
Na+
What is a mass of protoplasm containing several nuclei known as?
Syncytium
The connective tissue that surrounds the muscle as a whole is called the \_\_\_\_\_\_\_\_\_\_\_, the connective tissue around a single fascicle is the \_\_\_\_\_\_\_\_\_\_\_ and the connective tissue around a single muscle fibre is the \_\_\_\_\_\_\_\_\_\_\_\_.
epimysium
perimysium
endomysium
What is a bundle of muscle fibres called?
a fascicle
Where are the nuclei of skeletal muscle fibres found?
The periphery of the fibre beneath the sarcolemma
What colour are type I and Type IIB fibres?
type I—-red fibres
type IIB—— white fibres
How does the abundance of mitochondria and myoglobin vary between Type I and type IIB fibres.
Type I- abundant mitochondria and myoglobin
Type IIB- few mitochondria and less myoglobin
What are immature chondrocytes known as?
Chondroblasts
Chondrocytes are found in pockets within the extracellular space called _______.
Lacuna
Hyaline cartilage appears ____-_____ in colour.
blue-white
In utero Haemopoeisis occurs by the _____ and ______ and later moves to the bone marrow. By the early twenties haemopoeisis occurs only in the ____ skeleton and the ____ girdle.
liver
spleen
axial
limb
65% of bone is made up of ________ which is a form of ______ __________then 25% collagen and 10% water
Bioapatite
calcium phosphate
_______ bone is found in the shaft (diaphysis) whereas ____________ or ___________ bone is found in the ends of the bone (_________)
cortical
cancellous
trabecular
epiphysis
Cortical bone is made up of layers of ________. A group of lamellae is known as an __________. at the centre of each osteon is a _________ canal. the transverse vessels are called _________ canals.
lamellae
osteon
Haversian
Volkmans
How does trabecular bone differ histologically from cortical bone
Doesn’t possess Haversian canals
Osteoprogenitor cells act as a reserve of
_____________. ___________ are bone forming cells. __________ are responsible for the destruction of bone.
Osteocytes
Osteoblasts
osteoclasts
The action of osteoblasts and osteoclasts constantly _______ bone
remodels
Osteoblasts secrete _______ which becomes mineralised over time.
Osteoid
After a break the remodelled bone is known as ________ bone.
woven
What are pain receptors known as?
Nociceptors
The _____________ tract is involved in pain perception.
Spinothalamic
The two types of nociceptors are _______ fibres and _______ fibres. _______ fibres are myelinated while ___ fibres are unmyelinated therefore ______ fibres have a higher conductance velocity. ____ fibres respond to all noxious stimuli whereas ___ fibres only respond to noxious mechanical and heat stimuli.
Adelta-fibres C-fibres Adelta C Adelta C Adelta
Inflammatory pain is brought about by inflammatory _________. This results in heightened pain sensitivity to noxious stimuli (____________) and innocuous stimuli (________________).
mediators
hyperalgesia
allodynia
Identify 5 different categories of physical pain
nociceptive inflammatory referred neuropathic dysfunctional
Define enthesis
The point at which ligaments/tendons join to a bone
What makes up the tendons of muscles?
The combination of the perimysium and the epimysium
