Week 1- MSK science Flashcards by Jonny McClung

Are skeletal muscles myogenic or neurogenic?

Neurogenic

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What makes up a motor unit?

A single alpha motor neuron and all the skeletal muscle that it innervates.

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If a motor unit has a large number of muscle fibres which purpose is more likely? Precision or power?

Power

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Rank in order of size the following (smallest to largest):
muscle 
myofibril
muscle fibre (cell)
sarcomere

sarcomere
myofibril
muscle fibre
muscle

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Between which lines is a sarcomere measured?

Z lines

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What is excitation contraction coupling?

Where the surface action potential triggers calcium ion release from the sarcoplasmic reticulum.

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What complex is removed by Ca2+ ions in muscle contraction?

Troponin-tropomyosin complex

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______ is necessary to transport Ca2+ ions back into the __________ __________.

ATP

Sarcoplasmic Reticulum

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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.

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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

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____________ muscle unit ___________ during submaximal contraction helps prevent muscle fatigue.

asynchronous

recruitment

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Stronger muscle contraction is brought about by stimulation of more motor units. What is this known as?

Motor Unit recruitment

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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

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What type of muscle cannot be tetanised?

Cardiac muscle

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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

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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

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Skeletal muscle tension is conveyed to bone via the stretching of _______/________ _____ of muscle.

tendon

connective tissue

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Name the two types of skeletal muscle contraction

Isotonic

Isometric

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What is the difference between isotonic/isometric contraction?

isotonic- tension remains constant, muscle length changes

isometric-tension develops at constant muscle length

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Give two examples of isotonic and isometric contraction

isotonic- lifting objects, body movements

isometric- supporting objects in fixed positions, maintaining posture

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the greater the velocity of shortening the _______ the load

lighter

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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

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Define a reflex action

A stereotyped response to a specific stimulus

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stretch reflexes resist passive change in ________ _______ and so they maintain optimum muscle length

muscle length

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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

Week 1- MSK science Flashcards

(79 cards)