Transcript Nerves, Muscles and how they work

Muscles and how they work
LCSC06
Emily Burtenshaw
[email protected]
A reminder
• The directed study and reading are as
important as the lectures in helping you to
meet the learning outcomes of the module
• The learning outcomes are assessed in the 2
exams.
www.biologycorner.com
What is a motor neuron?
• They are efferent/afferent neurons which
control voluntary muscle.
• Voluntary muscle is also known as……muscle
and looks………under the microscope.
• Is a motor neuron a fast or slow transmitter?
www.nvo.com
Motor Unit
• Is comprised of a single nerve fibre,
neuromuscular junction(s) and nerve fibre(s)
• Motor Unit = The number of fibres in the
muscle innervated by a single neuron
• This determines the precision of movement
possible, as well as the force of contraction;
more precise control possible with a low ratio
Facial muscles, tongue, muscles of
mastication and larynx
• Have a low ratio of nerve fibre: muscle fibres
• Enables high degree of precision in movement
• Contrast this with larger limb muscles, or muscles to
control posture
• Larynx 1:6-12
v
Hip 1:2000
• https://www.youtube.com/watch?v=v9Wdf-RwLcs
Christopher, 6: Myasthenia gravis
For more info: www.mga-charity.org
• https://www.youtube.com/watch?v=XdpW5R
Mp-T0
• Directed study:
• What is the name of the medication available
to help with the symptoms of MG? how does it
work?
Muscles and how they contract:
• Directed study: read page 42-48 in Atkinson &
McHanwell or find relevant pages in other
texts.
• Watch the videos below (it is recommended
you do so in the order given):
• First, an overview of the musculoskeletal
system
• http://www.youtube.com/watch?v=NP29ejPr
OPE
More animations of muscle contraction – the
first is an overview, the rest should be viewed in
the sequence given:
• https://www.youtube.com/watch?v=CepeYFv
qmk4
• https://www.youtube.com/watch?v=y7X7IZ_u
bg4
• https://www.youtube.com/watch?v=8wa04qY
saps
• https://www.youtube.com/watch?v=Ct8AbZn
_A8A
Finally, read the relevant sections in
the link below:
• https://benchprep.com/blog/ap-biologyanimal-systems-vii-musculoskeletal-systempart-2/
Now try and answer these exam
questions
1) True/false:
1) actin is a long, thin molecule
2) The sarcoplasmic reticulum is the repository for Na+
ions
3) A myofibril contains many muscle fibers
3) Draw and label a sarcomere.
4) What role does ATP play in muscle contraction?
5) Name the disease which is characterised by
damage to the sarcolemma.
6) TRUE or FALSE:
a. the actin filament has a binding site for
the myosin filament
b. In the resting state, ATP is bound to a
region on the actin filament
c. when Sodium (Na+) enters the
sarcoplasmic reticulum, this results in the
binding site being exposed on the actin filament.
7) Describe what happens during the power stroke
phase of contraction. What happens to cause the
filaments to slide in relation to one another?
8) What is the name of the energy carrying
molecule involved in the process of muscle
contraction?
9) How does this release of energy result in the
relative movement of the actin and myosin
filaments?
www.nvo.com
www.completemuscletraining.blogspot.com
Sensory supply to muscles
• 40% of nerve supply for muscle is sensory in
nature
• Sends information re range, rate and force of
contraction, and position of muscle
• a. Proprioception = an awareness of body
position and movements of parts of the body
• b. Kinaesthesia = awareness of body motion
a. Proprioceptors
• Muscle spindles
• Tendon organs (Golgi tendon organs)
• Joint kinaesthetic receptors
Muscle spindles
Tendon organs
b. Joint kinaesthetic receptors
• Some are in the capsule of a joint and respond
to pressure
• Some are in the connective tissue outside the
capsule and respond to
acceleration/deceleration of joint movement
• Ligaments contain receptors similar to tendon
organs
• https://www.youtube.com/watch?v=FKxyJfE8
31Q
More sample exam questions:
• What is the sarcoplasmic reticulum and what
is its main function in muscle cell contraction?
• What is meant by a motor unit?
• Compare the innervation of the facial muscles
with that of the limbs, with reference to the
motor units involved.
• What is the function of the joint kinaesthetic
receptors?
What to do next:
• Ensure you have answered the directed study
questions posed in this lecture
• Do some reading in preparation for next week
(see timetable week 7): the Big Picture (the
organisation of the nervous system)
• Chapters 6 and 8 in Atkinson & McHanwell; Seikel
et al, Chap 11; Richards, Clark & Clarke, chap 1;
Manasco, Chap 2