Download Skeletal Muscles

Biomedicine: Human Sciences
Lecture 3:
Muscular System
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Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
Learning Outcomes
In today’s topic you will learn:
Ø Have knowledge and understanding of the structure, function, types of muscles in the human body.
Ø Be able to identify major muscles of the body and recognise their functions
Ø Knowledge of common muscular pathologies. http://www.endoszkop.com/
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Function
1. Movement –a result of muscular contraction and relies on the integrated functioning of the muscles, bones and joints.
1. Posture - stabilising joints, posture and balance through continual partial contraction of muscles.
2. Heat production - This process is called thermogenesis and helps maintain normal body temperature. (Shivering = involuntary contractions of the skeletal muscle)
3. Glycogen storage – energy (glycogen) and oxygen
4. Movement of substances: – Sphincters prevent out-flow from hollow organs (stomach and bladder).
– Smooth muscle in blood vessel walls helps control blood flow
– Smooth muscle contractions move food through the gastrointestinal tract (GIT), urine through the urinary system and gametes through the reproductive system.
– Skeletal muscle: diaphragm – draws air into airways/lungs
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Muscle Properties
1. Contractility – ability to contract (shorten).
2. Excitability – the ability to generate an electrical current. Nerve impulses also called action potentials are triggered by electrical signals or chemical stimuli (neurotransmitters, hormones) which causes the muscles to contract.
3. Extensibility – ability to stretch without being damaged.
4. Elasticity – can return to it’s original length and shape after contraction or extension (spring)
http://cinak.com/
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Muscle Properties
http://cinak.com/
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Muscle Types
Striated = From Latin ‘stria’ meaning furrow
1. STRIATED - cells are aligned in parallel bundles, so that their different regions form stripes visible with a microscope.
•
SKELETAL: voluntary muscle attached to bone & cartilage. •
CARDIAC: involuntary heart muscle = autorhythmic (auto = automatic, rhythmic = recurring regularity). http://www.kidsbiology.com/human_biology/muscles2.php
2. NON-STRIATED - randomly arranged cells (no stripes visible)
• SMOOTH: involuntary muscles in the walls of hollow organs, blood vessels etc. (i.e pupil constriction/dilation). Smooth muscle does not tire
http://www.mhhe.com/biosci/ap/histology_mh/nonstria.html
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Muscle Types
https://prezi.com/br7nbxpsahcs/tissue-types-sneed/
http://www.sciencelearn.org.nz/
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Muscle Anatomy
What might happen to muscles at puberty?
• Muscle is made up of cells called muscle fibres (myocytes)
• Muscle fibres are formed from the embryonic fusion of myoblasts so each muscle fibre (skeletal muscle cell) has many nuclei. • Once mature (fused) they can no longer undergo mitosis.
• Limited regeneration – by satellite cells.
my(o) is Greek, of or relating to muscle
cyt(o) is Greek for cell
blast(o) is Greek, for germ / bud hyper is Greek for beyond normal trophy is Greek for development • This means that the number of skeletal muscle fibres each person has is set at birth
• In contrast muscles can develop by:
• Hypertrophy = enlargement of existing fibres, induced by strength training.
• Atrophy = wasting. Associated with immobility, inactivity, injury and old age.
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Skeletal muscle
• 640 skeletal muscles in the body
• Comprises on average 40% of our body weight
• Under voluntary control (for the most part)
• Permits voluntary movement: • Motion and posture
• Speech (larynx, lips, tongue)
• Breathing
• Covered by fascia – dense sheet of connective tissue that organises muscle, secures it to skin and provides stability. Collagen is a major component. Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Video: Muscular Dissection
Lesson 1: Movement
https://www.youtube.com/watch?v=kbyUzsHP3Po
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Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
Skeletal Muscle Hierarchy
http://moodle2.rockyview.ab.ca/mod/book/view.php?id=52001&chapterid=25486
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
Skeletal Muscle Cells
• Sarcolemma = plasma membrane of a muscle cell • Transverse tubules = tubes extending from the plasma membrane surface into muscle cell.
• Sarcoplasm = muscle cell cytoplasm. Arranged as sarcoplasmic reticulum (SR). A tubular network that circulates cytoplasm. sarco is Greek for muscular
plasm – Greek for plasma – a semifluid translucent fluid
my(o) is Greek relating to muscle
globin from Latin globus - a sphere. Globin in biology is protein
fibril is Latin relating to fibre/filament
• Within the SR there are tiny sacs called terminal cisterns (which store calcium)
• Myoglobin = red coloured oxygen binding proteins present in sarcoplasm.
• Many mitochondria – located close to myoglobin
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https://www.studyblue.com/notes/note/n/muscle-tissue/deck/15713823
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
Skeletal Muscle Cells
• Action potentials travel through the sarcolemma and transverse tubules spreading through the muscle to cause contraction.
• Myofibrils are contractile threads arranged in a striated pattern:
• Each myofibril is surrounded by a network of sarcoplasmic reticulum.
• Made up of smaller filaments called myofilaments:
• Made up of protein molecules called actin (thin) and myosin (thick). • Overlap to form sarcomeres.
• ‘A bands’ = dark area where myofilaments overlap. myo = muscle
fibril is Latin relating to • ‘I bands’ = light area of only actin filaments
fibre/filament
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Repeated banding pattern forms striations
One sarcomere
sarco is Greek for muscular
mere from Latin meaning part H = Myosin only
A = Actin and Myosin
I = Actin only
https://www.studyblue.com/notes/note/n/other-structural-components-of-skeletal-muscle/deck/1411879
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Muscle Connective Tissues
• Muscles are surrounded by lots of connective tissue
• Collagen fibres in connective tissue assist to intermingle with other structures - tight connections transfers force better.
• Vessels pass through connective tissue to deliver blood.
1. Epimysium: Wrapped around entire muscles. Anchor point for fascia/tendons/ligaments.
2. Perimysium: Surrounds groups/bundles of 10-100 muscle fibres, forming fascicles
3. Endomysium: Thin sheath around individual muscle cells. epi = ‘upon’ or ‘over
peri = ‘around’
endo = ‘within’
mysium = muscle
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http://droualb.faculty.mjc.edu/course%20materials/elementary%20anatomy%20and%20physiology%2050/lecture%20outlines/skeletal_muscle_physiology.htm
Muscle Connective Tissues
epi- ;Greek, before, upon, on
peri-; Greek, denoting something with a position 'surrounding' endo-; Greek; denotes something as 'inside' or 'within‘
my(o) is Greek for relating to muscle
http://biologyonline.us/Online%20Human%20Biology/Northland/HB%20Lab/HB%20Lab%205/29.htm
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Neuromuscular Junction (NMJ)
Neuro – Greek for pertaining to nerves / muscular- pertaining to muscle
• Neuromuscular junction: the meeting point (synapse) where motor neurons meets motor end plate (muscle fibre).
• The axon of the neuron divides into synaptic end bulbs. Within synaptic end bulbs there are vesicles containing the neurotransmitter Acetylcholine
• Motor end plate: termination of motor neurons in minute pads on the muscle fibre. • Acetylcholine crosses the junction gap and opens post-synaptic channels (sodium) triggering action potential to continue along the sarcolemma.
• Motor unit: 1 nerve and its corresponding muscle fibres (between 1-1000)
• Strength of muscle contraction depends on the number of motor units in action at one time as well as the frequency of nerve impulses at which they are stimulated.
• When a motor unit responds to a single nerve impulse by contracting and relaxing we call this a ‘twitch’.
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Neuromuscular Junction (NMJ)
Video: Neuromuscular Junction
www.youtube.com/watch?v=CLS84OoHJnQ
https://online.science.psu.edu/biol141_wc/node/7548
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Sliding Filament Theory
Contraction:
sarco is Greek for muscular
plasm – Greek for plasma – a translucent fluid
1. Action potential arrives at the neuromuscular junction.
2. The action potential spreads along the sarcolemma and transverse tubules in to the muscle cell releasing calcium (Ca2+) from storage (sarcoplasmic reticulum) 3. Calcium & adenosine triphosphate (ATP) trigger myosin to bind to the actin filament next to it so that the filaments slide over each other thereby shortening the fibre (exposes heads)
• If enough fibres are stimulated at once the whole muscle will contract
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Sliding Filament Theory
http://www.thealevelbiologist.co.uk/the-sliding-filament-theory-of-muscle-contraction
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Sliding Filament Theory
http://legacy.owensboro.kctcs.edu/gcaplan/anat/notes/api%20notes%20j%20%20muscle%20contraction.htm
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Sliding Filament Theory
Relaxation:
1. Nerve stimulation stops: no action potential
2. Using magnesium (Mg) & ATP, Calcium is actively transported (pumped back) into storage, breaking the actin & myosin bond.
3. Actin & myosin slide back into starting positions, lengthening the fibre again = relaxation.
• Magnesium makes muscle fibres less excitable and prevents myosin binding with actin.
Video: Sliding Filament www.youtube.com/watch?v=hr1M4SaF1D4
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Muscle Metabolism
“The breakdown (or production) of compounds to produce
energy in the form of ATP for all bodily functions”
• “How we transform the food (glucose, fatty acids and amino acids) we eat into energy”
• Muscles require a good blood supply
• Blood provides oxygen & nutrients as well as removing waste
• Muscle contraction requires large amounts of ATP
• ATP is derived from breakdown of carbohydrates (glucose), fats and proteins. • ATP is converted into energy & heat.
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Muscle Metabolism
Muscle fibres have three ways of producing ATP:
ATP = adenosine triphosphate
1. Creatine phosphate (unique to muscles): 15 seconds
An- is Greek without
• Resting muscles store excess ATP as creatine phosphate Aerobic = with oxygen
• 3 - 6x more creatine phosphate in a muscle cell than ATP.
• During muscle contraction when ATP is used up, creatine phosphate is used to regenerate the ATP so contraction can be sustained for longer
2. Anaerobic respiration: 30 seconds of intense muscle activitiy
• Absence of oxygen
• Net production of 2 ATP + lactic acid
• Occurs via glycolysis (breaking down of glucose) 3. Aerobic respiration: hours of activity
• With oxygen
• Produces 38 ATP (36 net production) + water + carbon dioxide (CO2) – glucose, fats & protein metabolism
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Types of Skeletal Muscle
my(o) is Greek, of or relating to muscle
globin from Latin globus - a sphere. Globin in biology is protein
White muscle fibres
Less myoglobin
Red muscle fibres
Lots of myoglobin
more mitochondria
greater blood supply
Appear lighter (e.g. breast meat on a chicken)
Appear darker (e.g. leg meat on a chicken)
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Types of Skeletal Muscle
Fibre Type
Fibre name
Type I Fibres
SLOW TWITCH
Slow oxidative
Type IIa fibres
FAST TWITCH Fast oxidative – glycolytic
Type II b fibres
FAST TWITCH Fast glycolytic
Diameter
Small
Intermediate
Large
Colour Dark red (high myoglobin & mitochondria)
Dark red (high myoglobin, capillaries & GLYCOGEN)
White (low / no myoglobin, fewer capillaries & mitochondria)
Type of Respiration
Aerobic respiration (oxidative metabolism generates ATP)
Aerobic respiration (oxidative metabolism generates ATP)
Mainly Anaerobic respiration
Power
Least powerful (major storage fuel is triglycerides)
Medium power (major storage Most powerful (major storage fuel fuel is creatine phosphate & is glycogen)
creatine phosphate & glycogen)
Contraction type
Slowest contraction
Faster contraction
Quick & strong
Duration
Longest duration
Resistant to fatigue
Fatigue quickly
Good for:
Endurance
Walking & sprinting
Weight training / power training
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Types of Skeletal Muscle
• Most skeletal muscles are a mixture of muscle fibres in varying proportions
Ø Shoulders /arms: high amount of fast glycolytic
50% are Slow
Ø Legs & back (postural): fast oxidative-glycolytic and slow oxidative
Oxidative
• Relative ratio SO:FG fibres (and tendon/ligament elasticity) is genetically determined accounting for individual differences in physical performance.
• Proportions vary depending on the individual and their training/lifestyle
• Exercise can cause muscle fibres to change:
Ø Endurance training converts fast glycolytic to fast oxidative – glycolytic ( diameter and no. mitochondria, blood supply)
Ø Strength training increases the size & strength (hypertrophy) of fast glycolytic fibres
hyper is Greek for beyond normal trophy is Greek for development
glyco- sugar
-lytic from Latin to release
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QUIZ: What am I?
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
I am a red protein that binds oxygen in myocytes
I am an invagination into a muscle cell to assist in action potential conduction
I am the larger of the two proteins that form the myofilament structure
I am connective tissue that surrounds the entire muscle and anchors it to other structures
I am the molecule/structure that stores ATP in myocytes Slow oxidative muscle fibres are this colour
I am the largest type of muscle fibre, with low levels of myoglobin, but large amounts of glycogen stored that can be used for respiration
I am a method of ATP production that produces a net of 36 ATP molecules from 1 glucose
I am a type of cell in skeletal muscles that provides some regeneration capacity
I am the structure inside a muscle cell that stores calcium
Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Skeletal Muscles: Face
•
The names of most skeletal muscles describe some of their key features e.g. size, shape, action, number of origins, location, sites of origin or insertion.
Name Function /Action Occipitofrontalis
Occipit – of the occiput (back of head)
Frontalis = front
Raises eyebrows
Orbicularis oculi
Orbi = circular, Ocul = eye
Closes eyes
Orbicularis ori
Orbi = circular, Or = mouth
Closes/pouts lips Masseter Mastication i.e. elevates & protrudes mandible / closes the jaw
Temporalis
Mastication
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Skeletal Muscles: Face
Occipitofr
ontalis
Orbicularis Oculi
Te
mp
Orbicularis Oris
ora
lis
Masset
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Skeletal Muscles: Neck
Name Sternocleidomastoid:
Sterno = sternum Cleido = clavicle Mastoid = mastoid process of the temporal bone Function /Action Turns & tilts head
Trapezius: Pulls head backwards. Trapezi = trapezoid shape Elevates, retracts and depresses shoulders
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Skeletal Muscles: Back
Name Function /Action Supraspinatus (one of the rotator cuff muscles)
Initial abduction of shoulder
Psoas
Hip flexor: pulls thigh towards trunk Latissimus Dorsi
Latissimus = widest
Dorsi = of the back
Extends, adducts & medially/internally rotates arms
Quadratus Lumborum
Quad = four, Lumbo = lumbar region
Attached to 4 lumbar vertebrae
Bending backwards (vertebral extension)
Bending sideways (lateral flexion)
Erector Spinae (muscle group)
Erector = erect, Spinae = spine
Extension of the vertebral column
Keeps spine upright
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Skeletal Muscles: Back
Erector Spinae Latissimus Dorsi
Psoas
Quadratus Lumborum
http://www.corpshumain.ca/en/muscle_dos_en.php
http://www.musclesused.com/erector-spinae-2/
http://corewalking.com/psoas-quadratus-lumborum/
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Skeletal Muscles: Chest & Abdomen
Name Function /Action Pectoralis Major
Pector = chest, Major = largest
Attaches from clavicle & sternum
to humerus
Rectus Abdominis
Rectus = fascicles parallel to midline
Abdominis = of the abdomen
Attaches from pubis to lower sternum and ribs
Draws arms forward:
Shoulder flexion & adduction
Medial rotation
Transversus Abdominis Transversus = across
Abdominis = of the abdomen Compresses abdominal organs
Increased IAP
Internal & External Obliques
Internal = inner, external = outside, Rotation, bending sideways
Vertebral flexion: bending forward (“crunches”)
Increased Intra-abdominal pressure (IAP)
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Skeletal Muscles: Chest & Abdomen
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Respiratory Diaphragm
Name Diaphragm
Attaches to the lower 6 ribs, sternum and upper lumbar spine
Function /Action When contracts, it descends into the abdominal cavity, increasing the space for air to enter in the lungs (moves down concentration gradient)
http://www.inpursuitofyoga.com/blog/2015/3/11/chest-breath-vs-belly-breath
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Skeletal Muscles: Arm
Name Function /Action Deltoid
Attaches from the scapula, acromion and clavicle to the humerus
Flexion, abduction & extension of shoulder joint
Biceps Brachii
Biceps = two heads, Brachii = arm
Attaches from the scapula to the radius
Stabilizes shoulder joint, flexion & supination of forearm
Triceps Brachii: Triceps = 3 heads of origin – 2 on humerus, 1 on scapula
Brachii = arm
Arm adduction, extends elbow Flexor Carpi Ulnaris Attaches from the humerus to the carpal bones
Flexes the hand at the wrist joint (supination)
Ulnar deviation (adducts)
Extensor Carpi Radialis (Longus & Brevis) Extensor = increase angle, Carpi = wrist
In
Extend the hand at the wrist joint
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Skeletal Muscles: Arm
Deltoid
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Skeletal Muscles: Legs
Name Function /Action Gluteus Maximus Glute = buttock, Maximus = largest
Attaches from the ilium (pelvis) to the femur
External rotation, abduction and extension of the hip joint
Gluteus Medius
Attaches from the ilium (pelvis) to the femur
Abducts leg, Stabilises pelvis
Hamstrings: 3 separate muscles
1.Biceps Femoris 2.Semi-membranosus 3.Semi-tendinosus
Rectus Femoris
(One of 4 quadricep muscles)
Attaches from the ilium (pelvis) to the tibia (via patella ligament)
Bend knee (Flex knee)
Flexes hip
Extends knee “kicking a football”
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Skeletal Muscles: Legs
Name Function /Action Thigh Adductors
Attaches from the pubis to the femur
Squeeze the thighs together
Tibialis Anterior: Front of tibia
Attaches from the tibia to the metatarsals
Dorsiflexion and inversion of the foot
(& supports medial arch of foot!)
Soleus
Attaches from the posterior tibia & fibula to the calcaneum (heel bone)
Plantar flexion of the foot at the ankle. Stabilising ankle Gastrocnemius
Gastro = belly, cnem = leg
Attaches from the femur to the calcaneum (heel)
Flexes leg at the knee
Plantar flexion of foot
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Skeletal Muscles: Legs
Gluteus Maximus & Minimus Rectus femoris
The hamstrings..
https://healingbyyang.com/low-back-pain/
http://www.dailybandha.com/2014/06/the-rectus-femoris-muscle-in-yoga.html
http://www.footmechanicspodiatry.co.nz/problems/leg-pain/hamstring-tear/
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Skeletal Muscles: Legs
Soleus
Adductor longus Gastrocnemius
(deep to the gastrocnemius)
Tibialis Anterior
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Skeletal Muscles
SOURCE: http://www.e-missions.net/cybersurgeons/?/musc_teacher/
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Skeletal Muscle Mechanics
• Tendons attach the muscle to bone (periosteum)
• Fleshy part of a muscle is called the belly
• When tendons span across a joint they can produce movement (i.e. flex or extend the joint).
http://imgarcade.com/1/triceps-origin-and-insertion/
• When fibres contract the muscle becomes thicker & shorter.
• This exerts a force on the tendons which pull on bones producing movement.
• Unlike ligaments, tendons are inelastic. Allowing the full force of muscle contraction to be transferred onto the bone.
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Skeletal Muscle Mechanics
• When skeletal muscle contracts it pulls one articulating bone towards a stationary bone.
• Some sources describe muscle attachment points as origins and insertions. However, due to debate as to which point is what, they are now often simply referred to as attachments.
• Muscles that move a body part often do not cover that body part e.g. bicep – moves forearm.
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Skeletal Muscle Mechanics
• Movements are the result of several skeletal muscles acting as a group.
• Muscles can be prime movers, antagonists, synergists and fixators - depending on the movement.
• Most skeletal muscles are arranged in antagonistic pairs on opposite sides of the joint.
• Depending on the movement one muscle is the prime mover, the other the antagonist.
• A synergist muscle assists the prime mover in it’s action e.g. when flexing the bicep, the brachialis also helps by pulling the ulna towards the humerus.
• A fixator is a muscle that keeps the origin (anchor) bone stable while a prime mover contracts. Mostly found within the hip and shoulder joints.
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Skeletal Muscle Mechanics
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Cardiac Muscle
myo = muscle
cardium = heart
Inter = between
calate = ‘to proclaim’
http://sciencelearn.org.nz/Contexts/Sporting-Edge/Sci-Media/Images/Cardiac-muscle
• Specialised muscle only found in the heart. It forms the myocardium
• Fibres are striated http://www.cytochemistry.net/microanatomy/muscle/striated_cardiac_muscle.htm
• Intercalated discs: This interconnection of fibres allows contraction to spread from cell to cell like a wave. Unique to cardiac muscle.
• Has endomysium & perimysium but no epimysium
• More and larger mitochondria, less sarcoplasmic reticulum
• These fibres have a branched shape, so each cell is in contact with 3-4 other cells
http://bio1152.nicerweb.com/Locked/media/ch40/muscle-cardiac.html
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Cardiac Muscle
• Cardiac muscle stays contracted 10-15 times longer than skeletal muscle – calcium channels stay open for longer.
• Cardiac muscle contracts when stimulated by it’s own autorhythmic muscle fibres (about 75 times a minute at rest). auto = automatic
rhythmic = recurring regularity
What is another input
affecting the rate of cardiac
muscle contraction?
• Under involuntary control
• Cardiac muscle depends mainly on aerobic
respiration – requires a constant supply of oxygen.
• Can also use lactic acid to produce ATP
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Smooth Muscle
• Found in walls of blood vessels, airways, hollow organs (i.e. stomach), as well as the iris and arrector pili in the skin.
arrector = Latin for ‘to raise’
pili = latin for Hair
• Used to change diameter, shape or orientation of the tissue.
• Under autonomic nervous system control (involuntary)
• Also contracts in response to hormones, paracrine (cell-to-cell) signalling, and local chemical agents.
http://io9.gizmodo.com/5966571/why-do-your-pupils-get-larger-when-youre-on-drugs
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Smooth Muscle
• Each fibre is just 30 - 200 micro-metres long with a single nucleus (central)
• Non-striated: filaments are not arranged into orderly sarcomeres – giving it a smooth appearance.
• Filaments are attached to structures called dense bodies (similar function to Z-discs in skeletal muscle)
• During contraction the dense bodies are pulled closer together by the filaments causing the muscle to shorten & twist like a corkscrew.
• No T-Tubules and small amount of SR
http://medicalterms.info/anatomy/Smooth-Muscle/
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Smooth Muscle Types
1. Visceral / single unit:
• Found in the walls of vessels and hollow viscera e.g. stomach, arterioles, veins & venules, bladder etc.
• Auto-rhythmic
• Fibres connected by gap junctions to allow action potential to spread through the muscle.
• One stimulus causes contraction of many adjacent fibres together - functioning as a single unit.
2. Multi unit:
• Found in walls of large arteries & airways; iris & ciliary body that focuses lens of the eye and in arrector pili muscles in hair follicles.
• Fibres are stimulated individually & operate independently from each other.
https://www.studyblue.com/notes/note/n/muscle-physiology/deck/11561636
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Smooth Muscle
https://uk.pinterest.com/pin/210191507584664470/
http://flylib.com/books/en/2.953.1.41/1/
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Smooth Muscle
PROPERTIES:
• Slower and longer contractions – takes longer for calcium to get in and out of muscle cells (no T tubules). •
Shorten and stretch more than skeletal muscle.
•
Produce ‘Stress-relaxation response’ – allow organs such as stomach and bladder to expand when filled, causing a contraction in order to carry contents.
•
Continues partial contraction/tonicity (important for blood pressure regulation)
CONTRACTION in response to:
• Action potential from the autonomic nervous system.
• Stretching
• Hormones e.g. adrenaline
• pH, O2 and CO2 levels, temperature, ion concentration
what effect does
adrenaline have on
smooth muscle in
airways and blood
vessels?
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Muscle Types
Have a go at adding
more comparisons to
this table…
Skeletal
Cardiac
Smooth
Voluntary
Involuntary
Involuntary
Striated
Striated
Non-striated
Multinucleated
Single nucleus
Single nucleus
Contains T tubules
Contains T Tubules
No T Tubules
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Muscle Regeneration
hyper is Greek for beyond normal
trophy is Greek for development -plasia; Greek, formation or development
Skeletal Muscle • Cells can’t divide!
• Growth occurs by hypertrophy - enlargement of existing cells.
• Limited regeneration by satellite cells (muscle precursor cells) – when damage occurs, they divide slowly & fuse with existing fibres to assist muscle repair.
Smooth Muscle
• Can undergo hypertrophy. • Can also undergo hyperplasia - new muscle cells can be generated from pericytes - stem cells in capillaries & veins. peri- is Greek for 'surrounding' • Some areas retain capacity for division eg. Uterus
cyto is Greek for cell
Cardiac Muscle
• Can regenerate under certain circumstances (cardiac stem cells in endothelium).
• Can also hypertrophy – enlarged hearts.(athletes and heart disease)
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Homeostasis Within all body systems muscle tissue:
• Produces movement. • Stabilises body position. • Move substances within the body.
• Produces heat to help maintain body temperature.
Integumentary system (skin)
– Facial expression.
– Muscle action increases blood flow to skin.
Skeletal system
– Movement.
– Joint stability.
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Homeostasis Nervous system
• Muscle carries out commands of the nervous system.
• Shivering – generate heat and raise body temperature.
Endocrine (glands & their secretions – hormones)
• Exercise can improve action of some hormones e.g. insulin
• Muscle protects some endocrine glands.
Cardiovascular
• Cardiac muscle pumps heart.
• Smooth muscle in blood vessel walls controls blood flow.
• Muscle contraction in legs helps return blood to heart.
• Exercise leads to hypertrophy of cardiac muscle = increased efficiency.
• Lactic acid produced in skeletal muscle can be used to make ATP in the heart.
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Homeostasis Lymphatic (the interconnected system of spaces and vessels between body tissues and organs by which lymph circulates throughout the body)
• Muscle protects lymph nodes and vessels.
• Promotes lymph flow.
• Exercise can increase or decrease immune response.
Respiratory (organs, collectively, concerned with breathing / respiration)
• Respiratory muscle facilitate airflow in and out of lungs.
• Smooth muscle adjusts airway size.
• Skeletal muscle in larynx controls air flow past vocal cords – changes voice.
• Coughing and sneezing – clears airways.
• Exercise improves breathing efficiency.
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Homeostasis Digestive
• Skeletal muscle protects and supports digestive organs.
• Chewing and swallowing.
• Smooth muscle sphincters control volume of GIT organs.
• Smooth muscle in intestinal wall helps mix contents and move it through digestive system.
Urinary
• Smooth muscle sphincter and smooth muscle in. • Wall of bladder control stored and release of urine.
Reproductive
• Skeletal and smooth muscle contractions eject semen. • Smooth muscle contraction propel egg along uterine tubes, control menstrual flow and expel baby from uterus in childbirth. • Skeletal muscle contractions are associated with orgasm.
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Activity
• Get into groups of 3. Choose 1 person to model.
• Please identify the following muscles on the body surface:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Sternocleidomastoid
Trapezius
Pectoralis major
Rectus abdominis
Gluteus maximus
Deltoid
Triceps brachii
Rectus femoris
Tibialis anterior
Gastrocnemius
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Muscle Pathologies:
Muscle Fatigue and Shortening
Muscular Fatigue
• Muscle fibres can fatigue if overused • Common in sports, occupational overuse and poor posture
• Cell respiration becomes anaerobic and by-products such as lactic acid can cause pain
Muscle Shortening
• If a muscle is continuously contracted, the actin-myosin filaments remain attached
• Chronic muscle contracture causes muscle fatigue but also places a strain on the muscles skeletal attachments • For example, a ‘stressed’ individual commonly sustains prolonged contraction of the upper trapezius muscle fibres. As this muscle attaches to the cervical vertebrae, this may cause a strain of these joints and possibly even lead to headaches
http://www.popsugar.com/fitness/Relax-Already-Stiff-Neck-Shoulders-Gone-1845331
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Muscle Strain and Tear
MUSCLE STRAIN: • Over-stretching of muscle fibrils or the tendon. Occurs when a •
•
•
•
•
joint is forced beyond its normal range. The muscle remains whole
Blood supply to muscle is still sufficient to provide good healing Activated satellite cells divide slowly and fuse with existing fibres Commonly call strains "pulled" muscles. Hamstring and back overstraining injuries are common
MUSCLE TEAR:
• More significant
• The muscle tears - no longer whole!
• Can cause local separation of the tissue & defective blood supply.
• Preventing natural complete healing.
• Complication: muscular fibrosis Why do muscle
tears often
cause bruising?
http://triathlete-europe.competitor.com/2011/11/07/expert-advice-did-i-pull-or-tear-a-muscle
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Muscle Strain and Tear
TREATMENTS:
• RICE: Rest, ice, compression, elevation
• Herbal medicine (pain, inflammation, connective tissue repair), acupuncture, homeopathy (arnica), nutritional support (anti-inflammatory & tissue repair).
• If torn, avoid heat, exercise, massage
http://triathlete-europe.competitor.com/2011/11/07/expert-advice-did-i-pull-or-tear-a-muscle
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Impingement Syndrome
• The rotator cuff tendons connect the humerus and scapula. Together the group of muscles abduct and rotate the shoulder
Syndrome: a group of symptoms that indicates or or characterises a disease
• The space between the humeral head and the roof of the shoulder (acromion) is called the sub-acromial space. This contains one main bursae and the rotator cuff tendons.
• These tendons and/or bursae can become inflamed and torn
• Normally, when moving the shoulder, the structures have to maneuver intricately to prevent impingement.
• If the tendons or bursae become inflamed/damaged, these movements can be painful http://www.ortho-md.com/procedures/subacromial_decompression.html
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Impingement Syndrome: Rotator Cuff
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http://www.mayoclinic.org/diseases-conditions/rotator-cuff-injury/home/ovc-20126921
Impingement Syndrome
CAUSES: • Overuse & working with the arms raised overhead • More common with increasing age as blood supply is poor and the tendons degenerate • Positional fault – when the head of the humerus does not sit perfectly in the socket
• Bone spurs - can reduce the space available for the bursa and tendons to move under the acromion.
• Oddly sized acromion resulting in reduced space.
http://www.parkclinic.com.au/home/conditions-treatment/shoulder/shoulder-impingement/
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Impingement syndrome
SIGNS & SYMPTOMS:
• Shoulder ache in early stages
• Pain, mostly when abducting the shoulder or rotating (ie. Reaching into back pocket)
• Painful arc of movement
• A catching sensation is felt on lowering the arm. • Weakness and inability to raise the arm may indicate rotator cuff tear.
http://www.southmountainrehab.com/extra/news/shoulder_impingement_syndrome.php
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Impingement syndrome
TREATMENT: • Manual therapy, exercise
• Cortisone injection, anti-inflammatory drugs, surgery
ALTERNATIVE TREATMENT: • Herbal medicine, acupuncture, homeopathy (arnica), nutritional support (anti-inflammatory).
Video: Shoulder Impingement:
www.youtube.com/watch?v=vARsKXb7wNc
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Fibromyalgia
Fibro = fibrous tissue
-algia = painful condition
myalgia = muscle pain
• Widespread muscular and connective tissue pain, joint stiffness and fatigue (a chronic pain syndrome) • Often accompanied by multiple, unexplained symptoms, anxiety, depression and functional impairment of daily activities.
• An absence of objective findings on physical examination and usual clinical investigations (makes it still a controversial diagnosis) • Has a neurophysiologic basis, characterised by abnormalities in pain processing by the central nervous system (CNS). • A form of “Central allodynia”: pain perception to stimulus not normally painful.
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Fibromyalgia
Criteria for diagnosis: pain on palpation must be present in at least 11 of the 18 points.
The patient experiences pain at tender points at decreased threshold compared to ‘control’ patients
But…
Biopsy: shows no tissue specificity
EMG: no specific changes in muscle tone
Drug studies: no benefit of NSAIDS or steroids over placebo but significant benefit of SSRI/SSNRI
http://www.home-health-care-physical-therapy.com/Fibromyalgia-Tender-Points.html
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Fibromyalgia
Suspected causes and triggers
• Stress/trauma (neuroendocrine / Limbic system)
• Most common in women:men (15:1) aged 25-50 years.
• Sleep dysregulation
• Post viral / chronic toxic load
• Serotonin and noradrenaline deficiencies
• High levels of substance P (nerves more sensitized to pain)
http://www.durbanrheumatologist.co.za/fibromyalgia.php
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Fibromyalgia
SIGNS & SYMPTOMS:
• Pain that results from gentle pressure at specific “tender spots”.
• Generalised tenderness & muscle contracture
• Debilitating fatigue & sleep disturbance • Difficulty with swallowing, bowel & bladder function, IBS, numbness & tingling • Anxiety and depression
• Not all people with fibromyalgia experience all symptoms.
http://www.fibrocenter.com/fibromyalgia-symptoms
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Fibromyalgia
ALLOPATHIC TREATMENT: • Medications (anti-depressants  however these do not address the cause or cure the dysfunction. Often leads to high dependency on the medications)
• Patient education, exercise, help groups, CBT, counselling
ALTERNATIVE TREATMENT:
• Acupuncture, herbal medicine, homeopathy, nutritional (nerve and muscular function, antiinflammatory).
http://www.doctortipster.com/2480-fibromyalgia-causes-symptoms-risk-factors-and-treatment.html
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Muscular Dystrophies
• Group of inherited muscular diseases that cause degeneration and weakness of muscles
• Many types
CHARACTERISED BY: • Progressive skeletal muscle weakness/atrophy
• Death of muscle cells & tissue (final stages).
• Defects in muscle proteins Copyright CNM 2016-17: Human Sciences – Muscular System. Last updated 31st August 2016. BQ.
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Myasthenia Gravis
• Autoimmune disease characterised by fluctuating muscle fatigue & weakness.
• A disease of the neuromuscular junction (NMJ).
my(o)-; Greek, of or relating to muscle -asthenia; Greek, weakness What is an
autoimmune
disease?
• Antibodies block acetylcholine receptors on the motor end plate preventing a nerve impulse being sent to muscle fibres.
• Muscle becomes weaker, until it cannot function.
• Most common in women, age 20-50.
• Muscles of face & neck are commonly affected.
https://app.emaze.com/@ACCFICOW/Myasthenia-Gravis
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Myasthenia Gravis
SIGNS & SYMPTOMS: • Weakness of ocular muscles, double vision and ptosis
Ptosis = from Greek word “Fall”
It is drooping of the upper eye lid
• Weakness in facial muscles (expressions) which spreads to the proximal limbs
• Difficulty with speech, chewing and swallowing
• Death may result from failure of the respiratory muscles.
http://www.nhs.uk/Conditions/Myasthenia-gravis/Pages/Introduction.aspx
• Worsens throughout the day
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Myasthenia Gravis
ALLOPATHIC TREATMENT: • Acetylcholinesterase inhibitors, corticosteroids to reduce effects of the antibodies (side effects! Including osteoporosis, indigestion, rapid heartbeat, nausea, insomnia, mood changes, diabetes, glaucoma)
• Plasma Exchange in severe cases, injections of normal immunoglobulins/antibodies from healthy donors
ALTERNATIVE TREATMENT: • Herbal medicine (immune modulation), acupuncture, homeopathy, nutritional (nerve and muscular function) – calcium, magnesium.
Video: Myasthenia Gravis (Ice Test)
www.youtube.com/watch?v=oetVi29_qbE
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Duchenne Muscular Dystrophy
• Caused by a single gene defect on the X-chromosome
• Affects males, females can be carriers
• Affects 1 in 3500 males. Usually diagnosed 3-5 years
• Lack of a protein called dystrophin in muscle cells.
• Dystrophin anchors the cytoskeleton to the extracellular matrix (important for cell membrane integrity). • If this protein is missing, when the cell contracts there is no support and the cell membrane becomes leaky. Allowing calcium and other extra-cellular materials to flood in.
• This results in muscle degeneration and necrosis
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https://knowledgeforall1415.wordpress.com/about/
Duchenne Muscular Dystrophy
SIGNS AND SYMPTOMS
• Delayed walking
•
•
•
•
•
Waddling gait
Clumsiness
Proximal limb weakness
Speech delay
Gowers sign
DIAGNOSIS
• Serum creatine kinase (10-100x normal)
• Genetic analysis and muscle biopsy
https://app.emaze.com/@ALCOZWFZ/Duchenne-Muscular-Dystrophy
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Duchenne Muscular Dystrophy
• All muscle types affected: skeletal, smooth and cardiac. • Small amounts of dystrophin also present in nerve cells (IQ is affected).
• Prognosis poor: usually wheelchair support needed by 10yrs and ventilation by 20. • Death occurs in late 20s primarily cardiorespiratory failure.
• Therapeutic strategies aimed at prolonging independent walking, managing scoliosis, nutrition and weight management.
https://kin450-neurophysiology.wikispaces.com/Duchenne+Muscular+Dystrophy
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DYSTROPHY:
MYOTONIC CONGENITA MD
Inherited – DOMINANT (Chromosome 19 – CAUSE
many nucleotide CTG repeats)
Prolonged contraction of muscles. Disease PROCESS “Locking in place”
Which eventually leads to muscle atrophy
MUSCLES MOST Muscles of lower legs hands, neck & face
AFFECTED
Young adulthood, but can occur at any age
AGE of ONSET
SEX most AFFECTED
KEY SYMPTOMS PROGNOSIS
FACIOSCAPULOHUMERAL (FSHD) MD
Inherited – DOMINANT
Chromosome 4 defect
Gene makes a protein called DUX4 – that is toxic to muscles.
Progressive weakening & loss of skeletal muscles
Face, shoulder girdle & upper arms. Abdominal, hips, lower legs.
Usually by age 20 - 2nd most prevalent muscular dystrophy affecting ADULTS
Both
Both
Signs and symptoms of the disease become more severe with each successive generation 1. Wasting & weakness in lower legs, hands, neck & face 2. Mask-like, expressionless face
3. Premature Balding
4. Cataracts
5. Heart Arrhythmias No cure - severe case may require a wheelchair in later life.
Respiratory infections pose a great danger
1. Shoulder weakness ie. Difficulty reaching above head
2. Lower limb weakness ie. Foot drop 3. Scapular winging 4. Facial weakness. 5. Lumbar lordosis.
6. Muscle pain and aching around scapula
Most have a normal lifespan with varying degrees of disability / complications - hearing loss, vision problems & respiratory insufficiency
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The complex internal structure of a myocyte
https://www.jci.org/articles/view/38027/figure/1
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Summary Questions
1. Name the 4 properties of muscle 2. Explain one structural difference between cardiac muscle and other muscle types
3. What is the function of the following muscles: Hamstrings, deltoid, tibialis anterior, biceps brachIi, masseter.
4. Are skeletal, smooth and cardiac muscle striated or non-striated?
5. Name the three methods of producing ATP in muscle fibres
6. Name the two muscle myofilaments 7. Where is: a) oxygen and b) calcium stored in a muscle fibre?
8. Describe what takes place at a neuromuscular junction
9. Who is commonly affected by Duchenne's Muscular Dystrophy? What are the symptoms of this disease?
10. Describe the condition Myasthenia Gravis
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