Muscle Tissue Flashcards
Functions of muscle tissue?
- producing body movement
- stabilizing body positions/ posture/ joints
- movement of substances within the body
- opening and closing of passageways
- producing heat
What is muscle tone? What is the purpose?
-the involuntary contraction of a small number of muscle fibres
- keeps muscle firm even when relaxed
- maintains posture
- stabilizes and strengthens synovial joints
- maintains blood pressure (vessel walls)
What are the properties of muscle tissue?
contractility- muscles can contract
excitability- nerve signals stimulate muscle contraction
extensibility- muscles can stretch
elasticity- muscles can return to original state
How are the properties of muscle tissue characterized?
- presence or absence of striations
- control is voluntary or involuntary
What is the purpose of intercalated discs in cardiac muscle?
-to prevent the cells/ tissue from pulling apart when under a lot of force/pressure
What is the plasma membrane called? cytoplasm? endoplasmic reticulum?
- sarcolemma
- sarcoplasm
- sarcoplasmic reticulum
Endomysium
inner most layer
- surrounds each muscle fibre
- areolar connective tissue
Perimysium
middle layer
- surrounds fascicles (group of muscle fibres)
- DICT
Epimysium
outer most layer
- surrounds whole muscle
- DICT
What causes the striations of muscles?
the internal structure of myofibrils
What is the purpose of the sarcoplasmic reticulum?
- to store Ca2+
- tubules surrounding myofibrils
- carries the impulse to deep muscle to trigger the release of Ca2+ for muscle contraction
Explain sliding filament theory
- myosin heads attach to actin
- the heads pivot pulling actin towards the centre of the sarcomere shortening it
Spasm
involuntary contraction of single muscle
Cramp
painful spasm due to low electrolytes
Tic
involuntary twitching of muscles normally under voluntary control
Tremor
rhythmic, involuntary contraction of opposing muscle groups
Fasciculation/ Twitch
uncontrollable contraction of a small portion of a muscle/ local, involuntary discharge of bundle of muscle fibres
What is the role of Titin?
- resists overstretching
- holds myosin in place
- helps sarcomeres return to resting length
- accounts for elasticity and extensibility
When does rigor mortis occur?
3-4 hours after death
What is rigor mortis?
- Ca2+ leaks causing myosin and actin to bind
- can not detach because there is no ATP synthesis
When does rigor mortis go away?
after 24 hours because lysosomes digest myosin and actin
What are the three types of muscle fibres?
- slow oxidative
- fast oxidative
- fast glycolytic
Which of the 3 muscle fibres are O2 dependent?
-slow oxidative and fast oxidative
Slow oxidative fibres contract ________ and are _______ to _________ when O2 is present
- slowly
- resistant
- fatigue
What are slow oxidative fibres adapted for?
- maintaining posture by providing prolonged contraction
- aerobic endurance such as running a marathon
Slow oxidative fibres contain a ______ number of mitochondria
-large
Are slow oxidative fibres supplied with capillaries?
yes, richly
Fast oxidative fibres have _______ myoglobin content and a _______ supply of capillaries
- high
- rich
What are fast oxidative fibres adapted for?
walking
-somewhat fatigue resistant
Fast oxidative fibres contract at a ______ rate
fast
Fast glycolytic fibres contain _______ myoglobin and ______ mitochondria
- little
- few
Fast glycolytic fibres contract _______
- quickly
- large force in a short time
What are fast glycolytic fibres adapted for?
intense, short duration movements such as weightlifting, sprinting
Neck, back, and leg muscles have higher proportions of ___________ fibres
postural, slow oxidative
Shoulder and arm muscles have a higher proportion of _________ fibre
fast glycolytic
When does DOMS begin?
8-24hours after activity
What causes DOMS?
-microscopic tears in muscle fibres
What does DOMS result in?
- inflammatory response results in swelling in connective tissues around muscle fibres (endomysium)
- swelling compresses sensory nerve endings in muscle causing soreness
What is the one upside to DOMS?
-the tears stimulate increased production of myofibrils and myofilaments resulting in increased muscle strength and size
