Muscle Properties Flashcards
5 Functions of muscles
- Movement - muscular contraction
- Posture
- Heat production - aka thermogenesis maintains normal body temps
- Storage of substances - glycogen & oxygen
- Movement of substances
4 muscle properties
- Contractility
- Excitability - can conduct an electrical impulse/current
- Extensibility - stretch without damage
- Elasticity - return to original length
What is a striated muscle
Muscles that contain cell fibres that are aligned in parallel bundles which helps to control movement eg skeletal & cardiac muscles
What is a non-striated muscle
Contain cells that are randomly arranged eg smooth muscle
What is fascia
A dense sheet of connective tissue that organises muscle, secures it to skin and provides stability
What are myofibrils
Cylindrical structures formed of bundles of protein filaments within muscle fibre
What are the two types of myofilaments
- Actin - thin filament
2. Myosin - thick filament
What is a sarcomere
The basic unit of striated muscle where myofilaments overlap
What is endomysium
A thin sheath that surrounds Individual muscle fibres
What is perimysium
Bundles of 10-100 muscle fibres that surround fascicles
What is epiysium
Attaches the entire muscle to fascia and tendons
What is the neuromuscular junction
The meeting point (synapse) where motor neurons meet a muscle fibre
What is acetylcholine (ACH)
The neurotransmitting chemical at a junction
Describe the process of muscle contraction
Acetylcholine diffuses across the synapse & send nerve impulse across the sarcolemma & transverse tubules of a muscle fibre.
This releases calcium & ATP which cause the actin and myosin filaments to bind and slide over eachother
Describe the process of muscle relaxtion
Nerve impulses stop and use magnesium & ATP to break the actin & myosin bond which slide back into their original position
What role does magnesium play in muscle fibres
Makes them less excitable & prevents myosin binding with actin
What nutrients are essential for effective muscle activity & athletic performance
Calcium, magnesium, sodium, potassium iron
What hormones promote muscle hypertrophy
Growth hormone
Testosterone
Thyroid hormones
What are the two pathways for ATP synthesis
- Aerobic respiration
2. Anaerobic respiration
What are the 3 essential nutrients for ATP production
Glucose
Fatty acids
Amino acids
Where does aerobic respiration occur
Within mitochondria (often located next to myoglobin)
Where does anaerobic respiration occur
Takes place in the cytoplasm & occurs via glycolysis (breakdown of glucose)
What is creatine phosphate
A protein unique to muscles & a storage form of energy
Properties of slow oxidative muscles
Dark red - lots of myoglobin & mitochondria
In turn means aerobic respiring muscles
Good for endurance eg postural
Properties of fast oxidative glycolytic muscles
White-pink - less myoglobin&mitochondria
Aerobically and anaerobically respires
Also more resistant to fatigue
Good for walking & sprinting
Properties of fast glycolytic muscles
White - due to lack of myoblobin & mitochondria
Anaerobically respires
Fatigues quickly
Good for weights eg arms/shoulders
What attaches the skeletal muscles to the periosteum of bone
Tendons at muscle attachment points
What is a prime mover muscle
The main muscle contracting in a movement
What is an antagonist muscle
The muscle acting in opposition to the prime mover
What is a synergist muscle
A muscle that assists the prime mover muscle in its action
What is a fixator muscle
A muscle that stabilises the origin bone while a prime mover contracts
How do intercalated discs assist the myocardium
branching cells joined to end-to-end structures that allow contraction to spread from cells like a wave
Does the myocardium rely on aerobic or anaerobic respiration
Aerobic Highly! Lots of mitochondria as requires constant blood supply & deivery of oxygen & nutrients
Process of smooth muscle contraction
Similar structure to z disc in sarcomeres, arranged at 90 degree angle
Filaments attached to dense bodies are pulled together causing the muscle to shorten & twist like a crokscrew
Is slower & longer with clacium movement compared to the other muscles
Smooth muscle maintains partial contraction ie important for blood pressure
What is a smooth muscle stress-relaxation response
Where organs such as stomach & bladder to expand when filled & a contraction to carry contents
What do satellite cells help
They have a limited regeneration process that works to help skeletal muscles regenerate
What is the muscle cell membrane called
Sarcollema
What is the muscle cell cytoplasm called
Sarcoplasm
What does the muscle cells sarcoplasmic reticulum store
Stores calcium which is needed in assisting muscle contraction
What is the motor end plate
The location where motor neurons terminate in tiny pads on the muscle fibre
What is single unit smooth muscle
Fibres are connected by gap junctions and the cells relax and contract in a single unit
Eg walls of vessels
What is multi unit smooth muscle
Fibres are stimulated individually & operate independently of one another, contain no gap junctions
Eg found in walls of larger arteries & airways, iris & arrector pilli
How do muscles contribute to skin homeostasis
Facial expressions
Muscle action increases blood flow to skin
How do muscles contribute to nervous system homeostasis
Shivering - generates heat & raises body temperature
How do muscles contribute to endocrine gland homeostasis
Exercise can improve action of some hormones eg insulin
Muscle protects some glands
How do muscles conrtibute to cardiovascular homeostasis
Cardiac muscle Pumps blood
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
Lactic acid produced in skeletal muscle can be used to make ATP in heart
How do muscles contribute to reproductive homeostasis
Skeletal and smooth muscle comtractions eject semen
Contractions propel egg along uterine tubes, control menstrual flow & expel baby from uterus in birth
