Physiology Flashcards
What are the 3 kinds of muscle?
Cardiac (heart)
Smooth (stomach)
Skeletal (limbs)
What is the largest type of human tissue?
Muscle
What are muscles capable of?
developing tension
producing movement
contraction
What types of muscle are striated?
Skeletal and cardiac
What are the dark and light bands within muscle?
Dark = thick myocin Light = thin actin
What nervous system innervates skeletal muscle?
Somatic
What is a motor unit?
A single alpha motor neurone
TRUE or FALSE
Muscle that serve fine movements have less fibres per motor unit
TRUE
Does skeletal muscle contain gap junctions?
No, but cardiac muscle does
Does skeletal muscle have neuromusclular junctions?
Yes, but cardiac muscle does not
In skeletal muscle, where does Ca++ come from?
Entirely from the sarcoplasmic reticulum, in cardiac its also from ECF
How is the potential transmitted in alpha motor neurons cause muscle contraction?
Excitation contraction coupling
What is excitation contraction coupling?
process where the surface action potential results in activation of the contractile mechanism of the muscle fibre.
When in skeletal muscle is Ca++ released?
When the surface action potential spreads down the transverse (T)-tubules
What are T-tubules?
They are extensions of the surface membrane that dip into the muscle fibre
What is the neuromuscular junction transmitter?
Acetylcholine
What does each muscle fibre contain?
Myofibrils
How are actin and myocin arranged, and where?
In sarcomeres within each myofibril
What are the 4 zones of a sarcomere?
A-band, H-zone, M-line and I-band
What is the A-band?
Thick filaments along with the portions of thin filaments that overlap in both ends of thick filament
What is the H-zone?
Lighter area within middle of A-band where thin filaments don’t reach
What is the M-line?
It extends vertically down the middle of the A-band within the centre of the H-zone
What is the I-band?
Consists of remaining portion of thin filaments that do not project in A-band
What is Ca++ needed for?
to switch on cross bridge formation
What is motor neurone recruitment?
stimulation of more motor units resulting in a stronger contraction.
What does synchronous motor units recruitment during submaximal contractions help to prevent?
Muscle fatigue
What 4 things help dictate the tension developed during muscle fibre contraction?
- Frequency of stimulation
- Summation of contractions
- Length of muscle fibre at onset of contraction
- Thickness of muscle fibre
What prevents a tetanic contraction?
A long refractory period
What is a twitch?
a single contraction of the muscle
How much tension does a twitch produce?
Very little
TRUE OR FALSE
With increasing frequency of stimulation
the tension increases
TRUE
What are the two types of contraction?
Isotonic and Isometric
Explain isotonic contractions
For body movements and moving objects.
Muscle tension remains constant as the muscle length changes.
Explain Isometric contractions
Used for supporting objects in fixed positions and for maintaining body posture.
Give an example of a disease which involves chronic degeneration of contractile elements
Muscular dystrophy
Give an example of a disease which involves abnormalities in muscle ion channels
Myotonia
Give an example of inflammatory myopathies
Polymyosytis
Give 2 examples of endocrine myopathies
Cushing syndrome
Thyroid disease
Give 2 examples of toxic myopathies
Alcohol
Statins
What is a reflex action?
A stereotyped response to a specific stimulus
What type of reflex is the stretch reflex?
Monosynaptic reflex
The stretch reflex is an example of what?
Negative feedback
What type of change does the stretch reflex resist against?
Passive
What does the stretch reflex help maintain when walking?
Posture
What is the stretch reflex coordinated by?
Simultaneous relaxation of antagonist muscle
What spinal segments and peripheral nerve control the Knee jerk?
L3, L4, Femoral nerve
What spinal segments and peripheral nerve control the ankle jerk?
S1, S2, Tibial nerve
What spinal segments and peripheral nerve control the Biceps jerk?
C5, C6, Musculocutaneous nerve
What spinal segments and peripheral nerve control the Brachioradialis?
C5, C6, Radial nerve
What spinal segments and peripheral nerve control the Triceps jerk?
C6, C7, Radial nerve
What are muscle spindles and what are they known as?
Specialised muscle fibres and intrafusal fibres
What are ordinary muscle spindles referred to as?
Extrafusal fibres
What are the neurones that control muscle spindles called?
Gamma (y) motor neurones
What are slow-twitch fibres?
Slow oxidative type 1 fibres, used for prolonged relatively low aerobic activities
What are intermediate -twitch fibres?
fast oxidative type IIa fibres used for both aerobic and anaerobic and are useful in prolonged relatively moderate work
What are fast-twitch fibres?
Fast glycolytic type IIx fibres, anaerobic metabolism and are mainly used for short-term high intensity activities
What are the 3 types of joints?
- Synovial
- Fibrous
- Cartilaginous
What unites bone in a fibrous joint?
Fibrous tissue
What unites bone in a cartilaginous joint (Amphiarthrosis)?
Cartilage
What separates bones in synovial joints?
A cavity containing synovial fluid and united by a fibrous capsule
What produces synovial fluid inside the synovial membrane?
Synovial cells (Fibroblasts)
What covers the articular surfaces of bones?
Cartilage
What is synovium?
derived hyaluronic acid (mucin) a polymer of disaccharides
