Physiology Flashcards
Calcium required for contraction of skeletal muscle is found where?
- Sarcoplasmic reticulum
Skeletal muscle is under ____ control?
- voluntary control
- neurogenic initiation
Describe the motor unit in skeletal muscle
Single alpha motor neurone and all the skeletal muscle fibres it innervates
Muscles with fine movements will have __(more/less)___ fibres per motor unit?
- Less
- Precision more important than power
Muscle fibre is another term for what?
- Muscle cell
What is the name given to the functional unit of skeletal muscles?
- Sarcomere
Define functional unit
- The smallest component capable of performing all the functions of that organ
Where is the A band found in skeletal muscle?
- Made up of thick filaments along with portions of thin filaments that overlap
Where is the H zone?
- The lighter area within the middle of the A band where thin filaments don’t reach
Where is the M line?
- Down the middle of A band
ATP is dependant for ______ and _____ of skeletal muscle
- contraction
- relaxation
Why is ca2+ required for muscle contraction
- pulls tropomyosin out, to allow cross bridges to form
What neurotransmitter is required to allow excitation
-Acetylcholine
What effects the strength of skeletal muscle tension?
- Number of muscle fibres
- Tension developed
How do twitches arise in skeletal muscles?
- repetitive fast stimulation of skeletal muscles
- provides no opportunity for the muscle to relax
What is the effect on muscle length during isotonic contraction?
- Length changes
- Muscle tension remains constant
What is an example of an isotonic contraction?
- body movements
What is an example of an isometric contraction?
- maintaining posture
What is the effect on muscle length during isometric contraction?
- No effect on muscle length
- tension develops
What is the main source of ATP when O2 is not present?
- Glycolysis
What is the main source of ATP when O2 is present?
- Oxidative phosphorylation
Define reflexes?
- action is a stereotyped response to a specific stimulus
What is the simplest monosynaptic spinal reflex?
- Stretch reflex
What are muscle spindles?
- Specialised muscle fibres
- Sensory receptors for stretch reflex
What is a intrafusal fibre?
- muscle spindels
- specialised muscle fibre
What is the name given to the efferent neutrons that supply muscle spindles?
- Gamma motor neurons
What are some examples of causes of muscle diseases?
Genetics
Muscular dystrophy
Endocrine (Cushings)
Symptoms of muscle disease?
- Muscle weakness
- Delayed relaxation (myotonia)
- Muscle pain
Define Myotonia?
- delayed relaxation of muscle
Define myalgia?
- muscle pain
How are skeletal muscles innervated?
- fast alpha-motor neurone with myelinated axons and cell bodies in the spinal cord
Where are nicotinic ACh receptors located?
- at regions of the junctional folds that face active zones
Highlight the main steps involved in neuromuscular transmission
- Synthesis of ACh
- Uptake of ACh into synaptic vesicles
- Ca2+ dependant release of ACh into synaptic cleft
- ACh binding to nicotinic ACh receptors
Where is ACh synthesised?
- cytoplasm of bouton
What enzyme is involved in the synthesis of ACh?
- acetyltransferase
How is Ca2+ released?
- action potential arrives at T-tubule
- triggers release of Ca2+ from SR
What enzyme causes termination of ACh binding to nicotinic receptors?
- Acetylcholinesterase (AChE)
- Hydrolyses ACh to choline and acetate
Issac’s disease has reduce ___ conductance
- Reduced K+ conductance
LEMS has reduced ___ conductance
- reduced Ca2+ conductance
What is the drug treatment for mysthenia gravis
- Anticholinesterases
What are the 4 processes of pain?
- Transduction
- Transmission
- Modulation
- Perception
What are the names given to the afferent pain primary neurons?
- Nociceptors
- first order neurons
Subtypes of nociceptors?
alpha gamma (fast) c-fibers (slow - throbing)
hyperalgesia?
Causes heightened pain sensitivity to noxious
allodynia?
Heightened pain sensitivity to innocuous stimuli
Dysfunctional (pathological) pain?
No identifiable damage or inflammation
