Physiology Flashcards
Give 4 functions of skeletal muscle?
Maintenance of posture
Heat production
Whole body metabolism
Purposeful movement
What is a motor unit?
all of the skeletal muscle fibres a single alpha motor neurone innervates
what would more fibres in a motor unit result in?
more power and less precision
what would less fibres in a motor unit result in?
less power and more precision, ideal for muscles around the eyes and in the fingers etc
what is required for muscle contraction and relaxation?
ATP and Ca2+
Where does Ca2+ come from to aid with muscle contraction?
it is actively pumped in and out of the sarcoplasmic reticulum by ATP
what is asynchronous motor unit recruitment and what is its purpose?
muscle fibres are recruited at different times when a muscle tenses - they can be swapped about to prevent muscle fatigue
when can maximum contraction occur?
when the skeletal muscle is at optimum length (resting)
Explain how muscle contraction is produced?
- a single stimulation to a muscle creates a single twitch (contraction) - this isn’t enough to create muscle tension on its own
- repeated stimulation before the muscle has time to relax results in greater tension
- sustained contraction is produced if the muscle is repeatedly stimulated with no chance to relax between stimuli
what is the difference between isotonic and isometric contraction?
isotonic = muscle tension stays the same while length changes (body movements) isometric = muscle length stays the same while muscle tension develops (holding something in the same place)
which type of skeletal muscle fibres have high resistance to fatigue and slow contraction, for things like walking?
slow oxidative type I fibres
which type of skeletal muscle fibres have medium resistance to fatigue and fast contraction, for things like jogging?
fast oxidative type IIa fibres
which type of skeletal muscle fibres have low resistance to fatigue and fast contraction, for things like jumping?
fast glycolytic type Iix fibres
what is a stretch reflex?
negative feedback that resists passive change in muscle length so that it maintains its optimum length
what is transduction in terms of physiology of pain?
damaging stimulus (e.g. cut in the skin) being converted into electrical signals in the nociceptor
what is transmission in terms of physiology of pain?
spreading of the pain signal as the nerve impulses through the nervous system
what is modulation in terms of physiology of pain?
modification of the pain transmission in the nervous system (like natural painkillers e.g. indigenous opioids)
what is perception in terms of physiology of pain?
conscious experience of pain
what are nociceptors?
specific nerve endings that register pain that are activated by painful stimuli (mechanical, thermal or chemical)
explain how 1st, 2nd and 3rd order neurones work in the pain pathway?
nociceptors are 1st order neurones that relay info to 2nd order neurones in spinal cord which take the info to the thalamus. 3rd order neurones take the info from the thalamus to the sensory cortex in the brain and provoke a response
what is nociceptive pain?
normal response to injury - nociceptors triggered by damaging/painful stimuli in tissues
what is inflammatory pain?
pain to stop you doing more damage to an injury/let it repair - activated by mediators released at the site of inflammation
what is neuropathic pain?
pain caused by damage to neural tissue e.g. compression neuropathy. Causes burning/shooting pain/pins and needles
what is pathological pain?
dysfunctional pain where there is no identifiable cause e.g. fibromyalgia
what causes referred pain?
convergence of nociceptive visceral and skin afferents on the same neurones going to the thalamus at the same spinal level
what are fibrous joints?
bones united with fibrous tissue with pretty much no movement e.g. bones in the skull
what are cartilaginous joints?
bones united by cartilage with limited movement e.g. intervertebral discs
what are synovial joints?
bones separated by a synovial fluid-filled cavity and united by a fibrous capsule with a lot of movement
what is the difference between and compound and simple synovial joint?
simple = 2 articular surfaces e.g. fingers compound = more than 2 articular surfaces e.g. elbow joint
what is the fibrous capsule in synovial joints lined with and what does this structure do?
lined by synovial membrane - contains fibroblasts which produces the synovial fluid
give 4 functions of synovial fluid?
- lubricates joint & facilitates movement
- minimises wear & tear
- aids nutrition of articular cartilage
- supplies chondrocytes (cartilage cells) with oxygen and nutrients and takes away CO2 and waste products
what are the 3 main components of hyaline cartilage?
water
type II collagen
proteoglycans
what are 2 markers for cartilage degradation?
increased serum/synovial keratin sulphate
type II collagen in synovial fluid
why do inflammatory conditions (arthritis and arthropathies) increase the risk of cardiovascular complications?
Inflammation affects vessels - systemic conditions will potentially have an effect
Which bone has the most hyaline cartilage in the body?
Patella
