Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
60 Cards in this Set
- Front
- Back
|
initiation and propagation of contraction in skeletal muscle |
-neurogenic -neuromuscular junction present -no gap junctions |
|
|
initiation and propagation of contraction of cardiac muscle |
-myogenic -no neuromuscular junction -gap junctions present |
|
|
Ca+ comes from where in contraction of skeletal muscle? |
sarcoplasmic reticulum |
|
|
Ca+ comes from where in contraction of cardiac muscle? |
ECF and sarcoplasmic reticulum |
|
|
gradation of contraction of skeletal muscle is due to what? |
-motor unit recruitment -summation of contractions |
|
|
gradation of contraction of cardiac muscle is due to what? |
depends on the extent of heart filling with blood (frank-starling mechanism) |
|
|
define a motor unit |
a single alpha motor neuron and all the skeletal muscle fibres it innervates |
|
|
describe the appearance of myocin and actin respectively |
myocin- darker, thick filaments actin- lighter, thin filaments |
|
|
describe skeletal muscle fibres |
muscle fibres contain lots of myofibrils. these are specialised contractile intracellular structures. These have alternating segments of actin and myocin arranged into sarcomeres: these are the functional units of muscle. |
|
|
between which lines is a sarcomere found? |
between two Z lines |
|
|
how is muscle tension produced |
sliding of actin filaments on myocin filaments |
|
|
what is muscle tension dependent on? |
ATP-dependant interactions between actin and myocin |
|
|
what is ATP required for? |
both contraction and relaxation |
|
|
What is Ca+ required for? |
to switch on cross bridge formation |
|
|
what is excitation contraction coupling? |
process where surface action potential results in activation of the contractile structures of the muscle fibre |
|
|
in skeletal muscle, when is Ca+ released from the sarcoplasmic reticulum |
when the surface action potential spreads down the transverse tubules
|
|
|
what does Ca+ bind to on the muscle fibre? |
troponin |
|
|
Explain how frequency of stimulation & summation of contractions brings about increased tension in skeletal muscle
|
the duration of action potential is much shorter than the duration of twitching if you re-stimulate an action potential before the twich is over these will summate to bring about a stronger contraction |
|
|
Describe the two primary types of skeletal muscle contraction |
*depends on whether or not the muscle changes length isotonic contraction- muscle tension remains constant as the muscle length changes. Used for body movements and for moving objects isometric contraction- muscle tension develops at constant muscle length. Used for supporting objects in a fixed position |
|
|
Define the term “reflexaction”
|
a stereotypical response to a specific stimulus. they are the simplest form of coordinated movement. |
|
|
what is the stretch arch reflex |
serves as a negative feedback that resits passive change in muscle length to maintain optimal resting length in muscle the sensory receptor is the muscle spindle and is activated by muscle stretch, this increases firing in the afferent neurons |
|
|
cause and symptoms of intrinsic muscle disease |
-genetic- congenital myopathies, chronic degeneration, abnormalities in muscle membrane ion channels -acquired- inflammatory myopathies, non-inflammatory myopathies, endocrine myopathies, toxic myopathies |
|
|
highlight some investigations into diagnosis of neuromuscular disease |
-EMG (electromyography detects electrical activity of skeletal muscle) -nerve conduction studies -muscle enzymes in blood- CK -inflam markers- CRP, PV |
|
|
tension developed by skeletal muscle is influenced by what 2 factors? |
1.the number of muscle fibres contracting 2. tension developed by each individual contracting muscle fibre |
|
|
why cant cardiac muscle be tetanised |
because of the long refractory period |
|
|
what are the main differences between different types of skeletal muscle fibre?
(one motor unit usually only contains one type of muscle fibre) |
-enzymatic pathways for ATP synthesis -resistance to fatigue -activity of myosin ATPase (determines speed at which energy is made available for cross bridge cycling) |
|
|
In what ways can muscle gain ATP? |
-transfer of high energy phosphate (immediate) -oxidative phosphorylation (aerobic main source) -glycolysis |
|
|
describe slow oxidative (type 1) skeletal muscle |
-high resistance to fatigue -red in colour -used in maintenance of posture (ie walking) |
|
|
describe fast oxidative (type 2a) skeletal muscle? |
-uses both aerobic and anaerobic metabolism -useful in prolonged relatively moderate work (jogging) -red in colour |
|
|
describe fast glycolytic (type 2b) skeletal muscle? |
-low resistance to fatigue -white in colour -use anaerobic metabolism -useful for short bursts of energy (ie jumping) |
|
|
give an example of a fibrous joint |
skull sutures |
|
|
give an example of a cartilaginous joint |
intervertebral joints |
|
|
which joint type allows no movement? |
fibrous |
|
|
which joint type allows limited movement? |
cartilaginous |
|
|
describe the general structure of a synovial joint |
-synovial joints unite 2 or more bones by a fibrous capsule containing synovial fluid. -the inner aspect of fibrous capsule is lined with synovial membrane: this is a vascular connective tissue with capillary networks and lymphatics -synovial cells(fibroblasts) in the membrane produce synovial fluid -articular surfaces of bones are covered with cartilage |
|
|
what is the function of synovial fluid |
-lubricate joint -facilitate movement/reduce friction --aids in nutrition of articular cartilage -supplies chondrocytes with oxygen and nutrients + removes waste products |
|
|
describe the general characteristics of the synovial fluid? |
-high viscocity but variable with movement -continuously replenished and absorbed by the synovial membrane -other components are derived by dialysis of blood plasma -contains few cells (mainly mononuclear leucocytes) |
|
|
rapid movement is associated with what changes to synovial fluid |
-decreased viscocity -increased elasticity (these properties become defective in a diseased joint and viscocity is permanently low) |
|
|
describe the main functions of articular cartilage |
-provide a low friction lubricated surface
-distributes contact pressure to subchondral bone |
|
|
describe the general characteristics of articular cartilage |
-usually hyaline -it has a specialised ECM made up of water (70%), collagen (20%) and proteoglycans (10%) |
|
|
what is the function of water within the articular cartilage |
maintains resillience of the tissue and contributes to the nutrition and lubrication system |
|
|
what is the role of collagen within the articular cartilage |
maintains cartilage architecture (mainly type 2 collagen)- provides tensile stiffness and strength |
|
|
what is the role of proteoglycans within the articular cartilage
|
responsible for load bearing |
|
|
what cells synthesize, organize and degrade the ECM |
chondrocytes |
|
|
when would joint disease occur? |
-changes in the relative amounts of the three components of cartilage -if rate of degeneration>synthesis |
|
|
name some catabolic factors affecting collagen matrix turnover |
-stimulate enzymes and inhbit synthesis: -TNF alpha -IL 1 |
|
|
Name some anabolic factors affecting cartilage matrix turnover |
-stimulate synthesis and counteract effects of IL-1: -TGF- beta -IGF-1 |
|
|
name some markers of cartilage degeneration |
-serum and synovial keratin sulphate
-type 2 collagen in synovial fluid |
|
|
what is the definition of transduction in the physiology of pain? |
translation of noxious stimulus into electrical activity at the peripheral receptor |
|
|
what is the definition of transmission in the physiology of pain? |
propagation of pain signal as nerve impulses through the nervous system |
|
|
what is the definition of modulation in terms of the physiology of pain? |
modification of pain transmission in the nervous system (eg by inhibitory neurotransmitters like endogenous opioids) |
|
|
what does perception mean in terms of the physiology of pain? |
conscious experience of pain, causes physiological and behavioural responses |
|
|
define nociceptor |
specific primary sensory afferent neurons normally activated by intense noxious stimuli (thermal, chemical or mechanical)
they relay info to second order neurons in the CNS by chemical synaptic transmission |
|
|
describe A nociceptors |
mechanical/thermal nociceptors that are thinly myelinated. mediate fast pain. |
|
|
describe C fibres |
unmyelinated, respond to all noxious stimuli, mediate slow pain. |
|
|
describe nociceptive pain |
-normal response to injury of tissue by noxious stimuli -nociceptive pain is adaptive -functions as early earning physiological protective system to detect and avoid noxious stimuli |
|
|
describe inflammatory pain |
-caused by the activation of the immune system by tissue injury or infection -causes heightened pain sensitivity to noxious stimuli and pain sensitivity to innocuous stimuli -inflamatory pain is adaptive and promotes repair until healing occurs |
|
|
describe neuropathic (pathological) pain? |
-caused by damage to neural tissue -can be percieved as burning, shooting, numbness, pins and needles -examples include: compression neuropathies, peripheral neuropathies etc. |
|
|
describe dysfunctional(pathological) pain |
-no identifiable damage or inflammation -pathological pain is not protective but maladaptive -examples include: fibromyalgia, IBS etc |
|
|
explain the physiology of referred pain |
caused by the convergence of nociceptive visceral and skin afferents upon the same spinothalmic neurons at the same spinal level |
