Physiology Flashcards
What are the 3 types of muscle?
Skeletal
Cardiac
Smooth
Which muscles are striated?
Skeletal
Cardiac
What kind of nerve control is the skeletal muscle under?
Somatic nervous system therefore it is voluntary
Which is thin - actin or myosin?
Actin
Appears lighter.
What is a motor unit?
Single motor neurone and all the skeletal muscle fibres it innervates
True or False
The number of muscle fibres per motor neurone rise as the muscle performs finer movements.
False.
Fine movements require fewer fibres per motor unit.
Describe the levels of organisation in a skeletal muscle.
Muscle –>
Muscle fibre –>
myofibril –>
Sarcomere –> actin and myosin
True or False.
There are gap junctions in skeletal muscle.
False.
There are NO gap junctions.
Where does the Ca++ ions for contraction come from in skeletal muscle?
Sarcoplasmic reticulum.
Released when the AP reaches the T tubules
Which muscle has intercalated discs?
cardiac muscle
What is excitation contraction coupling?
When the action potential causes the muscles to contract.
What attaches a skeletal muscle to bone?
Tendons
What lies between 2 Z lines?
Sarcomere
What are the 4 zones of the sarcomere?
A band
H zone
M line
I band
What is in the A band?
A for all.
Actin and myosin.
What is in the H band?
This is within the A band.
There are no actin filaments here - only myosin
What is the M line?
Vertical line within the H zone of the A band
What is an I band?
Beside the A band.
No myosin, only actin.
How is muscle tension produced?
Actin filaments sliding over myosin filaments
What is ATP required for?
Contraction and relaxation.
What is Ca++ needed for?
Ca++ binds to troponin which causes the troponin to move to uncover the binding sites on actin.
How is the muscle relaxed?
ATP is needed to remove the Ca++ from troponin to close the cross bridge.
What factors affect the tension of a contracting muscle?
Frequency of stimulation
Length of muscle fibre
Thickness of muscle fibre
What is tentanus?
A maximal strained contraction after the muscle does not have time to relax
What might happen if a second AP is introduced after the refractory period?
A second twitch will be summated
Why can cardiac muscle not be tetanised?
Cardiac muscle has a long refractory period
What is the optimal length of a muscle?
The resting length of a skeletal muscle
What is an isotonic contraction?
Used for moving objects and general body movements
What affect does isotonic contraction have on muscle length?
Muscle length changes
What is an isometric contraction?
Used for supporting objects in fixed positions and maintaining posture
What affect does isometric contraction have on muscle length?
Muscle length stays the same
How is muscle tension transmitted to bone?
By elastic components i.e. tendons and connective tissue
True or False.
A stronger muscle will have more muscle fibres
True.
To obtain more precise movements there are less fibres
What is the velocity of muscle shortening?
How fast the muscle can revert back to its original length
What makes the velocity of shortening zero?
If the load is maximum i.e. carrying something heavy.
Muscle cannot shorten if it is being used.
What is a reflex?
A reflex is a stereotyped response to a specific stimulus
What is a stretch reflex?
Serves as a negative feedback that resists passive change in muscle length to maintain optimal resting length
When is the stretch reflex used?
To maintain posture.
What is the sensory receptor involved in the stretch reflex?
The muscle spindle.
It is activated by muscle stretch
How does the stretch reflex work?
Stretching the muscle spindle increases firing in the afferent neurons.
These synapse in the spinal cord with the alpha motor neurones that innervate the stretched muscle.
Which peripheral nerve is affected by the knee jerk reflex?
Femoral nerve of L3, L4
Which peripheral nerve is affected by the ankle nerve reflex?
Tibial nerve of S1, S2
What is a muscle spindle?
Sensory receptor for stretch reflex
What is an intrafusal fibre?
A muscle spindle
What are annulospiral fibres?
The sensory nerve endings on muscle spindles
What are the motor nerves which supply the muscle spindles calledd?
Gamma motor neurones
True or False
Each motor unit contains one type of muscle fibre
True.
What are the metabolic pathways which supply the muscle fibre with ATP?
Oxidative phosphorylation
Glycolysis (anaerobic)
What are the 3 types of skeletal muscle fibres?
Type I (slow oxidative) Type IIa (fast oxidative) Type IIb (fast glycolytic)
When are type I muscles used?
Prolonged, low work aerobic activities. Walking
When are type IIa muscles used?
Both aerobic and anaerobic e.g. jogging
When are type IIb muscles used?
Anerobic metabolism.
Jumping, sprinting.
What are the 3 types of joint?
Synovial
Fibrous
Cartilaginous
What is an example of a fibrous joint?
Bones of the skull
What are some examples of a cartilaginous joint?
Intervertebral discs
Pubic symphsis
Costochondral joints
What is the other name for a synovial joint?
Diathrosis
What is the other name for a cartilaginous joint?
Amphiarthrosis
What is the other name for a fibrous joint?
Synarthrosis
What produces synovial fluid?
Fibroblasts
What are the articular surfaces of the bone covered with?
Hyaline cartilage
What is a compound synovial joint?
More than one pair of articular surfaces involved
What is synovium?
Provides joint lubrication.
Formed from hyaluronic acid.
What does synovial fluid do?
Supplies the chrondrocytes with oxygen and nutrients
Lubrication and facilitates joint movements.
True or False
The synovial present at birth is present to death
False.
Constantly being replenished by the synovial membrane
What colour is normal synovial fluid?
Colourless and clear
When could synovial fluid be red?
Trauma (if you’ve done the tap badly)
Haemorrhagic arthritis
When would the WBC count in synovial fluid rise?
Inflammatory and septic arthritis.
What are the 3 layers of articular cartilage?
Superficial
Middle
Deep
What type of collagen is hyaline cartilage majoritively made of?
Type II
What is the majority of hyaline cartilage made of?
Water.
Water content decreases with age
What role does proteoglycan play in cartilage?
10% of weight.
Most found in the middle and deep zone.
Responsible for the compressive properties with load bearing
Which cells synthesise the cartilage ECM?
Chondrocytes
Where do chondrocytes get their nutrients from since the cartilage is avascular?
Synovial fluid.
What catabolic (breaking down) factors can affect cartilage matrix turnover?
TNF alpha
IL1
These inhibit proteoglycan synthesis
What anabolic (building up) factors can affect cartilage matrix turnover?
tumour growth factor beta (TGF beta)
Insulin-like growth factor 1 (IGF1)
What are common markers to check cartilage degradation?
Synovial keratin sulphate
Synovial Type II collagen
What is a nociceptor?
Peripheral primary sensory afferent neurones which are activated by intense stimuli.
What provides joint lubrication?
Synovium which comes from hyaluronic acid.
What is hyaluronic acid?
A disaccharide polymer
Why does synovial fluid have a high viscosity?
Mucin of hyaluronic acid
True or False
There are many cells present in synovial fluid
False.
There are few cells.
These would be monocytes.
True or False
Joint movement increases viscosity.
False.
Joint movement DECREASES viscosity
When could the synovial fluid appear opaque?
In sepsis
What factors would cause the turnover of cartilage to decrease?
Proteolytic enzymes such as collagenase
What crystals cause gout?
Uric acid
What crystals cause pseudogout?
Calcium pyrophosphate
What are nociceptors?
Peripheral primary sensor neurones which are activated by intense stimuli
What kind of stimuli affect nociceptors?
Extremes of temperature
Intense mechanical force
Chemical irritants
Of high threshold
True or False.
Nociceptive pain is adaptive and initiates a withdrawal reflex
True.
It needs an immediate response.
What is allodynia?
Innocuous stimuli causes pain.
Such as an unexpected touch
What is pain hypersensitivity?
Heightened sense of pain
In what circumstances is inflammatory pain brought into play?
the healing of a damaged body part since it discourages physical contact and movement
What can be used to alleviate inflammatory pain?
NSAIDs
What is pathological pain?
Maladaptive i.e. always painful
What are the two types of pathological pain?
neurological and dysfunctional
Describe neurological pain
Pain which results from a previous injury and is due to peripheral nerve damage
Describe dysfunctional pain
Positive pain symptoms but seemingly no cause.
What are the two types of nociceptor?
Adelta fibres
C fibres
Describe A delta nociceptors
Myelinated thermal/mechanical receptors.
Fast acting.
What kind of pain is describe that is elicited by A delta fibres?
Stabbing
Well localised
Describe C fibres
Unmyelinated which respond later to all stimuli.
What kind of pain is transmitted by C fibres?
Throbbing, aching, burning.
What does substance P do?
Vasodilation
Extravasation of plasma proteins e.g. histamine, bradykinin, prostaglandin
What is the primary neurotransmitter between the primary afferent and second order neurone?
Glutamate
Where are the primary afferent cell bodies located?
Dorsal root ganglia
Where do the axons terminate?
The dorsal horn of the spinal cord in laminae of Rexed
