Physiology Flashcards
1
Q
name the physiological functions of skeletal muscle
A
posture
movement/ respiratory movements
heat production
contributor to whole body metabolism
2
Q
skeletal muscle is striated/non striated and voluntary/ non voluntary
A
striated and voluntary
3
Q
which nerves innervate skeletal muscle?
A
somatic nervous system
4
Q
skeletal muscle has _______ initaion of contraction
A
neurogenic
5
Q
what is the transmitter at the neuromuscular junction of skeletal muscle
A
Ach
6
Q
skeletal muscle fibres are organised into what?
A
motor units- single alpha motor neuron
7
Q
muscles that allow for precise movements will have fewer/greater motor fibres per unit than for power?
A
fewer
8
Q
sort into levels of organisation 1. muscle fibre 2. sarcomere 3. myofibril 4. actin/filamin 5. whole muscle
A
- actin/filamin 2. sarcomeres 3. myofibrils 1. muscle fibre 5. whole muscle
9
Q
define functional unit
A
smallest component capable of performing all the functions of that organ
10
Q
sarcomere is found between what two lines?
A
Z lines
11
Q
what are the four zones of the sarcomere
A
A- band
H- zone
M- line
I- band
12
Q
describe the A- band
A
thick filaments with portions of thin filamwetns that overlap in both ends of thick filaments
13
Q
describe the H- zone
A
lighter area of the A-band where thin filaments dotn reach
14
Q
describe the M-line
A
extends vertically down A-band within the centre of H-zone
15
Q
describe I-band
A
remaining portion of thin filaments that don’t project in A-band
16
Q
muscle contraction is caused by what?
A
actin filaments sliding on myosin filaments
17
Q
force generation of muscle depends on what?
A
ATP- dependant interaction
18
Q
in skeletal muscle fibres Ca2+ is released from where?
A
lateral sacs of the sarcoplasmic reticulum
19
Q
the surface action potential of skeletal muscle spreads down what?
A
the transverse (T)- tubules (extensions of the surface membrane)
20
Q
what allows simultaneous contraction of muscle fibres?
A
motor units
21
Q
stimulating more motor units to achieve a stronger contraction is known as what?
A
motor unit recruitment
22
Q
asynchronous motor unit recruitment during submaximal contractions helps prevent what?
A
muscle fatigue
23
Q
tension developed by each contracting muscle fibre depends on what two things?
A
frequency of stimulation and summation of contractions
length of muscle fibre
24
Q
the action potential in skeletal muscle is longer than the duration of the resulting twitch true/false
A
false- the AP is shorter
25
describe single twitch in skeletal muscle
the muscle fibre has completely relaxed before being restimulated
26
with single twitch the second twitch is the same/greater magnitude than the first twitch
same magnitude
27
what happens if a muscle fibre is restimulated before it has completely relaxed?
the second twitch is added to the first resulting in twitch summation
28
what is tetanus?
when a muscle fibre is stimulated so rapidly it doesn't have time to relax between stimuli- maximal sustained contraction
29
what type of muscle cannot be tetanised and why?
cardiac muscle- long refractory period
30
when is maximal tetanic contraction achieved?
when the muscle is at its optimal length before the onset of contraction
31
the tension developed by skeletal muscle increases with what?
frequency of stimulation
32
what is the optimal length of skeletal muscle in the body?
the resting length
33
what are the two types of skeletal muscle contraction?
isotonic isometric
34
what movements is isotonic contraction useful for?
body movements moving objects
35
describe isotonic contraction
muscle tension remains constant as the muscle length changes
36
what movements is isometric contraction useful for?
supporting objects in fixed posn
maintaining body posture
37
describe isometric contraction
muscle tension develops at constant muscle length
38
how is muscle tension developed in both isotonic and isometric contractions?
transmitted to bone via elastic components of muscle
39
what are the contractile and elastic components of muscle?
contractile- sarcomeres
elastic- connective tissue/tendon
40
the velocity of muscle shortening increases/decreases as the load increases?
decreases
41
what are the main differences between types of skeletal muscle fibres?
ATP synthesis pathway
resistance to fatigue
activity of myosin ATPase
42
what are some of the metabolic pathways that supply ATP in muscle fibres?
transfer of high energy phosphate from **creatine phosphate** to **ADP** (immediate source)
**oxidative phosphorylation** (O2 present)
**glycolysis** (O2 isn't present)
43
what are the three types of skeletal muscle fibres?
**Type I-** slow oxidative
**Type IIa**- fast oxidative
**Type IIx**- fast glycolytic
44
give some feature of type I- slow oxidative muscle fibres
slow twitch
many mitochondria
low myosin ATPase activity
low glycogen content
45
what activities are type I- slow oxidative fibres useful for?
prolonged low work aerobic activitities e.g posture, walking
46
give some features of type IIa fast oxidative muscle fibres
intermediate twitch fibres
many mitochondria
high myosin ATPase activity
intermediate glycogen content
47
what activities are type IIa fast oxidative fibres useful for?
aerobic and anaerobic metabolism, prolonged moderate work e.g jogging
48
give some features of type IIx fast glycolytic muscle fibres
fast twitch
few mitochondria
high myosin ATPase activity
high glycogen activity
49
what activities are type IIx fast glycolytic muscle useful for?
anaerobic metabolism used for short term high intensity activiites e.g jumping
50
what is the simplest form of coordinated movement
reflex action
51
define reflex
reflex action is a stereotyped response to a specific stimulus
52
the stretch reflex is the simplest form of what kind of reflex?
monosynaptic spinal reflex
53
what is the stretch reflex?
negative feedback that resists passive change in muscle length to maintain optimal resting length of muscle
54
what does the stretch reflex help with?
posture e.g while walking
55
what sensory receptor in muscle is activated by muscle stretch?
muscle spindle
56
stretching the muscle spindle increases firing in what? where do they synapse?
afferent neurons synapse in the spinal cord with the alpha motor neurons
57
what are muscle spindles a collection of and what are they known as?
collection of specialised muscle fibres known as intrafusal fibres
58
what are ordinary muscle fibres referred to as?
extrafusal fibres
59
where are muscle spindles found?
within the belly of muscles and run parallel to ordinary muscle fibres (extrafusal)
60
what are annulospiral fibres?
the sensory nerve endings of muscle spindles
61
do muscle spindles have their own efferent (motor) nerve supply?
yes- gamma motor neurons
62
What do the gamma motor neurons do to muscle spindles?
Adjust the level of **tension** in muscle spondles to maintain their **sensitivity** during muscle contraction
63
contraction of intrafusal fibres contributes to the overall strenght of muscle contraction true/false?
false- they do not contribute to the overall strength of contraction
64
give examples of some geneticalluy determined myopathies
congenital
chronic degeneration e.g **Muscular dystrophy**
abnormalities in membrane ion channels e.g **myotonia**
65
give an example of aqcuired inflammatory myopathies
polymyositis
66
give an example of a non-inflammaotory acquired myopathy
fibromyalgia
67
give an example of an endocrine acquired myopathy
cushing syndrome
thyroid disease
68
give an example of a toxic acquired myopathy
alcohol
statins
69
what are the symptoms of muscle disease
muscle weakness/tiredness
delayed relaxation after voluntary contraction **(myotonia)**
muscel pain **(myalgia)**
muscle stiffness
70
what are some useful investiagtions in neuromuscular disease?
**Electromyography (EMG)**- electrodes detect presence of muscular activity
**nerve conduction studies**
**muscle enzymes** (CK)
**Inflammatory markers** C reactive Protien (CRP), plasma viscosity (PC)
**muscle biopsy**
71
What are the three type of joint in the body?
Synovial
fibrous
cartilaginous
72
describe fibrous joints and give an example
bones united by fibrous tissue
dont allow any movement
**bones of the skull** in adults
73
descirbe cartilaginous joints and give examples
bones united by cartliage
limited movement
**intervertebral discs, pubic symphsis, costochondral joints**
74
desrcibe synovial joints
seperated by a cavity and united by fibrous capsule
75
which joint is described as being **amphiarthosis?**
cartilaginous joint
76
which joint is described as being **synarthrosis?**
fibrous joint
77
which joint is described as being **diarthrosis?**
synovial joint
78
where is synovial fluid found?
the synovial cavity
79
in addition to the fibrous capsule what other structures unite and support synovial joints?
ligaments
tendons
bursae
80
the synovial membrane lines what aspect of the fibrous capsule?
the inner aspect
81
is the synovial membrane vascularised?
yes- it is a vascular connective tissue with capilary networks and lymphatics
82
synovial cells (fibroblasts) within the synovial membrane produce what?
synovial fluid
83
what are the two classes of synovial joint?
**simple**- one pair of articular surfaces
**compound**- more than one pair of artivualr surfaces
84
give an example of a **simple** synovial joint
metacarpophalangeal joint
85
give an example of a **compound** synovial joint
elbow joint
86
with regards to stress distribution the greatest share of loading energy is taken up where?
the muscles and tendons **crossing** each joint
87
give some functions of synovial fluid
lubrication
reduces friction
aids in nutrition of articular cartliage
supplies chondrocytes with O2 and removes CO2
88
the synovial fluid is continously replenished adn absorbed by what?
synovial membrane
89
what is responsible for the high viscosity of synovial fluid?
**hyaluronic acid** (mucin)- prod by synovial cells
90
uric acid in the synovial fluid are dervied by what?
dialysis of blood plasma
91
the synovial fluid contains few cells normally, what are these mainly?
mononuclear leucocytes
92
rapid movement is associated with inc/dec viscosity and inc/dec elasticity?
**decreased** vscosity
**increased** elasticity
93
in what disease do the viscous/elastic properties of synovial fluid become defective?
osteoarthritis
94
what colour is normal synovial fluid?
clear and colourless
95
what is the WBC count in normal synvoial fluid?
**\<200 WBC/mm3** of which polymorphs are usually \<25/mm3
96
when would synovial fluid turn red?
traumatic synovial tap
haemorrhagic arthirits
97
what kind of synvoial fluid would have a straw/yellow colour and give a total white cell count of 2,000-75,00
**inflammatory** synovial fluid
98
what kidn of synovial fluid would give a total white cell count of \>100,000
**septic** synovial fluid
99
the thin and opaque appearance of synovial fluid from a severely infected joint is due to what?
the very high polymorph count
100
what ares some of the main functions of articular cartliage?
low friction- help prevent wear-and-tear
distributes pressure
101
what are the four zones of articualr cartilage?
superfical
middle
deep
calcified
102
articualr cartilage is usually which type?
hylaiine
103
the ECM of articualr cartilage is synthesized, degraded and maintained by what cells?
chondrocytes
104
articular cartliage is vascular/avasuclar?
avascular
105
from what does articular cartilage recieve nutrients and O2
via synovial fluid
106
describe the rate of ECM degradation with the rate it is replaced in an normal joint
degredation doesnt exceed the rat eof replacement- there is a balance
107
changes in the relative amounts of the components of the ECM (water, collagen, proteoglycans) would also change what?
the mechanical properties of the cartilage
108
what would occur if the rate of ECM degredation exceeds the rate of synthesis?
joint disease
109
what are the catabolic factors in the ECM?
TNF alpha
IL- 1
110
what do catabolic factors do in the ECM?
stimulate proteolytic enzymes and inhibit proteoglycan synthesis
111
what are the anabolic factors in the ECM?
tumour grwoth factor TGF
insulin like growth factor (IGF)-1
112
what do anabolic factors do in the ECM?
stimulate proteoglycan synthesis and counteract effects of IL-1
113
what are some markers of cartilage degredation?
Serum and synovial keratin sulphate
Type II collagen in synovial fluid
114
deterioration of cartilage with age gives rise to what condition?
osteoarthritis
115
synovial cell proliferation and inflammation casue what condition?
rheuamatiod arthritis
116
depsoition of salt crystals e.g uric acid can cause what conditio?
gouty arthritis
117
injury and inflammation to periarticular structures causes what condition?
soft tissue rheumatism e.g injury to tendon causes tendonitis
118
subchondral sclerosis and subchondral cyst formation will be present in what condtion?
osteoarthritis
119
