5.5.1 neuronal comm. muscles Flashcards
what are the two types of nervous system?
somatic nervous system
autonomic nervous system
what is the somatic nervous system
where do impulses travel to
under conscious control
|»_space;used voluntarily to decide to do something like move muscles in arm and carries impulses to body muscles
what is the autonomic nervous system
where do impulses travel to
works constantly and is subconcious
»automatic response like heartbeat digestion ect
carries impulses to glands, smooth muscle of intestines and cardiac muscle
what does the autonomic nervous system split into
sympathetic- outcome increases activity
parasympathetic- decreases activity eg heart rate after exercise
examples of effects of sympathetic nervous system
funnily enough does opposite of what u think :) but most of these result in opposite effects in body
reduced saliva production from saliva gland
reduced peristalsis (contractions in stomach to digest)
decreased urine secreted
examples of effects of parasympathetic nervous system
bronchial muscle contracts in lungs
digestion increases in small intestine and more gastric juice secreted for digestion in stomach
how is the nervous system separated in terms of structurally
CNS- brain and spinal chord
peripheral nervous syst. all neurones that connnect CNS to rest of the body. Sensory neurones which carry nerve impulses from receptors to CNS and motor neurones which carry away
the peripheral is either AUTONOMIC or SOMATIC
and the autonomic is either sympathetic or parasympathetic
which neurotransmitters are released in:
somatic NS
sympathetic
parasympathetic
acetylcholine
Noradrenaline
acetylcholine
how myelinated is the neurone in the somatic nervous system
where do neurones go here
heavily myelinated single neurone from CNS to effector organs
how myelinated is the neurone in the sympathetic nervous system
where do neurones go here
lightly myelinated pre-ganglionic axons and unmyelinated post-ganglionic
neurones go from CNS to effector
but includes adrenal medulla necreting noradrenaline
how myelinated is the neurone in the sympathetic nervous system
where do neurones go here
lightly myelinated pre-ganglionic axons and unmyelinated post-ganglionic
neurones go from CNS to effector
describe the stages of the power stroke
1) myosin cross bridges attaches to actin myofilament
2) working stroke, the myosin head pivots and bends as it pulls on the actin filmament slding it towards the M line (ADP and P released)
3) as new ATP attaches to myosin head, the cross bridge detaches
4) as ATP is split into ADP and P, cocking of the myosin head occurs. (hydrolysis)
Process repeats
In the sliding filament model what happens to the:
>I band when muscle contracts
>A band when muscle contracts
what is each band?
I band- gets smaller as actin slides between myosin
A band- stays same as myosin length unchanged
A band is Anistrophic so dArk band
I is Isotrophic so LIght band
what does a greater overlap of the actin filaments mean for the contraction
there is a greater force
what happens to to the middle of the sarcomere during contraction?
stays the same
but the H band (where actin filaments overlap) gets smaller as greater overlap between actin and mysoin
what does a relaxed muscle need to contract
ATP and Ca2+ ions
whereas contracted to relaxed is passive
muscles work in antagonistic pairs
what are the thick and thin filaments made from in the sliding filament model
thick is myosin (these have the heads on that grab and hold actin/myosin filaments slide relatively )
thin is actin
what is myoglobin
iron- and oxygen-binding protein found in the skeletal muscle tissue
together with mitochondria makes ATP for contraction
transports oxygens to mitochondria in sarcolemma
an individual muscle is composed of hundreds of______
each of these is composed of many_______
these have distinctive banding due to _____
muscle fibres
myofibrils
microfilaments (also part of cytoskeleton) eg actin and myosin
which filaments are in the I/ light band
only actin microfilaments
which band has both actin and myosin filaments
A/ dark band
which zone has just myosin microfilaments
H zone
what does ATP do to the myosin head
alters the shape of the myosin head so that actin and myosin can slide relative to one another (ATP cocks the myosin head)
what do Ca+ ions do to myosin head
remove the protein tropomyosin which blocks the binding site on the actin molecule which the myosin heads can attach to during the sliding of actin/myosin over each other
what causes grey matter to be darker than white
many more nuclei (found in sensory and motor nerve pathway)
what are the 3 types of muscle
skeletal, cardiac and smooth(involuntary) muscle
what is skeletal muscle
make up most of body tissue. Voluntary movements
what is cardiac muscle
only in the heart, myogenic so contracts without need for nervous stimulus.
causes heart to beat in regular rhythm
what is smooth muscle
involuntary muscle found in places like walls of hollow organs such as stomach and bladddr and also walls of blood vessels and digestive tract. Also involved in peristalis
what is the fibre appearance of the 3 muscle types?
skeletal is striated
cardiac is specialised striated
smooth is non- striated
what is the arrangement of skeletal muscles
regularly arranged so muscle contracts in one direction
what is the arrangement of cardiac msucles
cells branch and interconnect resulting in simultaneous contraction
what is the arrangement of involuntary smooth msucle
no regular arrangement, different cells contract in different directions
what is the contraction speed of the 3 types of muscles
skeletal is rapid
cardiac is intermediate
involunatry is slow
what is the length of contraction for the 3 muscle types
skeletal is short
cardiac is intermediate
involuntary is long periods relatively
what is the structure of skeletal muscles
muscles showing cross striations known as striated or striped muscle fibres are tubular and multinucleated
what is the structure of cardiac muscle
doesnt show striations as much fainter
fibres branched and multinucleated
what is the structure of involuntary muscle
show no cross striations
fibres are spindle shaped and unnucleated
what is the sarcolemma
plasma membrane found in skeletal muscle containing muscle fibres
how are skeletal muscle cells much longer
contain lots of nuclei and are formed from individual embryonic cells fusing together
> > > this makes the muscle stronger as if there were junctions between cells it would make it weaker
what are T tubules and what is there purpose
parts of sarcolemma which fold inwards to spread electrical impulses through sarcoplasm
this is so that the WHOLE muscle fibre receives the impulse to contract at the same time.
what is the sarcoplasmic reticulum
modified version of the endoplasmic reticulum which extends through muscle fibres providing calcium ions for muscle contraction
what are myofibrils
long cyclindrical organelles made of protein which are specialised for contraction
when lined up in parallel are very powerful and provide max force when they contract together
which proteins are in myofibrils
actin +
myosin
so basically myofibrils have myofilaments which make up the sarcomere!
what happens to the sarcomere during contraction
reduced in legnth
what makes the light bands light?
actin and mysosin dont overlap
what is the Z line
found at the centre of each light band
the distance between adjacent Z lines is the sarcomere when muscle contracts the sarcomere shortens
actin is on z lines
what is the H zone
lighter coloured region in the centre of dark bands
only myosin
muscle contractions shorten.
what should you remember when drawing a sarcomere
show 2 z lines to show understanding of sarcomere length ensure heads present on myosin filaments connect actin to the Z line label light and dark bands show position of H zone
what are the properties of slow-twitch fibres and what are they used for
where do they get energy from
> fibres contract slowly
provide less contractions but over a longer period
used for endurance activities as they don’t tire easily
> energy from respiration
they have a rich supply blood vessels and mitochndria
which proteins are slow-twitch fibres rich in
> myoglobin, a bright red protein which stores oxygen which makes fibres appear red
where are slow twitch fibres found usually?
large proportions in muscle
this helps to maintain posture such as calf and back muscles. This are continuously contracting to keep body upright
properties of fast- twitch fibres
where do they get their energy from?
- contract very quickly
- produce powerful contractions but only for short periods
- used for short bursts of speed and power as they tire easily
get energy from anaerobic
appearance of fast twitch fibres
which filaments do they contain
pale as they have low levels of myoglobin and blood vessels
contain more and thicker myosin filaments
they also contain creatine phosphate which is a molecule which rapidly generates ATP from ADP in anaerobic conditions.
where are fast twitch fibres found
high proportions in muscles needing short bursts of energy such as biceps and eyes
why does the dark band remain the same width when contracts?
as the myosin filaments themsleves havent shortened but the now overlap the actin filaments more
what does the contraction of many sarcomeres mean
many myofibrils and muscle fibres are also contracting
characteristics of actin
binding site for myosin heads which can be blocked by tropomyosin often which is help in place by troponin when muscles are relaxed
when join with mysoin form actin/myosin cross bridges
what does myosin head need to detach from actin
ATP which is usually to reattach further along actin filament
how is a muscle contraction triggered
When an action potential arrives at a neuromuscular junction where motor neurone and skeletal muscle fibre meet
there are lotssss of these junctions so muscle fibres contract simultaneously.
why are there lots of neuromuscular junctions?
because if only one the muscle fibres would not contract altogther and contraction wouldnt be powerful
it would also be slower! as wave of contraction would have to travel across whole muscle
what is a motor unit
all muscle fibres (supplied by a single motor neurone)
if a strong force is needed how many motor unitswill be stimulated
a large numberrrr
what diffuses from synapse to synaptic knob? and what effect does this have
calcium ions
which cause synaptic vesicles to fuse with the presynaptic membrane which releases acetylcholine to synaptic cleft and it binds to sarcolemma/ post synaptic membrane
what is the effect of acetylcholine binding to the sarcolemma
sodium ion channels open and a wave of depolarisation sent across post synaptic membrane
what prevents the muscle being overstimulated by wave of depolarisation
acetylcholine is broken down by acetylcholinesterase
chlorine and ethanoic acid diffuse back into neurone and recombine to acetylcholine with energy
where does the wave of depolarisation from the sarcolemma go to
spreads through T tubules which are in contact with the sarcoplasmic reticulum (which absorbs and stores Ca2+ ions from sarcoplasm)
what happens when wave of depolarisation reaches the sarcoplasmic reticulum
it stimulates calcium ion channels to open so calcium ions flows down a conc. gradient
> > > this floods sarcoplasm with Ca2+
what is the effect of calcium ions in the sarcoplasm
bind to troponin causing it to change shape
»this pulls tropomyosin away from actin-myosin binding site so that myosin heads can bind there and form a cross bridge!!!
they also activate ATPase to break down/hydrolyse ATP which releases energy and then the myosin head can return back to origional position so it can bind another place
what happens after actin filament and myosin head flex (what is released and why)
ADP so a new ATP molecule can bind there
ATP which releases energy and then the myosin head can return back to origional position so it can bind another place along actin
happens along as muscle is stimulated
what is happening to actin/myosin cross bridges as stimulated
many breaking and forming which shortens sarcomere and contracts muscle
where is energy provided in muscle contraction
ATP hydrolysis
ATP can come from-
>aerobic respiration by OXIDATIVE PHOSPHORYLATION in mitochondria of muscle cells
>anaerobic resp. when oxygen used faster than blood supply. ATP made by GLYCOLYSIS and pyruvate becomes lactic acid
>Creatine Phosphate- chemical stored in muscle , creatine acts as store of phosphate and phosphylation makes ATP, store used quickly so only for short term burst of exercise. replenished from phosphate of ATP
how is muscle activity measured
what is it used to show
with ElectroMyoGram or EMG
an large output on EMG means increased force. electrodes attached
used to show characteritics of muscles when doing particular exercise
what does muscle fatigue do/caused by
long lasting reduction in ability to contract/exert force
can be beneficial to body builders but not for normal as causes injury
what is creatine phosphate
> Creatine Phosphate- chemical stored in muscle , creatine acts as store of phosphate and phosphylation makes ATP, store used quickly so only for short term burst of exercise. replenished from phosphate of ATP
