Muscle Flashcards
which muscle types are controlled by the autonomic nervous system
cardiac and smooth
which muscle type is responsible for voluntary movement of the skeleton
skeletal muscle
other than voluntary movement of the skeletal, what else is skeletal muscle functioning for
subconscious movement like balance and posture
what type of cells are found in the skeletal muscle fibres
elongated cylindrical cells
describe the nuclei of skeletal muscle cells
peripherally located, multiple
what is the main tissue type in skeletal muscles
skeletal muscle fibres
other than the skeletal muscle tissue, what other tissues compose skeletal muscles
nervous tissue
blood vessels
connective tissues
what are fascicles wrapped by
perimysium
what are individual muscle fibres wrapped by
endomysium
what are muscles wrapped by
epimysium
what kind of connective tissue is perimysium
loose
what is the cell structure of skeletal muscle specialised for
contraction
what makes up each individual muscle fibre
numerous myofibrils
what gives rise to the striated appearance of skeletal muscle
the arrangement of the myofibrils
what are myofibrils composed of
myofilaments
what are the dark bands on myofibrils
myosin
what are the light bands on myofibrils
actin
what bisects the actin binds
z lines
what is the function of z lines
to divide each myofibril into contractile units called sarcomeres
what are sarcomeres
contractile units of skeletal muscle tissue
how do sarcomeres contract
sliding filament mechanism
what innervates skeletal muscle
somatic motor neurons
what is the ratio of neuron to muscle fibre
an individual motor neuron can innervate several fibres
what is a motor unit
the combination of a single motor neuron together with all the muscle fibres
what is the chemical messenger of neuronal action potential in skeletal muscle
acetylcholine
where is the neuronal action potential converted to acetylcholine
at the neuromuscular junction
what stimulates the action potential in muscle fibres
detection of acetylcholine at the reeptors on the muscle fibres
describe excitation contraction coupling
the neuronal action potential is converted to acetylcholine at the neuromuscular junction which is detected by the receptors on the muscle fibres to stimulate actiokn potential in the fibres
what is the sarcolemma
outer membrane continous with the extracellular space that forms t tubules by invaginating into the sarcoplasm
what is the sarcoplasmic reticulum
modified smooth endoplasmic reticulum containing calcium ions
which elements of muscle fibres work together to support the contraction of sarcomeres
the sarcolemma and the sarcoplasmic reticulum
what is the function of cardiac muscle
continuous autonomic contraction of the heart in order to pump blood through the cardiovascular system
describe cardiac muscle cells
elongated and branched cylindrical cells
how many nuclei are found within cardiac muscle cells
one or two
where are cardiac muscle cell nuclei located
centrally
what are the three layers of the heart wall
pericardium
myocardium
endocardium
what is the pericardium
outer layer, supportive function
what is the myocardium
middle layer composed of cardiac muscle tissue
what is the endocardium
inner layer composed of endothelial cells
what are cardiomyocytes
cardiac muscle cells
what are intercalated discs
specialised intercellular junctions that anchor the cardiomyocytes together
where are intercalated dics found
cardiac muscle
what other tissues are found in cardiac muscle besides the cardiomyocytes
reticular connective tissue and a rich capillary network
what are the similarities that cardiac muscle shares with skeletal muscle
- both striated due to the sarcomere arrangement
- t tubules, SR, glycogen and lipids
- numerous mitochondria
- sliding filament mechanism
what are the differences between cardiac muscle and skeletal muscle
- involuntary contraction
- the SR are different, as there is slow leakage of calcium ions
- conducting system
- intercalated discs
describe the conducting system of the heart
- action potential is initiated at the sinoatrial node
- this makes the left and right atria contract
- intercalated discs and gap junctions facilitate the propagation of these electrical impules to contract the myocardial cells
- myocardial cells contract due to action potential
what are the nodal tissues of the heart
the sinoatrial and atrioventricular nodes
what do nodal tissues of the heart do
generate action potentials
what do conducting fibres do
conduct the action potentials
what are the conducting fibres of the heart
internodal and interatrial conduction pathways, bundle of his, bundle branches and subendocardiac branches (purkinje fibres)
what supplies the sinoatrial node
the sinoatrial node branch of the right coronoary artery
describe the intratrial conduction pathway
the sinoatrial node supplies impulses and this is then conducted to the atria
what is the atrioventricular node
the secondary pacemaker of the heart
what are purkinje fibres
the subendocardiac branches
describe the order of events of the conducting system in the heart
Impulse starts at the SA node → internodal and interatrial conduction pathways → AV node → AV bundle (of His) → bundle branches → subendocardiac branches
what does sympathetic innervation do the heart
increase the rate of the sinoatrial node activity ie increase heart rate
what is the parasympathetic effect on the heart
decrease heart rate by decreasing the activity of the sinoatrial node
where is the sinoatrial node on the heart
near the opening of the superior vena cava
what are P cells
the pacemaker cells of the sinoatrial nodethat contain both cholinergic and adrenergic receptors to respond to neurotransmiters released by the surrounding autonomic ganglion
which section of the heart is the location for the internodal conduction pathway
right atrium
what is the bundle of his
the initial segment of the atrioventricular node that penetrates through the fibrous trigone into the interventricular septum
what is the function of the av node of his
transmission of electrical impulse from the atrioventricular node to the purkinje fibres of the ventricles
what does the voluntary contraction of skeletal muscle occur via
motor neuronal stimulation
what does the involuntary contraction of cardiac muscle occur via
spontaenous contractile ability and rate of inherent rhythm
what allows the cardiac muscle contratile ability to be spontaneous
the pacemaker cells of the sinoatrial node and the slow release of calcium ions from the sarcoplasmic reticulum
what allows the rate of inherent rhythm of the cardiac conduction system
autonomic nervous stimulation and hormonal stimulation
what is the function of smooth muscle
continuous contraction of hollow organs to stimulate peristalsis
what is peristalsis
propelling of lumen contents
what is the structure of the smooth muscle cells
elongated, spindle shaped. tapered ends
describe the nuclei of smooth muscle cells
single and centrally located
are there sarcomeres in smooth muscle
no
why does smooth muscle not have striations
no sarcomeres
describe the GIT tract
muscular tube functioning in peristalsis
what are the layers of the gastrointestinal tract, from the inside out
lumen
epithelium
lamina propria
muscularis mucosae
submucosa
muscularis propria (inner circular and outer longitudinal)
adventitia
what lines the gastrointestinal tract
mucous membrane
what is the arrangement of layers in the GIT specialised for
peristalsis
what is the function of the inner circular layer
constrict lumen diameter
what is the function of the outer longitudinal layer
shorten the length of the GIT
what do the two muscularis propria layers function together to do
squeeze food through the GIT
what modulates the intensity of peristalsis
parasympathetic ganglia
do smooth muscle tissues contain myosin and actin
yes
are there myofibrils and sarcomeres in smooth muscle
no
how are actin and myosin in smooth muscle arranged
criss cross lattice
what is the function of dense bodies
anchor the actin and myosin to the cytoplasm and cell membrane, bind together the smooth muscle cells to transmit the contractile forces from cell to cell
what is desmin
intermediate filaments of smooth muscle tissue
how does the shape of smooth muscle change from relaxation to contracted
goes from elongated to shortened and globular
