muscle and nervous tissue Flashcards
name the connective tissue surrounding muscle from outer-innermost
epimysium; surrounds entire muscle. perimysium; surrounds individual fascicles. endomysium; surrounds individual fibres.
striated meaning
muscle that appears striped; has alternating light and dark bands/stripes
what is the smallest muscle in the body; length and location?
stapedius. 1.25mm, in the inner ear protecting the stapes.
where do you find skeletal muscle
attached to bones via tendons
heart fibres appear:
branched, striated
where is smooth muscle found
walls of hollow internal structures; e.g blood vessels, intestines, bladder
summarise the location, structure, control type, and function of skeletal muscle tissue (and contraction speed)
attached to bones by tendons, control voluntary movement (although can be unconscious, e.g posture). the muscle appears striated due to alternating myofilaments of the myofibrils. fibres are unbranched, long, and multinucleated, the peripheral nuclei are pushed to the side. controls voluntary movement, generates heat, maintains posture. contraction is fast.
around how many skeletal muscles are there
650
summarise the location, control type, structure, and function of cardiac muscle tissue
found in the heart. controls involuntary movement. striated, fibres are branched, uni-nucleated, and shorter than skeletal. fibres are joined end to end by intercalated discs. controls the motion of the heart.
summarise the location, control type, structure, and function of smooth muscle tissue (and contraction speed)
found in walls of hollow internal structure like blood vessels, intestines, bladder etc. controls involuntary movement. unstriated, short uni-nucleated fibres. controls involuntary movements like digestion and bloodflow. contraction is slow and controlled.
sarcolemma
plasma membrane of muscle fibres
sarcoplasm
cytoplasm of muscle fibres
fascicle; what is it, why important?
bundle of muscle fibres. allows different parts of the same muscle to behave differently as needed
describe the sarcomere and its basic structure
smallest functional unit of a muscle fibre. contractile. contains myofilaments actin (thin) and myosin (thick). M line runs down the middle of the sarcomere, connected to centres of thick filaments. A band (for ‘all’) spans the length of the thick filaments, contains thin filaments also. I band (for ‘in between’) alternates with A band and contains only thin filaments, spans between neighbouring sarcomeres. H zone is central, containing only thick filaments. z discs bookend sarcomeres and connect their adjacent thin filaments.
describe intercalated discs.
discs between cardiac muscle fibres, connecting them via desmosomes for mechanical strength/adhesion and gap junctions for electrical signal transmission.
purkinje fibres:
specialised cardiac muscle fibres with extensive gap junctions for enhanced electrical communication.
describe the contractile features of smooth muscle tissue
dense bodies, function similarly to z-discs, made of actinin. intermediate filaments make a rigid lattice criss-crossing the cell.
distinguish afferent and efferent activity
afferent activity relates to sensory information going TOWARDS the CNS. efferent activity relates to motor information going AWAY from the CNS.
describe the neuron’s structural components.
dendrites - input function- extend from the cell body and pick up electrical information.
cell today (soma) - contains the nucleus and other organelles.
axon - output function - extends from the cell body and send nerve impulses out through the axon terminal.
describe the 4 neuron types.
multipolar- 2+ dendrites surround cell body. one axon. all motor (skeletal) neurons are multipolar.
unipolar- cell body lies off to the side and axon to dendrite is a continuous line.
bipolar- one cell body between one dendrite end and one axon end.
anaxonic- has no distinguishable axon. little is known about function.
neurons vs neuroglia.
neuroglia are smaller but more numerous. neurons don’t divide, neuroglia divide. neurons carry electrical impulses, neuroglia don’t.
neuroglia functions (5)
phagocytic, nutrient supply to neurons, structure of nervous tissue, regulation of interstitial fluid in nervous tissue, repair of nervous tissue.
astrocytes form, function, and location
large, star-shaped cells that form groups called syncytium.
maintain the blood-barrier of the brain, acting as the gatekeepers to the brain’s environment. they also communicate, support, repair, and maintain the neuron’s environment.
found in CNS.
oligodendrocyte function and location
form the myelin sheet around CNS neurons’ axons. can wrap around several neurons, forming several sheaths.
found in CNS.
microglia function and location
phagocytic cells, clear debris away and engulf pathogens.
found in CNS.
epyndemal cells function and location
simple cuboidal epithelia cells. secrete CSF, have cilia to move the brains CSF around its ventricles, and microvilli to sample the CSF composition.
found in the CNS in the brains ventricles.
what is CSF, where is it made and found
cerebrospinal fluid.
made in the ventricles in the centre of the brain and found in the protective tissue around the brain/spinal cord.
schwann cells function and location
equivalent to oligodendrocytes of the CNS, except can only form myelin sheet for one neuron, although they can support several.
found in the PNS.
satellite cells function and location
equivalent to astrocytes of the CNS.
support neurons and maintain their environment.
found in the PNS.
why are nuclei of skeletal muscle pushed to the side
because the majority of the fibre is taken up by myofibrils
epimysium composition and function (and interconnection of these…)
dense irregular connective tissue. this provides for multi-directional pulling forces generated by muscular movement due to irregularly arranged collagen bundles. it is also strong and dense to support the muscle. compartmentalises it from other structures so it can move freely.
perimysium composition and function (and interconnection of these…)
dense irregular connective tissue. provides for multi-directional pulling forces. surrounds each individual fascicle allowing for more specific control within muscle.
endomysium composition and function (and interconnection of these…)
loose areolar connective tissue. surrounds individual fibres, and plays important role in nutrient exchange for the cell.
