muscle and nervous tissue

Question 1

name the connective tissue surrounding muscle from outer-innermost

Answer 1

epimysium; surrounds entire muscle.
perimysium; surrounds fascicles.
endomysium; surrounds individual fibres.

Question 2

what is the smallest muscle in the body; length, location, function

Answer 2

stapedius.
1.25mm
in the inner ear, stabilising the stapes and regulating volume.

Question 3

location of skeletal muscle

Answer 3

attached to bones via tendons

Question 4

structure of cardiac muscle fibres

Answer 4

short, single central nucleus, branched, striated (though less distinctly than skeletal muscle)

Question 5

locations of smooth muscle

Answer 5

walls of hollow internal structures; e.g blood vessels for contraction and intestines for peristalsis (also other places like bladder and stomach)

Question 6

structure of skeletal muscle fibres

Answer 6

striated, unbranched, long and cylindrical. multinucleated, and nuclei are peripheral as the sarcoplasm is packed with myofibrils.

Question 7

around how many skeletal muscles are there

Answer 7

650

Question 8

function and contraction characteristics of skeletal muscle

Answer 8

control voluntary movement (although can be unconscious, e.g posture). functions are movement, heat generation, and posture.
contraction is fast.

Question 9

function and contraction characteristics of cardiac muscle

Answer 9

controls the involuntary contraction of the heart.

Question 10

special structural characteristics of cardiac muscle

Answer 10

fibres are joined by intercalated discs which have lots of desmosomes for mechanical adhesion and preventing of cells separating due to forces of contraction, and lots of gap junctions for communication.
there are specialised cardiac cells called purkinje fibres which have less myofibrils and more extensive gap junctions than normal cardiac fibres for enhanced signalling.

Question 11

function and contraction characteristics of smooth muscle tissue

Answer 11

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.

Question 12

structure of smooth muscle fibres

Answer 12

single central nucleus. short, spindle-shaped cells. unbranched and unstriated. have packages of actin and myosin. actin is connected to dense bodies, which contain actinin. rigid intermediate filaments (vimentin and desmin) make a criss-crossing lattice around the cell.

Question 13

why are smooth muscle cells spindle-shaped

Answer 13

it is thought to aid in their wrapping around hollow structures, as is their twisting contraction style

Question 14

the sarcolemma is:

Answer 14

plasma membrane of muscle fibres

Question 15

the sarcoplasm is:

Answer 15

cytoplasm of muscle fibres

Question 16

what are fascicles and what do they do

Answer 16

bundles of muscle fibres.
allow different sections of the same muscle to behave differently as needed, allowing more dynamic movement.

Question 17

describe the sarcomere and its BASIC structure

Answer 17

basic functional, contractile units of the myofibril.
contains actin thin myofilaments and myosin thick myofilaments.

Question 18

describe the M-line and Z-discs

Answer 18

M-line is a protein structure in the centre of the sarcomere holding together the thick filaments, and orientating the fibres to enable correct sliding for contraction.
Z-discs are found separating sarcomeres, are made of actinin and connect actin of adjacent sarcomeres. they are connected to the M-lines by titin.

Question 19

distinguish afferent and efferent activity

Answer 19

afferent activity relates to sensory information going TOWARDS the CNS. efferent activity relates to motor information going AWAY from the CNS.

Question 20

describe the neuron’s structural components.

Answer 20

dendrites - extend from the cell body and pick up action potentials/electrical information.
cell today (soma) - contains the nucleus and other organelles.
axon - extends from the cell body and conveys action potentials out through the axon terminal to other neurons, muscles, cells, etc.

Question 21

neurons vs neuroglia.

Answer 21

neuroglia can divide, are smaller than neurons but more numerous, and they can’t propogate action potentials.
neurons don’t divide, can be very long, and coney action potentials.

Question 22

neuroglia functions (5)

Answer 22

phagocytic
nutrient supply to neurons
structure of nervous tissue
regulation of interstitial fluid in nervous tissue
repair of nervous tissue

Question 23

astrocytes form, function, and location

Answer 23

large, star-shaped cells that form groups called syncytium.
maintain the internal environment of neurons by surrounding them and regulating fluid exchange.
maintain the blood-barrier of the brain.
they also communicate with neurons, repair nervous tissue and create scars.
found in CNS.

Question 24

oligodendrocyte function and location

Answer 24

myelinate (form myelin sheaths around) CNS neurons’ axons to enhance conduction.
can myelinate several neurons.
found in CNS.

Question 25

microglia function and location

Answer 25

phagocytic cells, clear debris away and engulf pathogens. puff up when active. found in CNS.

Question 26

epyndemal cells structure, function, and location

Answer 26

simple cuboidal epithelial cells with cilia and microvili. produce, waft, and sample the cerebrospinal fluid (CSF). found in the CNS, in the brains ventricles and the central canal of the spinal cord.

Question 27

what are myelin sheaths (form and function)

Answer 27

protein lipid layers surrounding axons. they are insulatory, therefore enhance conduction.

Question 28

what does CSF do

Answer 28

it acts as a mechanical buffer, moving nutrients and waste

Question 29

schwann cells function and location

Answer 29

equivalent to oligodendrocytes of the CNS, except can only form myelin sheath around one neuron, although they can support several. found in the PNS.

Question 30

satellite cells function and location

Answer 30

equivalent to astrocytes of the CNS. support neurons and maintain their environment via fluid exchange. found in the PNS.

Question 31

why are nuclei of skeletal muscle pushed to the side

Answer 31

because the majority of the fibre is taken up by myofibrils

Question 32

epimysium composition and function

Answer 32

made of dense irregular connective tissue. this supports multi-directional pulling forces generated by muscular movement, and is also strong and dense to support the muscle. compartmentalises it from other structures (e.g adjacent anatomical muscles) so it can move freely.

Question 33

perimysium composition and function

Answer 33

made of dense irregular connective tissue. allows for multi-directional pulling forces. surrounds each individual fascicle allowing for more specific control within muscle.

Question 34

endomysium composition and function

Answer 34

loose areolar connective tissue. surrounds individual fibres, and contains nerves and capillaries, facilitating nutrient exchange for fibres.

Question 35

function and contraction characteristics of smooth muscle

Answer 35

controls the involuntary, slow sustained contraction of hollow internal structures like peristalsis of the ingtestines, and contraction of the blood vessels

Question 36

what is titin

Answer 36

a protein filament connecting z-discs and m-line, acting as a molecular spring that provides resting tension

Question 37

what proteins are found in the intermediate filaments of smooth muscle fibres

Answer 37

vimentin and desmin

Question 38

what are myofibrils

Answer 38

rope like structures that run the whole length of a muscle fibre and contain myofibrils in repeating sarcomere units.

Question 39

what is hyperacusis and its relation to bells palsy

Answer 39

hyperacusis is sound-sensitivity/sounds being too long. caused by damage to the nerves in the face/ear bells palsy is damage to the facial nerve, therefore can cause hyperacusis.

Question 40

describe the three zones of the sarcomere

Answer 40

A band and I band alternate: A band runs the length of the thick filaments, containing both thin and thick filaments. I bands run the length of thin filaments, and contain only thin filaments. the H zone is in the middle and contains only the thick filaments.

Question 41

what happens to the zones of the sarcomere during contraction

Answer 41

I- band and H-zone disappear, as filaments slide over each other therefore there is no space containing only one or the other. A-band stays the same, as thick filaments don't move.

Question 42

nervous system broad functions

Answer 42

maintains homeostasis initiates voluntary movement perception, behaviour, memory

Question 43

nervous system broad activities

Answer 43

sensory (detection of stimuli and conveying to CNS) motor (not just muscular movement, e.g gland secretion too) integrative (analysis and storage of info)