7: Histology - bone structure, core MSK

Question 1

Skeletal muscle cells are (striated / unstriated).

Answer 1

striated

Question 2

Skeletal muscle cells are (branched / unbranched).

Answer 2

unbranched

very long and tubular, myocytes span the entire length of the muscle

Question 3

How many nuclei do skeletal muscle cells have?

Answer 3

Hundreds - tens of thousands

Question 4

In skeletal muscle cells, nuclei are found at the (centre / periphery) of the cell.

Answer 4

periphery

(In cardiac muscle, single nuclei at the centre.)

Question 5

What is the plasma membrane of skeletal muscle cells called?

Answer 5

Sarcolemma

Question 6

What is the level of organisation one above single muscle fibres?

Answer 6

Fascicles

(bundles of muscle fibres)

Question 7

A muscle is typically split up into several ___.

Answer 7

fascicles

Question 8

Connective tissue surrounding the whole muscle is called the ___.

Answer 8

epimysium

Question 9

Connective tissue surrounding a single fascicle is called the ___.

Answer 9

perimysium

Question 10

Connective tissue surrounding single muscle fibres is called the ___.

Answer 10

endomysium

Question 11

Complete:

Skeletal muscle > Fascicles > ____ > ____ > Sarcomeres > Actin and myosin filaments

Answer 11

… Fascicles > Muscle fibres > Myofibrils …

Question 12

What is the specialised endoplasmic reticulum found in muscle cells?

Answer 12

Sarcoplasmic reticulum

Question 13

Apart from muscle cells, what do skeletal muscles (as organs) contain?

Answer 13

Blood vessels

Connective tissue

Lymphatic vessels

Question 14

What are the functional units of muscle?

Answer 14

Sarcomere

Question 15

Sarcomeres extend from one __ ___ to the next.

Answer 15

Z line

(see Physiology I for the other terms)

Question 16

To produce contraction, ___ filaments slide along ___ filaments and the Z lines move (closer together / further apart).

Answer 16

myosin , actin

closer together

Question 17

Why are skeletal muscle cells striated?

Answer 17

Alternating light and dark bands of actin and myosin are in alignment across each myofibril

(There’s nothing continuously running through the cell - optical illusion.)

Question 18

Myofibrils are held in ___ with one another.

Answer 18

registry

i.e aligned

Question 19

What is a motor unit?

Answer 19

Alpha motor neuron PLUS all the muscle fibres it supplies

Question 20

Motor neuron branches synapse with muscle fibres at ___ ___.

Answer 20

neuromuscular junctions

Question 21

Whether a muscle produces powerful or fine, precision movement depends on the number of ___ ___ in its motor units.

Answer 21

muscle fibres

Question 22

Which group of muscles has the least number of muscle fibres in its motor units (and therefore the most precise movements)?

Answer 22

Extraocular muscles

Question 23

Which type of muscle fibres are also known as red fibres?

Answer 23

Type I (slow oxidative / slow-twitch) fibres

Question 24

Type I muscle fibres depend on ___ metabolism and have lots of ___ and ___.

Answer 24

aerobic

mitochondria , myoglobin

Question 25

Type I fibres are resistant to ___.

Answer 25

fatigue

Question 26

Type IIa fibres are both ___ and resistant to ___.

Answer 26

fast , resistant to fatigue

Question 27

What colour are Type IIb/x fibres?

Why?

Answer 27

White

Less myoglobin as they don’t require oxygen

Question 28

Type IIb/x fibres use ___ metabolism, so they don’t have a lot of ___.

Answer 28

anaerobic

mitochondria