11 - Histology - Muscles and Nerves

Question 1

Types of muscle

Answer 1

1) Tissues - Skeletal, cardiac, smooth 2) Cells - Myoepithelial cells, myofibroblasts, pericytes

Question 2

Size of skeletal muscle cells

Answer 2

10-100 micrometers in diameter, up to 30cm long

Question 3

Arrangement of nuclei in skeletal muscle cells

Answer 3

Multinucleate, peripheral location of nuclei

Question 4

Types of striated muscle

Answer 4

Cardiac, skeletal

Question 5

Difference between myofibre and myofibril

Answer 5

Myofibre = whole muscle cell Myofibril = Contractile cytoskeletal unit within cell

Question 6

Smooth muscle fibre shape

Answer 6

Fusiform 200-300 micrometers long by 5-6 micrometers wide

Question 7

Histological appearance of skeletal muscle 1) 2)

Answer 7

1) Cross-section - peripheral nuclei 2) Longitudinal section - striated, peripheral nuclei, length of single cells

Question 8

Histological appearance of cardiac muscle 1) 2)

Answer 8

1) Cross-section - Thick cells, central nuclei 2) Longitudinal - Central nuclei, striations, branching, shorter muscle cells than skeletal

Question 9

Histological appearance of smooth muscle 1) 2) 3) 4)

Answer 9

1) Cross-section - Thin cels, central nuclei 2) Longitudinal - Central, elongated nuclei, branched, no striations. 3) Peripheral organelles 4) No myofibrils, t-tubules, sarcomeres

Question 10

Which type of muscle is this?

Answer 10

Skeletal muscle

Question 11

Which type of muscle is this?

Answer 11

Smooth muscle

Question 12

Which type of muscle is this?

Answer 12

Cardiac muscle

Question 13

Are myofibrils membrane-bound?

Answer 13

No

Question 14

Which part of sarcomere anchors thin filaments?

Answer 14

Z-disc

Question 15

What is the sarcoplasmic reticulum? 1) 2) 3)

Answer 15

1) Specialised ER 2) Network of membranes that store Ca2+ 3) Rich in Ca2+ ATPases that pump Ca2+ back into SR

Question 16

T-tubules 1) 2)

Answer 16

1) Allow depolarisation across myocyte membrane to enter into cell, to SR. 2) Surround each myofibril, two T-tubules per sarcomere (where actin and myosin overlap)

Question 17

Where do mitochondria sit in myocytes?

Answer 17

Lie in lines between myofibrils, in the same spaces that house T-tubules and SR membrane

Question 18

Light microscope appearance of cardiac muscle 1) 2) 3) 4)

Answer 18

1) Many capillaries 2) Mono- or binucleate 3) Cells joined by intercalated discs 4) Cells form a network

Question 19

Layout of intercalated discs in cardiac muscle 1) 2) 3)

Answer 19

1) Zig-zag pattern 2) When lying perpendicular to cells, made up of adherens junctions and desmosomes, to resist force 3) When lying parallel to cells, made up of gap junctions, to transmit depolarisation (electrically couple cells)

Question 20

Type of muscle that lacks t-tubules, sarcomeres and myofibrils

Answer 20

Smooth muscle

Question 21

Where does that connective tissue surrounding smooth muscle come from?

Answer 21

Smooth muscle cells generate connective tissue

Question 22

Shape of contracted smooth muscle cells

Answer 22

Corkscrew

Question 23

EM appearance of smooth muscle 1) 2)

Answer 23

1) Contains thick (myosin) and thin (actin) filaments 2) Dense bodies (made of same protein as Z-discs, anchor actin/thin filaments)

Question 24

Smooth muscle contraction (Schematic)

Answer 24

SMOOTH MUSCLE CONTRACTION

Question 25

Regeneration of muscle cells 1) 2) 3)

Answer 25

1) Limited regeneration of skeletal by satellite cells 2) No regeneration of cardiac 3) Good regeneration of smooth because of high plasticity

Question 26

Myoepithelial cells

Answer 26

Surround some exocrine glands (EG: breast tissue). Squeeze out contents with actin/myosin contraction

Question 27

Myofibroblasts

Answer 27

Involved in wound healing. Pull wound together, involved in scarring.

Question 28

Cell type that contracts exocrine glands

Answer 28

Myoepithelial cells

Question 29

Cell type that is involved in pulling a wond together

Answer 29

Myofibroblasts

Question 30

Pericytes

Answer 30

Surround capillaries, contract to alter capillary blood flow. Contractile with actin/myosin

Question 31

Cells that alter capillary tonicity

Answer 31

Pericytes

Question 32

Layers of connective tissue in nerves 1) 2) 3)

Answer 32

1) Epineurium surrounds entire nerve 2) Perineurium wraps fasicles (bundles of neurons) 3) Endoneurium wraps individual nerves

Question 33

Are myelinated axons visible in H&E stain?

Answer 33

No. Need a specialised stain to visualise myelination (EG: toluidine blue)

Question 34

Are Schwann cell nuclei visible in H&E sections?

Answer 34

Yes

Question 35

In a section, are nuclei visible in axons?

Answer 35

No. Nuclei of neurons are in cell body. Nuclei are probably from Schwann cells.