Muscle Tissue

Question 1

What is considered to be the other contractile cells?

Answer 1

myoepithelial cells - component of some secretory glands - contract to move secretions towards excretory ducts

Pericyte- smooth, muscle like cells–> vascular support, contraction of BVs to regulate blood flow and pressure

Myofibroblast- inconspicuous in normal tissue- important in healing and repair

Question 2

Muscle tissue is categorized on the basis of?

Answer 2

specialized ability to contract

-the shape, arrangement of muscle cells varies with muscle type

Question 3

Muscle cells contain contractile proteins in?

Answer 3

the cytoplasm

Question 4

Muscle classification is done based on?

Answer 4

function- voluntary (skeletal) vs involuntary (smooth)

Morphology- striated (skeletal, cardiac) vs smooth

Question 5

Skeletal muscle organization:

Answer 5

• myofilaments
• myofibril
• muscle fibres
• fascicle
• skeletal muscle

Question 6

Characteristics of skeletal muscle

Answer 6

myocyte appearance- syncytium, long, straight
nucleus- multinucleated, located peripherally
striations- yes, sarcomeres
nuclei pushed to the periphery so not in the way of contractile fibres arranged in sarcomeres (take up majority of cytoplasm)

Question 7

what is a syncytium

Answer 7

a single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by division of nuclei.

Question 8

CT support

Answer 8

Epimysium- ensheaths entire muscle- major vessels and nerves penetrate layer
Perimysium- surrounds fascicles- large BV and nerves travel within
Endomysium- surrounds each fibre (myocyte)

Question 9

Types of skeletal muscle fibres are detected only within?

Answer 9

a stain tha utilizes enzyme oxidation

ex NADH-TR

Question 10

Types of skeletal muscle fibres

Answer 10

Type 1-slow oxidative
-small fibre size
-slow twitch, fatigue resistant
-high oxidative enzyme activity 
Type IIa
-intermediate enzyme activity
-medium-sized fibres
-fast twitch, fatigue resistant 
Type IIb
-low oxidative enzyme activity
-large sized fibres
-fast twitch, fatigue prone

Question 11

Smooth muscle

Answer 11

Myocyte appearance- fusiform, short
Nucleus- single, located centrally, elongatre
striations- none, no sarcomeres -contractile proteins interspersed
Few mitochondria

Question 12

Cardiac muscle

Answer 12

myocyte appearance- narrow, short, branched
nucleus- one (or two), located centrally
striations- yes, sarcomeres
Intercalated discs, purkinje fibres

Question 13

Which junctions are located within the intercalated discs?

Answer 13

Fascia (zonula) adherens- adhering junction, located at sarcolemma where myofilaments bind

Desmosome- reinforce fascia adherens- prevent cell falling apart

Gap junciton- facilitates communication between cardiac muscle cells