Exam 1: Muscle

Question 1

Where does musculoskeletal tissue come from

Answer 1

Mesoderm

Question 2

Definition of tissue

Answer 2

Conglomerate of cells with similar morphology that serve one or several specific functions within an organism

Question 3

Parts of musculoskeletal tissue

Answer 3

Muscle
Bone
Cartilage

Question 4

Main characteristics of muscle tissue

Answer 4

Cytoplasm contains myofilaments = sarcoplasm

Myofilaments - actin and myosin

Sliding of myofilaments = contraction = movement

Question 5

Muscle contraction by activity

Answer 5

Voluntary - skeleton, tongue, eyes

Involuntary - heart, blood vessels, bronchioles, digestive tract

Question 6

The sarcomere

Answer 6

Myofilaments - actin, myosin, Ts
•Troponin, tropomyosin

Plus sarcoplasmic reticulum full of Ca

Question 7

Actin

Answer 7

Thin filaments
I band
Light band

Question 8

Myosin

Answer 8

Thick filaments
A band
Dark band

Question 9

Parts of the sarcomere

Answer 9

Z bands - sarcomere goes from Z band to Z band

H band - only myosin filaments

A band - whole myosin band
•Including area where actin and myosin overlap

I band - only actin filaments

Question 10

Myoblasts

Answer 10

Myoblasts from mesoderm - paraxial or lateral

-blast –> early forms of cells

Myoblasts are early muscle cells

Question 11

Embryonic origin of skeletal muscle

Answer 11

Fusion of myoblasts
•Multiple nuclei per myofibril

Paraxial mesoderm (somites and somitomeres) –> Myotomes –> Skeletal muscle

Question 12

Embryonic origin of cardiac muscle

Answer 12

Individual fibers held very close together by intercalated discs

Purkinje fibers - glycogen rich
•In heart - dictate how heart is going to contract by conducting nervous stimulus

Lateral mesoderm (Splachnopleura) –> Myotomes –> Cardiac myoblasts

Lateral mesoderm (Splachnopleura) –> Myotomes –> Myoblasts –> Purkinje fibers

Question 13

Embryonic origin of smooth muscle

Answer 13

Individual fibers - one nucleus per fiber

Inner eye muscles - neural crest

Lateral mesoderm (Splachnopleura) –> Myotomes –> Smooth muscle myoblasts

Question 14

Muscle types by function

Answer 14

Skeletal - voluntary
Cardiac - involuntary
Smooth - involuntary

Question 15

Skeletal muscle myofiber

Answer 15

Long
Multinucleated
Peripheral nuclei
Striated

Question 16

Skeletal muscle characteristics

Answer 16

Abundant myosin and actin

A, I, and Z bands (sarcomeres) , with special techniques

Voluntary contraction

Rich in myoglobin - helps cells have reserve of oxygen

Rich in glycogen - source of energy, skeletal muscle needs lots of energy

Red meat

Question 17

Myoglobin

Answer 17

Similar to hemoglobin - carries and stores oxygen

Very abundant in species that require oxygen in anaerobic condition –> marine mammals, turtles

Question 18

Cardiac muscle myofiber

Answer 18

Long and branching - cardiac syncytium
Single nucleus
Centrally located nucleus
Striation present but not as clear as skeletal muscle
Cells connected tightly to each other by intercalated discs

Question 19

Cardiac syncytium

Answer 19

Intramembranous unions - intercalated discs

Not to be confused with Z bands

Question 20

Cardiac muscle characteristics

Answer 20

Rich in glycogen

Involuntary and continuous short contractions

Question 21

Smooth muscle myofiber

Answer 21

Fusiform shape
Variable size
Irregular
No visible striations - actin and myosin crisscrossed 
Single nucleus
Centrally located nucleus

Question 22

Smooth muscle characteristics

Answer 22

Involuntary contraction

Lowest content of myoglobin

Lowest content of glycogen

Question 23

General overview of how sarcomere works

Answer 23

Relaxed - actin and myosin kept in place by T

Ca released from sarcoplasmic reticulum - Ts leave, actin slides across myosin

Question 24

Smooth muscle contraction

Answer 24

Myosin and actin crisscrossed
Tropomyosin
Calcium
Calmodulin
Dense bodeis

Question 25

Connective tissue in muscles

Answer 25

Endomysium Perimysium Epimysium

Question 26

Endomysium

Answer 26

Layer of connective tissue around each myofiber

Question 27

Perimysium

Answer 27

Layer of connective tissue around a bundle of myofibers

Question 28

Epimysium

Answer 28

Layer of connective tissue around a group of muscle bundles (muscle)

Question 29

Comparing muscle - Function

Answer 29

Skeletal - voluntary Cardiac - involuntary Smooth - involuntary

Question 30

Comparing muscle - striations

Answer 30

Skeletal - yes Cardiac - yes, but less clear than skeletal Smooth - no, no sarcomeres

Question 31

Comparing muscle - Z bands

Answer 31

Skeletal - yes Cardiac - yes Smooth - no, no sarcomeres

Question 32

Comparing muscle - Intercalated discs

Answer 32

Skeletal - no Cardiac - yes Smooth - no

Question 33

Comparing muscle - number of nuclei

Answer 33

Skeletal - multinucleated Cardiac - single nucleus Smooth - single nucleus

Question 34

Comparing muscle - location of nuclei

Answer 34

Skeletal - peripheral Cardiac - central Smooth - central

Question 35

Comparing muscle - myoglobin

Answer 35

Skeletal - most Cardiac - moderate Smooth - least

Question 36

Comparing muscle - Ca binding protein

Answer 36

Skeletal - troponin Cardiac - troponin Smooth - calmodulin