MCM Final - Muscle Tissue

Question 0

myofiber

Answer 0

made up of myofibrils

Question 1

myoblast

Answer 1

proliferative cell in muscles

Question 2

myofibroblast

Answer 2

primarily in wound healing

during the inflammatory response
-bind to connective tissue and contract to seal and close wound

actin filaments

similar to smooth muscle

Question 3

myoepithelial cells

Answer 3

specialized cells associated with glandular secretory units

help deliver gland product into duct

wrap around glandular units

actin and myosin filaments

similar to smooth muscle

Question 4

smooth muscle

Answer 4

involuntary contraction

centrally located nucleus

external lamina
-lamina densa and lamina rara

Question 5

dense bodies

Answer 5

attachment points in smooth muscle
anchors for sliding filaments

-results in smooth muscle to coil or "pleat"

Question 6

lamina densa and lamina rara

Answer 6

components of the external lamina of smooth muscles

lamina rara in between two lamina densas

Question 7

skeletal muscle

Answer 7

peripheral nuclei

voluntary contraction

multinucleated

Question 8

sarcomere

Answer 8

repeating unit of skeletal muscle

goes from z line to z line

contractile unit of the myofiber

Question 9

a band

Answer 9

broad dark band in sarcomere

Question 10

i band

Answer 10

light band

ends of two adjacent sarcomeres

Question 11

h band

Answer 11

light band in middle of sarcomere

middle of the a band

Question 12

myofiber

Answer 12

muscle cell

Question 13

endomysium

Answer 13

surrounds individual myofibers

Question 14

fascicle

Answer 14

bundle of myofibers in skeletal muscle

Question 15

perimysium

Answer 15

surrounds the fascicle in skeletal muscles

Question 16

epimysium

Answer 16

surrounds bundle of fascicles in skeletal muscle

Question 17

cardiac muscle

Answer 17

also striated
involuntary contraction
can beat without external stimuli

central nuclei

ends joined by intercalated discs (fascia adherens)

Question 18

intercalated discs

Answer 18

joins ends of cardiac muscles

fascia adherens

rich in gap junctions

Question 19

neuro-muscular junction

Answer 19

excitation signal transferred at motor end plate

release of acetylcholine stimulates contraction

Question 20

neurotransmitter for muscle contraction?

Answer 20

acetylcholine
-results in entry of sodium into the cell by opening up
Ach-gated ion channels

Question 21

excitation-contraction coupling

Answer 21

nerve impulse transmitted to the transverse tubule system of myocyte

T-tubules - organized into triads
-at A band / I band junction

terminal cisternae on each side of t-tubule extend to sarcoplasmic reticulum

sodium flux through Ach-gated channels in t-tubules results in opening of calcium channels in the sarcoplasmic reticulum

causes filament sliding

Question 22

filament sliding during contraction

Answer 22

shortens i and h band

a band width constant (A band is width of the thick filament myosin)

Question 23

thick filaments

Answer 23

myosin - length of a band

Question 24

thin filaments

Answer 24

actin filaments

anchored at z line

Question 25

myofilament structure

Answer 25

each myosin (thick fiber) surrounded by 6 actin (thin) filaments

Question 26

structure of myosin

Answer 26

thick filament

- to chains of heavy meromyosin
- hinge region
- light meromysin in the head region

Question 27

structure of actin

Answer 27

thin filament of contraction

polymer of actin
tropomyosin - covers actin binding site
troponin - binds calcium during activation of contraction

Question 28

Mechanism of Filament Sliding

Answer 28

1 myosin bound to ADP and P (resting)
2 Ca2+ binds troponin causing tropomyosin to uncover myosin binding sites on actin
3 myosin binds to actin releasing energy (ADP and P)
4 release of ADP and P causes conformation change in myosin head
5 ATP binds releasing myosin from actin (relaxes myosin)
6 ATP converted to ADP and P
7 start over

Question 29

low energy state of contraction?

Answer 29

binding of ATP causes the relaxation of myosin

- no ATP means you have no relaxation in myosin and constant contraction
	- rigor mortis

Question 30

contraction in smooth muscle

Answer 30

calcium released into cell and binds calmodulin

- results in activated myosin light chan kinase
- phosphorylated myosin interacts with and binds actin

Question 31

calmodulin

Answer 31

involved in smooth muscle contraction

Question 32

muscle bone connection

Answer 32

actin filaments insert at modified z line

- connective tissue surrounding muscle binds to bone
	- tendon, bone, and periosteum, sharpey's fibers

Question 33

muscle spindle organs

Answer 33

found in the muscle body

sense muscle length and tone

has two types of fibers:

- extrafusal
- intrafusal

proprioceptive sensor

- known as annulospiral ending
	- wraps around specialized muscle fibers with efferent and afferent fibers

Question 34

Golgi Tendon Organs

Answer 34

found in tendons

sense increased tension
contain only sensory fibers

axons terminate at spiral endings

wrap collagen strands