Skeletal and Smooth Muscle

Question 1

Structure of Skeletal Muscle:

Answer 1

Muscle Group
Fasciculi
Muscle Fiber/Muscle Cell/Myofiber
Myofibril
Myofilaments (Actin/Myosin)

Question 2

Sarcolemma

Answer 2

plasma membrane of a muscle fiber

Question 3

Myofibril

Answer 3

composed of myofilaments: actin and myosin

Question 4

Striations are formed by

Answer 4

overlapping of actin and myosin

Question 5

Sarcomere

Answer 5

from one z-disc to another

Question 6

T-Tubule

Answer 6

regular interval where the sarcolemma transfers the muscle cell in order to transmit action potentials

Question 7

Terminal Cisterna

Answer 7

where Ca++ is stored in the sarcoplasmic reticulum next to the

Question 8

Actin is made up of

Answer 8

G-actin molecules with myosin head binding sites which make F-actin strands, covered by tropomysoin

Question 9

Troponin

Answer 9

Troponin I - attached to actin
Troponin T - attached to tropomyosin
Troponin C - attracted to Ca++

Question 10

Each muscle cell is innervated by an efferent somatic motor neuron that uses Ca++ dependent exocytosis

Answer 10

Each muscle cell is innervated by an efferent somatic motor neuron that uses Ca++ dependent exocytosis

Question 11

In skeletal muscle fibers most of the Ca++ comes from

Answer 11

sarcoplasmic reticulum so extracellular Ca++ levels have very little effect

Question 12

In skeletal muscle fibers most of the Ca++ comes from

Answer 12

sarcoplasmic reticulum so extracellular Ca++ levels have very little effect

Question 13

Ratio of Actin to Myosin in skeletal/smooth muscle

Answer 13

Skeletal: 2 Actin:1 Myosin
Smooth: 5-10 Actin:1 Myosin

Question 14

Atrophy

Answer 14

decrease in muscle size d/t decrease in size of individual sarcomere from decrease amount of protein in myofilaments

Question 15

Hypertrophy

Answer 15

increase in muscle size d/t increase in size of individual sarcomere from increase amount of protein in myofilaments

Question 16

Hyperplasia

Answer 16

increase in number of muscle fibers, rare

Question 17

Type Types of Smooth Muscle

Answer 17

Multiunit - many discrete smooth muscle fibers which contract independently (ex. ciliary muscle of eye)
Single-unit - thousands of smooth muscle fibers that form a unit and contract together (ex. GI tract)

Question 18

Actin is attached to ____ in smooth muscles

Answer 18

dense bodies

Question 19

_____ attaches one smooth muscle cell to another

Answer 19

dense bodies

Question 20

Space between dense bodies

Answer 20

gap junction

Question 21

Latch Mechanism

Answer 21

in smooth muscle the myosin head are dephosphorylated by Myosin Phosphatase, but the head may not immediately detach, can stay attached for hours and days

Question 22

What dephosphorylates the myosin heads in skeletal vs. smooth muscle?

Answer 22

skeletal: ATPase
smooth: Myosin Phophatase