Muscles

Question 1

What are the 3 types of muscle tissue?

Answer 1

Cardiac
Skeletal
Smooth

Question 2

What is the structure of skeletal muscle?

Answer 2

Myofiber
Myofibril
Sarcomeres

Question 3

What are the components of smooth muscle?

Answer 3

Muscle cells, thick/thin filaments, dense bodies, attachment plaque

Question 4

How are smooth muscles usually layered?

Answer 4

Circular layer (usually inner)
Longitudinal layer (usually outer)

Question 5

What are the differences between single-unit smooth muscle and multi-unit smooth muscle?

Answer 5

Single - Forms a sheet or bundle of tissue, Contain gap junctions, Contract as a single unit
Multi - Contract as individuals

Question 6

How does smooth muscle contract?

Answer 6

[Ca2+] intracellular increases
Ca2+ binds to calmodulin
Ca2+-Calmodulin activates myosin light chain kinase (MLCK)
MCLK phosphorylates light chains in myosin heads and increases myosin ATPase activity
Active myosin crossbridges slide along the actin to create muscle tension

Question 7

How does smooth muscle relax?

Answer 7

Intracellular [Ca2+] decreases
Ca2+ unbinds from calmodulin
Myosin phosphate removes phosphate from myosin which decreases ATPase activity
Decrease in muscle tension

Question 8

Which hormones have an affect on smooth muscle actions?

Answer 8

Norepinephrine, Epinephrine, ACh, Angiotensin 2, oxytocin, vasopressin, serotonin, histamine