Physiology of Smooth Muscle

Question 1

Give examples of smooth muscle in in the following systems:
Integumentary (Skin) system

Answer 1

piloerector muscles (Tiny muscles in the skin’s hair follicles that contract, pull the hair upright, and a “goosebump” forms on the skin) - Regulate heat

Question 2

Give examples of smooth muscle in in the following systems: Eyes

Answer 2

Iris or ciliary body
+ nictitating membrane

Question 3

Give examples of smooth muscle in in the following systems: Respiratory system

Answer 3

Trachea, bronchi tube, alveolar ducts

Question 4

Give examples of smooth muscle in in the following systems: Cardiovascular system

Answer 4

Walls of blood vessels

Question 5

Give examples of smooth muscle in in the following systems: Gastrointestinal system

Answer 5

Walls of organs, ducts of digestive glands

Question 6

Give examples of smooth muscle in in the following systems: Urinary system

Answer 6

Ureter, bladder, urethra

Question 7

Give examples of smooth muscle in in the following systems: Reproductive system

Answer 7

Mammary glands, genital ducts, prostate gland, scrotum

Question 8

Which type of muscle has light/dark bands?

Answer 8

skeletal

Question 9

Which type of muscle has myofibrils?

Answer 9

skeletal

Question 10

Which type of muscle has sarcomeres?

Answer 10

skeletal

Question 11

Which type of muscle has T-tubules?

Answer 11

skeletal

Question 12

Which type of muscle has an orderly arrangement? Which has a scattered arrangement?

Answer 12

orderly- skeletal
scattered- smooth

Question 13

Which type of muscle has actin and myosin?

Answer 13

skeletal & smooth

Question 14

Which type of muscle has troponin?

Answer 14

skeletal

Question 15

Which type of muscle has tropomyosin?

Answer 15

skeletal & smooth

Question 16

Which type of muscle has actin?

Answer 16

skeletal & smooth

Question 17

Which type of muscle has myosin?

Answer 17

skeletal & smooth

Question 18

Single Unit or Multi Unit?
_______ unit have interconnecting gap junctions;
_______ unit do not.

Answer 18

single ; multi

Question 19

Single Unit or Multi Unit?
_______ unit have spontaneous contractions ; _______ unit do not.

Answer 19

single ; multi

Question 20

Single Unit or Multi Unit?
_______ unit have slow wave membrane potential

Answer 20

single

Question 21

Single Unit or Multi Unit?
_______ unit resemble skeletal muscle

Answer 21

multi

Question 22

What is the 1st chemical step in smooth muscle contraction?

Answer 22

intracellular Ca2+ increase when Ca2 enters the cell and is released from the sarcoplasmic reticulum.

1) - intracellular Ca2 is increased

Question 23

What is the 2nd chemical step in smooth muscle contraction?

Answer 23

Ca2+ binds to binds to calmodulin (CaM)

2) Ca2 - calcium binds to CaM

Question 24

What is the 3rd chemical step in muscle contraction?

Answer 24

Ca2+-calmodulin (CaM) activated myosin light chain kinase (MLCK)

3) Ca2+ CaM activated MLCK

Question 25

What is the 4th chemical reaction in muscle contraction?

Answer 25

MLCK phosphorylated light chains in myosin head & increases myosin ATPase activity | 4) Light chains increase in myosin head & increases myosin ATPase activi

Question 26

What is the 5th chemical reaction in smooth muscle contraction?

Answer 26

Active myosin crossbridges slide along actin & create muscle tension | 5) Myosin crossbridges slide & create tension

Question 27

What are the 5 simple steps of smooth muscle contraction?

Answer 27

1) intracellular Ca2+ is **increased** 2) Ca2+ binds to CaM (calmodulin) 3) Ca2+ (+) CaM (switch) **activated** MLCK 4) Light chains increase in myosin head & increases myosin ATPase activity 5) Myosin crossbridges slide along actin & create tension

Question 28

What is the 1st chemical reaction of smooth muscle relaxation?

Answer 28

Free Ca2+ in cytosol **decreases** when pumped out of the cell or back into the sarcoplasmic reticulum | **Pump the free Ca2 back** in the sarcoplasmic reticulum

Question 29

What is the 2nd chemical reaction of smooth muscle relaxation?

Answer 29

Ca2+ unbinds from calmodulin | 2) Ca2+ **unbinds** CaM

Question 30

What is the 3rd chemical reaction in smooth muscle relaxation?

Answer 30

Myosin phosphatase removes phosphate from myosin, decreasing ATPase activity | 3) Myosin & phosphate **breakup**

Question 31

What is the 4th chemical reaction in smooth muscle relaxation?

Answer 31

Less myosin ATPase results in decreased muscle tension | 4) **Less myosin** ATPase = **less tension**

Question 32

What are the three types of action potential (AP) in single unit SM?

Answer 32

1) Spike potential 2) Spike initiated by slow wave 3) Action potential with plateau

Question 33

What are the two types of AP in Multi unit SM?

Answer 33

Electrical activity initiated by nervous system Neurotransmitter release

Question 34

What controls smooth muscle?

Answer 34

Nervous system, humoral control

Question 35

Which parts of the nervous system control smooth muscle?

Answer 35

sympathetic and parasympathetic nervous systems

Question 36

What does humoral factors mean when it controls smooth muscle?

Answer 36

hormones and other neurotransmitters reacting to chemicals instead of direct stimulation

Question 37

What is myosin ATPase in smooth muscle compared to in skeletal muscle?

Answer 37

hydrolysis of ATP

Question 38

What is the latch bridge mechanism?

Answer 38

Sustained/ prolonged contraction in smooth muscle

Question 39

What is the nictating membrane in a cat?

Answer 39

The protective structure in the eye, known as the 3rd eyelid. It moves sideways like a windshield wiper.

Question 40

What does hypocalcemia do to smooth muscle?

Answer 40

It delays contraction