L14: Smooth Muscle

Question 1

Which process in the gastro-intestinal tract requires innervation

Answer 1

Secretion

Motility

Question 2

Why do we need need motility in the gut

Answer 2

To move food in the gut for absorption and expelling it out through anus

Question 3

What are the 2 layers of smooth muscles in the GIT

Answer 3

Longitudinal

Smooth

Question 4

What are the two ways that smooth muscle can act in

Answer 4

Phasic manner

Tonic manner

Question 5

What is meant by the phasic manic

Answer 5

Contracting and relaxing quickly

Question 6

What is the tonic manner

Answer 6

Sustained contraction

Question 7

Give an example of a structure that acts with tonic manner

Answer 7

Sphincters

Question 8

What are the pace making cells of the smooth muscle called

Answer 8

Interstitial cells of CAJAL

Question 9

How are interstitial cells of CAJAL coupled to other smooth muscle cells

Answer 9

Electrically coupled by GAP junctions

Question 10

What stimulates depolarisation in smooth muscles

Answer 10

Stretch
Acetycholine
Parasympathetics

Question 11

What is depolarisation

Answer 11

Excitation that causes contraction of the smooth muscle

Question 12

What is hyperpolarisation

Answer 12

Low membrane potential

Question 13

What is hypepolarization stimulated by

Answer 13

Noradrenaline

Sympathetics

Question 14

What does hyperpolarization cause

Answer 14

Relaxation of smooth muscle

Question 15

What has to me met before for depolarisation to occur

Answer 15

Electrical threshold

Question 16

What major ion causes smooth muscle contraction

Answer 16

Calcium

Question 17

How does calcium cause smooth muscle contraction

Answer 17

1) calcium influx occurs
2) calcium binds to calmodulin to activate inactive myosin light chain kinase into active form
3) active myosin light chain kinase (enzyme) phosphorylates myosin to myosin-P
4) myosin-P interacted with actin to give contraction by using ATP

Question 18

How does relaxation happen after the activity of active myosin light chain kinase

Answer 18

Myosin light chain phosphatase dephosphorylates myosin-P to myosin

Question 19

Where does calcium come from for contraction

Answer 19

Voltage operated calcium channels

Acetycholine mediated signals which gives IP3

Question 20

Where is calcium stores

Answer 20

Inside the smooth endoplasmic reticulum bound to calcesquestrin

Question 21

When in calcium stored

Answer 21

After contraction

Question 22

Why is calcium stored

Answer 22

To make the contraction efficient

Question 23

Apart from myosin light chain phosphatase what are the other ways of initiating relaxation

Answer 23

Phosphorylating myosin light chain kinase

Question 24

How is the myosin light chain kinase phosphorylated for relaxation of the smooth muscle

Answer 24

1) VIP initiates adenyl cyclase
2) adenyl cyclase gives CAMP
3) CAMP activated protein kinase A to its active form
4) protein kinase A phosphorylated myosin light chain kinase

Question 25

What nervous system innervated the extrinsic system

Answer 25

Parasympathetic | Sympathetic

Question 26

What nervous system innervates the intrinsic system

Answer 26

Enteric

Question 27

Overall what nervous system is the parasympathetic, sympathetic and enteric nervous system part of

Answer 27

Autonomic nervous system

Question 28

What are the two plexus of the enteric nervous system

Answer 28

Submucosal plexus | Myenteric plexus

Question 29

What two layers is the submucosal plexus located between

Answer 29

Mucosa | Circular muscle

Question 30

What two layers is the myenteric plexus located between

Answer 30

Circular muscle | Longitudinal muscle

Question 31

What does activation of the submucosal plexus lead to

Answer 31

Increased secretory activity | Modulates intestinal absorption

Question 32

What does activation of the myenteric plexus lead to

Answer 32

Increased tonic contraction | Increased intensity of rhythmic contraction

Question 33

What are the types of motor neurones in the enteric nervous system

Answer 33

Excitatory | Inhibitory

Question 34

What are the types of sensory neurones In the enteric nervous system

Answer 34

Mechano-reception | Chemo-reception

Question 35

What do mechanoreceptors-receptors detect in the enteric nervous system

Answer 35

Pressure

Question 36

What do chemo receptors detect in the enteric nervous system

Answer 36

Chemicals such as acid

Question 37

What activity does the parasympathetic nervous system cause in GIT

Answer 37

Depolarisation that causes contraction

Question 38

What activity does the sympathetic nervous system cause in the GIT

Answer 38

Hyper-polarisation that causes relaxation

Question 39

What main cranial nerve parasympathetically innervated the oesophagus to proximal 1/3rd colon

Answer 39

Vagus nerve (CN10)

Question 40

What main cranial nerve parasympathetically innervates distal 2/3rd of colon to anus

Answer 40

Pelvic nerves (S1-S3)

Question 41

What is hirschprung disease

Answer 41

Congenital lack of neuronal ganglionic cells in the ENS

Question 42

What is Chagas’ disease

Answer 42

Infectious disease of a parasite resulting in reduction of ganglionic cells in the ENS

Question 43

What is achalasia

Answer 43

Loss of myenteric plexus in the lower gastro-oesophageal region

Question 44

Where does hirschprung disease start and extend to

Answer 44

Start at anus | Extends to colon

Question 45

What can hirschprung disease result in

Answer 45

Megacolon