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1

What are the 2 functional types of smooth muscle

Multi-unit and unitary

2

In multi smooth muscle, each fiber is ____ of other fibers

Independent

3

Each multi-unit smooth muscle is innervate by:

It’s own nerve ending

4

Multi-unit smooth muscle is insulated from ____ ____ fibers by ____ and ____.

Other smooth muscle fibers

Collagen


Glycoproteins

5

Where is multi-unit smooth muscle found?

In ciliary muscle of the eye, iris, pilo-erector muscles

6

Unitary smooth muscle, AKA:

Syncytial smooth muscle

7

In unitary smooth muscle, multiple muscle fibers function as a ____ ___.

Fibers are arranges in ____ or ____.

Membranes are interconnected by ___ ___.

Single unit

Sheets or bundles

Gap junctions

8

Unitary Smooth muscles are found where?

Most viscera (gut, blood vessels, uterus, ureters, bile ducts)

9

In smooth muscle, Actin is attached to:


Adjacent ones are attached to each other by:

Dense bodies


Intercellular proteins

10

In smooth muscle, myosin is interspersed amongst the:

Actin

11

Smooth muscle contraction properties

Slow cycling of myosin cross bridges

Force of contraction

“Latch mechanism”

Stress-relaxation

12

The smooth muscle frequency is much (MORE/LESS) than skeletal muscle, and cross bridges hold for (LONGER/SHORTER) time

Less

Longer

13

Once tension has developed, _______ are maintained for a period of time with (LOTS/LITTLE) additional energy. This is an energy efficient way to maintain ___.

Cross-bridges

Little

Tone

14

Stress-relaxation response is seen principally in:

Visceral unitary muscle

15

The stress-relaxation response is a response to what?

Stretch

16

In stress-relaxation response, smooth muscle responds to stretch _____, then:

Briefly

Adapts to its new length


The new length retains its ability to contract

17

The stress-relaxation response enables organs such as the ____ and ____ to:

Stomach and bladder

Temporarily store contents

18

In smooth muscle contraction,

Stimulus causes increase in ____ ___.

This will bind to ______.

Intracellular calcium


Calmodulin

19

For smooth muscle contraction, Ca+2/calmodulin binds to and activates:

This phosphorylates :

Which is capable of:

Myosin light chain kinase (MLCK)

The light chains of the myosin heads

Binding to actin

20

Smooth muscle relaxation,


Contraction is stopped by :

Myosin phosphatase

21

Source of calcium for muscle contraction

Cell membrane calcium channels

Sarcoplasmic reticulum

22

Almost all of the calcium used in muscle contraction is used from:

Extracellular sources

23

The sarcoplasmic reticulum is ____ developed in smooth muscle

Poorly

24

Smooth muscle has rudimentary T-Tubules called:

Caveolae

25

Smooth muscle can be stimulated by:

The nervous system

Hormones

Local tissue factors

Stretch

26

For smooth muscle contraction, autonomic fibers end in ______ making _______. Nerve endings are closer to _______ smooth muscle cells as compared to ____ muscle

Varicosities

“Diffuse” neuromuscular junctions

Multi-unit

Visceral

27

Typical smooth muscle neurotransmitters are:

Ach and NE

28

Review pic in slide 9

Slide 9

29

Hormones may cause smooth muscle contraction or dilation based on:

The receptor type they bind to

30

Some hormone receptors for smooth muscles are themselves ____ ____ that cause ____ or _____ depending on:

Ion channels

Depolarization or hyperpolarization

Which ion they are specific to.

31

For smooth muscle

Some hormones use ____ ____ __ such as ____q

Second messenger systems

CAMP

32

Hormones used in smooth muscle contraction

Norepinephrine

Epinephrine

Acetylcholine

Angiotensin

Endothelin

Vasopressin

Oxytocin

Serotonin

Histamine

33

Many smooth muscles naturally maintain ___, such as those in:

Tone

Arterioles

Metarterioles

Pre-capillary sphincters

34

Vasodilation of smooth muscle tone results from:

Oxygen lack

Increased CO2

H+

Lactic acid

Adenosine

Increased body temp

35

Smooth muscle stretch reduces the ___ of the smooth muscle membrane potential leading to more ____ at the:

Negativity

Depolarization

Peaks of the slow waves

36

In smooth muscle membrane potentials, no true ___ ____ occur.

Cells are individually _____.

Cells are too ____ to generate an ___

Depolarizations are called:

Action potentials

Innervated

Small

AP

“Junction potentials”

37

In AP of unitary SM, _____ channels are more responsible for AP than:

V-gated CA+2

Na+2

38

AP patters for unitary SM

Spike potentials

Slow-waves (spontaneous, pace-maker like fluctuations in membrane potentials) with spike potentials

AP with plateaus

39

Depolarization factors of GI smooth muscle

Stretching

Acetylcholine/parasympathetic

Gastrointestinal hormones

40

Hyperpolarizing facotrs of GI smooth muscle

Norepinephrine/epinephrine/sympathetic

41

Function of GI

Propulsion of good through GI tract

Secretion of digestive juices

Digestion; chemical and mechanical digestion

Absorption of digestive products

Circulation of blood through the GI tract (to circulate absorbed digestive products)

Local, nervous and hormonal control of the above functions

42

Propulsion of food through the GI tract includes:

Swallowing (oropharynx)

Peristalsis (esophagus, stomach, small intestine, large intestine)

43

Mechanical digestion of the GI includes:

Chewing (mouth)

Churning (stomach)

Segmentation (small intestine)

44

Absorption of the GI includes:

Nutrients and water to blood vessels and lymph vessels (small intestine)

Water to blood vessels (large intestine)

45

GI tract wall layers, external to internal

Serous

Longitudinal smooth muscle

Circular smooth muscle

Submucose

Mucosa
-Epithelium
-Muscularis mucosa

Mucosal and submucosal glands

46

What is the enteric nervous system

The GI tracts own nervous system from the esophagus to the anus

47

Plexi of the enteric NS and their location

Myenteric (Auerbach’s) plexus
-Between longitudinal and circular muscle layers


Submucosal (Meissner’s) Plexus
- Within the submucosa

48

What plexus is mostly responsible for GI movements?

What is it composed of?

Myenteric plexus

A linear chain of interconnecting neurons extending the length of the GI tract

49

Excitation of the myenteric plexus increases:

Tonic (tone) contractions

Intensity of rhythmic contractions

Velocity of wave conduction

Release of vasoactive intestinal polypeptide (which relaxes pyloric and ileocecal sphincters)

50

Functions of the submucosal plexus

Control local intestinal secretion and absorption

Control local contraction of submucosal muscles (unfolding of the mucosa)

51

Which parasympathetic nerves innervates the esophagus -> 1st half of large intestine? What else does it innervate?

Cranial parasympathetic nerves (mainly vagus)


Pancreas

52

Parasympathetic innervation from distal large intestine -> anus

Sacral parasympathetic nerves (pelvic nerves)

53

Postganglionic parasympathetic neurons and ganglia are within the ___ ___.

Enteric plexus

54

Acetylcholine is largely _____ to the GI tract

Excitatory

55

Preganglionic neurons to the GI tract originate from where?

T5-L2

56

Postganglionic neurons originate from the:

Prevertebral ganglia

57

______ inhibits intestinal tract smooth muscle mainly via the ___ ___

Norepinephrine

Enteric plexus (except the muscularis mucosa which it excites)

58

80% of nerve fibers in the vagus nerves are ____.

Sensory

59

Afferents from the gut are sensitive to:

Irritation of the mucosa

Distention of the gut

Chemicals in the gut

60

What are the 3 types of GI reflexes

Enteric

Autonomic

Higher level

61

Enteric reflexes are entirely located where?


They control what?

Within the gut wall enteric nervous system


Control local GI secretions, peristalsis, mixing and local inhibitory effects

62

What are some examples of autonomic reflexes?

Gastrocolic reflex- Promotes evacuation of the colon

Enterogastric reflex- Inhibits stomach motility and secretions

Colonileal reflex- Inhibits emptying of ileal contents into the colon

63

Autonomic reflexes

Sensory signals originate from the gut -> prevertebral ganglia -> Then motor back to the gut

64

Higher level reflexes

Sensory signals from the gut to the spinal cord or brainstorm to the GI tract

65

Examples of higher level reflexes

Reflexes from the stomach and duodenum to the brain stem and back to control stomach motility and secretions

Pain reflexes that cause general inhibition of the GI tract

Defecation reflexes to from and to the colon

66

Gastric is secreted by what?

It stimulates:

“G” cells of the stomach

Gastric acid secretion and gastric mucosal growth

67

Cholecystokinin is secreted by what?

It stimulates:

“I” cells of the duodenum mucosa

Gall bladder contraction, slows gastric emptying and inhibits appetite

68

Secretin is secreted by what?

It stimulates:

“S” cells of duodenum mucosa

Pancreatic secretion of bicarbonate, and some effect on GI motility

69

Gastric inhibitory peptide is secreted by what?

It stimulates:

Upper small intestine

Insulting secretion, and decreases stomach motility

70

Peristalsis

Propulsive movements in one directions

71

GI Peristalsis is generally stimulated by:

Distention

Also by parasympathetic and irritation to the epithelium

72

GI peristalsis required:

The myenteric plexus

73

What are mixing movements of the GI?

Peristalsis towards a closed sphincter— causes a churning effect.


Local intermittent constrictive contractions creating a “chopping” or “shearing” effect

74

Arterial supply for splanchnic circulation

Celiac artery

Sup mesenteric art

Inf mesenteric art

75

The portal system drains what?

From the gut, spleen and pancreas to the liver - through sinusoids- to the IVC via hepatic veins

76

Within the liver, what removes any bacteria or particulate materials that may have gotten into the blood?

Reticuloendothelial cells (Kupffer/macrophages)

77

Water soluble nutrients go to the ____ where ____% gets stored there for further processing

Liver

50-75%

78

In portal system, fats are absorbed into the ____ which goes to the:

Lymph

Thoracic duct (bypasses the liver)

79

As motility and absorption increase in the gut, so does:

Blood flow in the microcirculation of the villus

80

What are vasodilator substances from the mucosa

Cholecystokinin

Vasoactive intestinal peptide

Gastrin

Secretion

81

Mechanism of microcirculation in the gut

Vasodilator substances from mucosa

Kinin vasodilators (bradykinin) from intestinal glands also vasodilator

O2 lack leading to vasodilation

Adenosine

Parasympathetic- increased glandular activity therefore increased blood flow by autoregulation

Sympathetic- causes vasoconstriction

82

Sympathetic vasoconstriction can be over ridden by _____.

Autoregulation (autogregulation escape)

83

Constriction is important during when

Intense exercise

Or in circulatory shock to shunt blood to general circulation

84

Incisors are for _____ and provide ___ lbs of pressure

Cutting

55

85

Molars are for ____, and have up to ____ lbs pressure

Grinding

200

86

Muscles of mastication are innervated by what?

CN V3 (Trigeminal)

87

Muscles of mastication

Temporalis

Masseter

Medial and lateral pterygoids

88

What forms the Dental arcades?

Alveolar processes of the maxillae and mandible

89

Describe the chewing reflex

Bolus causes pressure


Relaxes muscles to open jaw

Pressure is released

Stretch of muscles

Triggers contractions

Repeat

90

Importance of mastication

To break down food for ease of swallowing

To mix food with saliva

Breaks down cellulose to release nutrients in plant based foods

91

3 stages of deglutition

1- voluntary stage

2- Pharyngeal stage

3- esophageal stage

92

voluntary stage of deglutition

Tongue pushes food against palate and squeezes food towards oropharynx

93

What triggers the brain stem mediated reflexes to the pharyngeal muscles

Tonsilar pillars (have swallowing receptors)

94

What happens in the pharyngeal stage

The palate raises to close pose nares

Palatopharyngeal folds narrow to only allow smaller particles to pass into pharynx

Vocal cords approximate and larynx pulled upward to meet epiglottis to cover larynx

Laryngeal elevation also opens upper esophageal sphincter (normally closed to prevent ingestion of air)

Pharyngeal constrictor muscles propel food by peristalsis into esophagus

95

What happens in the esphageal stage

Primary peristalsis

2ndary peristalsis

Receptive relaxation

96

Primary peristalsis of the esophageal stage

Continuation of pharyngeal peristalsis

Extends from pharynx to stomach

Lasts 8-10 seconds, gravity aids process

97

2ndary peristalsis in the esophageal stage

Food that fails to descend distends the esophagus initiating enteric NS mediated waves of peristalsis


(This is what kicks in when you feel like you’re choking. It failed to go down the normal way so body kicks in)

98

Receptive relaxation in esophageal stage

Lower esophageal sphincter and stomach relaxes

99

Sensory innervation for swallowing

CN V and IX

100

Swallowing center is located where?

In the brainstem

101

Efferent innervation for swallowing

Mostly via CN X

102

The pharynx and upper 1/3 of the esophagus is ___ muscle.

The lower 2/3 is:

Striated

Smooth

103

The pharynx and upper 1/3 of the esophagus is innervated by:


The lower is innervated by:

CN 9 and 10



CN 10 and enteric NS