Section 7: Hormonal and Neural Regulation of the gastrointestinal tract and smooth muscle Flashcards Preview

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Flashcards in Section 7: Hormonal and Neural Regulation of the gastrointestinal tract and smooth muscle Deck (116):
1

Function of gastrointestinal tract;

exchange with external environment required for single cell metabolism

2

Layers of the lumen of gastrointestinal tract:

mucosa, submucosa, muscularis externa, and serosa

3

Layers within mucosa:

epithelium, lamina propria muscularis mucosa

4

Layers within submucosa:

major blood and lymphatic vessels and submucosal plexus

5

Layers within muscularis external:

circular muscle, myenteric plexus and longitudinal muscle

6

True or False? Exocrine cells line the lumen of the gastrointestinal tract, while endocrine cells do not.

F. they both do

7

Primary gastrointestinal processes:

Chemical and mechanical break down, mixing and movement by smooth muscle

8

Which is expensive and which efficient, chemical and mechanical break down vs. mixing and movement by smooth muscle

expensive: chemical and mechanical break down, efficient: mixing and movement by smooth muscle

9

Gastrointestinal processes are controlled by:

hormones and nerves

10

Speed of chemical regulators, fastest to slowest:

neurocrine, endocrine, paracrine

11

A stimulus can act on either __ or __ to elicit a change in a target cell.

nervous system or endocrine cell

12

"True hormones":

produced in response to a meal AND at physiological tissue concentrations

13

Hormone is aka:

endocrine

14

Two structurally similar families of true hormones:

Gastrin and CCK, Secretin and Gastric Inhibitory Peptide

15

Which portion of the "extrinsic" Autonomic nervous system is the most significant regulator?

Parasympathetic

16

Major extrinsic nerves of the autonomic nervous system:

vagus and pelvic nerves

17

The sympathetic branch of the autonomic nervous system is (excitatory/ inhibitory) in the gastrointestinal tract.

inhibitory

18

What is the "enteric" nervous system?

"Brain of the gut"

19

Enteric means:

internal

20

The myenteric plexus is found between:

the longitudinal and circular muscle

21

The submucosal plexus is found between:

the circular muscle and the muscularis mucosae

22

Neurotransmitter released form inhibitory motor neurons of the myenteric and submucosal nerve plexus:

VIP and NO

23

Neurotransmitter released form excitatory motor neurons of the myenteric and submucosal nerve plexus:

ACh and/or Substance P

24

The gastrointestinal system is involved in the transport of:

fluid and organic matter

25

In which body system does smooth muscle provide the driving force?

gastrointestinal tract

26

In which body system does smooth muscle provide the resistance to flow?

cardiovascular system

27

Smooth muscle is involved in the transport of:

materials in bulk quantities

28

What kind of muscle is smooth muscle?

unitary muscle

29

What permit coordinated contraction of unitary muscle?

Gap junctions

30

Synaptic contacts are aka:

varicosities

31

True or False? In multiunit smooth muscle each cell is innervated.

T. e.g., iris of the eye

32

These propagate slow wave activity to and between smooth muscle cells:

Gap junctions

33

How many subunits is a connexon made of?

6

34

What forms an open channel between adjacent cells?

two connections in register

35

Cells act as a ____.

synctium (can act as a unit), a single cell containing several nuclei, formed by fusion of cells or by division of nuclei.

36

These will pass through gap junctions:

inorganic ions (Na+, Ca2+), monosaccharides (glucose), amino acids, vitamins, nucleotides (ATP, cAMP)

37

These will not pass through gap junctions:

proteins, nucleic acids, polysaccharides

38

These are the current carriers through gap junctions:

inorganic ions

39

Signalling components of the gap junctions:

nucleotides (ATP, cAMP)

40

Metabolic components of gap junctions:

monosaccharides and amino acids

41

ion driving forces in smooth muscles:

K out, Ca2+ in

42

What causes depolarization in nerve cells?

opening of voltage-gated Na+ channels

43

What does a rise in cell Ca2+ initiate?

Cross-bridge cycling and contraction

44

This complex is needed to activate myosin:

active calmodulin/ MLCK complex

45

What is the most important source of Ca2+ in visceral smooth muscle?

extracellular Ca2+

46

Why is visceral smooth muscle slow?

because diffusion of Ca2+ from the outside is slow

47

From where does the Ca2+ needed form contraction of skeletal smooth muscle come?

intracellular stores

48

Why is skeletal smooth muscle fast?

Because the calcium comes from intracellular stores

49

What forms transverse tubules in skeletal smooth muscle?

Invaginations of plasma membrane

50

What makes up the triad?

2 sarcoplasmic reticulum cisterna and a transverse tubule

51

What is contained within the sarcoplasmic reticulum cisterna?

calcium stores

52

Why do special properties of visceral smooth muscle occur?

because smooth muscle cells have an unstable membranes potential that can be affected by enteric neurotransmitter

53

What causes greater tone?

greater number of AP's

54

What generatest spontaneous slow wave activity?

pacemaker cells of the interstitial cells of cajal

55

ICCs are interconnected into:

networks

56

What do ICC's contact?

gastrointestinal musculature

57

What connect the ICCs to the circular muscle?

gap junctions

58

Tubes of kidney are made of what type of cells?

epithelial cells

59

True or False? All of the digestive tract is lined with epithelial cells.

T

60

True or False? Feces is metabolic waste.

F. What we can not digest and can't absorb

61

Where is metabolic waste eliminated?

Lungs or kidney

62

True or False? There is communication between the submucosal and myenteric plexuses.

T

63

Secretion:

Out of blood or interstitial space

64

% of body water secreted each day into the lumen

20%, must be reabsorbed

65

Function of outer layer:

shortening, to help the outer layer in peristalsis

66

True or False? Endocrine cells are innervated by the nervous system.

T

67

True or False? Paracrine signals can be sent to target tissue via the blood stream.

F

68

Salivary secretion is regulated by:

nerves

69

Small and large intestines are controlled via this type of regulation:

paracrine regulation

70

Affect of opiates in the gastrointestinal tract:

slows motility in the gastrointestinal tract

71

True or False? There are many hormonal receptors in the salivary gland.

F.

72

Drugs largely effect:

receptors

73

Gastin;

gastric secretion

74

Effects gall bladder, bile release and fat processing:

CCK

75

Produces secretions by the pancreas:

secretin

76

GIP:

metabolic effects, not many on food processing

77

external nerves

external to gastrointestinal tract

78

Nerve that controls secretory functions of the stomach:

vagus nerve

79

Nerve that stimulates motility in the distal end of the gastrointestinal tract:

pelvic nerve

80

What extrinsic innervation is required for the enteric nervous system to function?

none

81

submucosal plexus interprets:

what happens in the lumen, then signals the myenteric plexus

82

NO:

gas, neurotransmitter, inhibitory

83

GRP:

Gastrin releasing peptide, released onto G cells, which release endocrine (gastrin) into circulation that stimulates more acid secretion from parietal cell (this is in addition to acetylcholine stimulating acid release from parietal cells via the vagus nerve/ bags nucleus)

84

smooth muscle cells:

lots of nuclei, not striated, smallest of muscle type cells, connect to each other in units

85

Unitary:

What happens in one cell can be transmitted total he adjacent cells

86

True or False? smooth muscle cell action potentials are activated by Na rushing in.

F. calcium

87

Visceral smooth muscle resting potential:

-60 to -40 mV (30 mV less negative than skeletal muscle)

88

How can smooth muscle be self excitatory?

due to spontaneous slow wave action

89

What causes the upstroke of the action potential in visceral smooth muscle?

activation of voltage-gated Ca2+ channels that bring Ca2+ into the cells

90

What causes basal tone?

slow waves and APs (causes spontaneous activity too)

91

Basal resting tone =

tension in the absence of external stimuli (e.g., intestines are much longer after death)

92

True or False? Spontaneous activity happens without innervation or circulation.

T

93

True or False? Visceral smooth muscle contract in the absence of neural or endocrine influences.

T

94

T or F? visceral smooth muscle contracts in response to stretch.

T

95

How do enteric nerves regulate smooth muscle?

release neurotransmitters, acetylcholine contracts smooth muscle

96

How does the release of acetylcholine by enteric nerves affect Ca2+ levels?

Ca2+ increases and initiates contraction

97

What type of neurotransmitters activate calmodulin/ MLCK complex?

those that raise Ca2+

98

What type of neurotransmitters interfere with phosphorylation by calmodulin/MLCK complex?

those that raise cAMP/cGMP

99

What do puringenic enteric nerves release?

VIP or NO, causing a rise in cAMP/cGMP and relaxation

100

What does the release of VIP or NO from enteric nerves cause?

a rise in cAMP/cGMP and relaxation

101

Factors that control overall regulation of smooth muscle:

action potentials can be elicited by electrical stimulation, hormones, neurotransmitter, or stretch . intracellular Ca2+ can be altered by hormones and neurotransmitter without action potentials/ local tissue factors, hormones and neurotransmitter can cause smooth muscle contraction without action potentials

102

How are unitary muscle cells connected?

gap junctions, allow passage

103

MLCK:

Myosin light chain kinase

104

What does Calicium bind in visceral smooth muscle once it enters?

calmodulin

105

True or False? There are intracellular stores of calcium released in visceral smooth muscle.

T. Not substantial amounts

106

True or False? skeletal muscle has tension when at rest.

F

107

What can lead to longer activation and more action potentials?

Acetylcholine release that makes potential less negative.

108

True or False? Parasympathetic neurotransmitter input is required for resting tone.

F

109

True or False? Oscillation of smooth muscle is a property of smooth muscle.

F. (?)

110

Where are the pacemaker cells connected to the visceral smooth muscle cells?

varicosities

111

What type of potential does visceral smooth muscle have?

ocilating potential

112

True or False? Resting tone will continue without innervation or circulation.

T

113

Neurotransmitter released by the plexus:

acetylcholine, excitatory (contraction)

114

What nerves supply input to the plexuses?

vagus and pelvic

115

Purinergic nerves control:

positive control of relaxation, blocks phosphorylation, leads to relaxation

116

Purinergic:

mediated by purine nucleotides and nucleosides such as adenosine and ATP