Physiology Flashcards

1
Q

Where does carbohydrate digestion start

A

Mouth

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2
Q

What are the 3 salivary glands

A

Parotid
Sublingual
Submandibular

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3
Q

Which salivary gland secretes the least amount of saliva

A

Parotid

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4
Q

Which salivary gland secretes the most amount of saliva

A

Submandibular

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5
Q

Which salivary gland secretes the most viscous saliva

A

Sublingual

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6
Q

What other enzyme does the mouth produce

A

Lingual lipase

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7
Q

Where is the draining of parotid gland located at

A

upper 2nd molar teeth

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8
Q

List the layers of GI mucosa from outermost to innermost

A
Serosa
Muscularis externa 
submucosa
muscularis mucosae
lamina propria
epithelium
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9
Q

What does muscularis externa consist of

A

Circular and longitudinal smooth muscles

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10
Q

Which muscle is next to serosa (outermost muscle)

A

Longitudinal muscle

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11
Q

What is between the circular and longitudinal muscle layers

A

Myenteric plexus

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12
Q

What is between the submucosa and circular muscle layers

A

Submucosal plexus

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13
Q

What does lamina propria contain

A

Capillaries
Enteric neurones
gut associated lymphoid tissue

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14
Q

What is right underneath the epithelium

A

Lamina propria

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15
Q

What does submucosa contain

A

Connective tissue
glands
large blood and lymph vessels

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16
Q

What nervous systems control the GI tract

A

Enteric nervous system

Parasympathetic and sympathetic nervous systems

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17
Q

Which nervous system is most important at regulating GI tract

A

Parasympathetic nervous system

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18
Q

Which nerves are included in parasympathetic NS for GI tract

A

Vagus nerves

Pelvic nerves

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19
Q

What are the effects of sympathetic stimuli

A

Decreases motility, secretion and blood flow

Causes contraction of sphincters

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20
Q

What are the effects of parasympathetic stimuli

A

Increases motility

Increases gastric, duodenal, pancreatic secretion

Relaxes sphincters

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21
Q

What are the abdominal prevertebral ganglia that innervates the abdominal, pelvic and perineal organs

A

Coeliac
superior mesenteric
Inferior mesenteric

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22
Q

What are the neurones of enteric nervous system

A

sensory
Interneurones
effector

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23
Q

What is the function of interneurones

A

alter activity of effector neurone

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24
Q

What is special about enteric nervous system and what affects the ENS

A

Can operate by itself but it is heavily affected by hormones and extrinsic nerves (parasympathetic / sympathetic )

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25
Q

What is the function of muscularis mucosae

A

Contraction changes the absorptive and secretory area of mucosa

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26
Q

What feature allows smooth muscle in GI tract to depolarise at the same time

A

Gap junctions

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27
Q

What neurotransmitters do excitatory neurones release

A

ACh and substance P

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28
Q

What neurotransmitters do inhibitory nervous system release

A

NO and VIP

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29
Q

What are the pacemaker cells in GI tract called

A

Interstitial cells of cajal (ICC)

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30
Q

Function of ICC

A

Continuously generate slow wave of depolarisation to control motility

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31
Q

Do all slow waves cause smooth muscle contraction?

A

No, because not all slow waves reach threshold

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32
Q

What does the strength of contraction depend on

A

how long the membrane potential has stayed above threshold

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33
Q

What affects the threshold for contraction

A

Neuronal, hormonal and mechanical stimuli

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34
Q

How do neuronal, hormonal and mechanical stimuli affect slow waves

A

Shifts the membrane potential in a depolarising manner, allowing each cell to have different starting MP

35
Q

Where is the enteric nervous tissue located at

A

myenteric and submucosae plexus

36
Q

Describe peristalsis

A

Rhythmic contractions ; the smooth muscle in front of food bolus relaxes while the smooth muscle behind contracts

37
Q

Function of gastrin

A

Stimulate gastric acid secretion
Stimulate pepsinogen and IF secretion
Inhibit migrating motor complex

38
Q

What triggers the release of gastrin

A

Distension of stomach

39
Q

What inhibits the release of gastrin

A

Low pH

Somatostatin

40
Q

Function of Secretin

A

Increase pancreatic and biliary bicarbonate secretion

Decreases gastric acid secretion

41
Q

What stimulates the release of secretin

A

In response to presence of fatty acids and H+ in intestinal lumen

42
Q

Which cells secrete gastrin

A

G cells in stomach

43
Q

Which cells secrete secretin

A

S cells in duodenum

44
Q

Function of CCK

A

Inhibit gastric emptying
Stimulate release of pancreatic enzyme
Stimulate relaxation of sphincter of oddi and contraction of gall bladder to release bile
Potentiates action of secretin

45
Q

What triggers the release of CCK

A

Monoglycerides, fatty acids, amino acids in intestinal lumen

46
Q

Which hormone induces satiety

A

CCK

47
Q

Resistance in which hormone causes obesity

A

Leptin

48
Q

How does leptin resistance cause obesity

A

It reduces satiety and causes overconsumption of food

49
Q

Function of GIP

A

Stimulates the release of insulin

Inhibits gastric emptying

50
Q

Which cell secretes CCK

A

I cell in duodenum

51
Q

Which cell secretes GIP

A

K cells in duodenum and jejunum

52
Q

Function of somatostatin

A

Inhibit gastric acid secretion by binding to receptor on parietal cells hence inhibiting adenylyl cyclase
Inhibits CCK and secretin

53
Q

Which cell produces somatostatin

A

D cells in pyloric gland area (stomach)

54
Q

Where is pyloric gland area

A

Antrum

55
Q

Where are G cells located

A

Pyloric gland

56
Q

Function of enterochromaffin cells

A

Release histamine

57
Q

How does histamine stimulate production of gastric acid

A

1) histamine binds to H2 receptors on parietal cells
2) activates adenylyl cyclase: ATP converted to cAMP
3) PKA activated by cAMP
4) proton pump on parietal cells are stimulated

58
Q

Which cell produces gastroferrin and what other hormones does this cell produce

A

Parietal cell; also secretes intrinsic factors and HCL

59
Q

Function of gastroferrin

A

Allows Fe2+ to bind hence allow absorption

60
Q

Function of intrinsic factors

A

Bind to vitamin B12, allowing absorption

61
Q

Signs of vitamin B12 deficiency

A

Macrolytic
Pernicuous anaemia
Paraesthesia

62
Q

What activates pepsinogen

A

HCL, causing pepsinogen -> pepsin

63
Q

How does the activation of pepsinogen amplifies itself

A

Pepsinogen activated by HCL -> pepsin

Pepsin activates more pepsinogen

64
Q

Which cell produces pepsinogen and gastric lipase

A

Chief cells

65
Q

Function of GLP-1

A

Stimulate release of insulin
Decreases appetite
Decrease glucagon secretion

66
Q

What stimulates the release of GLP-1

A

glucose and fats

67
Q

Which cell releases GLP-1

A

L cells in distal ileum

68
Q

Function of motilin

A

Stimulates migrating motor complex

69
Q

What stimulates the release of motilin

A

when duodenum and jejunum are empty

70
Q

Which cells produce motilin

A

M cells in duodenum and jejunum

71
Q

What is migrating motor complex

A

Strong peristaltic contraction to expel small intestine debris / undigested remains through ileocaecal valve to the caceum

72
Q

What triggers the migrating motor complex

A

Motilin

73
Q

Why does Migrating motor complex only occur between meals

A

To avoid losing nutrients

74
Q

Describe the mucosa of small intestine

A

Simple columnar epithelium with microvilli
Villi
With crypts of lieuberkuhn between villi

75
Q

What cells are at the bottom of crypts of lieuberkuhn

A

Paneth cells

76
Q

What cells are at the upper portion of crypts of lieuberkuhn

A

Stem cells

77
Q

Function of paneth cells

A

Produce substances that attack bacteria

78
Q

Which enzyme activates trypsinogen

A

Enterokinase in duodenal mucosa

79
Q

What is in submucosal layer of duodenum

A

Brunner’s glands

80
Q

Function of Brunner’s glands

A

Release alkaline mucous to neutralize the chyme

81
Q

When is somatostatin released

A

After meal when pH is low

82
Q

What are the 3 phases of gastric acid secretion

A

Cephalic
Gastric
Intestinal

83
Q

What stimulates cephalic phase

A

smell, sight, chewing, swallowing

84
Q

What does somatostatin inhibit

A

CCK and secretin