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z:Physl 210A/B > GIT Lec 2: Mouth + Esophagous > Flashcards

GIT Lec 2: Mouth + Esophagous Flashcards

1
Q

Neural and hormonal control of GI system has three parts:

A
  • cephalic (head) phase
  • gastric (stomach) phase
  • intestinal phase
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2
Q

The three phases of GI control are classified

A

-based on the place in the body where the stimuli initiates the reflex

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3
Q

Cephalic (head) phase - receptors

A

-receptors in head stimulated by sight, smell, taste, chewing of food, emotional state

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4
Q

Cephalic (head) phase - reflex

A
  • parasympathetic fibres activate neurons in GI nerve plexus
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5
Q

Gastric (stomach) phase - receptors

A

-receptors in the stomach stimulated by distension, acidity, a.a, peptides

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6
Q

Gastric (stomach) phase - reflex

A

-short + long neural reflex: trigger release of gastrin

+ ach release

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7
Q

Intestinal phase -receptors

A

-receptors in intestine stimulated by distension, acidity, osmolarity, digestive products

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8
Q

Intestinal phase- reflex

A

-mediated by short + long neural reflexes and by hormones (secretin, CCK, GIP)

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9
Q

control of food intake is by

A
  • hypothalamus
  • satiety centre in ventromedial region
  • orexigenic factors
  • anorexigenic factors
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10
Q

Hypothalamus has (centre)- food control

A
  • has a feeding centre in lateral region, activation increases hunger, inhibition decreases hunger
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11
Q

Satiety centre in ventromedial region- food control

A

activation: makes you feel full
inhibition: increases hunger, gain weight

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12
Q

Orexigenic factors- food control (def. and examples)

A
  • increase intake

- EX. neuropeptide Y (NPY), Ghrelin

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13
Q

neuropeptide Y (NPY)

A

-neurotransmitter in hypothalamus stimulates hunger

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14
Q

Ghrelin

A
  • released from endocrine cells in stomach when fasting

- stimulates release of NPY from hypothalamus

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15
Q

Anorexigenic factors- food control (def. and examples)

A
  • decrease intake

- EX. leptin, insulin, peptide YY, melanocortin

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16
Q

Leptin is from

A

-adipose tissue

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17
Q

Insulin is from

A

-pancreas

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18
Q

Peptide YY is from

A

intestines

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19
Q

Melanocortin is from

A

hypothalamus

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20
Q

Leptin pathway

A

increase fat= increase leptin
decrease appetite/energy intake
increase metabolic rate

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21
Q

control of water intake is by

A
  • hypothalamus (osmoreceptors, baroreceptors)
  • dry mouth stimulates thirst
  • overhydration
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22
Q

increased plasma osmolarity (physiological conditions)-water control

A
  • osmoreceptors in thirst center within hypothalamus activate
  • vasopressin (antidiuretic hormone) is released- water conserved at kidney
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23
Q

decreased plasma volume (significant blood loss) - water control

A

-baroreceptors in kidney afferent arteries activate renin angiotensin system and produce angiotensin II to increase thirst

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24
Q

overhydration is prevented by

A

stimuli by mouth, throat and GIT– stop drinking before water in GIT

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25
Q

Three salivary glands (1 each side)

A
  • parotid gland
  • submandibular gland
  • sublingual gland
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26
Q

an adult produces an average of (saliva)

A

1500 ml of saliva/day

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27
Q

serous secretion

A

watery secretion

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28
Q

parotid gland produces

A

serous secretion

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29
Q

submandibular gland produces

A

serous/mucous secretion

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30
Q

sublingual gland produces

A

mucous secretion

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31
Q

composition of saliva

A
  • water (97-99.5%)
  • electrolytes
  • digestive enzymes (amylase, lipase)
  • glycoproteins (mucin)
  • anti-microbial factors
32
Q

saliva is (description)

A

-hypotonic, slightly alkaline

33
Q

saliva electrolytes

A

rich in K+, HCO3-

poot in Na+, Cl-

34
Q

mucin+water

A

mucous

35
Q

lysozyme, lactoferrin in saliva

A

breaks down bacteria walls

-chelate iron, prevent multiplication of bacteria

36
Q

Functions of saliva

A
  • moistens + lubricates food
  • initiates digestion
  • dissolves food for taste buds for stimulating appetite
  • antibacterial
  • speech aid
  • buffering action
37
Q

Three types of saliva cells:

A
  • acinar cells
  • myoepithelial cells
  • ductal cells
38
Q

Acinar cells

A
  • important for protein, electrolyte +water secretion
  • secrete initial saliva (water, electrolytes, proteins (enzymes, mucous))
  • proteins, Cl-, HCO3-, K+ actively secreted
  • Na+, H2O paracellular pathway through leaky tight junctions
  • isotonic secretion
39
Q

myoepithelial cells

A

smooth muscle + epithelial cells type of cell, push saliva from acinus into duct

40
Q

ductal cells

A
  • important for alkaline +hypotonic nature
  • impermeable to water
  • net loss of Na+/Cl- (active reabsorption)
  • addition of K+/HCO3- (active secretion) to lesser extent
  • net loss of solute into duct capillary
41
Q

saliva flow + duct capillary blood flow are…

A

in opposite direction

42
Q

Basal level of saliva production is .. and after stimulation…

A
  • 0.5ml/min

- x 10 (5ml/min)

43
Q

The type of regulation of saliva production

A

neural regulation, no hormonal regulation

-only GIT component with no hormonal regulation

44
Q

Neural regulation of saliva..

A
  • parasympathetic + sympathetic pathway

- parasympathetic is the predominant pathway

45
Q

Parasympathetic regulation of salivary gland function (actions)

A
  • increases blood flow to glands increasing secretion, providing metabolic and fluid requirements
  • increases protein secretion by acinar cells
  • stimulates myoepithelial cells
46
Q

Parasympathetic regulation of salivary gland function (stimulated, inhibited by)

A

stimulated by smell + taste, pressure receptors in mouth, nausea
inhibited by fatigue, sleep, fear, dehydration, drugs

47
Q

Sympathetic regulation of salivary gland function (actions)

A
  • minimally increases saliva flow
  • increases protein secretion by acinar cells
  • stimulates myoepithelial cells
48
Q

Starch digestion (saliva)

A
  • starts in mouth by amylase (ptyalin)

- 95% digested by pancreatic amylase in small intestine

49
Q

Plant starch made of

A

amylose + amylopectin

50
Q

amylose

A

a 1-4 linkage

51
Q

amylopectin

A

a 1-4 linkage + a 1-6 linkage

-branched

52
Q

product of starch digestion

A

maltose, maltotriose (a 1-4 linkage)

a-limit dextrin (has a 1-6 linkage)

53
Q

lingual lipase is active

A

in the mouth and stomach

54
Q

amylase + lingual lipase (minor or major digestion?)

A
  • minor

- more important in pathological issues and babies

55
Q

Xerostomia

A
  • dry mouth

- salivary secretion is impaired

56
Q

Xerostomia is a result of

A

autoimmune disease (Sjogren’s syndrome
drugs
radiation treatment

57
Q

Consequences of Xerostomia

A
  • dry mouth, decreased oral pH, tooth decay, esophageal erosions
  • difficulty + lubricating and swallowing food
58
Q

Treatment of Xerostomia

A

frequent sips of water +fluoride

59
Q

Swallowing is a

A

reflex initiated by pressure receptors in pharynx by food +liquid

60
Q

Swallowing receptors send

A

signals to swallowing Centre in brainstem which send signals to pharynx +esophagus +respiratory muscles

61
Q

Larynx

A

voice box btw pharynx + trachea

62
Q

glottis

A

area around vocal cords

63
Q

epiglottis

A

tissue flap covers larynx/trachea during swallowing

64
Q

Swallowing mechanism

A
  1. tongue pushes food bolus to back of pharynx
  2. Soft palate elevates to prevent food entering the nose
  3. Signals from swallowing centre in brainstem inhibits respiration, raise larynx, close glottis
  4. Epiglottis covers glottis to prevent food from entering trachea
  5. Food enters esophagus
65
Q

esophagus transfers

A

food from mouth to stomach

66
Q

esophagus size

A

18-25 cm long tube

67
Q

type of epithelium in esophagus

A

stratified squamous epithelium (20-30 cells thick)

68
Q

absorption in esophagus?

A

no absorption, mucous glands for lubrication

69
Q

type of sphincters in esophagus

A

two sphincters- closed expect when swallowing, vomiting, burping

  • upper esophageal sphincter
  • lower esophageal sphincter
70
Q

upper esophageal sphincter

A

ring of skeletal muscle below pharynx

71
Q

lower esophageal sphincter

A

ring of smooth muscle at stomach

72
Q

Esophageal phase of swallowing

A
  1. relaxation of upper esophageal sphincter
  2. Peristalsis move food down esophagus (5-9 s)- gravity assists but not necessary
  3. lower sphincter opens and allows food into stomach
73
Q

Lower esophageal sphincter prevents

A

gastric contents from reaching esophagus

74
Q

acid in esophagus stimulates

A

peristalsis, salivary secrection

75
Q

Heartburn is caused by

A

inefficient sphincter, big meal, pregnancy

z:Physl 210A/B (28 decks)

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