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

GIT Lec 2: Mouth + Esophagous Flashcards

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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
Three salivary glands (1 each side)
- parotid gland - submandibular gland - sublingual gland
26
an adult produces an average of (saliva)
1500 ml of saliva/day
27
serous secretion
watery secretion
28
parotid gland produces
serous secretion
29
submandibular gland produces
serous/mucous secretion
30
sublingual gland produces
mucous secretion
31
composition of saliva
- water (97-99.5%) - electrolytes - digestive enzymes (amylase, lipase) - glycoproteins (mucin) - anti-microbial factors
32
saliva is (description)
-hypotonic, slightly alkaline
33
saliva electrolytes
rich in K+, HCO3- | poot in Na+, Cl-
34
mucin+water
mucous
35
lysozyme, lactoferrin in saliva
breaks down bacteria walls | -chelate iron, prevent multiplication of bacteria
36
Functions of saliva
- moistens + lubricates food - initiates digestion - dissolves food for taste buds for stimulating appetite - antibacterial - speech aid - buffering action
37
Three types of saliva cells:
- acinar cells - myoepithelial cells - ductal cells
38
Acinar cells
- 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
myoepithelial cells
smooth muscle + epithelial cells type of cell, push saliva from acinus into duct
40
ductal cells
- 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
saliva flow + duct capillary blood flow are...
in opposite direction
42
Basal level of saliva production is .. and after stimulation...
- 0.5ml/min | - x 10 (5ml/min)
43
The type of regulation of saliva production
neural regulation, no hormonal regulation | -only GIT component with no hormonal regulation
44
Neural regulation of saliva..
- parasympathetic + sympathetic pathway | - parasympathetic is the predominant pathway
45
Parasympathetic regulation of salivary gland function (actions)
- increases blood flow to glands increasing secretion, providing metabolic and fluid requirements - increases protein secretion by acinar cells - stimulates myoepithelial cells
46
Parasympathetic regulation of salivary gland function (stimulated, inhibited by)
stimulated by smell + taste, pressure receptors in mouth, nausea inhibited by fatigue, sleep, fear, dehydration, drugs
47
Sympathetic regulation of salivary gland function (actions)
- minimally increases saliva flow - increases protein secretion by acinar cells - stimulates myoepithelial cells
48
Starch digestion (saliva)
- starts in mouth by amylase (ptyalin) | - 95% digested by pancreatic amylase in small intestine
49
Plant starch made of
amylose + amylopectin
50
amylose
a 1-4 linkage
51
amylopectin
a 1-4 linkage + a 1-6 linkage | -branched
52
product of starch digestion
maltose, maltotriose (a 1-4 linkage) | a-limit dextrin (has a 1-6 linkage)
53
lingual lipase is active
in the mouth and stomach
54
amylase + lingual lipase (minor or major digestion?)
- minor | - more important in pathological issues and babies
55
Xerostomia
- dry mouth | - salivary secretion is impaired
56
Xerostomia is a result of
autoimmune disease (Sjogren's syndrome drugs radiation treatment
57
Consequences of Xerostomia
- dry mouth, decreased oral pH, tooth decay, esophageal erosions - difficulty + lubricating and swallowing food
58
Treatment of Xerostomia
frequent sips of water +fluoride
59
Swallowing is a
reflex initiated by pressure receptors in pharynx by food +liquid
60
Swallowing receptors send
signals to swallowing Centre in brainstem which send signals to pharynx +esophagus +respiratory muscles
61
Larynx
voice box btw pharynx + trachea
62
glottis
area around vocal cords
63
epiglottis
tissue flap covers larynx/trachea during swallowing
64
Swallowing mechanism
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
esophagus transfers
food from mouth to stomach
66
esophagus size
18-25 cm long tube
67
type of epithelium in esophagus
stratified squamous epithelium (20-30 cells thick)
68
absorption in esophagus?
no absorption, mucous glands for lubrication
69
type of sphincters in esophagus
two sphincters- closed expect when swallowing, vomiting, burping - upper esophageal sphincter - lower esophageal sphincter
70
upper esophageal sphincter
ring of skeletal muscle below pharynx
71
lower esophageal sphincter
ring of smooth muscle at stomach
72
Esophageal phase of swallowing
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
Lower esophageal sphincter prevents
gastric contents from reaching esophagus
74
acid in esophagus stimulates
peristalsis, salivary secrection
75
Heartburn is caused by
inefficient sphincter, big meal, pregnancy

z:Physl 210A/B (28 decks)

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