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Gastrointestinal 1 Flashcards

1
Q

Where does the GI system begin? How does it continue after?

A

*Begins at the Mouth
*Followed by (in order) the esophagus–>stomach–>small intestine (duodenum, jejunum, and ilium)–> large intestine–>anus.

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2
Q

What 4 organs/glands serve excretory functions in the GI system?

A
  1. Salivary glands
  2. Pancreas
  3. Liver
  4. Gall Bladder
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3
Q

What three systems provide integrated regulation to the GI?

A
  1. Local
  2. Nervous
  3. Hormonal
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4
Q

(T/F) Circular smooth muscle contraction decreases the diameter of the GI segment.

A

TRUE

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5
Q

(T/F) Longitudinal muscle contraction increases the length of the GI segment.

A

FALSE.
*Decreases the length of the GI segment

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6
Q

What two types of contraction are responsible for the characteristic motility in the GI?

A
  1. Circular smooth muscle contraction
  2. Longitudinal muscle contraction
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7
Q

(T/F) Peristalsis and Segmentation are a part of the GI motility.

A

TRUE

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8
Q

What is the Master Integrator? Where does it receive sensory inputs from?

A
  1. The Enteric Nervous System
  2. From Gut & Effector inputs from the SNS and PNS
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9
Q

Continuous with the mesenteries & consists of an enveloping layer of connective tissue, covered with squamous epithelial cells.

A

Serosa

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10
Q

Includes 2 layers of smooth muscles:

Circular inner layer, and longitudinal outer layer

A

Muscularis

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11
Q

What is present between the two layers of the Muscularis?

A

Enteric Neurons

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12
Q

Consists of loose connective tissue and larger blood vessels; also contains submucosal glands & Submucosaal nerve plexus (Meissner’s)

A

Submucosa

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13
Q

Consists of the epithelial layer, and an underlying layer of loose connective tissue (LAMINA PROPRIA)

A

Mucosa

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14
Q

(T/F) Mucosa contains capillaries, enteric neurons and immune cells (mast cells)

A

TRUE

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15
Q

What is the thin layer of smooth muscle in the Mucosa?

A

Lamina Muscularis Mucosae

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16
Q

(T/F) The surface area of the epithelial layer is amplified by several mechanisms.

A

TRUE

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17
Q

(T/F) Few cells have microvilli on their apical surfaces.

A

FALSE
*Most cells

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18
Q

How are villi and crypts formed?

A

The evagination of the cells in the epithelial layer.

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19
Q

How is the mucosa organized?

A

In large folds

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20
Q

What 2 functions do epithelial cells serve in the GI mucosa?

A

Absorptive & Excretory functions
*Shape and type of secretions change with the site of cells in the GI tract.

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21
Q

All of the GI tract has smooth muscle except for what 3 places?

A
  1. Pharynx
  2. Upper 1/3 of esophagus
  3. External anal sphincter
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22
Q

What type of muscle is GI smooth muscle? What ensures smooth and coordinated contraction?

A
  1. Visceral “unitary” type
  2. Gap junctions
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23
Q

Name 4 ways GI muscles are stimulated.

A
  1. Self excitation
  2. Activated by stretch
  3. Hormones
  4. Local Tissue factors
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24
Q

What 3 drugs can affect GI smooth muscle?

A
  1. Nicotine
  2. Alcohol
  3. Caffeine
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25
Where are slow waves of membrane potential generated?
Interstitial cells of Cajal
26
(T/F) Slow waves are rhythmic changes in threshold potential initiated by interstitial cells of Cajal.
FALSE *changes in membrane potential
27
(T/F) Interstitial cells of Cajal are also known as pacemaker cells.
TRUE
28
Name each segment involved in slow waves and their specific frequency. HINT: There are 5 segments
1. Stomach- 3/min 2. Ilium- 8/min 3. Colon- 11/min 4. Small intestine- 12/min 5. Rectum- 17/min *Determines maximal possible frequency of contraction
29
(T/F) Spike potentials develop on top of slow waves when they reach threshold potential (~ -40 mV).
TRUE
30
Describe the relationship between amplitude, spike potentials, and gut motility. HINT: Starts with amplitude, ends with gut motility.
Higher amplitude --> More spike potentials --> stronger gut motility
31
When at rest, what organ maintains a positive pressure that is higher than the pressure in adjacent organs. What does this characteristic prevent?
1. Sphincter 2. Prevents both anterograde (forward) and retrograde (backward) flow.
32
Sensory information from the GI system is received, integrated, and responded to by what?
1. Enteric Nervous System (ENS) (Intrinsic)
33
What are the 4 short reflexes that regulates the GI?
1. Secretion 2. Motility (peristalsis, mixing concentrations) 3. Local inhibitory effects 4. Growth
34
In the gut wall, there are two plexuses that receive sensory signals from the gut lumen or the CNS. What are they?
1. Myenteric Plexus 2. Submucosal Plexus
35
The enteric nervous system can function independently. But stimulation by either the PNS or SNS systems can do what?
Greatly enhance or inhibit GI functions.
36
What three characteristics to afferent sensory fibers that pass from the luminal epithelium to the enteric plexuses have?
1. Irritation of gut mucosa 2. Excessive gut distension 3. Presence of peptides, H+
37
Name the nerve and whether it is PNS or SNS: Upper GI through ascending colon (including striated muscle of esophagus)
Vagus Nerve (PNS)
38
Both afferent and efferent limbs are in the Vagus nerve. But are these called?
Vagovagal reflexes (PNS)
39
Name the nerve and whether it is PNS or SNS: Lower GI (colon and anal striated ms)
Pelvic Nerve (PNS)
40
Where do preganglionic fibers synapse? (PNS)
In the walls of the GI, within the myenteric and submucosal plexuses (PNS)
41
What are the two categories of post-ganglionic neurons? (PNS)
1. Cholinergic (Ach) 2. Peptidergic (VIP)
42
Information from the PNS are coordinated in what plexus? Where is the info relayed too?
1. Enteric plexus 2. Smooth muscle, Endocrine cells, Secretory cells
43
Where do pre-ganglionic fibers synapse in the SNS?
Outside the GI tract
44
What are the 4 sympathetic ganglia of the SNS?
1. Celiac 2. Superior mesenteric 3. Inferior mesenteric 4. Hypogastric
45
What is the post-ganglionic neuron of the SNS?
Adrenergic (NE)
46
(T/F) Adrenergic fibers can synapse with enteric plexuses or directly with smooth muscles, and mucosa.
TRUE
47
What three things can NE cause?
1. Relaxation of smooth muscles 2. Contraction of sphincters 3. Increase salivary secretion
48
What are the 3 GI regulatory substances?
1. Endocrine (hormones) 2. Paracrines 3. Neurocrines
49
Cells of the GI mucosa, not concentrated in glans but are single cells or groups of cells spread over large areas. They pass through the portal circulation to systemic circulation.
Endocrine (hormones)
50
What does the endocrine hormone Gastrin do?
Causes acid secretion
51
What does the endocrine hormone Gastric Inhibitory Peptide (GIP) or glucose-dependent insulinotropic peptide do?
Release insulin from beta cells of the Pancreas
52
Name two other endocrine hormones?
1. Cholecystokinin (CCK) 2. Secretin
53
Act locally within the same tissue
Paracrines
54
What are the two paracrines?
1. Somatostatin 2. Histamine
55
(T/F) Somatostatin is secreted by D cells of GI mucosa (in response to low pH), and inhibit H+ secretion.
TRUE
56
(T/F) Histamines are peptides that stimulate H+ secretion.
FALSE *Not peptides
57
Synthesized in neurons of the GI tract and are released following stimulation.
Neurocrines
58
(T/F) Neurocrines can be eleased by either PNS (Ach and GRP), SNS (NE) or enteric plexuses (VIP, NO, & Enkephalins “opiates”)
TRUE
59
Aims at mixing and fragmenting food and mixing it with digestive enzymes, to be digested and absorbed.
Gut Motility
60
What are the two types of movements involved in gut motility?
1. Peristalsis 2. Mixing food
61
In peristalsis which of the following is proximal and which is distal to the food: 1. Reflex contraction 2. Relaxation
1. Reflex contraction is proximal to the food 2. Relaxation is distal to the food
62
What direction does food move in peristalsis?
Caudal direction (toward the tail)
63
In the mixing of food, circular and longitudinal muscles alternate contraction and relaxation causing what two things?
1. Segmentation 2. Pendular movements
64
(T/F) The mixing of food ensures that chyme and digestive enzymes maintain variable composition and texture.
FALSE *maintain uniform composition and texture
65
(T/F) Mixing of food ensures nutrients are in contact with epithelial cells for proper absorption.
TRUE
66
What are the four processes of the Digestive system?
1. Ingestion and Swallowing 2. Digestion and Secretion 3. Absorption 4. Motility and Defecation
67
How does the digestive system maintain homeostasis?
Volume of fluid entering GI tract by intake or secretion MUST EQUAL volume leaving the lumen by absorption or excretion
68
The chemical and mechanical breakdown of foods into smaller units that can be taken up across the intestinal epithelium into the body.
Digestion and Secretion
69
Mixes food with salivary mucus to lubricate it and facilitate swallowing, reduce size of food parts, and mixes carbs with salivary AMYLASE to begin digestion.
Chewing
70
What are the three phases of swallowing?
1. Oral phase (voluntary) 2. Pharyngeal phase (involuntary) 3. Esophageal phase
71
Tongue positions food against hard palate. Entrance of the food triggers a swallowing reflex.
Oral phase
72
Step 1 of Pharyngeal phase: what closes the nasopharynx?
The soft palate retracting
73
Step 2 of Pharyngeal phase: (T/F) Vocal cords are pulled together and the larynx is moved forward and upward against the epiglottis.
TRUE
74
Step 3 of Pharyngeal phase: What relaxes to receive the food bolus?
Upper Esophageal Sphincter (UES)
75
Step 4 of Pharyngeal phase: (T/F) Superior constrictor muscles of the pharynx contract to force the bolus into the pharynx and through UES.
TRUE
76
Partly controlled by the swallowing reflex and partly by the enteric nervous system.
Esophageal phase
77
In the esophageal phase of swallowing, when the food bolus passes the UES, the reflex closes the sphincter to prevent reflux, and then what begins?
A primary peristaltic wave begins
78
What are the three main groups of salivary glands?
1. Parotids 2. Submandibular 3. Sublingual
79
Produce water or serous saliva rich in enzymes
Parotids
80
Serous and mucus elements
Submandibular
81
Produce mucus saliva
Sublingual
82
What function to small buccal glands have?
Antibacterial function
83
What unique characteristic of salivary glands further increases with salivary gland stimulation?
High Blood Flow
84

Physiology (2 decks)

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