Bio 465 - Physio > Chapter 18 - Digestive System > Flashcards

Chapter 18 - Digestive System Flashcards

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1
Q

What are the 4 main functions of the Digestive System?

A
  1. Motility
  2. Secretion
  3. Digestion
  4. Absorption
  5. (Storage and elimination)
  6. (Immune Barrier)
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2
Q

Which type of reaction is used to break down food molecules into their monomers?

A

Hydrolysis

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3
Q

What are the four tunics of the digestive tract, listed inside out?

A

Mucosa, submucosa, muscularis, serosa

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4
Q

Which tunic of the GI tract is the inner most layer, lining the lumen of the GI Tract?

What are the 2 main functions of this layer?

What type of cells?

A
  1. Mucosa
  2. Absorption and Secretion
  3. Simple Columnar Epithelium
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5
Q

What tunic layer of the GI tract is the muscularis Mucosae found? What is its function?

A
  • Mucosa layer
  • Thin layer of smooth muscle, responsible for the numerous small folds in portions of the GI tract greatly increasing surface area.
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6
Q
  • This layer of the GI tract is thick, vascular, connective tissue that serves the inner mucosa layer?
  • This layer also has nerve plexuses called - submucosal plexus (or [] [] )
A
  • Submucosa
  • Meissner’s plexus
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7
Q
  • This layer of the GI tract is responsbile for the segmental contractions and peristalitic movemetn through the GI tract.
  • What are the two layers of muscle located in this tunic?
A

Muscularis (muscularis externa)

Inner Circular and Outer longitudinal layer of smooth muscle

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8
Q

In which GI tunic is the Myenteric Plexus found?

What are these Plexus function?

Does this receive parasympathetic or sympathetic innrvation?

A
  • Muscularis - between circular and longitudinal muscle layers
  • Provides major nerve supply to entire GI tract
  • Includes fibers and ganglis from both sympathetic and parasympathetic nervous systems
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9
Q

What is the outer tunic of the GI tract?

A

Serosa

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10
Q

How are the Meissner’s Plexus stimulated for action?

A
  • Independent of lower nerve net
  • Stretching of the intestine will cause AP and then cause stimulation through the entire muscle
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11
Q

T/F

Smooth muscles cells contain lower amounts of actin/myosin with larger sarcomeres than skeletal muscle?

A
  • False
  • Contain a bunch of actin and a little bit of myosin (16 to 1)
  • Contains ZERO Sarcomeres
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12
Q

These structure in smooth muscles are analogous ot the Z discs of striated muscle. They “anchor” the thin filaments in smooth muslce

A

Dense Bodies

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13
Q

What are the 2 components of a contraction in smooth muscles?

A

Slow Wave

Depolarization

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14
Q

What are the two functional categories of smooth muscle and how are they innervated?

What are examples of each?

A
  • Multi-Unit: arrector pili muscles in the skin and ciliary muscles attached to the eye
    • Require much more innervation
  • Single- Unit: Most smooth muscle in digestive tract and Uterus
    • Only some cells are innervated - ACh can diffuse into neighboring cells via the numerous gap junctions between adjacent cells
    • Myogenic - electrical activity - contracts in response to stretching (independent of nerve stimulation)
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15
Q

Sustained smooth muscle contractions are produced in response to extracellular [] that diffuses through the [] into the smooth muscle cells…

A
  • Ca2+
  • Sarcolemma
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16
Q

On what subunit of troponin does Calcium bind to in smooth muscles?

A

None, Ca2+ binds with calmodulin in smooth muscles, not troponin.

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17
Q

The Ca2+-calmodulin complex in smooth muscle active this enzyme [], through []

A
  • MLCK - myosin light chain kinase
  • De-phosphorylation
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18
Q

Which enzyme phosphorylates the Mysosin cross bridges in smooth muscle and which enzyme removes the phosphate group?

A
  1. MLCK - myosin light-chain kinase phosphorylates
  2. MLCP - myosin light chain phosphatase removes the phosphate group
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19
Q

[] starts the degradation of starchs in the mouth

A

Salivary Amylase

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20
Q

Where is the automatic acti of swallowing controlled?

A

swallowing center of the brain

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21
Q

This sphincter guards the junction of the stomach and the duodenum of the small intestine?

A

The pyloric spinchter

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22
Q

What are teh 4 main functions of the stomach?

A
  1. store food
  2. initiate the digestion of proteins
  3. kill bacteria with somtach acids
  4. move food into the small intestine
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23
Q

What are 6 cell types normally found in Gastric Glands?

A
  1. Mucous Neck Cells
  2. Parietal Cells
  3. Chief Cells
  4. Enterochromaffin-like (ECL) Cells
  5. G Cells
  6. D Cells
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24
Q

What are the the 3 regions of the stomach?

A
  • Fundus - mainly storage
  • Body - Secretes mucus and pepsinogen and HCL
  • Antrum - secretes a lot more mucus and pepsinogen and also gastrin
    • Also is the main location for the mixture and creation of chime.
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25
What do Mucous neck cell secrete?
Mucus
26
What do parietal cells secrete?
Hydrochloric Acid
27
What do Chief Cells Secrete?
Pepsinogen (inactive form of protein digesting enzyme pepsin)
28
What do enterochromaffin-like (ECL) cells secrete?
histamine 5-hydroxytryptamine (serotonin) Paracrine regulators of GI tract
29
What do G cells secrete?
Gastrin
30
What do D cells secrete?
Somatostatin
31
What hormone is used by the stomach and brain to signal hunger?
Ghrelin - secreted by the stomach
32
The production of [] by the stomach is required for intestinal absoprtion of Vitamin B[] - which is necessary for the production of RBCS!
1. Intrinsic Factor 2. B12
33
What are the 4 phases of Gastric Motility?
1. **Gastric Filling** 1. stomach starts to fill 2. Stomach expands starting to bring in small, slow wave of depolarization 2. **Gastric Storage** 1. Happens in fundus 3. **Gastric Mixing** 1. Occurs in Antrum to form chime 4. **Gastric Emptying** 1. Drives chime into the duodenum
34
Cl- is allowed to enter the parietal cell via what mechanism?
Secondary active transport of bicarbonate into the blood from the parietal cell
35
How is HCL formed in stomach lumen?
* Cl- is brought into the cell from the transport of bicarbonate into the blood (2nd active) * H+ is pumped out to the lumen by H+/K+ ATPase pumps * K+ is pumped in, but then recycled because there are K+ leak channels into the lumen * Cl- has channels that it can facilitatively diffuse out of and into the stomach lumen
36
The low pH of the gastric juice serves three functions:
1. Ingested proteins begin to denature at low pH 2. Under acidic conditions, weak pepsinogen enzymes partially digest each other 3. Pepsin is more active under acidic conditions.
37
What are two commonly ingested substances that can be absorbed across the stomach wall?
Aspirin and Alcohol
38
What are the 5 Entergastrone Hormones?
1. Secretin 2. Gastrin 3. Cholecystokinin (CCK) 4. Gastric inhibitory Peptide (GIP) 5. Ghrelin
39
What are the 3 phases of autonomic regulation of stomach function?
1. Cephalic 2. Gastric 3. Intestinal
40
What is the Cephalic Phase of Gastric Secretion?
1. Sight, smell, and taste of food cause stimulation of vaus nuclei in brain 2. Vagus stimulates chief cells to secrete pepsinogen 3. Vagus stimulates gastric acid secretion by stimulating **ECl cells** to secrete **histamine**, which stimulates parietal cell to secrete **HCl** 4. Occurs during first 30 minutes of meal
41
What is the Gastric Phase of Gastric Secretion?
* Distension of stomach stimulate vagus nerve, vagus stimulates acid secretion * Amino acids and peptides in stomach lumen stimulate acid secretion * Direct stimulation of parietal cells (lesser effect) * Stimulation of gastrin secretion; gastrin stimulates acid secretion (major effect) * Gastrin secretion inhibited when pH of gastric juice falls below 2.5
42
What is the Intestinal Phase of Gastric Secretion?
1. Neural inhibition of gastric emptying and acid secretion 1. arrival of chyme in duodenum causes distension, increase in osmotic pressure 2. These stimuli activate a nueral reflex that inhibits gastric activity 2. In response to fat in chyme, the dueodenum secrete an entergastrone hormone that inhibits gastric motility and secretion.
43
Gastrin is secreted from where? What are its effects on parietal cells and chief cells? Gastrin maintains the structure of the [] []...?
1. Stomach 2. Stimulates Parietal cells to secrete HCL and Chief cells to secrete pepsinogen 3. Gastric mucosa
44
Secretin is secreted from where? What is secretins effect on the pancrease?
1. Small Intestine 2. Stimualtes water and bicarbonate secretion in pancreatic juice 1. So it brings the acidity levels **down**
45
CCK (cholecystokinin) is secreted from where? What is CCK's effect on the gallbladder and pancrease? CCK maintains the structure of exocrine []..?
1. Small Intestine 2. Stimulates contractino of gallbladder and Stimulates secretion of pancreatic juice enzymes 1. inhibits gastric motility and secretion so **acidity levels decrease**
46
GIP (gastric inhibitory peptide or glucose dependent insulinotropic peptide) is secreted from where? What is its effect on gastric ascid secretion? What is its effect on the pancrease?
1. Small Intestine 2. GIP inhbits gastric motility and secretion - so **acidity levels decrease** 3. Stimulates secretion of insulin from pancreatic islets
47
48
How does nexium affect stomach acid?
Blocks H+/K+ pumps, lowering the concentration of H+ in stomach and increasing pH
49
The small intestine (specific section - ileum) empties into the large itnestine through the [] valve...
iliocecal
50
What is the main function of the Pancrease (exocrine)? What does it secrete, and what are these secretion's function?
* Secretion of enzymes and bicarbonate (non-digestive endocrine functions as well * Secretes * Enzymes * Digets carbs, fats, proteins, nucleic acids * Bicarbonate * neutralizes HCL coming into the small intestine from the stomach
51
What is the exocrine function of the liver? What does it secrete, and what are the functions of these secretions?
* Liver secretes bile and many other nondigestive enzymes * Secretes * Bile Salts * solubilize water-soluble fats * Bicarbonate * neutralize HCl coming into the small intestine from the stomach * Organic Waste Products and Metals * Elimination of Feces
52
What is the exocrine function of the gallbladder?
Store and concentrate bile between meals
53
What is the exocrine function of the small intestine? What does it secrete and what are these secretion's functions?
1. Digestion and Absorption of most substances; mixing and propulsion of contents 2. Secretes 1. Enzymes 1. involved in food digestion 2. Salt and Water 1. maintin fluidity of luminal contents 3. Mucus 1. Lubrication
54
What is the exocrine function of the Large Intestine? What does it secrete, and what is the function of these secretions?
1. Storage and Concentration of undigested matter; absorption of salt and water; mixing and propulsion of contents 2. Secretions 1. Mucus 1. lubrication
55
What are liver cells called?
Hepatocytes
56
Where does intestinal blood go first - how does it get there?
1. Goes to the liver first 2. Capillaries in digestive tract drain into the **hepatic portal vein** which takes the blood to the liver.
57
What cells produce bile? What structure in the liver drains the bile?
1. Hepatocytes 2. Thin channels called **bile canaliculi** 1. Leads to bile ducts --\> hepatic ducts that carry bile away form liver.
58
5 Major Categories of Liver Function
1. Detoxification of Blood 2. Carbohydrate Metabolism 3. Lipid Metabolism 4. Protein Synthesis 5. Secretion of Bile
59
The liver helps regulate the blood [] concentration by either removing [] from the blood or adding [] to it, according to the needs of the body (think sugar).
Glucose
60
Contraction of the [] layer of the gallbladder ejects bile thorugh the cystic duct into the [] [] duct, which conveys bile into the duoedenum
Muscularis layer Common bile duct
61
The common bile duct and the pancreatic duct empty into the duodenum at what junction? What Sphincter controls this emptying?
Duodenal Papilla Sphincter of ampulla (sphincter of Oddi)
62
What are the exocrine secretory units of the pancrease called?
Acini
63
What causes lipid digestion to begin in the stomach of adults?
* Lipid digestion beings in the duodenum of adults! * when lipids arrive in duodenum, bile is secreted which beings **emulsification**
64
What does emulsification do in the small intestine?
* bile salt micelles are secreted into the duodenum * Act as detergents to break up the fat droplets into tiny emulsification droplets of triglycerides
65
Which enzyme breaks up the emulsified droplets into free fatty acids and monoglycerides? What process breaks up the triglyceride?
1. Pancreatic lipase 2. Hydrolysis
66
What are the small particles formed by triglycerides, phopholipids, and cholesterol inside the digestive tract epithelial cells\>?
Chylomicrons
67
Bio 465 - Physio
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