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z_A&P II: BIO426 > Ch 25: Digestive System > Flashcards

Ch 25: Digestive System Flashcards

1
Q

What are the six functions of the digestive system?

Give a brief description of each.

A
  1. Ingestion: Taking in food through mouth
  2. Mechanical breakdown: In mouth and stomach
  3. Propulsion: Movement of food through the digestive tract via peristalsis
  4. Digestion: Chemical breakdown of food with enzymes all along the process
  5. Absorption: Taking in the chemical nutrients from food. Occurs mostly in the small intestines
  6. Defication: Removal of digestive waste via the anus
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2
Q

What are the two basic parts of the digestive system?

Briefly explain each.

A
  1. Alimentary canal: Pathway of food, from mouth to anus
  2. Accessory organs: Aid in digestion, but food does not pass through them
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3
Q

What are the two modes of digestive regulation?

A
  1. Extrinsic
  2. Intrinsic
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4
Q

What is extrinsic digestive regulation?

A
  • Regulation that comes from outside the digestive system.
  • Comes from brain and nervous system
  • Specifically the PNS
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5
Q

What is intrinsic digestive regulation?

A
  • Regulation that comes from inside the digestive system
  • Occurs via gut hormones and the enteric nervous system via a group of nerves found in submucosa of plexus that provide for hunger feelings of the stomach
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6
Q

What are the anatomical parts of the alimentary canal?

A
  1. Mouth
  2. Pharynx
  3. Esophagus
  4. Stomach
  5. Small Intestines
  6. Large Intestines
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7
Q

What are the two accessory organs of the digestive system?

A
  1. Liver, including gall bladder
  2. Pancreas
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8
Q

Where is the esophageal sphincter and what is its purpose?

A
  • It is located at the base of the esophagus where it meets the stomach.
  • It closes to prevent backflow of stomach contents into the esophagus
  • Prevents stomach acid from damaging esophageal tissues (acid reflux/heartburn)
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9
Q

Where is the pyloric sphincter, and what is its purpose?

A
  • The pyloric sphincter is located at the exit point of the stomach where it meets the intestines.
  • It controls the release of stomach contents to the duodenum
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10
Q

The process of taking in food from the mouth is called _____.

A

ingestion

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11
Q

The mechanical breakdown of food in the mouth uses what parts?

A
  • Teeth
  • Tongue
  • Cheek muscles
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12
Q

The process of chewing is called _____.

A

mastication

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13
Q

Chemical digestion starts in the mouth with _____.

A

saliva

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14
Q

Saliva is exreted via _____.

A

salivary glands

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15
Q

Saliva consists of __% water, making it a _____ solution.

A

99%, hypotonic

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16
Q

Besides water, saliva also contains some _____, _____, _____, and _____.

A

acids, ions, amylase, antibiotic substances

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17
Q

*Amylase is an enzyme in _____ that breaks down _____.

A

saliva, starch

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18
Q

What are the antibiotic substances found in saliva and what purpose do they serve?

A
  • Mucin
  • Lysozyme
  • IgA
  • To kill microorganisms in food
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19
Q

Saliva is secreted constantly for _____ and _____.

A

cleanliness, moisture

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20
Q

The pharynx consists of…

A
  • Hard palate
  • Soft palate
  • Nasopharynx
  • Oropharynx
  • Tonsils
  • Laryngopharynx
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21
Q

The act of swallowing is called _____.

A

deglutition

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22
Q

What are the 3 phases of swallowing?

A
  • Buccal/Oral
  • Pharyngeal
  • Esophageal
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23
Q

Describe the Buccal/Oral phase of swallowing.

A
  • Voluntary
  • Tongue and cheek muscles push food to back of mouth and down to laryngopharynx
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24
Q

Describe the pharyngeal phase of swallowing.

A
  • Involuntary
  • Soft palate blocks nasopharynx
  • Tongue blocks entry to mouth
  • Epiglottis blocks trachea
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25
Q

Describe the esophageal phase of swallowing.

A
  • Food is pushed into espophagus
  • Perstalsis takes it from there, moving bolus to the stomach
  • Relaxation of the lower esophageal sphincter admits it into the stomach
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26
Q

What are the physical characteristics of the esophagus?

A
  • Collapsed muscluar tube
  • Mucosa consists of stratified squamous cells to protect from abrasion/acidic juices from the stomach
  • Uses peristalsis to move bolus to stomach
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27
Q

The stomach is a _____, and its walls are _____.

A

storage sack, destendable

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28
Q

Define destendable.

A

The ability to expand due to internal pressure

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29
Q

Define rugae.

A

The folds of the enner walls in the stomach that allow it to be distended.

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30
Q

The first stomach sphincter of control is called the…

A

esophageal sphincter

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31
Q

The muscular layer of the stomach is called the _____.

A

muscular externa

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32
Q

The lining of the stomach is ….

A

discontinuous/incomplete

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33
Q

True or False

Stomach muscles contract via peristalsis

A

False

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34
Q

The irregular contraction of the stomach is called _____ and it is for _____.

A

churning, mechanical breakdown

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35
Q

What is the purpose of the alkaline mucus secreted in the stomach?

A

To protect the stomach from digestive acids

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36
Q

What are the two types of glands in the stomach lining?

A
  1. Gastric
  2. Pyloric
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37
Q

_____ stomach epithelium is closer to the esophagus, whereas _____ stomach epithelium is closer to the small intestines.

A

cardiac, pyloric

38
Q

What are the five types of gland cells in the stomach lining?

A
  1. Mucus
  2. Regenerative
  3. Parietal
  4. Chief
  5. Enteroendocrine
39
Q

What is the purpose of the mucus cells of the stomach?

A

To protect the lining of the stomach by excreting alkaline mucus to counteract stomach acids.

40
Q

The regenerative cells of the stomach lining are…

A

stem cells that produce new epithelial cells

41
Q

Parietal cells secrete _____, which _____ stomach pH.

A

Hydrochloric Acid (HCl), reduces

42
Q

A normal stomach pH level is…

A

2.0

43
Q

The addition of HCl to the stomach converts the bolus into _____.

A

chyme

44
Q

*What orexigenic hormone is secreted by parietal cells and what is its purpose?

A
  • Ghrelin
  • Increases need to eat
45
Q

*What two enzymes are secreted by chief cells?

Name functions.

A
  1. Lipase: breaks down lipids
  2. Pepsinogen: when released it is converted into pepsin by stomach acids and will breakdown proteins
46
Q

Enteroendocrine cells secrete _____, which stimulates secretion of _____.

A

gastrin, hydrochloric acid (HCl)

47
Q

Regulation of gastric secretions is through the _____ and _____ systems.

A

endocrine, nervous

48
Q

What are the three phases of regulation of gastric secretions?

A
  1. Cephalon phase
  2. Gastric phase
  3. Intestinal phase
49
Q

What are the characteristics of the Cephalon phase?

A
  • Starts before food hits stomach
  • Just the thought, sight or thought of food will start digestive system
  • Sensory or mental input initiates HCl secretion nd enteroendocrine cells to stimulate gastrin
  • Preps stomach for receipt of food
50
Q

What are the characteristics of the Gastric phase?

A
  • Food enters stomach
  • Semi-digestion of proteins
    • protein breakdown produces ammonia (NH3)
    • NH3 increases pH and makes stomach more alkaline
    • This stims gastrin production
    • Gastrin initiates HCl, which decreases pH
    • It is a negative feedback loop
    • Too much HCl would inhibit gastrin
    • Stres can also inhibit gastrin
51
Q

What are the characteristics of the Intestinal phase?

A
  • Food leaves stomach through pyloric sphincter
  • Chyme slowly released into intestines
  • Small intestines secrete intestinal gastrin
  • Food is currently partially digested
  • Enterogastric reflex
52
Q

What are the characteristics of the enterogastric reflex?

A
  • Found in small intestines
  • Prevents too much food from leaving stomach
53
Q

What are the two main functions of the small intestines?

A
  1. Complete digestion
  2. Absorption
54
Q

What two accessory organs assist the small intestines with digestion?

A
  1. Liver
  2. Pancreas
55
Q

Explain absroption in the small intestines.

A

When all food is broken down into its smallest components, they diffuse out of the small intestines into the capillaries

56
Q

Explain the histology of the small intestines.

A
  • Mucosa and submucosa folded into villi
  • Simple columnar epithelia has a microvilli brushborder
  • Villi and microvilli serve to increase surface area and increase diffusion
  • Microvilli has enzymes that further breakdown disaccharides (sucrose and lactose)
57
Q

What antibacterial juices are secreted in the small intestines?

A
  • water
  • mucin
  • lysozyme
  • T-cells
58
Q

What do the alcholine secretions do in the small intestines?

A

neutralize chyme

59
Q

Small intestines also contain MALT which is _____ and helps fight _____.

A

mucus associated lymphatic tissues, infection

60
Q

_____ are collections of MALT in SI that monitor _____ and prevent the growth of _____ in the intestines.

A

intestinal bacteria populations, pathogenic bacteria

61
Q

EXTRA CREDIT QUESTION

Relate urinary and digestive systems.

A
  • The liver synthesizes the urea exreted by the kidneys
  • This urea also contributes to the osmotic gradient that enables the kidneys to concentrate urine
  • Intestines complement the kidneys in water and electrolyte reabsorption
62
Q

TEST QUESTION

Describe the hepatic portal system of the digestive system.

A
  • The two capilary beds of the hepatic portal system are located at the small intestines and the liver.
  • Flow to small intestines:
    • Aorta -> Superior mesentaric artery -> SI capillaries
    • Purpose: supply blood to SI tract
  • Flow to liver:
    • small intestines -> Hepatic portal vein -> Liver
    • Purpose: regulation of blood glucose levels and removal of any toxins
  • Flow to heart: Liver-> Hepatic vein -> Inferior vena cava -> Heart
63
Q

What is the blood flow to liver?

A

Aorta -> Celiac trunk -> Hepatic artery -> Liver

64
Q

All blood from the SI goes through _____ before heading back to the heart.

A

the liver

65
Q

What are the three main functions of the accessory organs?

State the organ of each.

A
  1. Bile production: Liver
  2. Regulation of blood glucose levels: Pancreas
  3. Removal of toxins: Liver
66
Q

Bile is _____ that allows _____ to dissolve in H2O.

A

an emulsifier, lipids

67
Q

Bile allows for the absorption of…

A
  • fatty acids
  • colesterol
  • lipid based vitamins
68
Q

Bile is produced by what type of cells?

A

hepatocytes

69
Q

What is the flow of bile from hepatocyte to gall bladder?

A

hepatocyte -> bile canicul -> bile ductules -> hepatic ducts -> cystic ducts -> bile duct -> gall bladder

70
Q

Regulation of blood glucose levels occurs through _____ and _____ that are secreted by the _____.

A

insulin, glucose, pancreas

71
Q

Insulin _____ blood glucose levels by _____ cellular uptake.

A

lowers, increasing

72
Q

Absorption of glucose _____ blood glucose levels.

A

reduces

73
Q

_____ stimulates glycogen production.

A

Insulin

74
Q

Glycogen takes _____ out of blood and stores it in the _____.

A

glucose, liver

75
Q

Glucagon is a hormone formed in the _____ which promotes the breakdown of _____ to _____ in the liver.

A

glycogen, glucose

76
Q

The breakown of glycogen _____ blood glucose levels.

A

raises

77
Q

What organ is responsible for the removal of toxins?

A

Liver

78
Q

What two secretions of the pancreas regulate blood glucose levels?

A
  1. insulin
  2. glucagon
79
Q

Insulin and glucagon are _____ in that they are used to effect change (raise/lower) in blood _____ levels.

A

antagonistic, glucose

80
Q

Pancreatic juices contain _____ that complete _____.

A

enzymes, digestion

81
Q

What enzyme is secreted by the pancreas that is a base that neutralize chyme?

A

sodium bicarbonate (NaHCO3)

82
Q

The pancreas secretes juices into the _____ which fuses with the _____.

A

pancreatic duct, bile duct

83
Q

Bile and pancreas secretions are secreted into the _____ of the small intestines through the _____.

A

dodenum, hepatopancreatic sphincter

84
Q

Define absorption as it pertains to the digestive process of the small intestines.

A
  • All food is broken into its smallest components
  • diffuses out of SI into capillaries
  • Removes all nutrients
85
Q

The large intestines are responsible for

A

the packaging of digestive wastes and H2O reabsorption.

86
Q

What are the epithelial characterstics of the large intestines?

A
  • mucosa not folded
  • no enzymes
  • goblet cells secrete mucus to lubricate fecal movement
87
Q

What are the purpose of the bacterial flora of the large intestine?

A
  • Help metabolize host molecules that can ferment undigested material
  • Synthesize some vitamins (K, biotin)
88
Q

The movement of material through the large intestines is by _____.

A

haustral contractions.

89
Q

Describe haustral contractions.

A
  • Movement is triggered through the distention of the hastral segments of the large intesteines
  • One haustrum distends as it fills with chyme, which stimulates muscles to contract, pushing the contents to the next haustrum.
90
Q

Defication is the removal of

A

solid wastes.

91
Q

Chyme that has had its water content reabsorbed into the body is called.

A

Feces

92
Q

Explain the process of defication from the end of the large intestine.

A
  • fecal matter moves from large intestine into the rectum which contains stretch receptors letting the individual know its time to eliminate.
  • stretch receptors cause defication reflex which causes contraction toward the external sphincter
  • External sphincter is under voluntary control defication occurs under will of the individual.

z_A&P II: BIO426 (31 decks)

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