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Anatomy and physiology 2 > digestive system > Flashcards

digestive system Flashcards

1
Q

what is the main function of digestive system?

A

– Take in food
– Break it down into nutrient molecules
– Absorb molecules into the bloodstream
– Rid body of any indigestible remains

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2
Q

what are the 2 groups of the digestive system?

A

-– Alimentary canal (gastrointestinal or G I tract or gut)
- – Accessory digestive organs

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3
Q

– Alimentary canal (gastrointestinal or G I tract or gut) function

A

 Continuous muscular tube that runs from the mouth to anus
 Digests food: breaks down into smaller fragments
 Absorbs fragments through lining into blood
 Organs: mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus

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4
Q

– Accessory digestive organs

A

 Teeth
 Tongue
 Gallbladder
 Digestive glands: produce secretions that help break down foodstuffs
– Salivary glands
– Liver
– Pancreas

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5
Q

what is digestion?

A

-Eating

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6
Q

what is propulsion?

A
  • movement of food through the alimentary canal, which includes:
     Swallowing
     Peristalsis: major means of propulsion of food that involves alternating waves of contraction and relaxation
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7
Q

what is mechanical breakdown?

A
  • includes chewing, mixing food with saliva, churning food in stomach, and segmentation
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8
Q

what is segmentation?

A
  • local constriction of intestine that mixes food with digestive juices
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9
Q

what is digestion?

A

series of catabolic steps that involves enzymes that break down complex food molecules into chemical building blocks

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10
Q

what is absorption?

A

passage of digested fragments from lumen of G I tract into blood or lymph

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11
Q

what is defecation?

A

elimination of indigestible substances via anus in form of feces

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12
Q

what is peritoneum?

A

serous membranes of abdominal cavity

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13
Q

what is visceral peritoneum?

A

membrane on external surface of most digestive organs

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14
Q

what is parietal peritoneum?

A

membrane that lines body wall

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15
Q

what peritoneal cavity?

A

– Fluid-filled space between two peritoneums
– Fluid lubricates mobile organs

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16
Q

what is mesentery?

A

double layer of peritoneum; layers are fused back to back
– Extends from body wall to digestive organs
– Provides routes for blood vessels, lymphatics, and nerves
– Holds organs in place and also stores fat

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17
Q

what is intraperitoneal (peritoneal) organs?

A

organs that are located within the peritoneum

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18
Q

what are retroperitoneal organs?

A

located outside, or posterior to, the peritoneum
– Includes most of pancreas, duodenum, and parts of large intestine

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19
Q

what is peritonitis?

A

– Inflammation of peritoneum
– Can be caused by piercing abdominal wound, perforating ulcer, or ruptured appendix
– Peritoneal coverings stick together, which helps localize infection
– Dangerous and lethal if it becomes widespread
– Treatment: debris removal and megadoses of antibiotics

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20
Q

what are the 4 layers all digestive organs have?

A

– Mucosa
– Submucosa
– Muscularis externa
– Serosa

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21
Q

what is mucosa?

A

– Tunic layer that lines lumen
– Functions: different layers perform one or all three
 Secretes mucus, digestive enzymes, and hormones
 Absorbs end products of digestion
 Protects against infectious disease

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22
Q

what are the sublayers of mucosa?

A

 Epithelium
 Lamina propria
 Muscularis mucosae

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23
Q

what is epithelium and its function?

A

 Simple columnar epithelium and mucus-secreting cells in most of tract
– Mouth, esophagus, and anus are made up of stratified squamous epithelium
 Secretes mucus
– Protects digestive organs from enzymes
– Eases food passage
 May secrete enzymes and hormones (e.g., in stomach and small intestine)

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24
Q

what is lamina propria?

A

 Made up of loose areolar connective tissue
 Rich supply of capillaries located here
– Needed for nourishment and absorption
 Also contains lymphoid follicles that help defend against microorganisms
– Follicles are part of M A L T (mucosa-associated lymphoid tissue)

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25
Q

what is muscularis mucosae?

A

 Smooth muscle that produces local movements of mucosa

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26
Q

what is submucosa?

A

– Consists of areolar connective tissue
– Contains blood and lymphatic vessels, lymphoid follicles, and submucosal nerve plexus that supply surrounding G I tract tissues
– Has abundant amount of elastic tissues that help organs to regain shape after storing large meal

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27
Q

what is muscularis externa?

A

– Muscle layer responsible for segmentation and peristalsis
– Contains inner circular muscle layer and outer longitudinal layers
 Circular layer thickens in some areas to form sphincters

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28
Q

what is serosa?

A

– Outermost layer, which is made up of the visceral peritoneum
 Formed from areolar connective tissue covered with mesothelium (single layer of squamous epithelium) in most organs
 Replaced by fibrous adventitia in esophagus
– Dense connective tissue that holds esophagus to surrounding structures
 Retroperitoneal organs have both an adventitia and a serosa

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29
Q

what does splanchnic circulation include?

A

– Arteries that branch off aorta to serve digestive organs
 Hepatic, splenic, and left gastric arteries
 Inferior and superior mesenteric arteries
– Hepatic portal circulation
 Drains nutrient-rich blood from digestive organs
 Delivers blood to liver for processing

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30
Q

what is enteric nervous system?

A

G I tract nervous system and it is also called gut brain.

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31
Q

gut brain

A
  • Gut brain is made up of enteric neurons that communicate extensively with each other
    – Major nerve supply to G I tract wall that controls motility
    – Enteric neurons make up bulk of two main interconnecting intrinsic nerve plexuses:
    – Submucosal nerve plexus
     Regulates glands and smooth muscle in mucosa
    – Myenteric nerve plexus
     Controls G I tract motility
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32
Q

what is short flexes?

A

mediated by enteric nerve plexuses (gut brain); respond to stimuli in G I tract

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33
Q

what is long reflexes?

A

respond to stimuli arising inside or outside of gut, such as from autonomic nervous system
 Parasympathetic system enhances digestive process
 Sympathetic system inhibits digestion

34
Q

3 key concepts to regulate G I activity?

A

digestive, effector and neurons activity

35
Q

what is digestive activity?

A
  • Digestive activity is provoked by a range of mechanical and chemical stimuli
    – Receptors located in walls of G I tract organs
    – Respond to stretch, changes in osmolarity and p H, and presence of substrate and end products of digestion
36
Q

what is effector of digestive activity?

A
  • Effectors of digestive activity are smooth muscle and glands
    – When stimulated, receptors initiate reflexes that stimulate smooth muscle to mix and move lumen contents
    – Reflexes can also activate or inhibit digestive glands that secrete digestive juices or hormones
37
Q

what is neuron digestive activity?

A
  • Neurons (intrinsic and extrinsic) and hormones control digestive activity
    – Nervous system control
     Intrinsic controls: involve short reflexes (enteric nervous system)
     Extrinsic controls: involve long reflexes (autonomic nervous system)
    – Hormonal controls
     Hormones from cells in stomach and small intestine stimulate target cells in same or different organs to secrete or contract
38
Q

what are the associated organs with mouth?

A
  • Associated organs include:
    – Mouth
    – Tongue
    – Salivary glands
    – Teeth
39
Q

what is mouth?

A
  • Also called the oral (buccal) cavity
    – Bounded by lips anteriorly, cheeks laterally, palate superiorly, and tongue inferiorly
    – Oral orifice is the anterior opening
    – Walls of mouth lined with stratified squamous epithelium
     Tough cells that resist abrasion
     Cells of gums, hard palate, and part of tongue are keratinized for extra protection
40
Q

lips and cheeks

A

– Lips (labia): composed of fleshy orbicularis oris muscle
– Cheeks: composed of buccinator muscles
– Oral vestibule: recess internal to lips and cheeks, external to teeth and gums
– Oral cavity proper: lies within teeth and gums
– Labial frenulum: median attachment of each lip to gum

41
Q

what is palate?

A

– Palate forms the roof of the mouth and has two distinct parts

42
Q

what is hard palate?

A

formed by palatine bones and palatine processes of maxillae with a midline ridge called raphe
– Mucosa is slightly corrugated to help create friction against tongue

43
Q

what is soft palate?

A

fold formed mostly of skeletal muscle
– Closes off nasopharynx during swallowing
– Laterally, soft palate anchored to tongue by palatoglossal arches
– Also anchored to wall of oropharynx by palatopharyngeal arches
– Area in between two arches is called fauces
* Palatine tonsils are located in fauces

44
Q

what is uvula?

A

: fingerlike projection that faces downward from free edge of soft palate

45
Q

tongue and its function

A
  • Tongue occupies floor of mouth
  • Composed of interlacing bundles of skeletal muscle
  • Functions include:
    – Gripping, repositioning, and mixing of food during chewing
    – Formation of bolus, mixture of food and saliva
    – Initiation of swallowing, speech, and taste
  • Intrinsic muscles change shape of tongue
  • Extrinsic muscles alter tongue’s position
46
Q

what is lingual frenulum?

A

attachment to floor of mouth
* Superior surface bears papillae, peglike projections of underlying mucosa

47
Q

what is filiform papillae?

A

gives tongue roughness to provide friction; only one that does not contain taste buds; gives tongue a whitish appearance

48
Q

what is fungiform papillae

A

mushroom shaped, scattered widely over tongue; vascular core causes reddish appearance of tongue

49
Q

what is vallate (circumvallate) papillae?

A

: 8–12 form V-shaped row in back of tongue

50
Q

what is foliate papillae?

A

located on lateral aspects of posterior tongue

51
Q

what is terminal sulcus and it function?

A

groove located posterior to vallate papillae
– Marks division between:
 Body: portion of tongue that resides in oral cavity
 Root: posterior third residing in oropharynx
– Does not contain papillae, but still bumpy because of lingual tonsil, which lies deep to its mucosa

52
Q

what is ankyloglossia?

A

: congenital condition in which children are born with an extremely short lingual frenulum
– Often referred to as “tongue-tied” or “fused tongue”
– Restricted tongue movement distorts speech
– Treatment: surgical snipping of frenulum

53
Q

what is the function saliva?

A

– Cleanses mouth
– Dissolves food chemicals for taste
– Moistens food; compacts into bolus
– Begins breakdown of starch with enzyme amylase

54
Q

what is minor salivary glands?

A

are scattered throughout oral cavity; augment slightly.

55
Q

what major salivary glands?

A

parotid, submandibular, and sublingual?

56
Q

what is parotid?

A

anterior to ear and external to masseter muscle
 Parotid duct opens into oral vestibule next to the second upper molar

57
Q

what is submandibular and its function?

A

medial to body of mandible
 Duct opens at base of lingual frenulum

58
Q

what is sublingual and its function?

A

: anterior to submandibular gland under tongue
 Opens via 10–12 ducts into floor of mouth

59
Q

what is serous cells?

A

produce watery secretion, enzymes, ions, bit of mucin

60
Q

what is mucous cells function?

A

produce mucus

61
Q

what is Xerostomia?

A

dry mouth, uncomfortable condition caused by too little saliva being made

62
Q

what is the composition of saliva?

A

– Mostly water (97–99.5%), so hypo-osmotic
– Slightly acidic (p H 6.75 to 7.00)
– Electrolytes: N a+, K+, C l−, P O42−, H C O3−
– Salivary amylase and lingual lipase
– Proteins: mucin, lysozyme, and I g A
– Metabolic wastes: urea and uric acid
– Lysozyme, I g A, defensins, and nitric oxide from nitrates in food protect against microorganisms
– 1500 m l/day can be produced
– Minor glands continuously keep mouth moist

63
Q

– Major salivary glands are activated by parasympathetic nervous system when:

A

 Ingested food stimulates chemoreceptors and mechanoreceptors in mouth, sending signals to Salivatory nuclei:
– Salivatory nuclei in brain stem that stimulate parasympathetic impulses along fibers in cranial nerves VII and IX to glands
– Strong sympathetic stimulation inhibits salivation and results in dry mouth (xerostomia)
– Smell/sight of food or upset G I can act as stimuli

64
Q

Teeth

A
  • Teeth lie in sockets in gum-covered margins of mandible and maxilla
65
Q

what is mastication?

A

process of chewing that tears and grinds food into smaller fragments

66
Q

what is the definition and dental formula?

A

– Primary dentition consists of 20 deciduous teeth, or milk or baby teeth, that erupt between 6 and 24 months of age
– 32 deep-lying permanent teeth enlarge and develop while roots of milk teeth are resorbed from below, causing them to loosen and fall out
 Occurs around 6–12 years of age
– All but third molars (wisdom teeth) are in by the end of adolescence
 Third molars may or may not emerge around 17–25 years of age

67
Q

what are the 3 teeth’ classified shapes?

A

– Incisors: chisel shaped for cutting
– Canines: fanglike teeth that tear or pierce
– Premolars (bicuspids): broad crowns with rounded cusps used to grind or crush
 Molars: broad crowns, rounded cusps: best grinders
– During chewing, upper and lower molars lock together, creating tremendous crushing force

68
Q

what is the dental formula?

A

shorthand indicator of number and position of teeth
– Shows ratio of upper to lower teeth for only half of mouth; other side is mirror image
– Primary
– Permanent

69
Q

what is the crown and its function?

A

exposed part above gingiva (gum)
– Covered by enamel, the hardest substance in body
* Heavily mineralized with calcium salts and hydroxyapatite crystals
* Enamel-producing cells degenerate when tooth erupts, so no healing if tooth decays or cracks; needs artificial repair by filling

70
Q

what is root?

A

portion embedded in jawbone
– Connected to crown by neck
– Canines, incisors, and premolars have only one root
 First upper premolar often has two
– First two upper molars have three roots
– First two lower molars have two roots
– Third molar roots vary; often single fused root

71
Q

what is cement and its function?

A

calcified connective tissue
– Covers root; attaches it to periodontal ligament

72
Q

what is periodontal ligament?

A

– Forms fibrous joint called gomphosis
– Anchors tooth in bony socket (alveolus)

73
Q

what is gingival sulcus?

A

: groove where gingiva borders tooth

74
Q

what is dentin?

A

bonelike material under enamel
– Maintained by odontoblasts of pulp cavity

75
Q

what is pulp activity?

A

surrounded by dentin

76
Q

what is pulp?

A

connective tissue, blood vessels, and nerves

77
Q

what is root canal?

A

as pulp cavity extends to root

78
Q

what is apical foramen?

A

– Entry for blood vessels, nerves, etc.

79
Q

what is impacted tooth?

A

a tooth that remains trapped in the jawbone
* Can cause a good deal of pressure and pain
* Wisdom teeth are most commonly involved.
* Treatment: surgical removal

80
Q

what is dental caries?

A

demineralization of enamel and dentin from bacterial action
– Dental plaque (film of sugar, bacteria, and debris) adheres to teeth
– Acid from bacteria dissolves calcium salts
– Proteolytic enzymes digest organic matter
– Prevention: daily flossing and brushing

81
Q

what is gingivitis?

A

– Plaque calcifies to form calculus (tartar)
– Calculus disrupts seal between gingivae and teeth
– Anaerobic bacteria infect gums
– Infection is reversible if calculus removed

82
Q

what is periodontitis?

A

– Neglected gingivitis can escalate to disease
– Immune cells attack not only bacterial intruders, but also body tissues
 Can destroy periodontal ligament
 Can activate osteoclasts, which leads to dissolving of bone and possible tooth loss
– May increase heart disease and stroke two ways:
 Promotes atherosclerotic plaque formation
 Bacteria entering blood can cause clot formation in coronary and cerebral arteries
– Risk factors: smoking, diabetes mellitus, oral piercings

Anatomy and physiology 2 (3 decks)

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