chapter 24 Flashcards Preview

A&P 2 lecture > chapter 24 > Flashcards

Flashcards in chapter 24 Deck (98):
1

consists of 2 essential parts

1. digestive tract
2. accessory organs

2

digestive tract
-definition
-known as 2 other names

muscular tube from mouth to anus
-gastrointestinal tract and alimentary canal

3

the accessory organs
-mostly
-7

glands
-1. liver
2. gallbladder
3. pancreas
4. salivary glands
5. teeth
6. tongue
7. gastric and intestinal glands

4

functions of the digestive system

1. ingestion
2. mechanical digestion
3. digestion
4. secretion
5. absorption
6. excretion

5

ingestion

materials entering digestive tract through the mouth

6

mechanical digestion

crushing and breaking up of ingested material

7

digestion

chemical breakdown of food into smaller molecules suitable for absorption

8

secretion

release of H2O acids, enzymes, buffer and salts along the digestive tract

9

absorption

movement of organic substances, ions, vitamins, and H2O from digestive into interstitial fluids

10

excretion

removal of waste products

11

digestive tract
-

1. oral cavity (mouth)
2. pharynx
3. esophagus
4. stomach
5. small intestine
6. large intestine

12

small intestine
-why is it known as small
-3 parts

-in diameter
-1. 1st duodenum (10 in)
2. Jejunum (8 ft)
3. iliem (12 ft)

13

Large intestine
-why is it known as large
-4 parts

-in diameter
-1. cecum
2. colon
3. rectum
4. anus

14

colon
-4 parts

1. Ascending
2. transverse
3. descending
4. sigmoid

15

Histological organization of digestive tract
-4 layers

1. mucosa
2. submucosa
3. muscularis externa
4. serosa

16

mucosa
-innermost or outermost layer
-lines what
-function

-innermost
-lumen
-secretes mucus

17

mucosa
-3 layers

1. muscularis mucosa
2. lamina propria
3. epithelium

18

muscularis mucosa
-definition
-function

-thin layer of smooth muscle
-alters lumen shape

19

lamina propria
-contains

areolar CT, blood vessels and lymphatics

20

epithelium of the mucosa
-type of epithelium
-contains what

-simple columnar
-goblet cells

21

submucosa
-contains

CT, blood and lymphatic vessels

22

muscularis externa
-definition
-controlled by

-double layer of smooth muscle cells
-controlled by the myenteric plexus

23

serosa
-structure
-does not cover

-peritoneum
-oral cavity, pharynx, esophagus or rectum

24

submucosal gland
-type of gland
-function

-exocrine gland
-secretes buffers and enzymes

25

meissner plexus

sensory and autonomic

26

2 movements of digestive materials

1. mixing
2. peristalsis

27

mixing
-known as
-definition
-where does it occur
-what does it do
-are movements well coordinated
-contractions of

-segmentation
-constricting the tube and dividing its contents
-mostly in the small intestine
-mixes material being digested with intestinal secretions
-no
-muscularis externa and muscularis mucosa

28

peristalsis
-definition
-depends on
-circular layer
-longitudinal layer
-moves materials toward

-coordinated wave of muscular contraction that propels material through the tube
-coordinated contractions of the muscularis externa
-contracts behind the material while relaxing in front of it
-contracts ahead of the material and shortens the tube
-toward the anus

29

Oral cavity
-mouth
-lined by

-opens into the oral (buccal) cavity
-oral mucosa

30

oral mucosa

stratified squamous epithelium

31

Oral cavity
-4 functions

1. sensory analysis of materials before swallowing
2. mechanical processing of food begins= formation of bolus
3. lubrication of food bolus in preparation for swallowing
4. some digestion occurs

32

Swallowing
-known as
-___ function of the mouth
-voluntary or involuntary
-controlled

-deglutition
-motor
-voluntary
-subconsciously

33

steps of digestive tract to stomach

1. Buccal phase
2. Pharyngeal phase
3. Esophageal Phase
4. Bolus enters stomach

34

Buccal phase
-4 steps

1. Compression of bolus against the hard palate
2. retraction of tongue forces bolus into oropharynx
3. soft palate elevates
4. Food enters oropharynx

35

Pharyngeal phase
-5 steps

1. bolus in contact with oropharynx
2. swallowing reflex
3. muscles of pharynx will contract
4. larynx elevates and epiglottis folds
5. bolus is propelled into esophagus

36

swallowing reflex
-begins when
-controlled by

-begins when bolus passes uvula
-CN V, IX, X

37

CN V
-name
-functions

-trygeminal
-sensation to face and controls chewing

38

CN IX
-name
-functions

-Glossopharyngeal
-sensation to posterior part of the tongue and motor function

39

CN X
-name
-function

-Vagus
-provide motor to pharynx

40

Esophagus
-what is it
-lined by
-serosa?

-muscular tube
-stratified squamous epithelium
-no

41

Espohageal stage
-2 steps

1. Bolus is pushed toward stomach by peristaltic waves
2. Lower esophageal sphincter opens and bolus continues into stomach

42

Bolus enters stomach

chemical digestion of food continues

43

Stomach
-parts

1. Fundus
2. Body
3. Rugae
4. Pylorus
5. Cardia

44

Fundus of the stomach
-contains what
-function

-contains gastric glands
-secretes acids and enzymes for gastric digestion

45

Body of the stomach

mixing tank for food secretions

46

Rugae

folds of the mucosa that flatten as the stomach fills with food

47

pylorus

secretes mucus and digestive hormones

48

Cardia

produces mucus that helps to protect the esophagus

49

2 curvatures of the stomach

1. lesser curvature (by liver)
2. Greater curvature (by spleen)

50

4 functions of the stomach

1. Storage of ingested foods
2. mechanical breakdown of ingested foods
3. disruption of chemical bonds in foods through the action of acids and enzymes
4. production of intrinsic factor for absorption of vitamin B12
-1st 3 functions produces chyme

51

chyme

soupy mixture of partially digested food, highly acidic

52

factors that iincrease stomach mobility
-increased stomach mobility =
-2

-increased stomach emptying
1. distention of the stomach
2. gastrin hormone

53

distention of the stomach
-definition
-stimulates what

-stretching of stomach wall (food enters)
-mechanoreceptors

54

mechanoreceptors
-function

activates parasympathetic NS which promotes contractions of muscularis externa

55

Gastrin
-produced by
-secreted by what (1)
-secreted by (2)
-promotes

-endocrine glands
-stomach in response to arrival of food
-duodenum when chyme containing partially digested materials enter
-gastric secretions and contraction of muscularis externa

56

2 factors that decrease stomach motility

1. distention of the duodenum
2. Hormones: cholecytokinin, secretin and gastric inhibitory peptide

57

distention of the duodenum
-definition
-function

-stretching of the duodenum when chyme enters
-activation of enterogastric reflex

58

enterogastric reflex
-2 functions

1. inhibits contraction of muscularis externa
2. promotes contraction of pyloric sphincter

59

hormones that decrease stomach motility
-3
-produced by
-function

-1. cholecytokinin
2. secretin
3. gastric inhibitory peptide
-the duodenum
-function to reduce gastric secretions and motility

60

small intestine
-local
-2 components

-movements are controlled by myenteric plexus = PNS
-1. segmentation
2. peristalsis

61

segmentation of the small intestine
-how many times/min
-function

-11-12 times/min
-mix chyme with intestinal secretions

62

peristalsis of the small intestine
-movements are
-moves how many cm/sec
-how long does it take chyme to move through the sm intestine
-what does it direct

-very weak propulsive movement
-0.5-2.0 cm/sec
-3-5 hours
-coordinated movements

63

2 reflexes that control movements
-stimulated in response to

-1. gastroenteric reflex
2. gastroileal reflex
-to stretch receptors in the stomach

64

gastroenteric reflex

stimulates motility and secretion along the entire small intestine

65

gastroileal reflex

triggers relaxation of the ileocecal valve

66

stimulation of the gastroenteric and gastroileal reflex promotes

the passage of materials from the small intestine to the large intestine

67

large intestine
-conversion of what
-3 processes

-chyme into feces
-1. haustral churning
2. mass movements
3. defecation

68

Haustral churning
-2 steps

1. Taenia coli contract and bunch up which produces bulges called haustra
2. new contractions produce mixing of colon contents necessary for the production of feces

69

taenia coli
-location
-definition

-large intestine
-longitudinal bands of smooth muscle

70

mass movements
-what is this
-feces move as a __ down the colon
-occurs towards the beginning or end
-occurs where
-how many times per day
-function

-peristalsis in the large intestine
-unit
-end
-in the transverse and descending colon
-1-2 times per day usually right after the gastrocolic reflex
-push feces down into the rectum

71

what do mass movements initiate

defecation

72

defecation

elimination of feces from the body

73

the defecation reflex
-stimulus
-response
-response leads to

-feces in the rectum
-stretch receptors are stimulated
-increase in peristalsis in rectum and action potentials are conducted along afferent neuron

74

3 consequences of the defecation reflex

1. strong contraction of descending sigmoid colon and rectum
2. internal anal sphincter relaxes (opens-no control)
3. external anal sphincter contracts (closes)

75

Internal anal sphincter
-type of muscle

smooth

76

external anal sphincter
-type of muscle

skeletal

77

socially unacceptable
-2 things

1. voluntarily keep external anal sphincter closed
2. feces back up and out of rectum and reflex dies

78

socially acceptable
-3

1. voluntarily relax external anal sphincter
2. to initiate defecation take a deep breath
3. push feces into anal canal and expel

79

what does taking a deep breath while defecating do

increase abdominal pressure

80

Chemical digestion
-definition
-what does this produce

breakdown of food from high molecular weight components to low molecular weight components
-produces a form that can be absorbed

81

basic strategy of chemical digestion
-proteins ->
-carbs ->
-fat ->

-protein fragments (short polypeptides )-> AA (absorbed)
-small fragments (di and trisacharrides) -> monosaccharrides (absorbed)
-triglycerides -> glycerol and FA (absorbed)

82

saliva
-produces ___ /day
-pH
-contains 3 things

-1-1.5 L/day
- ~7.0
-1. 99% H2O
2. salt and mucus
3. enzymes

83

enzymes of saliva

1. lysozyme
2. lingual lipase
3. salivary amylase

84

lysozyme

destroys bacteria

85

lingual lipase

fat digestion

86

salivary amylase

carb digestion

87

4 functions of saliva

1. clean mouth (lysozyme kills bacteria)
2. dissolves food for taste
3. helps to form bolus for swallowing
4. beginning stages of digestion

88

digestion by saliva: salivary amylase
-starch ->

-salivary amylase convert starch to di and trisaccharides

89

regulation of salivary secretions

1.smell, sight, thoughts of food and/or food in the mouth stimulates cranial nerves V, VII, IX, or X
2. salivary nuclei in medulla oblogata
3. parasympathetic stimulation stimulates increase secretion from salivary glands

90

3 pairs of salivary glands

1. parotid
2. submandibular
3. sublingual

91

chemical digestion: stomach
-2 components

1. gastric juice
2. gastric pits and glands

92

gastric juice
-basic or acidic
-pH
-produced by

-highly acidic
-2
-by the cells of the gastric gland

93

gastric pits and glands
-4 components

1. mucous cells
2. parietal cells
3. chief cells
4. G cells

94

Mucous cells
-location
-what are they doing
-function

-in the gastric pit
-actively dividing
-secrete thick protective mucus

95

parietal cells
-cells of the
-function

-gastric gland
-secrete intrinsic factor and hydrochloric acid (HCl)

96

intrinsic factor of parietal cells

facilitates absorption of vitamin B12 needed for erythropoesis

97

hydrochloric acid
-explains what
-3 functions

-acidity
-1. kills microbes
2. softens cell wall of plant material
3. helps denature protein

98

what is the gastric pit called

the lumen of the stomach