Digestive System Flashcards
1
Q
Digestive sys. function
A
to break down food into simple chemicals, to allow absorption into the blood & lymph & utilization by cells
2
Q
2 Divisions of digestive sys
A
1) Alimentary tube
2) Accessory organs
3
Q
Alimentary tube
A
- oral (buccal) cavity
- pharynx, oesophagus, stomach, small intestine, large intestine
4
Q
Accessory organs
A
teeth, tongue, salivary glands, liver, gall bladder, pancreas
5
Q
DIGESTION types
A
Mechanical
Chemical
6
Q
Mechanical digestion
A
the physical breaking up of food into smaller pieces
7
Q
Chemical digestion
A
digestive enzymes break down complex organics into simpler organics & inorganics; each enzyme is specific for the food it will digest
8
Q
Digestion
A
takes place in the oral cavity, stomach & small intestine
9
Q
The end products of digestion
A
- carbs
- fats
- proteins
- vitamins, minerals and water
10
Q
Carbohydrates
A
broken down into monosaccharides
11
Q
Fats
A
broken down into fatty acids & glycerol
12
Q
Proteins
A
broken down into amino acids
13
Q
ORAL CAVITY contains:
A
Teeth
Tongue
Opening of the ducts of the salivary glands
14
Q
Oral cavity
A
-Food enters the oral cavity by way of the mouth
Boundaries of the oral cavity are hard & soft palates
15
Q
Boundaries of the oral cavity are hard & soft palates
A
superiorly; the cheeks laterally; the floor of the mouth inferiorly
16
Q
PHARYNX
A
- Food passageway from the oral cavity to the esophagus
- No digestion takes place
17
Q
PHARYNX function
A
-the mechanical movement of food,(propulsion)
18
Q
Swallowing reflex is coordinated by the
A
medulla
19
Q
Swallowing reflex pathway
A
Constriction of the pharynx
Cessation of breathing
Elevation of the soft palate to block the nasopharnyx
Elevation of the larynx, closure of the epiglottis
Peristalsis (propulsion)by the oesophagus
20
Q
ESOPHAGUS
A
- Muscular tube
- No digestion takes place
- Peristalsis propels food in one direction to the stomach
- Lower oesophageal sphincter- LES or cardiac sphincter
21
Q
Muscular tube
A
food passageway from the pharynx to the stomach
22
Q
Lower oesophageal sphincter - LES or cardiac sphincter
A
- a circular muscle at the junction of the oesophagus & stomach
- contracts to prevent the backup of stomach contents
23
Q
ALIMENTARY TUBE STRUCTURE- 4 layers
A
1) mucosa
2) submucosa
3) serosa
4) external muscle layer
24
Q
Mucosa
A
epithelial, areolar connective & 2 types of smooth muscle
25
Submucosa
- areolar connective tissue - with many blood vessels
| - lymph vessels - “brain of the gut” Meissner’s plexus
26
Serosa
- in oesophagus - fibrous connective tissue
| - below the diaphragm - the mesentery or visceral peritoneum, (serous membrane)
27
External muscle layer
2 layers of smooth muscle
>inner circular
>outer longitudinal layer,(Auerbach’s plexus)
28
STOMACH
- A muscular sac that extends from the oesophagus to the small intestine
- Gastric juice is secreted by gastric pits
29
The pyloric sphincter at the junction of the stomach & the duodenum prevents
backup of intestinal contents
30
Begins the digestion of protein
stomach
31
Reservoir for food
stomach
32
where is the stomach located
Upper Left abdominal quadrant
33
Rugae
folds of the mucosal lining of the stomach
34
Gastric pits
glands of the stomach; secrete gastric juice; consist of several types of cells
35
Mucous
secrete mucus which coats the lining & prevents erosion by the gastric juices
36
Chief
secrete pepsinogen – an inactive form of the enzyme pepsin
37
Parietal
- secrete hydrochloric (HCL) acid which converts pepsinogen to pepsin
- which begins the digestion of proteins; secrete intrinsic factor which is necessary for the absorption of Vitamin B12
38
Parasympathetic response
gastric juice is secreted at the sight or smell of food
39
Food in the stomach causes the G cells to secrete
-gastrin , a hormone that stimulates the secretion of more gastric juices
40
External muscle layer consists of 3 layers of
- smooth muscle
| - circular, longitudinal, & oblique
41
Impulses carried by the vagus (10th cranial) nerve provide for
-mechanical digestion of the food to change it into chyme, released in small amounts into the duodenum
42
SMALL INTESTINE
- Coiled within the center of the abdominal cavity
- Extends from the stomach to the colon
- Approximately 1 inch (2.5cm) in diameter & 20 feet (6m) long
43
Duodenum
- in small intestine
| - 1st 10 inches (25cm), common bile duct enters at the ampulla of Vater
44
Jejunum
- in small intestine
| - 8 ft long
45
Ileum
- in small intestine
| - 11 ft long
46
where is digestion completed
small intestine
47
end products are absorbed into
the blood & lymph
48
The mucosa has simple
columnar epithelium that include microvillus & goblet cells that secrete mucus
49
Lymph nodules
- Peyer’s patches
| - abundant in the ileum to destroy absorbed pathogens
50
3 sources of digestive secretions function within the small intestine:
liver
pancreas
small intestine
51
what completes digestion
enzymes secreted by the intestinal glands (crypts of Lieberkuhn)
52
Most absorption takes place & requires a
large surface area
53
Structures that increase surface area: (3)
1) Plica circulares
2) Villi
3) Microvilli
54
Plica circulares
macroscopic circular folds of the mucosa & submucosa
55
Villi
folds of the mucosa that contain a capillary network & a lacteal
56
Microvilli
folds of the cell membrane; “brush border”
57
Each villus has a
capillary network & lacteal (dead-end lymph capillary)
58
What is absorbed absorbed by active transport
- Monosaccarides
- amino acids
- +ions
- water soluble nutrients
59
What is absorbed by osmosis
H20
60
Vitamin B12 requires
intrinsic factor
61
Calcium ions require
parathyroid hormone & VitD
62
What is absorbed through the lacteals of the villi
Fat-soluble nutrients (Vit A,D,E,K, fatty acids & glycerol, combined to form chylomicrons)
63
LARGE INTESTINE
- Extends from the small intestine to the anus
- Approximately 2.5in,(6.3cm) in diameter & 5ft,(1.5m) in length
- No digestion takes place
64
LARGE INTESTINE- function
absorption of H2o, minerals, & vitamins;
| >elimination of undigested material
65
The colonic mucosa
secretes mucus
66
Taeniae coli
- lrg intestine
| - longitudinal smooth muscle layer that gathers the colon into puckers (haustra)
67
Cecum
junction with the small intestine is the ileocecal valve;
| >appendix (vestigial organ) is attached
68
Colon parts: (7)
- Cecum
- Ascending colon
- Transverse colon
- Descending colon
- Sigmoid colon
- Rectum
- Anal canal
69
About ___% of H2O that enters the ____ is absorbed, approximately _00-_00mls/day
80, colon, 400-800
70
Normal flora (bacteria) inhibit
the growth of pathogens
71
Vitamins are produced by
the normal flora
72
where is vitamin k produced and absorbed
large intestine
73
what is produced in small amounts in the large intestine (4)
Riboflavin
thiamine
biotin
folic acid
74
ACCESSORY ORGANS- defintion
Digestion does not take place within these organs but each contributes to the digestive process
75
ACCESSORY ORGANS (6)
```
Teeth
Tongue
Salivary glands
Liver
Gallbladder
Pancreas
```
76
TEETH- Deciduous
20 teeth; between 6 months & two years; lost throughout childhood
77
TEETH- Deciduous Function
chewing ; mechanically breaks down food
78
TEETH- Permanent
32 teeth; 6 year molars; incisors; canines; premolars; molars; wisdom teeth
79
TEETH- Permanent Function
chewing ; mechanically breaks down food
80
TONGUE
- Skeletal muscle innervated by the hypoglossal nerves (12th cranial)
- Papillae
- Keeps food between the teeth
- Mixes food with saliva
- Elevates to push food backward for swallowing
81
Papillae
small projections on the upper surface; many contain taste buds
>7th, facial & 9th, glossopharyngeal
82
SALIVARY GLANDS- 3pairs
1) parotid
2) submandibular
3) sublingual
83
SALIVARY GLANDS- secret
saliva continuously, but the amount varies
84
SALIVARY GLANDS- made of
blood plasma
85
The digestive enzyme of the salivary gland is
salivary amylase
86
Increase saliva production is a _____ response
parasympathetic
87
LIVER
Consists of 2 large lobes, (Rt & Lt) & fills the upper right & centre of the abdominal cavity, just below the diaphragm
88
The structural unit is of the liver is
the liver lobule made up of hepatocytes (liver cells)
89
Between adjacent lobules are
branches of the hepatic artery & portal vein
90
Capillaries are called
sinusoids
91
Sinusoids
receive blood
92
Digestive secretion in liver is
bile
93
Hepatic duct- liver
takes bile & unites with the cystic duct from the gallbladder to form the common bile duct that empties into the duodenum
94
Bile salts emulsify
fats; mechanical digestion
95
Excess ____ & ____ are excreted by the liver into bile
cholesterol & bilirubin
96
LIVER ( other functions)
- Carbohydrate metabolism
- Amino acid metabolism
- Lipid metabolism
- Synthesis of plasma proteins
- Formation of bilirubin
-Phagocytosis by Kupffer
Storage – Vitamins B12, A, D, E, K & minerals iron & copper
detoxification
97
GALL BLADDER
- A sac approximately 3-4 inches (7.5-10cm) long located on the under surface of the right lobe of the liver
- Bile from the hepatic duct (liver) flows through the cystic duct into the gall bladder
98
GALL BLADDER- function
stores & concentrates bile until it is needed by the small intestine
99
When food enters the duodenum the cells of the mucosa food enters the duodenum the cells of
the mucosa secrete the hormone cholecystokinin
100
The Gall Bladder stimulates
- the smooth muscle to contract
| - forces the bile into the duodenum
101
PANCREAS
- Approximately 6 inches (15 cm) long
- Located in the upper left abdominal quadrant between the curve of the duodenum & the spleen
- Exocrine glands are acini that produce enzymes
102
Exocrine glands are acini that produce enzymes (3)
1) Amylase
2) Lipase
3) Trypsinogen changes to trypsin in the duodenum
103
Amylase
starch to maltose
104
Lipase
fats to fatty acids & glycerol
105
Trypsinogen changes to trypsin in the duodenum which
digests polypeptides to amino acids
106
what unite to form the pancreatic duct
small ducts
107
Pancreatic duct joins the _____ and empties into the ___
common bile
| duodenum
108
The pancreas produces
bicarbonate juice
109
bicarbonate juice
-reduces the acidity of the gastric juice (HCL) as it enters the duodenum
110
What prevents damage to the duodenal mucosa
bicarbonate juice
111
AFFECTS Of AGING
-Sense of taste becomes less acute
-Less saliva produced
Periodontal disease, loss of teeth
-Effectiveness of peristalsis is decreased
-Diverticula may form
Risk of oral & colon cancer increases
- Liver & pancreas usually function well
- Gallbladder – cholecystitis more frequent
