Digestive System Flashcards
1
Q
The digestive system is also known as…
A
…the digestory system
2
Q
What is the GI tract?
A
continuous tube that extends from the mouth to the anus
3
Q
What does the GI tract travel through?
A
travels through the thoracic and abdominopelvic cavities
4
Q
What are the organs of the GI tract?
A
the mouth, pharynx, oesophagus, stomach, small intestine and large intestine
5
Q
The mouth is also known as the…
A
…buccal/oral cavity
6
Q
What are the accessory digestive organs?
A
the teeth, tongue, salivary glands, liver, gallbladder and pancreas
7
Q
What do teeth aid?
A
physical breakdown of food
8
Q
What does the tongue assist with?
A
chewing and swallowing
9
Q
muscles along GI tract organ walls in
state of…
A
…sustained contraction
10
Q
muscular contractions in wall of GI tract physically breakdown…
A
…food by churning and propulsion.
- also help dissolve foods by mixing
with fluids secreted in GI tract.
11
Q
Role of accessory digestive organs?
A
apart from teeth/tongue, these produce or store secretions.
12
Q
Accessory digestive organs aid in the…
A
… chemical breakdown of food
13
Q
What are the basic processes of digestion?
A
1) Ingestion (eating)
2) Secretion (enhances digestion and absorption)
3) Mixing and propulsion (motility)
4) Digestion (mechanical and chemical)
5) Absorption
6) Defaecation (elimination)
14
Q
Ingestion (eating) involves…
A
…mastication (chewing) and deglutition (swallowing)
15
Q
What generally happens in secretion?
A
Water, acid, buffers and enzymes (7 litres) secreted into lumen
16
Q
What generally occurs in mixing and propulsion?
A
- alternating contractions and relaxations of smooth muscle
– mix food and secretions and move them toward the anus
17
Q
What generally occurs in digestion?
A
breakdown ingested food into smaller molecules
18
Q
What generally occurs in absorption?
A
– products of digestion enter epithelial cells lining GI tract lumen
– pass into blood or lymph and circulate to cells throughout body
19
Q
What generally occurs in defaecation (elimination)?
A
– removal of waste, indigestible and unabsorbed material via anus
20
Q
Frenulum is latin for…
A
…‘small bridle’
21
Q
What is the Frenulum?
A
Fold of connective tissue that secures/
restricts the motion of soft tissue organs.
22
Q
What does the lingual frenula do?
A
attaches inferior and superior lips to gums
23
Q
What does the lingual frenulum do?
A
limits movement of the tongue posteriorly
24
Q
What is the Palatine Uvula?
A
Projection of soft palate made up of connective tissue and muscle
25
Role of Palatine Uvula?
Articulation of some sounds
26
What is the tongue composed of?
skeletal muscle covered with mucous
membrane.
27
Each half of the tongue consists of...
...identical complement of extrinsic (EM) and intrinsic muscles (IM).
28
What do extrinsic muscles (EM) do?
EM move tongue from side to side & in and out to manoeuver food for chewing and swallowing.
29
What do intrinsic muscles (IM) do?
IM alter shape and size of tongue for speech and swallowing.
30
Primary role of the tongue?
Gustation (Taste)
31
How many primary tastes of the tongue?
5
32
Taste is detected by...
... taste buds
33
Where are most taste buds located?
most located in papillae
34
Upper and lateral surfaces of
tongue covered with...
...papillae
35
Projections of lamina propria covered with...
...stratified squamous epithelium
36
What do many papillae contain?
- Taste buds
- Receptors for touch and food.
37
Lingual (von Ebner’s) glands secrete...
...both mucous and watery serous fluid
38
What are von Ebner's glands ?
Lingual glands
39
Lingual (von Ebner’s) glands secrete both mucous and watery serous fluid.
What does this contain?
- lingual lipase
40
Lingual (von Ebner’s) glands secrete both mucous and watery serous fluid.
Contains lingual lipase. This acts on...
...as much as 30% of dietary triglycerides (fats/oils).
41
The lingual lipase converts...
...to simpler fatty acids and diglycerides
42
How many pairs of salivary glands?
3 pairs - not all supply the same ignrediants.
43
What are the different salivary glands?
- Parotid glands
- Submandibular glands
- Sublingual glands.
44
What do the parotid glands secrete?
- watery (serous) liquid
- Salivary amylase
45
What do the submandibular glands secrete?
- amylase fluid thickened with mucous
- mucins, lysozyme and bicarbonates
46
What do sublingual salivary glands secrete?
- mostly mucous.
- Mucins, lysozyme and bicarbonates.
47
What is saliva chemically made up of?
Chemically made up of 99.5% water and 0.5% solutes.
These solutes are:
- ions (sodium, potassium, chloride, bicarbonate, phosphate)
- dissolved gases (urea and uric acid; mucous; immunoglobulin (Ig) A/
- salivary amylase (enzyme that acts on starch); lysozyme (bacteriolytic enzyme)
48
How much saliva is secreted daily?
On average, 1.0-1.5 litres of saliva are secreted daily.
49
What is salivation controlled by?
Salivation is controlled by autonomic nervous system
50
Secretion is a reflex response to...
... taste bud stimulation
51
- Salivation is controlled by autonomic nervous system
- Secretion is a reflex response to taste bud stimulation
- Also stimulated by the brain in response to...
... smell, sight, sound or thought of food.
52
What is mumps caused by?
papamyxovirus
53
Mumps is also known as...
...Epidemic parotitis
54
Mumps typically attacks...
...the parotid glands
55
Mumps involves...
...inflammation and enlargement
56
What are the symptoms of mumps?
Fever, malaise, extreme pain in throat
57
Mechanical breakdown of food is carried out by...
...chewing (teeth in oral cavity)
58
Enzymatic breakdown begins with...
...salivary enzymes
59
What do salivary enzymes get released from?
released from the salivary glands; enter oral cavity via same-named ducts
60
Main goal of oral cavity?
to prepare a food bolus suitable for deglutition.
61
Chewed food, mixed with saliva, is formed into...
... a bolus
62
- Chewed food, mixed with saliva, is formed into a bolus.
- Moved to the back of the mouth for...
...swallowing
63
During swallowing, the epiglottis moves...
...downward
64
During swallowing, the epiglottis moves downward
- This prevents the food bolus from...
...entering the trachea (windpipe).
65
* Chewed food, mixed with saliva, is formed into a bolus
* Moved to the back of the mouth for deglutition (swallowing)
* During swallowing, the epiglottis moves downward – prevents the food bolus from entering the trachea (windpipe)
* The food bolus then enters the...
...oesophagus
66
* Chewed food, mixed with saliva, is formed into a bolus
* Moved to the back of the mouth for deglutition (swallowing)
* During swallowing, the epiglottis moves downward– prevents the food bolus from entering the trachea (windpipe)
* The food bolus then enters the oesophagus
* Food is moved down the oesophagus and into...
... the stomach
- achieved by muscular waves of contraction known as peristalsis
67
Describe the mechanism of swallowing.
1) Chewed food, mixed with saliva, is formed into a bolus.
2) It is moved to the back of the mouth
for deglutition (swallowing).
3) During swallowing, the epiglottis moves downward to prevent the food bolus from entering the trachea.
4) Food is moved down the oesophagus to the stomach by muscular waves of contraction (peristalsis).
68
Describe Peristalsis in the Oesophagus.
1) The lower oesophageal sphincter relaxes and the bolus moves into the stomach.
2) A progression of coordinated contractions and relaxations of the circular and longitudinal layers of the muscularis push the bolus onward.
69
What are the four regions of the stomach?
cardia, fundus, body and the pyloric part
70
Functions of the stomach?
- mixing saliva, food and gastric juice to form chyme
- serving as a reservoir (store) for food before release into small intestine (SI)
- secreting gastric juice
- secreting gastrin into blood
- controlling passage of food into SI
71
Describe secretion of gastric juice in the stomach.
Secreting gastric juice, which contains
HCl(kills bacteria & denatures proteins),
pepsin(begins the digestion of proteins),
intrinsic factor(aids vit. B12absorption)
and gastric lipase (aids digestion of triglycerides).
72
Whats the stomach wall composed of?
Stomach wall composed of same basic layers as rest of GI tract.
– mucosa, submucosa, muscularis (muscle layers) and serosa
73
What are the different muscle layers of the stomach?
– mucosa, submucosa, muscularis (muscle layers) and serosa
74
When the stomach is empty, the mucosa lies in ...
...large folds or rugae.
75
Epithelial cells extend down in the mucosa to form...
...columns of secretory cells
– gastric glands
76
Several gastric glands open into...
...bottom of narrow channels.
- gastric pits
77
In the stomach, secretions flow from...
...glands -> pits -> lumen of stomach.
78
How many types of exocrine glands cells are found in gastric glands?
Three types.
79
Three types of exocrine gland cells found in gastric glands...
...secrete their products into stomach lumen
80
The main stomach cells directly involved with digestion are:
1. Mucous-secreting cells
2. Gastric Chief Cells (AKA Gastric Zymogenic Cells)
3. Parietal cells
81
How much absorption is there in the stomach?
Limited absorption occurs in the stomach.
82
What is absorbed in the stomach?
water, salts, alcohol and certain drugs (e.g., aspirin, thiopental, secobarbital)
83
How does the stomach help to digest food?
Mixes and partially digests food
84
In the stomach, mixing mainly occurs in the...
... lower region of the stomach (the pylorus)
85
After 3.5 – 4.0 hours, the partially digested food (now called chyme) is released into...
...small intestine
86
Whats chyme?
partially digested food.
87
Causes of gastritis?
* Alcohol
* Nonsteroidal anti-inflammatory drugs
* Traumatic injury
* Infection – Helicobacter pylori
* Chronic bile reflux
* Stress
88
What occurs in the small intestine?
Most digestion and absorption of nutrients occurs in small intestine.
89
Most digestion and absorption of nutrients occurs in small intestine.
Structure is therefore...
...specially adapted
90
Length of the small intestine provides...
... large surface area (SA).
91
Surface area of small intestine is further increased by...
...circular folds, villi and microvilli.
92
Where does the small intestine begin?
Begins at pyloric sphincter of the stomach.
93
The small intestine coils through...
... central and inferior part of abdominal cavity
94
The small intestine eventually opens up into...
...caecum of large intestine
95
Small intestine divided into...
... three regions.
96
Small intestine is divided into 3 regions which are:
1) Duodenum
2) Jejunum
3) Ileum
97
Length of jejunum?
2 - 3 m
98
Main functions of jejunum?
1) Digestion
2) Absorption (Carbohydrates, amino acids, lipids, water and fat soluble compounds)
99
Function of ileum?
1) Absorption of vitamin B12, bile salts, nutrients not absorbed in the jejunum.
100
What is the small intestine wall made up of?
Same four layers as most of GI tract
101
Small intestine epithelial layer of mucosa consists of...
...simple columnar epithelium
102
What does the simple columnar epithelium consist of?
Many types of cells:
1) Absorptive cells
2) Goblet cells
3) Enteroendocrine cells
4) Paneth cells
- Each of these cells has a specific function in the small intestine.
103
Function of absorptive cells?
- release enzymes that digest food
- contain microvilli that absorb nutrients found in small intestinal chyme
104
Function of goblet cells?
secrete mucous
105
Function of enteroendocrine cells?
Produce S cells (secretin)
Produce CCK cells (cholecytokinin)
Produce K cells (glucose-dependent insulinotropic peptide (GIP))
106
Function of Paneth cells?
secrete lysozyme and capable of phagocytosis; regulate microbial pop. in SI
107
Enterocytes are intestinal...
...absorptive cells.
108
What are enterocytes?
Simple, columnar epithelial cells found in the small intestines and colon
109
Enterocytes are also ...
... Microvilli on the apical surface
110
Enterocytes increase...
...surface area for digestion and transport of molecules from intestinal lumen.
111
Pancreas lies posterior to...
... the greater curvature of the stomach
112
The pancreas consists of a...
... head, body, and tail
113
the pancreas is usually connected to the duodenum by...
...two ducts
114
the pancreas is usually connected to the duodenum by two ducts which are...
1) Pancreatic (duct of Wirsung)
2) Accessory
115
Whats the pancreatic duct known as?
duct of Wirsung
116
Pancreatic juice enters the small intestine via...
...pancreatic (duct of Wirsung) and accessory ducts.
117
The pancreas has [...] and [...] functions
The pancreas has endocrine and exocrine functions.
118
Whats responsible for the exocrine functions of the pancreas?
Pancreatic acini
119
Whats responsible for the endocrine functions of the pancreas?
Islets of Langerhans
120
Describe exocrine functions of pancreas (pancreatic acini) (SI cavity)
- Pancreatic juice
- Sodium bicarbonate
121
Describe endocrine functions of pancreas (islets of langerhans + blood)
- Glucagon
- Insulin
- Somatostatin
- Pancreatic polypeptide
122
Whats glucagon secreted by?
secreted by alpha cells
123
Whats insulin secreted by?
beta cells.
124
Whats somatostatin secreted by?
delta cells
125
Whats pancreatic polypeptide secreted by?
gamma cells.
126
The liver is involved in...
... nutrient metabolism
127
Two types of nutrient metabolism in the liver?
Anabolic and Catabolic
128
Example of anabolic metabolism?
gluconeogenesis (glucose from pyruvate)
129
Example of catabolic metabolism?
glycogenolysis (glycogen to glucose)
130
What does the liver secrete?
Secretes bile -> bile salts
131
Function of bile?
Fat emulsification
132
What does the liver synthesise?
Synthesizes blood proteins and clotting proteins
133
What does the liver store?
Stores minerals (Fe, Cu) and vitamins (A, D, E, K, B12)
134
The liver converts...
...ammonia to urea for excretion
135
What does the liver break down?
- Breaks down some types of bacteria (immune cells)
- Breaks down worn out erythrocytes
136
What is the liver divided into...
... two principal lobes; large right lobe and smaller left lobe.
137
Hepatocytes are the...
... major functional cells of the liver
138
Hepatocytes perform a wide array of...
...metabolic, secretory and endocrine functions
139
Grooves are in the...
... cell membranes
140
Grooves in the cell membranes provide...
...spaces for canaliculi
141
What colour is bile and what state is it in?
a yellow, brownish, or olive green liquid
142
What is bile secreted into?
Into grooves in the cell membranes
143
Bile serves as both an...
...excretory product and a digestive secretion.
144
Bile duct + branch of hepatic artery and vein = ?
Bile duct + branch of hepatic artery + vein = portal triad
145
What makes up the portal triad?
Bile duct + branch of hepatic artery + vein
146
Enzymes of oral cavity responsible for carbohydrate digestion?
- Salivary amylase
- Dextrins
- Maltose
147
Enzymes of small intestine (lumen) responsible for carbohydrate digestion?
- Pancreatic amylase
148
Enzymes of small intestine (brush border) responsible for carbohydrate digestion?
- Maltase
- Lactase
- Sucrase
149
What does maltase break down maltose into?
glucose
150
What does lactase break down lactose into?
glucose + galactose
151
What does sucrase break down sucrose into?
glucose + fructose
152
Products of digestion of carboydrates and proteins exit through...
...Intestinal capillaries & hepatic portal system to liver
153
What breaks down proteins in the stomach?
Pepsin
154
What does pepsin break down protein into?
Peptones and proteoses
155
What enzymes break down proteins in the small intestine (lumen)?
Trypsin and chymotrypsin (into peptones and proteoses)
156
What enzymes break down proteins in the small intestine (brush border)?
carboxypeptidases and aminopeptidases
157
What do carboxypeptidases and aminopeptidases break down proteins into?
Dipeptides
158
What breaks down dipeptides in the small intestine (brush border)?
dipeptidases
159
Dipeptidases break down dipeptides into...
... amino acids.
160
What enzymes break down fat in the oral cavity?
lingual lipase?
161
What enzymes break down fat in the stomach?
gastric lipase
162
What enzymes break down small fat droplets in small intestine (lumen)?
Pancreatic lipase
163
Product of fat digestion?
chylomicrons
164
Chylomicrons are excreted through the...
... Lymphatic system and hepatic portal system to liver
165
The large intestine (bowel or colon) is the ...
...final stages of digestion and absorption
166
Whats found in the large intestine?
gut microbiota
167
Gut microbiota is also known as?
intestinal flora
168
Main regions of the large intestine?
1. Caecum (not well developed)
2. Appendix (not well developed)
3. Ascending colon
4. Transverse colon
5. Descending colon
6. Sigmoid colon water absorption
7. Rectum
8. Anus
