Digestive System Flashcards
1
Q
You are what you… (3)
A
- Digest
- Absorb
- Dont Excrete
2
Q
name the 6 digestive system components…
A
- Mouth
- Pharynx
- Oesophagus
- Stomach
- Small intestine
- Large intestine
3
Q
Name the 4 (5) accessory organs of the digestive system…
A
- Salivary glands
- Pancreas
- Liver
- Gall bladder and biliary tract
4
Q
List the digestive processes in order (6)
A
- Ingestion
- Secretion
- Mixing and propulsion
- Digestion
- Absorbtion
- Elimination
5
Q
What is meant by ingestion?
A
Oral intake of substances
6
Q
What is meant by secretion?
A
Digestive juices - water, acid, emulsifiers, buffers and enzymes. (saliva, gastric juices, pancreatic juices)
7
Q
What is meant by Mixing and propulsion?
A
Contraction/relaxation in walls to help mix and propel food through the GI Tract.
8
Q
What is meant by Digestion?
A
Mechanical and chemical processes break down ingested food and liquids into absorbable substances.
9
Q
What is meant by absorption?
A
Substances passing through walls in the alimentary canal into blood and lymph.
10
Q
What is meant by elimination?
A
Excretion of waste and indigestible materials
11
Q
What does GIT stand for?
A
Gastrointestinal Tract
12
Q
The entire GIT contains the same basic four-layer arrangement of tissues, name them…
A
- Mucosa
- Submucosa
- Muscularis
- Serosa (peritoneum)
13
Q
What is ‘lumen’
A
Lumen is the central part of the tube - digestive tract/blood vessel …
14
Q
The first layer (innermost layer) of the Mucosa is…
A
The epithelium
15
Q
The epithelium in the mucosa layer is there for protection mainly, how are the cells bound.
A
The cells of the epithelial layer are bound together very tightly via ‘tight junctions’ - cells bound together using transmembrane proteins.
16
Q
The mucosa layer: Innermost layer of the GI Tract is divided into 3 layers. Name them
A
- Epithelium
- Lamina propria
- Muscularis mucosa
17
Q
What kind of epithelium tissue does the stomach and intestines have and why?
A
Columnar epithelium - tall cells, designed more for absorption
18
Q
The stomach and intestines have columnar epithelium with: (name the three characteristics)
A
- Microvilli - foldings within the cell membranes - increase surface area to maximise absorption.
- Goblet cells - secretion of mucous to lubricate food and process against digestive juice erosion.
- Enteroendocrine cells - specialised endocrine cells that secret hormones into blood. (enter- = intestine)
19
Q
What is layer 2 of the Mucosa called?
A
Lamina Propria
20
Q
What does Lamina Propria consist of and what does it allow?
A
The lamina propria consists of connective tissue containing many blood and lymphatic vessels that allow absorption of nutrients.
21
Q
The Lamina Propria contains MALT. What does MALT stand for and what do we call it when it is in the GI Tract.
A
MALT = Mucosa Associated lymphoid tissue
MALT in the GIT is called GALT = Gut associated lymphoid tissue
22
Q
What is MALT?
A
A collection of immune cells e.g lymphocytes, macrophages.
23
Q
Where is the MALT especially prevalent in the body? (5)
A
- tonsils
- oesophagus
- small intestine
- appendix
- large intestine
24
Q
What is the percentage of immune cells found in the GALT.
A
70%
25
What is the name for the 3rd layer of the Mucosa
Muscularis Mucosa (outer part of the mucosa)
26
Fill in the missing words:
The muscularis mucosa is a very thin layer of 1____ _____. This layer of muscle creates the 2.____. (small folds) which 3______ the 4. _______ _____ for 5._______ and 6._________.
1. smooth muscle
2. villi
3. increases
4. surface area
5. Absorption
6. Digestion
27
The Submucosa Layer is a connective tissue layer that lies between....
the mucosa and muscularis
28
Give examples of what the submucosa layer may contain -
Contains blood and lymph vessels which receive absorbed food molecules Contains network of neurons called the submucosal plexus (brain of the gut) And may contain glands and lymphatic tissue.
29
Muscularis externa. Name the 4 areas of the digestive system that contain skeletal muscle...
1. mouth
2. pharynx
3. upper oesophagus
4. sphincter
30
The rest if the GIT is mostly smooth muscle , involuntary (autonomic) which contains 2 layers:
1. Inner circular muscle
2. Outer longitudinal muscle
note: the stomach has 3 layers of smooth muscle to support mechanical digestion.
31
The involuntary smooth muscle contractions aids...
| name two actions.
1. Mixing of food with digestive juices
| 2. Propelling food along the digestive tract. (peristalsis)
32
Gastrointestinal Tract summary - name the four layers and the 3 sub layers of the first inner layer.
1. Mucosa
- mucosal epithelium
- lamina propria
- muscularis mucosa
2. Submucosa
3. Muscularis
4. Serosa (Peritoneum)
33
The peritoneum is the largest serous membrane in the body. Describe where it is in the body and what it provides.
The peritoneum weaves between the digestive organs and is supplied with many blood and lymph vessels. it provides a physical barrier to local spread of infection.
34
What are the two layers of the peritoneum called and what resided between these layers?
1. Parietal layer - covers wall of the abdomen and pelvic cavity
2. Visceral layer - covers the organs
The peritoneal cavity is the space between the two layers and contains a lubricating serous fluid.
35
Peritoneal pathology: Explain what is meant by Ascites and list some causes.
Ascites in the accumulation of fluid in the peritoneal cavity. Causes include, liver cirrhosis, GIT malignancies, heart failure, pancreatitis.
35
Peritoneal pathology: Explain what is meant by Ascites and list some causes.
Ascites in the accumulation of fluid in the peritoneal cavity. Causes include, liver cirrhosis, GIT malignancies, heart failure, pancreatitis.
36
Peritoneal pathology: Explain what is meant by Peritonitis and list some causes.
Peritonitis is an acute inflammation of the peritoneum. Causes of these can be bacterial infection, ruptured appendix, friction, surgical wounds.
37
What is the largest fold in the peritoneum called?
Greater Omentum
38
Describe the greater omentum...
- Drapes over transverse colon and small intestine like an apron.
- Its a double sheet that folds back on itself (hence four layers)
- Stores fat: contains adipose tissue which can greatly expand with weight gain.
- Has many lymph nodes containing macrophages and plasma cells - which produce antibodies - to combat infections of the GIT.
39
Name the 3 main functions of the greater omentum
1. insulation
2. Immunity
3. Protection
40
What is the lesser omentum...
The lesser omentum is a peritoneal fold that suspends the stomach and the duodenum (first part of the small intestine) from the liver.
41
# Fill in the missing words:
The lesser omentum contains the 1. _____ _____ ____, common hepatic artery, common bile duct and 2.____ ____.
1. Hepatic portal vein
| 2. Lymph nodes
42
What does the word enteric relate to?
The intestines
43
What is the Enteric nervous system and where is it found?
The enteric nervous system is the brain of the gut and extends from the oesophagus to the anus.
44
how many neurons does the enteric nervous system contain?
100 million neurons
45
Explain how the sympathetic and parasympathetic affect the digestive system
- Parasympathetic system = rest and digest. It increases muscular activity (peristalsis > myenteric plexus) and increase glandular secretion (submucosal plexus)
- Sympathetic system = fight or flight (stress) decreases both the muscular activity and glandular secretions
46
The enteric nervous system is arranged in two plexuses (network of nerves) list them and their main control.
1. Myenteric plexus - controls strength and frequency of muscle contraction: gut motility
2. Submucosal plexus - controls digestive secretions and detects sensory information
47
Enteric nervous system. Name the three types of Neurons.
1. Motor Neurons (outgoing / action signal)
2. Sensory neurons (incoming signal)
3. Interneurons - connect the two plexus
48
Which organ filters the blood and processes nutrients before entering the systemic circulation
The liver
49
Which vein drains the lower oesophagus, stomach, pancreas, small and large intestine, upper rectum and spleen.
The Portal vein
50
What do the iliac veins drain
the lower part of the rectum and anal canal
51
What is Peristalsis
the wavelike muscular contraction in the digestive tract
52
Name the four main parts of the Oral cavity …
1. Hard palate - bony partition between the oral and nasal cavities. Allows simultaneous chewing and breathing
2. Soft palate - an arch of muscle
3. Uvula - swings up and blocks the nasopharynx preventing food from entering the nasal cavity
4. Tongue - voluntary skeletal muscle structure attached to the hyoid bone and mandible.
53
What is the superior surface of the tongue covered with and what do they contain ?
The tongue is covered with Papillae which contain taste buds
54
The Oral Cavity performs the following functions… (4)
1. Mastication
2. Speech
3. Taste
4. Swallowing
55
How many teeth do adults have?
32 teeth
56
Name the three parts of the tooth
1. Crown
2. Neck
3. Root
57
Teeth are covered by what?
Enamel (the hardest tissue in the body)
58
Name the three glands that produce saliva …
1. Parotid glands
2. Submandibular glands
3. Sublingual glands
59
Saliva is produced by glands via a reflux controlled by the …
Autonomic nervous system
60
The parasympathetic nervous system stimulates continuous salivation, how much saliva is produced daily and what does it provide
1-1.5 litres per day which provides lubrication
61
The sympathetic nervous system stimulation does what to salivation?
Reduces salivation
| Causing dryness of the mouth
62
Name the 5 senses that can stimulate salivation…
1. Touch
2. Taste
3. Smell
4. Sight
5. Sound
63
List the 7 compositions of Saliva
1. Water (99.5%)
2. Mineral salts
3. Enzymes : salivary amylase, lysozymes
4. Mucus
5. Immunoglobulins
6. Blood clotting factors
7. pH 6.35 - 6.85 (mildly acidic)
64
List the 7 saliva functions
1. Digestion - chemical breakdown
2. Lubricating and dissolving food
3. Cleansing of oral cavity and teeth
4. Defence - non-specific (IgA and lysozymes)
5. Taste
6. Buffer - for acidic foods
7. Waste removal - urea / Uric acid from the body
65
How long is the oesophagus and where is it located?
The oesophagus is a 25cm long muscular tube, attached to the larynx, posterior to trachea, passes through the diaphragm to the 10th vertebrae.
66
# Fill in the missing words.
The oesophagus is lined with 1.______ and lubricated with 2._________.
1. Epithelium
| 2. Mucus
67
What is the epiglottis?
A flap of elastic cartilage which prevents food entering the trachea. (Wind pipe)
68
What is the lower oesophageal sphincter and what does it prevent?
The lower oesophagus sphincter acts as a seal on the starch to prevent reflux of stomach contents into the oesophagus.
69
What shape is the stomach and name the four regions …
```
The stomach is J-shaped
Four regions:
1. Cardia
2. Fundus
3. Body
4. Pyloric
```
70
Where is the lesser and greater curvature of the stomach?
Lesser - inside curve
| Greater - outside curve
71
How many layers of muscle does the stomach have?
3 layers
| To aid the churning and mixing of food with gastric juices
72
Name the two sphincters of the stomach and where they are situated
Cardiac sphincter - top of the stomach
| Pyloric sphincter - bottom of the stomach
73
What is chyme?
Partially digested food
74
Neural feedback.
| When food distends the stomach what does it stimulate?
Stretch receptors in its walls
| Which in turn stimulates nervous activity (submucosus and myenteric plexus)
75
What do chemoreceptors monitor?
pH changes
76
How much highly acidic gastric juice does the stomach secrete daily and what is it’s pH
2 to 3 litres of gastric juices
| pH 2-3 (highly acidic)
77
# Fill in the missing words.
The 1._______ produced by 2.______ cells in the stomach provide a 3.________ against the 4.______ present within the stomach.
1. Mucus
2. Goblet
3. Barrier
4. Acidity
78
What kind of Epithelial cells do the stomach contain and how often do they replace themselves.
Columnar epithelial cells
| Fast turnover - replacing the lining every 3 days
79
Low stomach mucus can mean the acid in the stomach damages it’s own lining.
What might occur if there is low stomach acid? (3)
1. Compromises the digestion of proteins by not activating pepsin properly.
2. Compromises the digestion of fats by not activating bile flow
3. Allows pathogens to survive in the digestive system
80
Stomach cells.
| Name the three types of exocrine cells
1. Parietal cells
2. Chief cells
3. Goblet cells
81
Name the two substances secreted by the parietal exocrine cells
1. Intrinsic factor (IF)
| 2. Hydrochloride acid (HCI) (secretes H+ and Cl separately combining in the stomach)
82
Intrinsic factor is needed for the absorption of which vitamin?
Vitamin B12
83
What does Hydrochloric acid do/activate? (4)
* Activates pepsin
* Acts as an anti-microbial agent
* Iron ingested is converted into a soluble form
* assists in activating bile and pancreatic juice flow
84
Vitamin B6 and Zinc is used to make…
Hydrochloric acid
85
Intrinsic factor latches onto B12 providing a carrier molecule. Where in the GIT is b12 absorbed?
Absorbed in the terminal Ilium (the last part of the small intestine)
86
What two substances do Chief cells secrete?
1. Pepsinogen
| 2. Gastric lipase
87
Which cells secrete mucus and what does the mucus do in the stomach,
Goblet cells secrete mucus which protects against the acidity of the digestive juices.
88
Describe the function of pepsinogen and gastric lipase…
- Functions to digest proteins and lipids
- HCI (Hydrochloric acid) converts pepsinogen to the active enzyme pepsin
- En = breaks down proteins
- Ase = breaks down fats
89
List the 7 functions of the stomach...
1. Mixing chamber - churns up food
2. Holding reservoir - storage
3. Defence - non-specific defence from gastric acidity
4. Absorption (limited) - water, alcohol, drugs
5. Digestion - mechanical nut also chemical digestion of proteins and lipids
6. Iron - is made more soluble with stomach acid
7. Satiation - tells you to stop eating
90
Name the two stomach hormones released by Enteroendocrine cells. ..
1. Ghrelin - stimulates hunger
2. Gastrin - (produced by G cells) - responds to stomach distension. Stimulates gastric juice secretion and gastric motility (an organ thats contracting)
91
The pancreas is an accessory organ of the digestive system that has both exocrine and endocrine functions. Whats the difference between these two functions.
Endocrine glands are the glands that secrete hormones without ducts, while exocrine glands secrete hormones through ducts
92
Pancreatic juice is a clear liquid that is excreted into the small intestine, approximately how many litres are excreted per day?
1.2 - 1.5 litres a day
93
Why is the sodium bicarbonate an important exocrine function of the Pancreas
Because sodium bicarbonate neutralises the pH of the acidic chyme coming from the stomach into the duodenum (first part of the small intestine).
94
Pancreatic juice is released into the ______ _____ before being excreted into the duodenum of the small intestine.
Pancreatic Duct
95
The endocrine function of the Pancreas regulates blood sugar, releasing hormones into the blood.
Name the 3 endocrine hormones secreted by the Pancreas.
1. Insulin
2. Glucagon
3. Somatostatin
96
Pancreatic enzymes are imperative for digestion. Name the 6 enzymes...
1. Pancreatic Amylase
2. Pancreatic lipase
3. Trypsin
4. Chymotrypsin
5. Ribonuclease
6. Deoxyribonuclease
97
What is the main function of Pancreatic amylase?
Breaks down starches into sugars
98
What is the main function of Pancreatic lipase?
Lipid / fat digestion
99
What is the main function of Trypsin?
Protein digestion
100
What is the main function of Chymotrypsin?
protein digestion
101
What is the main function of Ribonuclease?
Digest RNA
102
What is the main function of Deoxyribonuclease?
Digest DNA
103
How long is the pancreas and where is it located in the body?
Approximately 15cm long and retroperitoneal (behind the peritoneum) it is connected to the duodenum via the pancreatic duct.
104
What is the biliary tree?
A system of ducts that connects the liver, gallbladder and the pancreas all joining and secreting into the duodenum.
105
The gall bladder is a pear-shaped sac measuring 7-10cm in length - where in the body can this organ be found?
in the liver
106
# Fill in the missing words:
Bile ducts project from the 1.______ and 2.______, meeting at the 3.______ bile duct.
1. Gallbladder
2. Liver
3. Common
107
Bile ducts collect bile produced by what?
| Which pools in the gallbladder.
produced by hepatocytes
108
What does bile do?
Bile helps with digestion by emulsifying fats.
It also helps get rid of excess cholesterol from the body.
Emulsification breaks down the lipids into smaller molecules. This increases the surface area fro lipid enzymes (lipase) to work.
109
What is bile composed of?
| 3
1. bile salts
2. cholesterol
3. bilirubin (breakdown of RBC - formed in the spleen and conjugated in the liver)
110
90-95% of bile is absorbed and transported back to the liver from the ileum. What is this called?
Enterohepatic circulation
111
What are the functions of the small intestine? (4)
1. Digestion
2. Absorption
3. Immunity
4. Satiety
112
What is the function of the villi?
To maximise surface area to increase absorption
113
Name the three region of the small intestine...
1. Duodenum - emulsification and most digestion occurs here (30cm)
2. jejunum - most absorption occurs here (2.5m)
3. Ileum - vitamin B12 is absorbed (3.5m)
114
Approximately how long is the small intestine?
6.5 meters
115
What are villi?
Villi are finger like projections with blood capillaries and lacteals (lymophatic capillaries)
116
What are microvilli?
Microvilli, in the most simplistic terms, are tiny little microscopic projections that exist in, on, and around cells. They can exist on their own or in conjunction with villi. On each of the villi, there are even smaller folds that stick out like fingers called microvilli.
Microvilli are most often found in the small intestine,
117
Thousands of microvilli form a structure called the brush border that is found on the apical surface of some epithelial cells, such as the small intestines.
Name three enzymes found in the brush border
Maltase, sucrase and lactase.
118
What do the enzymes maltase, sucrase and lactase do?
Breakdown sugars into glucose, fructose and galactose etc...
119
What does Dipeptidase do?
Breakdown proteins into amino acids
120
What do Nucleosidases and phospatases do?
Breakdown RNA and DNA
121
What does CCK stand for?
Cholecystokinin
122
CCK (Cholecystokinin) performs the following functions: (3) detailed
1. Stimulates the pancreas to secrete pancreatic enzymes (and hence digest fat / protein / carbs)
2. Increases hepatic production of bile and stimulates contraction of the gall bladder
3. Mediates satiety
123
What is cholecystokinin?
Is a peptide hormone secreted by enteroendrocrine cells in the duodenum.
124
Name the 5 functions of the small intestine...
1. Movement (peristalsis of food)
2. Digestion
3. Absorption (of nutrients and water)
4. Hunger and Satiety
5. Immunity (Peyers patches (cluster of white blood cells) and bacterial microflora )
125
What percentage of absorption occurs in the small intestine?
90%
126
Which body system will fatty acids be absorbed into after entering cells of the gut wall?
Lymphatic system
127
How are monosaccharides and amino acids transported into capillaries?
Monosaccharides: Active/Passive transport
| Amino acids: Active transport.
128
Fatty acids, glycerol, cholesterol and fat soluble vitamins (A,D,E,K) are:
Fill in the missing words:
1. Emulsified by _____
2. Enter intestinal cells by simple _____
3. Packaged into _____, absorbed into lacteals.
4. Travel through the _____ _____ and enter the blood in the subclavian vein.
1. Bile
2. Diffusion
3. Chylomicrons (protein + fatty acids joined together)
4. Lymphatic system
129
Where is vitamin B12 absorbed and what substance is needed for absorption?
B12 needs intrinsic factor for absorption in the terminal ileum (last part of the small intestine)
130
What kind of fluid movement occurs when water is absorbed in the GIT?
Osmosis
131
Osmosis is bi-directional therefore absorption of water also depends on...
name the three elements that maintain an osmotic balance/concentration gradient with the blood.
1. electrolyte
2. monosaccharide
3. amino acid
132
What is the large intestine?
The large intestine is the terminal portion of the GIT, where the final stages of digestion, absorption and stool formation occurs.
133
name the valve that allows one way flow of materials from the small to the large intestine...
The ileocaecal valve
134
Name the four regions of the large intestine...
1. Caecum
2. Colon
3. Rectum
4. Anal Canal
135
Describe the Caecum
The cecum or caecum is a pouch within the peritoneum that is considered to be the beginning of the large intestine.
136
Describe what the appendix is and where it is joined.
Appendix is attached to the caecum of the large intestine.
Its a twisted tube about 8cm in length.
Part of our immune system containing macrophages, lymphocytes, bacteria.
137
The large intestine hosts a rich community of microbes. Approximately how many?
100 trillion microbes
138
# Fill in the missing words...
The final stages of 1_____ _____ occur in the colon through 2.______ ______
1. nutrient extraction
| 2. microbial fermentation
139
Bacteria ferment fibre in the large intestines to produce short chain fatty acids (SCFA's) what does this support?
This supports GI tight junctions
140
What is decomposed into simpler molecules?
| Its pigment contributes to the colour of faeces.
Bilirubin
141
What percentage of faeces is bacteria?
30-50%
142
Name three things that the large intestine absorbs?
1. Water
2. Vitamins
3. Nutrients
143
What do symbiotic microbes do?
They help digest food, absorb nutrients, and assist with waste excretion. They also protect the host against invasion by pathogenic bacteria.
144
What organ is the second largest and the heaviest gland?
The liver
145
The liver uses approximately what percentage of the bodies resting metabolism?
27%
146
How many litres of blood can the liver filter every minute?
1.4 litres
147
Which artery bring oxygenated blood from the heart to the liver?
The hepatic artery
148
What are the specialised phagocytic cells in the liver called?
Kupffer cells
149
Which vein brings in nutrient and toxin rich blood into the liver from the GIT?
The portal vein
150
What is the hepatic first pass?
All blood from the GIT is transported to the liver via the portal vein to be filtered / metabolised before entering systemic circulation
151
The liver is estimated to have over 500 functions. List ten key functions
1. Cleansing blood of microbes
2. Detoxification - metabolising drugs, toxins, alcohol
3. Bile production and secretion
4. Haemolysis (kupffer cells)
5. Synthesis of plasma proteins (blood clotting and coagulation factors)
6. Hormone homeostasis - deactivating all hormones
7. Metabolism of glucose, fats store and amino acids
8. Heat production - thermogenesis
9. Synthesis - vitamin A, CoQ10, and activation of vitamin D
10. Storage - vitamins (A,D,E,K,B12) iron, copper, glycogen
7.
152
Where does blood from the portal vein and hepatic artery mix?
In the sinusoids (capillary) (columns between hepatocytes)
153
Name the three compounds metabolised by the liver…
1. CARBOHYDRATES
- excess glucose is converted to glycogen for storage
- glycogen to glucose is required
2. FAT
- metabolised fat from storage as required
- synthesises cholesterol and triglycerides
3. PROTEIN
- converts essential amino acids into non-essential amino acids
- removes nitrogen groups from amino acids to form urea to be excreted
- breaks down nucleotides to form uric acid to be excreted
154
Liver detoxification is highly dependent on… (2)
1. Energy (ATP)
| 2. Nutrients
155
# Fill in the missing words
1. _________ convert toxins into 2.____
| - ______ metabolites which can then be 3._______ from the body
1. Hepatocytes
2. Non-toxic
3. Excreted
156
Name the two major classifications of chemical compounds
1. Hydrophilic
| 2. Lipophilic
157
Hydrophilic chemical compounds are excreted in urine and bile. What needs to happen to Lipophilic compounds?
Lipophilic compounds must be chemically altered into hydrophilic compounds to facilitate elimination
158
Transforming Lipophilic compounds is done in 2 phases. Name them
Phase 1: bio-activation
| Phase 2: conjugation reactions
159
Bio-activation involves a key group of enzymes, what are they called?
CYP450 family of enzymes (a class of more than 50 enzymes)
160
What do enzymes like CYP450 do during bio-activation
Converts water-insoluble toxins into water soluble substances to be excreted by the kidneys
Converts toxins to more reactive substances which can metabolised in phase 2
161
Liver detoxification. What happens during phase 2: conjugation reactions
Molecules are attached to the toxins to neutralise them making them stable (non-reactive) and water soluble to be excreted
162
Name a key anti-oxidant in phase 2 of liver detoxification
Glutathione
163
How many anatomical quadrants can the abdomen be divided into to help us be specific about locations of the body
9 anatomical quadrants
164
9 anatomical quadrants
| The locations are divided into three main lines:
1. Right and left hypochodrium, epigastric region
2. Right and left flank, umbilical region
3. Right and left groin, Pubic region
