Gastrointestinal tract Flashcards
1
Q
How many portions of fruit or veg should you eat a day
A
5
2
Q
Whats happening in energy intake (EI)
A
fat
alcohol
carbohydrate
protein
3
Q
what is happening in energy expenditure (EE)
A
basal metabolic rate (BMR)
Thermogenesis
Physical activity
4
Q
What BMI is classed as underweight
A
<18.5 kg/m^2
5
Q
What BMI is classed as normal
A
18.5-24.9 kg/m^2
6
Q
What BMI is classed as overweight
A
25-29.9 kg/m^2
7
Q
What BMI is classed as obese
A
30-39.9 kg/m^2
8
Q
What BMI is classed as morbidly obese
A
> 40 kg/m^2
9
Q
What are some obesity contributors
A
endocrine disorders psychological cultural psychiatric disorders environmental disorder environmental factors genetics medications
10
Q
What are some generic obesity treatment options
A
lifestyle changes
pharmacotherapy
bariatric surgery
11
Q
What are things to do with lifestyle changes for managing weight
A
reduced energy diet
increased physical activity
12
Q
What things does pharmacotherapy do
A
appetite suppressants
Fat absorption inhibitors
13
Q
What things does bariatric surgery do
A
gastric band
gastric bypass
sleeve gastrectomy
14
Q
Symptoms of malnutrition
A
loss of appetite weight loss (unintentional 5-10% of bodyweight in 3-6 months) tiredness reduced ability to perform normal tasks reduced physical performance altered mood poor concentration poor growth in children
15
Q
Define digestion
A
processes by which foodstuffs are degraded to produce smaller molecules that can be absorbed
16
Q
Define absorption
A
processes by which nutrient molecules are absorbed by cells that line the GI tract and enter the bloodstream
17
Q
Define protection
A
the processes by which lining of the GI tract is protected from damage during digestion of foodstuffs
18
Q
Layers that make up the GI tract (from middle to outward (abdomen))
A
mucosa epithelium lamina propia muscular mucosae submucosa muscular externa serosa
19
Q
What is GALT
A
gut associated lymphoid tissue
20
Q
What are lymph nodes or GALT important in
A
recognising foodstuffs and protecting against infection
21
Q
Where are glands in submucosa located
A
at the bottom of the oesophagus and bottom of the small intestine (duodenum)
22
Q
What are the submucosa glands in the duodenum known as
A
brunners gland
23
Q
What is the myenteric plexus also known as and where is it located
A
Auerbach’s plexus
located in submucosa throughout the GI tract
24
Q
What is the submucosal plexus also known as and where is it located
A
meissners plexus
found in small and large intestine
25
What are the 5 major sites of GI secretions
```
salivary glands
gastric glands
exocrine pancreas
liver-biliary system
small intestine
```
26
Total amount of GI secretions a day
6-7L a day
27
What do GI secretions contain
enzymes, ions, water, and mucus
28
Function of GI secretions
breakdown large compounds, regulate pH, dilute and protect
29
What does endocrine do
release of a transmitter into blood for delivery to distant target cell
30
What does paracrine do
release of a transmitter from a sensor cell to affect adjacent target cells without entering the blood or activating neurones
31
What does neuronal refer to
electrical signalling via neurons
32
What cells produce gastrin and where are they located
G cells located in the stomach
33
What cells produce cholecystokinin (CCK) and where are they located
I cells located in the small intestine
34
What cells produce secretin and where are they located
S cells located in the small intestine
35
What cells produce glucose-dependent insulinotropic peptide (GIP) and where are they located
K cells located in the small intestine
36
What cells produce somatostatin and where are they located
D cells located in the stomach, pancreatic islets and small intestine
37
Three phases of GI control
cephalic
gastric
intestinal
38
What is the cephalic phase
sight, smell, taste and chewing
39
What is the gastric phase
distention and acidity
40
What is the intestinal phase
distention, acidity and osmolarity
41
Three functions of motor activity
non propulsive movements (segmentation)
peristaltic movements
reservoir function
42
What are the two types of muscle contraction and how long do they typically last
phasic (seconds)
| tonic (minutes-hours)
43
What are sphincters
specialised circular muscles that separate two adjacent compartments of the GI tract
44
What does antegrade mean
regulate forwards
45
what does retrograde movement mean
reverse movement
46
Location of sphincters
```
upper oesophageal sphincter (UES)
lower oesophageal sphincter (LES)
pyloric sphincter
iliocecal sphincter
internal and external anal sphincter
sphincter of odd
```
47
What happens in the swallowing reflex
food goes to touch receptors (back of tongue) which goes to the medulla and lower pons
This stimulates the vagus nerve to the oesophagus and cranial nerves to the pharynx and upper oesophagus
48
3 Phases of swallowing
oral phase (voluntary phase)
pharyngeal phase
oesophageal phase
49
What is the oral phase of swallowing
tongue presses food against hard palate
| bolus is forced into the pharynx and stimulates touch receptors
50
What happens in the pharyngeal phase of swallowing
soft palate elevates
epiglottis closes trachea
upper oesophageal sphincter relaxes
51
What happens in the oesophageal phase of swallowing
upper oesophageal sphincter closes
| peristalsis starts
52
What is peristalsis
the sequential contraction of ring of muscle
53
What happens during vomiting
forced inspiration occurs against a closed epiglottis
diaphragm is lowered
decreases intrathoracic pressure
as a consequence intraabdominal pressure increases
reflex relates the upper oesophageal sphincter
54
Describe peristalsis in the stomach
contractions begin in the corpus and travel towards the pylorus (propulsion)
they increase in force and velocity as they approach the gastroduodenal junction
mixing (grinding) occurs mainly in the antrum
retropulsion is very effective at mixing and breaking down gastric content
55
Non-propulsive movements motility in the small intestine
most frequent type of movements in the small intestine
caused by rhythmic contraction and relaxation of the muscular externa
effectively mixes chyme and brings digested nutrients into contact with the mucosal surface
56
Peristalsis in the small intestine
occurs at low frequency
caused by contraction of successive sections of muscularis externa
propels chyme for a short distance, allowing time for digestion and absorption
57
Functions of colonic contractions in the large intestine
mixing the chyme, to improve the absorption of water and salts from the colon
kneading the semisolid contents
moving the contents towards the anus (5-10cm an hour)(termed segmentation)
58
mass peristalsis in the large intestine
specialised type of movement
| 1-3 times a day, move the colonic contents towards the anus
59
What happens in defaecation
distention of rectum
relaxation of internal and external anal sphincter
contraction of abdominal wall muscles and relaxation of pelvic wall muscles
flexure of hips and descent of pelvic floor
60
Four functions of liver and gallbladder
metabolism
synthetic function
biliary system
storage
61
What does the liver store
glycogen
62
Another word for aminotransferases
transaminases
63
What is ALT
alanine aminotransferase
64
What does raised levels of ALT suggest
sign of hepatocellular damage
65
Where should aminotransferases be
in hepatocytes not bloodstream
66
What is the synthetic function of the liver
albumin
clotting factors
acute phase proteins - CRP (C-reactive protein)
67
What percentage does albumin make up of plasma proteins
50%
68
Reference range of albumin
35-45g/L
69
What is albumin a main factor in
maintaining oncotic pressure
70
Causes of hypoalbuminaemia
liver disease
nephrotic syndrome
malnutrition
burns
71
What does low albumin cause
peripheral oedema
72
What is cholestasis
malabsorption of vitamin K
73
What are bile acids synthesised from
cholesterol
74
Salivary secretion from parotid gland
serous (watery) secretion rich in ⍺-amylase
75
Salivary secretion from submandibular and sublingual glands
seromucous secretion
76
3 roles of stomach in digestion
reservoir - gastric motility
digests proteins - pepsins
essential for the absorption of vitamin b12-intrinsic factor
77
Composition of gastric secretions
HCl, pepsins, intrinsic factors, mucus and HCO3-
78
What are ECLs
entrochromatin like cells
79
What do ECLs secrete
histamine
80
What do mucus neck cells secrete
mucus
81
optimal pH of pepsins
<3
82
Functions of HCl
promotes the activation and activity of pepsins
kills and inhibits microorganisms
stimulates secretions in the small intestine
83
What regulates mucus and HCO3-
acetylcholine and prostaglandins
84
describe the secretions from the pancreas
1.5 litres a day
pH: 7.8-8.4
composed of salts and enzymes
85
Describe the secretions from the liver
0.5 litres a day
pH: 7.4
composed of bile acids, cholesterol and phospholipids
86
Describe the secretions from the small intestine
1 litre a day
pH: 7.6
composed of mucus enteropeptidase, salt and water
87
Endocrine pancreatic secretions
insulin and glucagon
88
exocrine pancreatic secretions
salts and water, enzymes
89
Functions of pancreatic juice
salts and water (HCO3-, NaCl, H2O): create the right environment for enzymes to work
enzymes: important for digestion of all major classes of foodstuffs
90
What do enzymes are in pancreatic juice and what do they do
proteases- digest proteins
lipases- digest fats
⍺-amylase - digest carbohydrates
91
Where are secretions of the liver specifically secreted from and where are they stored
secreted from hepatocytes
| stored in gallbladder
92
what do bile acids, cholesterol and phospholipids form
micelles for the absorption of fatty acids
93
What does the enterohepatic circulation do
control of bile synthesis and secretion
94
what happens if blood glucose drops below 2mM
brain becomes starved of fuel
95
What do humans synthesise glucose from
pyruvate, glycerol and amino acids
96
what is gng
gluconeogenesis
97
Where is the main site for gng
the liver
98
Can we use lactate to synthesise glucose
yes
99
What does GNG cost
4 ATP, 2 GTP, and 2 NADH per glucose molecule
100
What is glycogen synthase activated for
to convert excess glucose into glycogen
101
What is glycogen phosphorylase activated for
to convert glycogen into glucose-1-phosphate
102
what is glycogen synthase activated by
glucose and glucose-6-phosphate
103
What is glycogen phosphorylase activated by
AMP (Adenosine monophosphate) and Ca2+ in muscle
104
What hormones are glycogen synthase and glycogen phosphorylase under the control of
insulin, glucagon and adrenaline
105
When does homeostasis occur
when metabolite concentrations are at a steady state
106
Average half-life in days of following tissues: liver, kidney, heart, brain, muscle
```
liver-0.9
kidney-1.7
heart-4.1
brain-4.6
muscle-10.7
```
107
what is hexokinase inhibited by
glucose-6-phosphate
108
what is phosphofructokinase inhibited by
ATP
109
What does AMPK do generally speaking
shifts metabolism away from energy consuming synthetic pathways
110
What does AMPK do in extra hepatic tissues
shifts the metabolism towards the use of fatty acids
111
What does AMPK do in the liver
triggers GNG to provide glucose for the brain and slows synthetic pathways
112
What does AMPK do in the brain
stimulates feeding behaviour to provide more dietary fuel
113
What is AMPK activated by
AMP, by the sympathetic nervous system, exercise and by peptide hormones produced in adipose tissue
114
Where does one-third of our energy needs come from
dietary triglycerides
115
What are fats used for
long-term energy needs
116
what're glucose and glycogen used for
short-term energy needs
117
Where are dietary fatty acids absorbed
in the vertebrate small intestine
118
What do intestinal lipases do
degrade triglycerides
119
what are chylomicrons
the product of triglycerides and cholesterol and apolipoproteins
120
What do chylomicrons do
move through lymphatic system and bloodstream to tissues
121
how are fatty acids transported into the mitochondria
the carnitine shuttle
122
Stages of the carnitine shuttle
stage 1: β oxidation. Fatty acids are oxidised two carbons at a time and combine with CoA to form acetyl-CoA, and high energy electrons in the form of NADH and FADH2
Stage 2: Acetyl CoA enters the citric acid cycle and is used to form NADH and FADH2
Stage 3: the high energy electrons in NADH and FADH2 are used to synthesise ATP in oxidative phosphorylation
123
What three ketone bodies are produced in the liver
acetoacetate, β-hydroxybutryate, and some acetone
124
What are ketone bodies a major fuel source for
the heart, skeletal muscle and kidneys
125
What vitamins are fat soluble
A, B-12, D,E,K
126
Function of vit A
rhodopsin, retinoic acid/antioxidant
127
Function of vit C
collagen synthesis/antioxidant
128
Function of vit D
calcium absorption/antioxidant
129
Function of vit E
Mixed/antioxidant
130
Function of Vit K
formation of blood clotting factors/coenzyme
131
Function of thiamine B1
precursor of dehydrogenase cofactor
132
Function of riboflavin B2
precursor of FAD/FADH2
133
Function of niacin B3
precursor of NAD and NADP
134
Function of vit B6
cofactor in amino acid metabolism
135
Function of biotin
cofactor of carboxylases
136
Function of pantothenic acid (formation of B3 and B5)
precursor of CoA
137
Function of folic acid
DNA synthesis, etc.
138
Function of cobalamin B12
DNA synthesis, etc.
