Chamberlin Study Guide Flashcards
0
Q
What is the set point reached between glucagon and insulin?
A
70-100 mg/dl
1
Q
What is the relationship between glucagon and insulin?
A
When one goes up — The other goes down
and a set point is reached
2
Q
If there were a reduction in insulin levels across all levels of blood glucose levels, how would this change the glucose equilibrium point?
A
Blood glucose levels would rise and a new, higher set point will be established.
3
Q
How are decreased insulin levels and insulin resistance related?
A
Both do the same thing - blood glucose levels rise
4
Q
What organ has both endocrine and exocrine function?
A
Pancreas
5
Q
Which cells produce insulin?
A
beta (B) cells
6
Q
Which cells produce glucagon?
A
Alpha cells
7
Q
Which cells produce somatostatin?
A
D cells in the stomach
Delta cells in the pancreas
8
Q
What is the difference between D cells and delta cells?
A
Both secrete somatostatin into the blood stream
9
Q
What are the two mechanisms glucagon employs to increase blood glucose?
A
Glycogenolysis and gluconeogenesis
10
Q
What 3 things stimulate glucagon secretion?
A
- Low glucose
- Amino acids
- ACh, Epinephrine, Norepinephrine
11
Q
What 3 things inhibit glucagon secretion?
A
- High glucose
- Insulin
- Fatty acids
12
Q
Why does activation of the sympathetic nervous system stimulate glucagon release?
A
Fight or flight - you need to put as much immediately usable fuel into the circulatory system to provide for the needs of the muscles.
13
Q
What is paracrine secretion?
A
Secretion into the local area only
14
Q
Which pancreatic hormone utilizes paracrine secretion?
A
Somatostatin
15
Q
What is the purpose of somatostatin?
A
Down regulate both insulin and glucagon secretion so that levels of both don’t get out of control
16
Q
Why is calming things down important?
A
So you don’t exhaust nutrients too quickly
17
Q
What stimulates somatostatin release?
A
- Glucagon
- Insulin
- Amino Acids
18
Q
What is the most effective and most immediate treatment for hypoglycemia?
A
Glucagon
19
Q
Why does glucagon reduce the uptake of glucose into adipose cells?
A
To keep as much glucose as possible in the circulatory system.
20
Q
What are the multiple ways insulin is expressed to cells?
A
- insulin receptors
- tyrosine kinase
- other enzymes (IRS, insulin receptor substrates)
21
Q
What is insulin’s action on glucose in relation to cells?
A
It stimulates glucose uptake into cells.
22
Q
What synthetic processes are a result of insulin?
A
Synthesis of…
- Protein
- Fat
- Glycogen
23
Q
What expressions does insulin facilitate?
A
Growth and gene expression
24
What signals are stimulated by insulin?
Satiety signal
25
What is IRS?
The receptor that binds with insulin
26
What doe the IRS cause?
Glucose channels to increase in number on the cell membrane
27
What is the benefit of IRS increasing the number of glucose channels on the cell membrane?
It increases glucose uptake into the cell
28
What does the IRS trigger?
Translocation of GLUT 4 (glucose transporter) into the cell membrane to facilitate glucose absorption
29
What are the old antiquated classifications of diabetes?
Insulin and non-insulin dependent
30
Why was it important to change the old classification of diabetes?
Eventually most non-insulin dependent diabetics will require insulin
31
How do the autoimmune processes of type I and type II diabetics differ?
Type I: involves destruction of the beta cells in the pancreas
Type II: alteration of the IRS and/or GLUT 4 receptors in the target adipose tissue
32
If the body chooses to store glucose, what are the 2 primary forms that it is stored as?
Glycogen and TAG
33
Where is glycogen normally stored?
Liver and muscle
34
Where are TAG normally stored?
Adipose tissue
35
Do myocytes normally store fat for later use as energy?
NO. They store glycogen
36
Does insulin cause lipogenesis or lypolysis?
In adipose tissue and liver - STIMULATES lipogenesis
| It INHIBITS lipolysis of TAG
37
Where are GLUT 2 receptors found?
Beta cells in the pancreas
38
What is the effect of the activation of GLUT 2 receptors?
Insulin is released from the pancreas
39
Does insulin travel through the pancreatic duct to the duodenum?
NO. Only the exocrine products (lipase, HCO- etc.) hormones are secreted in the vascular system
40
In what phase does parasympathetic activity stimulate beta cells?
Cephalic phase
41
What is the ultimate function of the interaction between glucagon and insulin?
Keep blood glucose levels within a very narrow range during fasting.
42
When a person gets hypoglycemia, why does the sympathetic nervous system activate?
To keep the person conscious. The brain relies on glucose alone for energy on a second to second basis.
43
If stress is causing continuous sympathetic activation, what will happen to the equilibrium point of glucose?
The ANS will cause constant glucagon release, the point will shift upward, resulting in a higher concentration of fasting glucose levels. (Stress can lead to diabetes)
44
Where is iron specifically absorbed?
Duodenum
45
Which 6 nutrients are absorbed in the duodenum?
Cl-, SO4-, iron, calcium, magnesium, zinc
46
Where is B-12 absorbed specifically?
Terminal ileum
47
Which 7 nutrients are absorbed in the jejunum?
glucose, galactose, fructose, Vit. C, Thiamin, Riboflavin, Pyridoxine (water soluble vitamins)
48
What are 7 nutrients absorbed in the ileum?
Folic acid, amino acids, di-and tri-peptides, Vitamins A, D, E, K, Fat, cholesterol, bile salts and Vit. B-12
49
What nutrients are absorbed in the colon?
Na+, K+, Vitamin K (formed by bacterial action), and H2O
50
True/False: Fat soluble vitamins avoid the first pass effect.
True
51
What is the first pass effect?
Substances with a high fat content avoid being degraded by the liver by bypassing it and going to the peripheral tissues first.
52
Where does intestinal absorption occur, where does intestinal secretion occur?
Enterocytes; secretion occurs in the crypts of Lieberkuhn
53
Daily secretion and absorption of fluid are massive. About how much fluid is secreted a day by the stomach alone? Entire GI system?
Stomach: 2L
| GI System: 9L
54
Both small and large intestine absorb water, but do entirely different things with K+, what are they?
Small intestine: absorbs K+
| Large intestine: secretes K+
55
Why does most NaCl and water absorption occur in the duodenum and jejunum and less absorbed in the ileum and colon?
The tight junctions in the duodenum and jejunum are more permeable to water and solutes than in the ileum and colon
56
Na+ follows Cl- movement and H2O follows both. If by controlling Cl- and thus controlling Na+, how does controlling just one molecule control all other things?
Mechanisms have developed so that every time a Na+ enters a cell, it drags an glucose with it and expels a H+ at the same time.
57
Where is Na+ co-transported with glucose?
Jejunum
58
In which part of the small intestines does Cl- diffuse into and around the cell for absorption? Which part contains a pump for absorption via exchange with HCO3-
duodenum and jejunum; ileum and colon
| THIS IS NOT THE SAME AS THE CFTR PUMP!
59
What is the difference between the way Cl- is absorbed and secreted?
It is absorbed by diffusion through gap junctions.
60
What method is used when Cl- needs to be secreted into a lumen?
CFTR (cystic fibrosis transmembrane regulator)
61
Approximately how much water is secreted and reabsorbed into the intestines in a 24 hour period?
8900-9000ml
62
How much water is lost a day?
about 100ml
63
Why is secretory diarrhea so deadly?
It causes the CFTR to endlessly secrete Cl- (thus, water) down low below the duodenum and jejunum where water would normally be reabsorbed. (instead of 100ml a day being lost, it would be liters)
64
How does secretory diarrhea differ from osmotic diarrhea?
Osmotic diarrhea doesn't involve the CFTR - this results in a "water drag" situation where overall water losses are much smaller.
65
How can losing just 2 BMI points lead to a vast change in health?
- The visceral fat "dissolves" first, lessening intrabdominal mass effects (i.e. hiatal hernia).
- Decreases the likelihood of an autoimmune reaction in the peripheral fat.
66
How does fat storage differ in men and women?
Men: store visceral fat first
Women: store peripheral fat first
67
Which cytokines are thought to cause damage of peripheral fat cell receptors as a result of type II diabetes mellitus?
TNF, IL-6, and excess free fatty acids
68
What is the consequence of damaging the IRS?
GLUT 4 receptors cannot translocate to the cell membrane and thus the adipocyte cannot uptake glucose
69
Why are these IRS damaging cytokines thought to be released?
Because of an immune reaction occurring between visceral fat and bacterial agents in the GI system
70
TNF secreted from visceral fat causes _______ _________ in what other tissues?
insulin resistance; subQ fat and muscle
71
TNF secretion and insulin resistance interferes with ___ ________ in cell signaling of what?
IRS protein; GLUT-4 translocation
72
A similar mechanism can be responsible for atherosclerosis that is seen in insulin resistance. What is the mechanism in the heart?
Cytokines (adipokines) attack the coronary arteries instead of the IRS and causes atherosclerosis
73
How is the amount of fat a person has normally determined?
Body weight (adiposity) is normally stabilized by balancing energy intake and energy expenditure (homeostasis)
74
How does homeostasis occur?
Neural & endocrine afferent pathways provide feedback for regulating neural and behavioral aspects of eating
75
What is homeostatic regulation of energy uptake?
The result of feedback regulation from the internal milieu on hypothalamic/brain stem actions on eating.
76
What is non-homeostatic regulation of energy uptake?
Involves cognition, motivation, drive, stress (the limbic system's processing of environment, early life events, predisposition etc.)
77
How does the "ileal brake" work?
Inhibition of glucagon release, GI motility, and secretion
78
How can the "ileal brake" be used clinically for weight loss?
Slower eating permits activation of the satiety signals to reduce meal size.
79
What are the basic gastric cell types?
- Mucous Cells
- Parietal Cells
- Peptic Cells
- Enterochromaffin-like Cells
80
What stimulates the production of HCL?
- Peptides stimulate gastrin release - stimulating acid secretion
- Vagus nerve stimulates acid secretion and inhibits somatostatin release
81
What inhibits HCL production?
Acid stimulates somatostatin (SS) release which inhibits gastrin release
82
What does Vit B12 absorption depend upon?
- Secretion of intrinsic factor from gastric parietal cells
| - Uptake by ileal cells
83
Gastric R-proteins are dissociated by _______, and dependent on acid
pepsin
84
Intrinsic factor is released from _______ cells and combines with vitamin ____
parietal; B12
85
Vit B12 absorption requires what 3 factors?
- Dissociation from R-proteins by pepsin
- Binding with intrinsic factor
- Absorption by ileal cells and transport into portal vein
86
Decreased parietal cell activity, (eg. ulcers), causes diminished release of:
- Acid (hypochlorhydria or achlorhydria)
| - Intrinsic factor (B12 deficiency, pernicious anemia)
87
What is the function of gastric mucus
All areas of the stomach secrete mucus because all areas of the stomach need protection from HCl
88
Protein digestion depends on secretions from which cell types?
Parietal, peptic, and enteroendocrine cells (ECL, G and D cells)
89
Parietal cells secrete intrinsic factor for what purpose?
for vit B12 absorption
90
Parietal cells secrete acid via which mechanism?
carbonic acid
91
Acid initiates protein digestion in the stomach by converting pepsinogen to ___________, which is a _________.
pepsin: a protease
