Carbohydrate Digestion, Absorption and Blood Sugar Homeostasis Flashcards
1
Q
Give three classifications of carbohydrates
A
- Monosaccharides
- Disaccharides
- Polysaccharides
2
Q
Name some common monosaccharides
A
- Glucose
- Fructose
- Galactose
3
Q
What are carbohydrates?
A
Hydrated carbons
4
Q
Name some common disaccharides
A
Maltose
sucrose
lactose
5
Q
Give the simplest formulate fro monosaccharides
A
C6H1206
6
Q
Name some common polysaccharides
A
- Starch
- Glycogen
3, Cellulose
7
Q
In which form do we most commonly obtain carbohydrates from out diet
A
Starch from
8
Q
Name the 2 different types of starch
A
- Amylose
2. Amylopectin
9
Q
What is the difference between amylose and amylopectin
A
Amylose is a straight linear chain
Amylopectin is branched
10
Q
How are monosaccharides bonded to each other in starch?
A
Via the alpha 1-4 bond
11
Q
In branching how are monosaccharides bonded?
A
Via a alpha 1-6 bond (Only at branching points)
12
Q
How are monosaccharides bonded to each other in cellulose
A
In linear chain alpha 1-4 but between chains theres beta 1-4 bonding
13
Q
Which bond is easier to digest the A1-4 or the A1-6?
A
The alpha 1-4
14
Q
Why is cellulose indigestible?
A
As the beta 1-4 bond is indigestible
15
Q
Where are carbohydrates digested?
A
In the mouth and small intestines
16
Q
How does carbohydrate digestion begin?
A
in the oral cavity food is mechanically squashed and mixed with amylase
17
Q
How many major salivary glands do we have?
A
3 pairs of major glands
18
Q
Name the 3 major salivary glands
A
- Parotid gland
- Sublingual gland
- Submandibular gland
19
Q
Name the 2 different types of secretion
A
mucous and serous
20
Q
Name the 2 different types of glands in the body?
A
Endocrine
Exocrine
21
Q
What are endocrine
A
Secrete hormones directly into the blood stream
22
Q
What are exocrine
A
Secretes enzymes into blood stream via ducts
23
Q
What type of glands are the salivary glands?
A
Exocrine
24
Q
Where is salivary amylase secreted?
A
Secreted by serous acini of parotid and sub mandibular salivary glands
25
State of the optimal pH for salivary amylase
6.7
26
Why does carbohydrate digestion not occur in the stomach?
Acidic conditions so amylase can not function
27
What proportion of carbohydrate digestion occurs in the oral cavity
5%
28
What is the mode of action fro salivary amylase
Hydrolysis of alpha 1-4 linkage in polysaccharides producing a mixture of oligosaccharides
29
What are oligosaccharides?
3-10 Monosaccharides bonded together
30
Name the enzymes involved I intestinal digestion of carbohydrates
1. Pancreatic amylase
| 2. Brush border enzymes
31
Where is pancreatic amylase secreted from?
Secreted from the pancreatic exocrine acini into the duodenum through the pancreatic duct
32
State the optimal pH for pancreatic amylase
6.7-7
33
What is the mode of action for pancreatic amylase
Hydrolysis of alpha 1-4 linkage
34
What is pancreatic amylase responsible fro?
Responsible for the digestion of more complex carbohydrates that take longer to break down to to disaccharides or oligo saccharides
35
Give examples of Brush border enzymes
1. Maltase
2. Sucrase
3. lactase
36
Where are Brush border enzymes found?
In the membrane surface of the micro villi (brush border) of the epithelial cells lining the wall intestine
37
State the optimal pH for Brush border enzymes
7-8
38
What is the mode of action fro Brush border enzymes
Hydrolysing disaccharides into monosaccharides
39
Name a condition where you cannot digest lactose?
Lactose intolerence
40
How can a person have lactose intolerance?
Genetics
| Trauma
41
How can lactose intolerance be treated?
By avoiding diary or m=by adding lactase to food
42
Deficiency of which enzyme can lead to lactose intolerance?
Lactase deficiency
43
What does lactase do?
Breaks down lactose into glucose and galactose
44
What does maltase do?
Breaks down matose into 2 glucose molecules
45
What does sucrase do?
Breaks down sucrose into glucose and fructose
46
Where does carbohydrate absorption occurring?
In the small intestine
47
Why are microvilli and villi important?
They increase the surface area which facilitated absorption
48
Which from of carbohydrates in the most absorbable?
Monosaccharides
49
How do glucose and galactose enter the intestine?
Enters the epithelial cells through the apical border via active transport using sodium dependant co transporters
50
What does the sodium potassium pump require?
Require energy as you are going against the concentration gradient
51
How do glucose and galactose lave epithelial cells?
Leave through the basolateral side using diffusion and and glucose co-transporter- 2 (GLUT-2) into the circulation
52
Does the glucose co transporter 2 require energy?
No
53
How odes fructose enter and leave epithelial cells?
Enters and lives the epithelial cells using facilitated diffusion
54
Name the 3 mechanisms of diffusion
1. Passive diffusion
2. Facilitated diffusion
3. Active transport (requires energy)
55
Describe in detail how glucose and galactose are absorbed
1. Glucose attaches to sodium dependant pump (SGLT1) to enter the cell (active transport)
2, To leave the cell it will attach to GLUT2 (facilitated diffusion)
56
Describe in detail how fructose isabsorbed
1. Fructose attaches to GLUT5 to enter the cell (facilitated diffusion)
2. To leave fructose attaches to GLUT2 (facilitated diffusion)
57
Name some factors that affect carbohydrate absorption
1. Absorption is faster through intact mucosa (inflammation or injury to mucosa can slow down absorption)
2. Thyroid hormones INCREASE the rate of absorption of glucose.
3. Mineralocorticoid: e.g. Aldosterone INCREASE the rate of absorption.
4. High Na+ coon increases the rate of absorbtion
58
Why is glucose important?
1. It is the main nutrient forth brain and retina under non starvation conditions
2. It is also the sole nutrient for red blood cells
3. It is a key source of energy to body cells via respiration
59
How much energy glucose produce?
Glucose produces 3.75 K-calories of energy/ gm
60
Name the hormones involved in glucose homeostasis
1. Insulin
| 2. Glucagon
61
Where is insulin secreted?
Secreted by the beta cells in the islets of langerhans of the pancreas
62
What type of glands are the beta cells in the islets of langerhans ?
Endocrine glands
63
What does insulin do?
It is responsible fro regulating levels of glucose in blood by stimulating body cells to take up glucose
64
Where is glucagon secreted?
It is hormone secreted by the alpha cells in the islets of langerhans of the pancreas
65
What does glucagon do?
It is responsible for converting glycogen stored in the liver to glucose and releasing it in the blood when blood glucose levels are low
66
If blood sugar rises what happens?
1. Beta cells secrete insulin
2. This triggers cells to take up glucose by body cells
3. Excess glucose is stored in the liver as glycogen
67
If blood sugar falls what happens?
1. Alpha cells in the islets of langerhans secretes glucagon
2. This triggers the lover to break down Glycogen into glucose released in blood
68
Describe the structure of insulin
2. Insulin is a small protein made up of 2 polypeptide chains A and B looked by a disulphide bond
69
If a person has insufficient or no insulin what can patients have?
Diabetes Mellitus
70
State normal blood glucose levels
Fasting= 80-90mg/100ml
| After a meal 120-140mg/100ml
71
Name the main hormone responsible for regulating blood glucose levels
INSULIN
72
What can insulin deficiency/ resistance lead to?
hyperglycaemia and diabetes mellitus
73
Give some symptoms of diabetes
1. Fatigue
2. Blurred vison
3. Slow healing sores
4. Unusual weight loss or gain
5. Yeast infection
6. Dry mouth
7. increased urination
8. Excessive thirst
9 Nausea
74
What macrovascular complications can arise due to diabetes?
1. Brain: cerebrovascular diseases such as stroke, transient schema and cognoticec impairment
2. Heart: Coronoary syndrome, heart attack and failure
3. Extremities: Diabetic foot, skin ulcers, amputation
75
What microvascular complications can arise due to diabetes?
1. Eye: Retinopathy. cataract and glaucoma
2. Kidneys: renal failure
3. Nerve can be affected
76
What dent complications are associated with diabetes?
1. Dry mouth
2. Gum and periodontal disease
3. Loss of teeth
4. Impaired and delayed healing g
4, Infections
77
Name the hormone produced by the beta cells in the islets of langerhans
Insulin
78
How can dentist manage diabetic patients?
1. Ensure regular visits to the dentist and dental hygiene
2. Maintainece of oral hygiene
3. Regular periodontal check and management
4. Antibiotic coverage fro surgeries
5. Controlled blood sugar levels before any surgical intervention
6. Mouth wash
7. Artificial saliva if required
