Topic 3 - Nutrition & Digestion Flashcards
(181 cards)
1
Q
What proportion of society is considered overweight?
A
Over 1/3 of adults and nearly 1/3 of children
2
Q
Simplified, what causes obesity?
A
Too much energy-rich food and too sedentary a lifestyle
3
Q
What are the possible neurological effects of excessive fat storage?
A
- Headache
- Stroke
- Dementia, inc. Alzheimer’s
- Vision loss from diabetic complications
- False brain tumour (pseudo tumour cerebri)
- Diabetic neuropathy (weak/numbness)
4
Q
What are the possible respiratory effects of excessive fat storage?
A
- Asthma
- Sleep apnoea
- Pulmonary embolism (blockage of the main artery of the lung)
- Pulmonary hypertension (increased blood pressure in the arteries of the lungs)
5
Q
What are the possible urological effects of excessive fat storage?
A
- Diabetes
* Kidney cancer
6
Q
What are the possible circulatory effects of excessive fat storage?
A
- High blood pressure
- High cholesterol
- Atherosclerosis (fatty deposits in the arteries)
- Irregular heartbeat
- Heart attack/failure
- Poor circulation
- Leg/ankle swelling
- Peripheral artery disease (buildup of plaque in arteries)
- Certain lymphomas
7
Q
What are the possible psychological effects of excessive fat storage?
A
- Depression
- Anxiety
- Eating disorders
8
Q
What are the possible gastrointestinal effects of excessive fat storage?
A
- GERD
- Oesophageal cancer
- Colon polyps
- Fatty liver disease
- Cirrhosis (disease of the liver)
- Liver cancer
- Gallstones
- Gallbladder cancer
9
Q
What are the possible pancreatic effects of excessive fat storage?
A
- Type 2 diabetes
- Pancreatitis
- Pancreatic cancer
10
Q
What are the possible nutritional effects of excessive fat storage?
A
- Vitamin D deficiency
* Other vitamin/mineral deficiencies
11
Q
What are the possible female reproductive effects of excessive fat storage?
A
- Irregular periods
- Infertility
- PCOS
- Ovarian/Endometrial/Cervical/Breast cancer
12
Q
What are the possible male reproductive effects of excessive fat storage?
A
- Prostate cancer
- Infertility
- Erectile dysfunction
13
Q
What is adipose tissue?
A
Body fat - specialised connective tissue made of lipid-rich cells called adipocytes
14
Q
What does the term ‘lean body mass’ refer to?
A
All body organs (eg bone, muscle, lungs) which do not store fat
15
Q
What are the two types of adipose tissue?
A
- White adipose tissue
* Brown adipose tissue
16
Q
What is white adipose (WAT) tissue?
A
- The most common type of adipose tissue found in the body
* Stores energy as fat
17
Q
What is brown adipose (BAT) tissue?
A
Tissue whose primary function is thermoregulation
18
Q
What is the function of brown adipose tissue?
A
To produce body heat from the energy which comes from the food we consume
19
Q
What is the function of white adipose tissue?
A
Its main function is insulation and energy storage
20
Q
Where is brown adipose tissue typically stored?
A
- The neck
* Around the large blood vessels of the thorax
21
Q
What are adipocytes?
A
Cells which are specialised in the synthesis and storage of fat
22
Q
We need some white adipose tissue (WAT), but what for?
A
Cushioning, insulating and protecting organs and bones in the body
23
Q
What are the factors which likely affect a person’s volume of adipose tissue (adiposity)?
A
- Genetics
- Age
- Sex
- Physical activity
- Diet
24
Q
Where do men tend to carry their excess fat?
A
Abdomen
25
Where do women tend to carry their excess fat?
* Thighs
| * Hips
26
After what age do people tend to lose fat and lean body mass?
70
27
How does the WHO recommend assessing an individual's adiposity?
By using their waist-to-hip ratio in combination with their BMI
28
What are the two factors that make up an individual's TEE (total energy expenditure)?
* The total energy required to carry out basic processes of life (eg heartbeat, breathing)
* The total energy required for other tasks such as brain activity
29
What is the definition of BMR?
The number of calories your body uses to maintain vital functions, such as breathing, heart rate, and brain function
30
How would you be in a state of energy balance?
If your total energy intake (TEI) exactly matches your total energy expenditure (TEE)
31
How would you be in a state of positive energy balance?
If your total energy intake (TEI) is greater than your total energy expenditure (TEE)
32
How would you be in a state of negative energy balance?
If total energy intake (TEI) is less than total energy expenditure (TEE)
33
Is obesity caused by a positive or negative energy balance?
A positive energy balance
34
What is catabolism?
The breaking down of complex substances in to simpler ones, with the release of energy
35
Are catabolic reactions exergonic or endergonic?
Exergonic
36
Define exergonic
A reaction which relases or generates more energy than it uses
37
Define endergonic
Reactions which use more energy than they release
38
What is anabolism?
The process by which the body utilizes the energy released by catabolism to synthesize complex molecules
39
In which part of the cell is ATP made?
The cytosol
40
What is glycolisis?
The process that combines sugars and glycerol to produce ATP
41
What is the TCA (tricarboxylic acid) cycle?
A series of metabolic reactons that occur in the mitochrondria producing ATP
42
By what other term is the TCA cycle known?
Aerobic respiration
43
What are the waste products of the TCA cycle?
* Water
| * Carbon dixoide
44
Which is more efficient: anaerobic or aerobic respiration?
Aerobic
45
How many more times more ATP than anaerobic respiration does aerobic respiration produce?
15 times
46
During periods of heavy exercise, what is the main source of ATP, glycolysis or aerobic respiration?
Glycolysis
47
What is de novo lipogenisis?
The process which converts glucose and some amino acids in to fat
48
What are the six key nutrient groups?
* Carbohydrates
* Fats
* Proteins
* Minerals
* Vitamins
* Water
49
Which nutritional group is important to assist with the maintenance of ionic gradients?
Minerals
50
What is the definition of the term macronutrients?
The nutrients required in large amounts in the diet, i.e. carbohydrates, fats and protein
51
What is the definition of the term micronutrients?
Nutrients that are needed in only very small quantities by the body
52
What is the definition of the term antioxidants?
Molecules, including certain vitamins, that can inactivate harmful free radicals
53
What proportion of your energy intake does the WHO recommend to come from carbohydrates?
55-75%
54
What proportion of your energy intake does the WHO recommend to come from fats?
Less than 30%
55
What proportion of your energy intake does the WHO recommend to come from proteins?
10-15%
56
What are some of the main roles of iron within the body?
| What can arise from deficiency in this?
* Transport of oxygen in the blood
| * Anaemia, the reduction of the capacity to transport oxygen
57
What are some of the main roles of zinc within the body?
| What can arise from deficiency in this?
* Regulation of several biochemical pathways
* Stunt growth in children
* Reduce effectiveness of immune system
58
What are some of the main roles of folate within the body?
| What can arise from deficiency in this?
Fetal development
| Neural tube defects
59
What are some of the main roles of vitamin A within the body?
What can arise from deficiency in this?
* Development and maintenance of immune and visual systems
* Blindness
* Susceptibility to infection
60
What are some of the main roles of vitamin C within the body?
What can arise from deficiency in this?
* Facilitates absorption of iron in the gut
* Involved in several enzymatic pathways, inc. collagen synthesis
* Scurvy due to breakdown and poor maintenance of connective tissues containing collagen
61
Which of the following types of carbohydrate has the simplest structure?
Polysaccharaide
Monosaccharide
Disaccharadie
Monosaccharide
62
What do polysaccharaides consist of?
Linear or branched chains of sugars joined together
63
Which sugars are polysaccharides?
* Starch
* Cellulose
* Glycogen
64
Name the two monosaccharides
* Glucose
| * Fructose
65
Which sugar is a disaccharide?
Sucrose
66
What percentage of body mass do lipids account for?
Roughly 18-25%
67
What functions can lipids perform?
* Structural components of cell membranes
* Signalling molecules
* Long-term energy storage
68
Which of the following is the simplest form of lipid?
Fatty acids
Triglycerides
Phosopholipids
Steroids
Fatty acids
69
What is the typical cellular structure of steroids?
Multiple carbon rings
70
Is a fatty acid with one or more carbon-to-carbon covalent bonds in its tail a saturated or unsaturated fatty acid?
Unsaturated
71
What are the functions of lipids?
* Protection
* Insulation & thermoregulation
* Formation of the plasma membrane
* ATP synthesis
72
What are the components of a the basic structure of an amino acid?
* Hydrogen group
* Amine group
* Carboxyl group
* R group
73
What do all amino acids have in their structure?
A central carbon atom with four entities bonded to it
74
What is the term used to describe cells which are exposed to the external environment?
Epithelial cells
75
In the process of digestion, where does absorption start?
The small intestine
76
What is the enzyme produced in the mouth which helps begin to break down food?
Salivary amylase
77
What is the name for chewed and partially digested food?
The bolus
78
What is receptive relaxation (in terms of digestion)?
| Which are the muscles that relax as part of this?
* The relaxation of the stomach in response to swallowing
| * The sphincter and upper stomach muscles
79
What are the minimum and maximum volumes of the stomach?
* 50ml
| * 1500ml
80
Up to how many times in size can the stomach increase?
30
81
What is the gastric mucosa?
The mucus membrane lining of the stomach
82
In which region of the stomach does gastric empyting occur?
The pyloric region
83
How much chyme does the stomach release with each of its contractions?
3ml
84
What is the hormone produced in the gastric mucosa?
Gastrin
85
With regards to the stomach and digestion, what are neck cells?
Mucus-producing cells which cover the inside of the stomach, protecting it from the corrosive nature of gastric acid.
86
With regards to the stomach and digestion, what are chief cells?
Epithelial cell that are found mainly in the mucosal layer of the stomach lining and which secrete pepsinogen and gastric lipase, as well as chymosin
87
With regards to the stomach and digestion, what are parietal cells?
Epithelial cells in the stomach that secrete hydrochloric acid (HCl) and intrinsic factor
88
Which type of gastric cell is responsible for secreting hydrochloric acid and intrinsic factor?
Parietal cells
89
Which type of gastric cell is responsible for secreting pepsinogen, gastric lipase and rennin?
Chief cells
90
Which type of gastric cell is responsible for secreting (stomach) mucus?
Neck cells
91
In the mouth, carbohydrates such as starch are digested into which smaller molecules?
Maltose and short-chain polysaccharides
92
Which enzyme is present in saliva?
Salivary amylase
93
In the stomach, what is food broken further down into?
* Amino acids
| * Peptides
94
In the stomach, which enzyme and which secreted substance denature and partially break down food?
* Pepsin
| * Hydrochloric acid
95
In the stomach, what are the two things lipids are broken down into?
* Mologlycerides
| * Fatty acids
96
What is the name for the finger-like projections in the small intestine?
Villi
97
In the small intestine, how many villi are there (roughly) per square centimetre?
20 to 40
98
Approximately how long is the small intestine?
5m
99
What is the purpose of the villi in the small intestine?
To increase surface area, which aids in absorption
100
By how much do the villi in the small intestine increase its surface area?
Around 600-fold
101
What are the secretions which enter the GI tract?
* Saliva
* Gastric digestive secretions
* Gastric mucus secretions
* Bile from the liver
* Pancreatic secretions
102
What are the three parts of the small intestine?
* Duodenum
* Jejunum
* Ileum
103
What is the luminal surface (in the small intestine)?
The surface facing the lumen of the GI tract
104
In biology, what is a lumen?
The inside space of a tubular structure, such as an artery or intestine
105
In the small intestine, what is the surface of each villus folded in to?
Small, finger-like projections calls microvilli
106
What is the name for the microvilli layer (within the small intestine)?
The brush border
107
Roughly what is the size of the surface area of the human small intestine?
Approximately 300 sq m
108
What is the sphincter of Oddi?
A muscle that opens and closes to allow bile and pancreatic juice to flow between the pancreas and the small intestine
109
What are the names for the cells which the pancreas produces?
* Exocrine cells
| * Endocrine cells
110
What is the distinguishing feature of all exocrine cells?
They release their fluids via ducts, onto an epithelial surface
111
What is an example of an exocrine secretion?
Sweat
112
Where do the secretions from endocrine cells go?
Directly into the bloodstream
113
What is pepsinogen?
A protein digesting enzyme (proteolytic)
114
What is the active form of pepsinogen?
Pepsin
115
What type of ions are produced by the exocrine cells of the pancreas?
For what purpose?
* Bicarbonate ions
| * They neutralise the hydrogen ions in the chyme and neutralise the acidity of the contents of the duodenum
116
Is pepsin released as an active or inactive precursor?
Inactive
117
What is the name of the enzyme which activates the digestive enzymes in the duodenum?
Enterokinase
118
Where is enterokinase located?
The brush border of the intestinal mucosa
119
What is the pancreatic enzyme which is activated by enterokinase?
Trypsinogen
120
What is the active form of trypsinogen?
Trypsin
121
What is unusual about enterokinase?
It is not free in the lumen, but is restricted to the brush border
122
What are the main pancreatic enzymes?
* Trypsin
* Chymotrypsin
* Elastase
* Carboxypeptidase
* Pancreatic amylase
* Pancreatic lipase
* DNA/RNA
123
What is the function of trypsin, chymotrypsin and elastase?
To break peptide bonds in proteins in order to form peptide fragments
124
What is the function of carboxypeptidase?
To remove terminal amino acids from the carboxyl end of the chain
125
What is the function of pancreatic amylase?
To split polysaccharides into disaccharides and short chains of glucose units (dextrins)
126
What is the function of pancreatic lipase?
To split two fatty acids from each tryglyceride molecule in order to form free fatty acids and monoglyceride
127
What is the largest gland in the body?
The liver
128
What does the liver produce and secrete?
| Where does this secretion go?
* Bile
| * The duodenum
129
What is bile?
An aqueous mixture of:
* Bicarbonate ions
* Phospholipids
* Cholesterol/cholesterol-derived products (bile salts)
* Waste products such as bilirubin
130
What is bilirubin?
A yellow/brown molecule which is derived from the catabolism of aged red blood cells which have reached the end of their useful life
131
Where in the body is bile stored in between meals?
The gall bladder
132
What are bile salts involved in the digestion of?
Lipids
| Fats
133
How do bile salts break up the globules of lipids?
Emulsification
134
How would you describe the enzymatic action of lipases?
They act on triglycerides by splitting it into monoglyceride and two fatty acids
135
What are micelles?
Lipid molecules that arrange themselves in a spherical form in aqueous solutions
136
What is the shortest section of the small intestine?
What is the longest?
How long are they?
* Duodenum - 25cm
| * Ileum - 3 metres
137
In which part of the intestine does most of digestion occur?
The small intestine
138
The formation of a peptide bond liberates a molecule of what, an is an example of what type of reaction?
* Water
| * Condensation reaction
139
The cleavage of a peptide bond consumes a molecule of what?
Water
140
What does carboxypeptidase release from peptide chains?
* Amino acids from one end
| * Aminopeptidase from the other end
141
Are amino acids able to diffuse across the cell membrane?
| If not, how do they cross it?
* No, they are hydrophilic
| * They are transported by carrier proteins
142
How is the hydrogen ion gradient maintained in the absorptive cells of the gut epithelium?
Because hydrogen ions are transported out of the cells into the gut lumen by antiporter proteins
143
How is the hydrogen ion gradient (of the gut) maintained?
By secondary active transport
144
What are the end products of protein digestion?
Free amino acids
145
If food is chewed thoroughly, how much of ingested protein can be broken down into amino acids and absorbed?
Roughly 98%
146
What does the enzyme maltase break down into glucose?
* Maltose (disaccharide)
| * Maltotriose (trisaccharide)
147
What are dextrins broken down by?
Dextrinase
148
What maintains the sodium ion gradient for the transport of glucose or galactose into the absorptive cells of the gut epithelium?
The action of the sodium-potassium pumps on the basal membrane
149
How do monoglycerides and fatty acids cross the cell membrane?
They diffuse across it
150
What does the smooth endoplasmic reticulum convert fatty acids and monoglycerides in to?
Triglycerides
151
What is a chylomicron?
A lipoprotein rich in triglyceride and common in the blood during fat digestion and assimilation
152
What is pinocytosis?
The process by which extracellular fluids are taken into a cell by the invagination of the cell membrane to form small vesicles
153
Which vitamin must be present to enhance the absorption of calcium?
Vitamin D
154
In the human body, iron comes in two forms; what are they?
* Haem
| * Iron salts
155
Roughly how much (percentage) of ingested iron salts actually enter the bloodstream?
10-15%
156
Which vitamin enhances the absorption of iron?
Vitamin C
157
In the body, iron exists in two positively charged forms (ferric and ferrous).
What are their charges?
* Ferric FE3+
| * Ferrous FE2+
158
Of the two types of iron in the body (ferric/ferrous), which is the form that is absorbed by the gut epithelium?
Ferrous iron
159
What is haem iron?
Iron which is derived from meat and fish and is mainly bound to proteins
160
What is ferric iron also known as?
Non-haem iron
161
How is ferric iron absorbed by the body?
An enzyme called ferrireductase converts it to FE2+ (ferrous iron)
162
What is the protein which ferric iron is bound to so that it can be transported in the bloodstream, or stored in tissues?
Transferrin
163
How are fat soluble vitamins absorbed?
Fat-soluble vitamins such as vitamin D are transported by micelles, together with digested lipids, to the brush border where they then diffuse into the intestinal cell
164
What must vitamin B12 bind to in order to be taken up by the epithelial cells of the ileum?
Intrinsic factor
165
What is the purpose of vitamin B12?
It promotes enzymatic activity in many biochemical reactions
166
Where is most of the water in the GI tract absorbed?
The small intestine
167
What is the paracellular route?
A route between cells via very small pores located at the junctions between them
168
What does the large intestine mainly absorb?
Water and salts
169
Does the large intestinal mucosa have villi?
No
170
What is the gut microbiome?
The totality of microorganisms, bacteria, viruses, protozoa, and fungi, and their collective genetic material present in the gastrointestinal tract
171
What conditions can be associated with a disturbed gut flora?
* Diarrhea
* Diabetes
* Obesity
* Atherosclerosis
* Colitis
* Crohn's disease
* Autism
172
What types of flora exist in the body?
* Gastrointestinal tract
* Genitourinary tract
* Skin
* Conjunctiva
* Nose/nasopharynx
* Upper respiratory tract
173
Aside from causing disease, what other effects can a disturbed gut flora cause?
* It influences brain development
| * Anxiety behaviour
174
What does the term 'hunger' refer to?
The processes which make eating more likely
175
What does the term 'satiety' refer to?
The processes which make eating more likely to stop once it has started (to feel full)
176
Which part of the brain regulates many of the homeostatic functions?
The hypothalamus
177
What is leptin?
| What is its purpose?
* A protein hormon released mainly by adipocytes
* It acts on the brain to stimulate the satiety centre and inhibit the hunger centre, reduces the desire to eat, promotes a sense of being full
178
What is ghrelin?
| What is its purpose?
* A hormone which is released by endocrine cells in the gastric mucosa
* It promotes feelings of hunger, inhibits feelings of satiety
179
Which part of the brain can be stimulated by food?
| What effects can occur?
* The ventral striatum
| * Feelings of reward and pleasure
180
Which neurotransmitters are released due to stimulation of the ventral striatum as a result of ingesting food?
Dopamine
181
What happens to the amount of dopamine receptors in an obese person?
They decrease
