Physiology 🫁 Flashcards
1
Q
what is the importance and the definition of ATP?
A
- It is used as an energy source for almost all cellular functions or its similar nucleotide guanosine triphosphate (GTP) .
2
Q
what is the energy currency of the body?
A
ATP (adenosine triphosphate)
3
Q
what are the sources of ATP generation?
A
- Combustion of carbohydrates mainly glucose
(but also small amount of other sugars as fructose), which occurring by the process of glycolysis and by the krebs cycle. - Combustion of proteins: hydrolysis to amino acids then its degradation to intermediate compounds of citric acid cycle.
- Combustion of fatty acids in the mitochondria by beta oxidation .
4
Q
what is the definition of phosphocreatine?
A
- Accessory storage depot for energy .
- It is the most abundant store of high energy phosphate bond in the cells.
5
Q
what happens when ATP begins to be used up?
A
the energy in phosphocreatine is transferred rapidly back to ATP.
6
Q
what is the significance of phosphocreatine?
A
- It thus keeps the concentration of ATP nearly constant .
- The concentration of ATP must be maintained constant because the rate of chemical reactions in the body depends on this constancy.
7
Q
what are the uses of ATP?
A
- Energizes the synthesis of cellular components:
- Formation of peptide linkages amino acids during synthesis of proteins.
- Synthesis of glucose from lactic acid
- Synthesis of fatty acids from acetyl co enzyme A .
- Synthesis of phospholipids, cholesterol and hormones.
- Synthesis of urea from ammonia. - ATP energizes muscle contraction.
- ATP energize active transport across cell membrane.
- ATP energizes nerve conduction.
- Digestion ,absorption and processing of food.
- Maintenance of body temperature.
8
Q
what is considered as a major controlling factor of energy releasing reactions in the cell?
A
ADP concentration as amajor controlling foctor of the energy releasing reactions in the cell:
- When the cell become active, ATP is converted to ADP , when its concentration increases ,it enhances the rate of all energy releasing reactions in the cell.
- In abscence of cellular activity ,all these reactions stops because all ADP is converted toATP.
9
Q
what is the definition of metabolism and metabolic rate?
A
Metabolism: all chemical reactions in all body cells.
Metabolic rate: rate of heat liberation during the
chemical reactions .
10
Q
what is the end product of almost all the energy released in the body?
A
Heat
11
Q
what is the percentage of energy that becomes heat during ATP formation?
A
50% becomes heat during ATP Formation.
12
Q
what are the forms in which the energy is lost as heat during ATP formation & Synthesis?
A
- 50% becomes heat during ATP Formation.
- Heat is released as energy is transferred from ATP to functional systems of cells.
- No more than 27% of all energy from food is finally used by functional systems ,this also becomes heat during
13
Q
what is the amount of energy that is finally used by functional system?
A
- No more than 27% of all energy from food is finally used by functional systems ,this also becomes heat during
14
Q
how does the 27% of energy used in functional system become heat?
A
- During protein degradation :part of energy stored in peptide linkages is released as heat.
- Overcoming the viscosity of muscles and other tissues during muscle contraction and body movements.
- Friction between the different layers of blood as blood flows through blood vessels.
- The only significance exception is when the muscles uses this energy to perform work.
15
Q
A
..
16
Q
what is the amount of calories consumed by an average man waiting 70 kg and lies in bed all day?
A
1650 calories
17
Q
what is the amount of calories consumed by an average man waiting 70 kg and eating a resoanable diet?
A
1850 cals per day
18
Q
what is the amount of calories consumed by an average man waiting 70 kg and sits in a chair all day?
A
2000 -2250 calories per day.
19
Q
what does the amount of energy used to perform a physical activity vary according to?
A
- Type of physical activity
- Amount of physical activity
20
Q
what is the amount of total energy expenditure used during normal daily activities?
A
25%
21
Q
give an example for variation in energy expenditure according to activity:
A
- A person performing heavy labour can achieve a maximal rate of energy utilization as graet as 6000 to 7000 calories.
- Even in sedentary individuals significant energy is spent to maintain muscle tone and body position and other non exercise activities.
22
Q
what is the definition of heat value of food?
A
Amount of heat released by oxidation of 1 gm food.
23
Q
what are the units of heat?
A
Calorie (C) (= 1000 small calorie, c)
24
Q
what are the physiological and physical heat values of macronutrients?
A
25
why is a physical and physiological heat value of carbohydrates and fats equal in vitro & in vivo?
because they are completely oxidized to CO2 + H2O in & out the body.
26
Why is physical and physiological heat value of proteins different?
**Proteins contain 16% N2**
- Outside the body : → completely oxidized
- Inside the body: → not completely oxidized otherwise N2 is oxidized into nitric acid → fatal decrease in pH). This N2 is transformed to urea by liver→ excreted in urine (causing loss of part of energy of protein).
27
what is the definition of (Specific Dynamic Action (SDA) or Postprandial Thermogenesis)?
Power of food to stimulate metabolic rate & heat production.
28
when does SDA start?
1 hour after ingestion of food.
29
when does SDA reach maximum rise?
a maximal rise after 3 hours.
30
when does SDA decrease to normal?
Decrease to normal in 10 – 12 hours.
31
what are the factors affecting SDA?
32
what are the causes of SDA?
- Increased sympathetic activity after feeding
- Metabolic reactions through which food is metabolized
1. **CHO:** Metabolic processes that occur in liver e.g. glycogenesis
2. **Fat:** Direct stimulating effect of fatty acids on the metabolic processes in the tissues
3. **Protein:** Metabolic processes that occur to amino acids in liver as deamination and urea formation, A direct stimulating effect of amino acids on metabolic processes in tissues
33
what is the significance of SDA?
**It is a waste heat liberated after food ingestion**
1. During exposure to cold → proteins ingestion keep body temperature constant.
2. Guard against development of obesity.
34
regulation of food intake
**Short term control system:**
1. Make the person eat much smaller quantities at each eating session to make digestion and absorption work at optimal rates.
2. Prevent persons from eating amounts at each meal that would be too much for metabolic storage system .
**Long term control system:**
- It help maintain constant stores of nutrients in the tissues thus preventing them from becoming too low or too high .
35
what are the hypothalamic feeding centers (Appestat)?
**1. The lateral nuclei:** Feeding centre ( hunger centre).
**2. The ventromedial nuclei:** Satiety centre.
**3. The paraventricular nuclei:** satiety centre.
**4. Dorsomedial nuclei:** feeding centre.
**5. The arcuate nuclei:** are the sites where multiple hormones released from the gastrointestinal tract and adipose tissues converge to regulate food intake and energy expenditure.
**6. Amygdala and prefrontal cortex:** control appetite.
36
what is the definition of hunger and what is it associated with?
- organic sensation that indicates the need for food
- It is associated with hunger pains due to rhythmic contraction of the stomach
37
what is the definition of appetite?
- Organic sensation that indicates that desire for a particular type of food
38
what is the definition of satiety?
sense of satisfaction as regard feeding
39
what do the hypothalamic centers receive? **(Concerning food appetite and satiety)**
1. Neural signals from the gastrointestinal tract that provide sensory information about stomach filling.
2. Chemical signals from nutrients in the blood (glucose ,amino acids and fatty acids) that signify satiety.
3. Signals from GIT, Adipose tissue & cerebral cortex that influence feeding behavior (smell ,sight taste).
40
what are the neurotransmitters and hormones that influence feeding and satiety centers in the hypothalamus?
**1. Orexigenic (increase feeding):**
- Neuropeptide y
- Ghrelin
- Galanin
- Cortisol
- Orexin A & B
- Endorphins
**2. Anorexigenic(decrease feeding):**
- Leptin
- Insulin
- Corticotropin releasing hormone
- Glucagon like peptide.
- Peptide yy
- Cholecyctokinin
41
what are other neural centers that influence feeding?
- Appetite center
- Centers that regulate the mechanics of feeding as salivating chewing & swallowing
42
what is the site of appetite Center?
Amygdala
43
what happens if there is a lesion in the appetite Center?
loss of appetite control (type & quality of food).
44
what is the site of the centers that control the mechanics of feeding?
brain stem.
45
what are the types of nerve fibers in the arcuate nucleus?
- Proopiomelanocortin ( POMC)
- Agouti related peptide
46
what is Pro-opio-melano-cortin (POMC)? And what does its activation lead to?
- A type of neurone in the arcuate nucleus of the hypothalamus that produce alpha melanocyte stimulating hormone( alpha MNS) which act on MCR4 receptor.
- decrease food intake and increase energy expenditure
47
what is agouti related peptide?
A neuron in the acruate nucleus which has opposite effect to POMC
48
what are the importance of short term of control of food intake?
Regulate the size of each meal.
49
what are the factors that affect short term control of food intake?
- Rapid neuroendocrine interaction that suppress feeding
- Gastrointestinal filling
- Mouth receptors
- Others
50
what are examples of Neuro endocrine interactions that suppress feeding?
51
how does GIT filling inhibit feeding?
Distension of stomach & duodenum by food → sends inhibitory impulses through vagi → inhibits feeding center → decreases desire for food.
52
how do mouth receptors inhibit feeding?
- As food enters the mouth → certain oral receptors stimulated by certain factors related to feeding such as chewing ,salivations ,swallowing and tasting register (measure) the amount of food ingested → sends satiety signals to stimulate satiety center.
- Degree of hunger decreases after reasonable amount of food.
53
what is the evidence that mouth receptors stimulate satiety centers?
During sham-feeding ---> Swallowing food causes satiety, although no food reaches the stomach
54
what are other factors that affect food intake?
1. Voluntary control
2. psychological factors, especially stress
3. Cultural and environmental factors
55
what Is the importance of long-term control of food intake?
Maintain normal quantities of energy stores in the body.
56
what does Decrease in nutrient storage of the body lead to?
stimulation feeding centers → increase feeding → restore
energy stores at normal level (set point).
57
what are the factors that affect long-term control of food intake?
- Effect of blood conc of nutrients (glucostatic, aminostatic & lipostatic theories)
- Effect of body & environmental temp. on food intake
- Feedback signals from adipose tissue
58
how does fasting affect food intake?
Decrease blood concentration of glucose, aa, F.A & ketoacids e.g during fasting→ stimulates feeding center and inhibits satiety center → restore blood nutrient concentration to normal.
59
how does eating affect food intake?
Increase blood concentration of glucose, aa, lipids → stimulates satiety center & inhibits hunger center → decrease feeding.
60
how does cold weather affect food intake?
stimulates feeding center → eats more → increase metabolic rate and provide insulating fat layer.
61
how does hot weather affect food intake?
inhibits feeding center → eats less.
62
what is the cause of Affection of food intake by body and environmental temperature?
interaction within the hypothalamus between temperature & food intake regulating centers.
63
where is leptin hormone secreted from?
from adipocytes of fat tissues(most of stored energy in the body is in the form of fat) into blood in proportion to the amount of fat in the adipose tissue.
64
what are the actions done by leptin hormone?
Leptin circulates to reach the brain → stimulates specific receptors at hypothalamic nuclei (including arcuate nuclei and paraventricular nuclei) → decrease energy storage by:
- Decrease production of neuropeptide Y, which is a hypothalamic neuro-transmitter that stimulates eating.
- Decrease insulin secretion by pancreatic beta cells → decrease energy storage.
- Increase activity of sympathetic. N.S. → increase energy expenditure.
- Increase production of hypothalamic corticotropic hormone → decrease food intake.
65
what is the definition of overweight & Obesity?
Large accumulation of fat (extreme over-weight)
66
Determination of overweight & Obesity
67
what are the causes of overweight & Obesity?
- Genetic (Hereditary)
- Environmental
- Neurogenic
- Endocrinal
68
Genetic causes of overweight & Obesity
69
what is the most common monogenic form of obesity?
Mutation of POMC and MCR4 is the most common monogenic forms of obesity .
70
Environmental causes of overweight & Obesity
- Family dietary pattern.
- Decrease level or physical activity.
- Psychological factors
71
what are the phsycological factors that contribute to overweight & Obesity?
1. Using food as a reward for children.
2. Overeating to cope with tension, anxiety, depression.
3. Childhood overnutrition may contribute to adult obesity (hyperplastic obesity).
72
what are the neurogenic factors that contribute to overweight & Obesity?
- Damage to hypothalamic areas such as ventromedial N.
(by hypophysial tumor , Frolich syndrome).
- Abnormalities of neurotransmitters or receptor mechanism in the neural pathways that control feeding.
73
what are the endocrine factors that contribute to **overweight & Obesity**?
Endocrine gland disorders (e.g. myxoedema, Cushing disease)
74
what is the definition of starvation?
Nothing taken by mouth except water.
75
what are the causes of starvation?
76
what are the metabolic changes that occur during starvation? **(Concerning CHO metabolism)**
77
what are the metabolic changes that occur during starvation? **(Concerning Fat metabolism)**
78
what are the metabolic changes that occur during starvation? **(Concerning Protein metabolism)**
79
what is the amount and site of CHO stores?
- CHO stores in the form of glycogen:
- Limited, 1/2 kg in liver and skeletal muscles.
80
when are CHO stores depleted?
Rapidly depleted in 12-24 hours without food.
81
what needs a continous supply of glucose?
CNS, PNS, Kidney, bone marrow, RBCs
82
what does the breakdown of 6.25gm of proteins form?
Breakdown of 6.25 gm proteins --->1gm N2 in urine.
83
when does vitamin deficiency appear in starvation? and what vitamines are mostly affected? and what does it lead to?
- Appear early.
- Vitamins, especially water soluble as B & C, do not last long in starvation.
- Lead to cellular dysfunction and death.
84
what is cachexia?
It is a metabolic disease of increased eneray expenditure leading to weight loss e.g wasting syndrome in AIDS and Chronic inflammatory disorders.
85
what are the muscle metabolic systems in exercise?
1. Phosphagen energy system.
2. Glycogen lactic acid system.
3. Aerobic system.
86
what does phosphagen energy system include?
ATP and cell Creatine phosphate
87
how long does phosphagen energy systes Provide energy?
- Together provide energy for only 8-10 seconds during exercise of maximal intensity.
88
what is the energy produced from ATP?
- Contain two high energy bond.
- Each of these bonds store 7,300 calories of energy per mole of ATP.
89
what is the amount of energy produced from creatine phosphate?
- Its high energy bond contain 10,300 calories per mole.
90
what is the amount of creatine phosphate?
- Present in much great amount in muscle than ATP.
- Most muscles have 2 to 4 times as much phosphocreatine as ATP.
91
How is new ATP Continuously formed?
It is essential that new ATP be formed continuously as follows;
1. Phospho-creatine ---> creatine + phosphate, phosphate used to regenerate ATP
2. Glycogen ---> lactic acid + ATP
3. Glucose, fatly acids or amino acids+ O2 ---> ATP
92
Duration of anaerobic system (glycogen lactic acid system)
- It can provide 1.3 to 1.6 minutes of maximal muscle activity in addition to 8-10 seconds provided by the phosphagen system in mild to moderate exercise.
93
Duration of aerobic system
- It is required for prolonged athletic activity ( unlimited Time as long as nutrients are available).
94
mechanism of release of energy by anaerobic system (glycogen lactic acid system)
- Stored glycogen form glucose by glycogenolysis.
- Then glucose is converted into 2 pyruvic acid + 4 ATP molecules.
- Then pyruvic acid is converted into lactic acid.
95
mechanism of release of energy by aerobic system
- It is the oxidation of glucose, FA, AA to produce energy in presence of O2 in mitochondria.
- This will produce acetyl COA which enter Krebs cycle with release of Co2 + H2o + 38 ATP molecules.
96
what are the advantages and disadvantages of anaerobic system?
**Advantage:** Rapid
**Disadvantrage:** Not Economic (Only 4 ATP)
97
what are the advantages and disadvantages of aerobic system?
**Advantage:** Economic (38 ATP)
**Disadvantrage:** Slow
98
recovery of muscle metabolic system after exercise
1. Recovery of phosphagen system.
2. Recovery of glycogen lactic acid system
3. Recovery of glycogen system
4. Recovery of aerobic system (oxygen debt)
99
what causes muscle fatigue and burning sensation?
lactic acid
100
how is lactic acid removed?
- Small portion of lactic acid is converted to pyruvic acid which enters Krebs cycle releasing H2O +CO2 + energy.
**In liver:** remaining lactic acid is converted into glucose.
- Glucose + O2 ---› ATP.
- Glucose ----> glycogen to replenish glycogen stores in muscle.
101
recovery of glycogen lactic acid system
102
recovery of glycogen system
- It requires days.
- In persons who consume a high carbohydrate diet, full recovery occurs in about 2 days.
- In people consuming a high fat, high protein diet or no food at all, show very little recovery even after as long as 5 days.
- It is important for athletes to consume a high CHO diet before undergoing athletic event and not participate in exhaustive exercise during the 48 hours preceding the event.
103
what is the amount of O2 stored in the body?
104
For how much time does all the stored O2 get used in heavy exercise?
**In heavy exercises:** all this stored O2 is used within a minute for aerobic metabolism.
105
how is the Stored O2 replenished after exercise is over?
- After exercise is over, The stored O2 must be replenished by breathing extra amounts of oxygen over and above normal requirements.
106
what is the amount of O2 used to replenish O2 stores, phosphagen system & lactic acid system?
- The amount of O2 used to replenish O2 stores is about 3.5 litres (The alactic O2 debt).
- The amount of O2 used to reconstitute the phosphagen system and lactic and system is 8 litres (the lactic acid O2 debt)
- So, Total is 11.5 litres.
107
nutrients used during muscle activity
**1) few second or minutes of exercise:** most of energy is derived from carbohydrate.
**2) At Time of exhaustion:** as much as 60% 80% of energy is derived from Fats.
108
what is the importance of glucose solution given to an athlete during an athletic event?
As it can provide 30% - 40% of energy required during prolonged events such as marathon races.
109
what is the rate of O2 consumption??
110
what is the definition of VO2 max?
is the rate of oxygen usage (in L/ min) under maximal aerobic metabolism.
111
what determines VO2 max?
Respiratory system and heart.
112
Do genetics play a role in VO2 max?
- Vo2 max of the marathoner may be genetically determined rather than accepted by Training
- e.g people who have greater chest sizes in relation to body size and stronger respiratory muscle may select themselves to become marathoners.
113
what is the definition of O2 diffusing capacity?
the rate at which O2 can diffuse from pulmonary alveoli into blood.
114
what determines O2 diffusing capacity?
**Training improve diffusing capacity:** as all pulmonary capillaries become perfused at their maximal rate due to increased blood flow through lungs.
115
what does (The normality of O2 pressure in arterial blood and CO2 Pressure in venous blood) demonstrate? and explain the mechanism
- Demonstrate the extreme ability of respiratory system to provide adequate areation of blood even during heavy exercise.
- Part of this effect is due to stimulation of the respiratory centre by same nervous signals that are transmitted from brain to muscles to cause exercise
116
blood flow to muscle during rest and exercise
- Resting blood flow 3.6ml/100g muscle per min.
- During maximal exercise 90ml per 100gm muscle per min.
117
what is the cause of increase in blood flow to muscle during exercise?
1. Intramuscular Vasodilatation due to increased muse metabolism.
2. Increased blood pressure.
3. Increased venous return and cardiac output.
4. Heart hypertrophy in well trained subjects which increase its effectiveness as a pump.
118
what is the amount of body heat converted into work during exercise?
20 -25% is converted into work.
119
where does the remainder of energy go during exercise?
The remainder of energy is converted into heat energy that create muscle work is also converted into heat because:
- Overcoming viscous resistance to in the muscles and joints.
- Overcoming the friction of blood flowing through the blood vessel.
120
what is heat stroke?
- Intolerable and lethal condition result from Prolonged exercise on a very hot and humid day that prevents the sweating mechanism from elimination heat.
121
what causes weight loss in athletes during athletic events?
result from loss of sweat.
122
how does weight loss during athletic events affect athletes and how is it treated?
- Can significantly diminish exercise performance.
- Therefore, it is essential to replace fluid as it is lost.
123
what is the cause of hyponatremia in athletes?
- **Exercise associated hyponatremia:** can occur after sustained physical exertion
- This hyponatremia is caused by loss of large amount of NACL in sweat.
124
what is the effect of hyponatremia in athletes?
hyponatremia cause tissue edema especially the brain and can be lethal.
125
what is the cause of hypokalemia in athletes?
- Potassium loss can result from increase of aldosterone during heat exertion acclimatization.
126
what should athletes take when performing exercises on hot humid days?
- All athletes should Take salt tablets especially when performing exercise on hot humid days.
127
what are the drugs related to athletes?
- Caffiene
- male sex hormones (Androgens and anabolic steroids)
- Amphetamine and cocaine
128
what is the effect of male sex hormones (androgens and anabolic steroids) on athletes?
- It can increase athletic performance under some condition, which is the result of increased muscle strength.
129
what are the side effects of male sex hormones (androgens and anabolic steroids) on athletes?
1. Risk of vasular diseases due to a hypertension
2. Increased LDL.
3. Decreasd HDL.
4. Decreased Testicular function
5. In women appearance of facial hair, thickening of voice and amenorrhea.
130
what is the effect of Amphetamine and cocaine on athletes?
Experiments have failed to prove the value of These drugs in increasing athletic performance except as a psychic stimulant.
131
what is the side effect of Amphetamine and cocaine on athletes?
1. Interactions between such drugs and the norepinephrine and epinephrine.
2. One of the possible causes of death under these conditions is over excitability of the heart leading to ventricular fibrillation.
