2. Definition:
Chemical changes occur in the body.
1) Catabolic reactions:
* Definition: breakdown of large organic molecule with release of energy:
Protein (CHO or fat) CO2 + H2O + Energy. [ATP] used as:
a) Work energy. 25% used for essential functions.
b) Heat energy. 75%
2) Anabolic reactions:
Synthesis of organic large molecules with uptake of energy.
4. *Definition:
The rate of energy production [kcal] / unit time (on hour) /m2
surface area.
*Measured under 3 basal conditions:
1- Complete physical & mental rest:
for at least 1/2 an hour but without sleep as
sleep
decreases the BMR by 10%.
2- Post - absorptive state:
12-14 hours after the last meal to avoid specific
dynamic action (SDA).
3- In a comfortable external temperature:
Neither shivering nor sweating
5. also known as thermic effect of food (TEF)
or dietary induced thermogenesis (DIT), is the
amount of energy expenditure above
the basal metabolic rate due to the cost of
processing food for use and storage
6. The thermic effect of food is one of the
components of metabolism . A commonly
used estimate of the thermic effect of food is
about 10% of one's caloric intake, though the
effect varies substantially for different food
components. For example, dietary fat is very
easy to process and has very little thermic
effect, while protein is hard to process and
has a much larger thermic effect.
7. The thermic effect of food is the energy
required for digestion, absorption, and
disposal of ingested nutrients. Its magnitude
depends on the composition of the food
consumed:
Carbohydrates: 5 to 15% of the energy
consumed
Protein: 20 to 35%
Fats: at most 5 to 15%
8. Rate of energy input [food] = Rate of energy
output.
Accordingly:
1] If energy input > energy output :
+ve energy balance.
Increase the body weight.
2] If energy input < energy output :
-ve energy balance.
Decrease the body weight.
The adult basal level of caloric intake = 2000
kcal/day.
9. * Normal standard:
For adult man = 40 Kcal / hour / m2 ± 15%.
* Clinically: it is expressed as % deviation from normal standard:
E.g. if BMR = 60 Kcal /Hr/ m2. ……….Thus, it is + 50%.
* BMR is expressed per unit surface area and not per unit body
weight because
It is through the skin that most heat is lost to the atmosphere.
* It is the unavoidable cost of life:
I.e. metabolic activities of heart, respiratory muscles, liver,
muscle tone.
11. 1] Age:
Newly born infants = 25 KCal/h/m2
2- 5 years = 60 KCal/h/m2
Puberty = 55 KCal/h/m2
Adult = 40 KCal/h/m2 ±15%
Old age:1 Kcal decrease /10 years
2] Sex: BMR is decreased in female than male by 7% due to:
Greater fat stores [Fat has little metabolic activity].
3] Pregnancy and lactation: increase BMR due to:
++ Thyroid activity, & the added metabolism of the fetus.
4] Sleep: decrease BMR by 10% due to:
-- Muscle tone & --sympathetic activity.
5] Environmental temperature:
Cold shivering increase the MR maintains normal body temperature.
Hot increase the body temperature increase the MR.
6] Food: Increase the MR by the specific dynamic action.
7] Muscular exercise: Increase the MR.
12. Factors that increase MR:
1) Hyperthyroidism ++MR up to + 100% [except brain].
2) Hyperpituitarism:
a) ++ GH ++ MR.
b) ++ TSH ++ T4 ++ MR.
3) Hyperadrenalism: ++ catecholamines ++ MR.
4) Fevers: increase the body temperature ++ MR.
5) Heart failure due to ++ activity of respiratory muscles to
fight dyspnea.
6) Blood diseases: as polycythemia - the hematocrit (the volume
percentage of red blood cells in the blood) is elevated- due to
over activity of bone marrow.
13. increase in the number of red blood
cells ("absolute polycythemia") or
decrease in the volume of plasma ("relative
polycythemia").
14. 1) Hypothyroidism: --MR by 40% of the normal.
2) Hypopituitarism: due to atrophy of endocrine
glands.
3) Hypothermia:
-- body temperature by 1oC--MR by 13%.
4) Under-nutrition: due to -- energy producing cell
nutrients.
5) Hypo-function of adrenal cortex: due to --
corticoids.
15. Factors regulating the activity of appestate center:
1) Psychological conditions:
Vision, smell of food affect centers in limbic lobe.
2) Receptors in the mouth & esophagus:
Monitoring food intake.
3) Stomach distension: stop of feeding.
4) GIT hormones and insulin: stimulate satiety center.
5) The blood levels of glucose, amino acids, fatty acids &
glycerol affect hypothalamus.
6) SDA of food ++body temperature inhibition of food
intake.
7) Cold environment ++ food intake.
N.B Satiety center and appetite center are located in the
hypothalamus
16. a) The lipostatic hypothesis:
* Adipose tissue:
Humoral signal [proportionate to the amount of fat].
Acts on the hypothalamus --food intake &++energy
output.
b) The gut peptide hypothesis:
* Food in the GIT secrete GIT polypeptides.
Acts on the hypothalamus --food
intake.
c) The glucostatic hypothesis:
* Glucose utilization in the hypothalamus sensation of
satiety.
d) The thermostatic hypothesis:
* --Body temperature ++ appetite.
* ++Body temperature -- appetite.
17. 1 – burn cho
2- burn stored glycogen
3- burn fat
4- burn proteins of muscles
5- burn proteins of blood plasma proteins
and immunoglobulins
6-died
Editor's Notes
الانسان لا يستخدم ال 25% كلها و لكن بيستخدم مثلا 17 ال 18 % فقط و لما لاعبين الكرة بياخدوا منشطات دا علشان يحاولوا يوصلوا الى 25 %
ال 75% بيضيعوا او حايا بيقولوا انهم بيستخدموا مع بعض الانزيمات و التفاعلات
Satiety center and appetite center are located in the hypothalamus
ملحوظة هامة وجود انسولين كتير معناه ان الشخص واكل كتير فحصل افراز كتير للانسولين فيعدى فى الدم على مراكز الشبع فى المخ فيشعر ان الانسولين كتير اذن واكل
Lipostatic hypothesis المخ بيعمل monitor لل free fatty acids (ffa)اللى فى ال blood و احنا عارفين ان ال ffa بيجى من ال fat metabolism فلو ال brain شاف ان ال ffa قليلة اذن الfat metabolism كان قليل اذن الشخص دا شيعان علشان كدا مش بيحرق ال fat ودا ب يعمل stimulation لل satity center و اذا كان ال ffa عالية يبقى ال fat metabolism كانت عالية يبقى بيكسر fat كتير و دا معناه ان هو مش بياكل اذن فهو جعان و ال brain بيعمل inhibition لل satiety center و يخليه يحس بالجوع hunger علشان ياكل
باقى النظريات التلاتة التانين بتعتمد على ان satiety center فى ال hypothalumusلما بتحس ان الحاجة موجودة فى الدم بتخليه يحس انه شبعان و مياكلش لكن لما الحاجة مبتبقاش موجودة ال center بتحس انها مش موجودة و بتخليه يحس بالجوع و ياكل