Physiology 🫁 Flashcards
1
Q
what is the definition of body temperature?
A
Body temp. is a measure of heat concentration in the body.
2
Q
what are the values of body temperature?
A
- Normal body temperature ranges from : 36.6 - 37.2C.
- 37.5 C is called fever.
- 36.6 -35C is called subnormal temperature.
- 35C is called hypothermia.
3
Q
what is the absolute limit of life within body temperature?
A
20 - 43°C
4
Q
what are the types of body temperature?
A
- Core temp
- Surface (shell) temperature
5
Q
what is core temperature?
A
temp of the interior of the body (deep structures as brain, heart and lung)
6
Q
what is shell temperature?
A
- It is temp. of skin and underlying tissues which varies markedly according to environmental temp.
7
Q
Variation of body temperature
A
- Diurnal variations: (Circadian rhythm)
- Hormonal variations
- Psychological variation
- Variations with age
8
Q
normal variation of shell body temperature
A
- Skin covering head, chest and abdomen have high temp 34°C
- Skin covering large ms of leg and arm 30°C.
- Skin covering small ms of hands and feet 28°C.
9
Q
diurnal variation of body temperature
A
- Lowest temperature at 6.a.m
- Slightly higher in early morning.
- Highest in late afternoon due to metabolic reaction.6 p.m
10
Q
hormonal variation of body temperature
A
- Body temperature increase at time of ovulation about 0.5oc.
- Thermogenic effect of progesterone in pregnant women.
11
Q
psychological variation of body temperature
A
inc body temperature at time of emotions and exercise.
12
Q
variation of body temperature with age
A
Premature babies: ↓ temperature.
Children: ↑ temperature.
Adults: Diurnal variations.
Old age: ↓ temperature.
13
Q
what is used to measure body temperature?
A
medical thermometer.
14
Q
what are the types of medical thermometers?
A
1- Glass (with mercury) thermometers:
2- Digital electronic thermometers:
3- Ear (Infra red) thermometers
4- Temperature strips (Head strips)
15
Q
structure of glass thermometer
A
- Medical consists of mercury store, and graduated tube (35C to 42C)
16
Q
why is there a construction in glass thermometer?
A
There is a constriction between mercury store and tube to allow passage of mercury from the store to tube only when its temperature is raised
17
Q
how do digital thermometers measure temperature?
A
with a heat sensor
18
Q
how long does it take a digital thermometer to measure?
A
usually in less than 30 seconds.
19
Q
how do ear thermometers (infra-red
thermometer) work?
A
- electronic thermometers work by remote sensing: an infrared sensor responds to the radiation spectrum emitted from the location
- a thermometer which senses the temperature of the eardrum without touching it is inserted into the ear canal).
20
Q
what are temperature strips?
A
- A liquid crystal thermometer contains heat-sensitive (thermochromic) liquid crystals in a plastic strip that change color to indicate different temperatures.
21
Q
what are the methods of Temperature of measurement?
A
- Oral method = standard method, most popular.
- Axillary method. (0.5°C lower than oral temp.).
- Rectal method (the most accurate). (0.5°C higher than oral temp.).
- Meatal method by ear thermometer.
22
Q
what affects oral method of temperature measurement?
A
- Oral temp. is affected by hot or cold fluids, mouth breathing, gum chewing and cigarette smoking
23
Q
Meatal method by ear thermometer
A
- By flexible probe inserted close to tympanic membrane.
- This method uses an infrared sensor to measure the flow of heat from the tympanic membrane and ear canal.
- The method is easy and correlate well with rectal temperature.
24
Q
what are the steps of oral method of Temperature measurement?
A
25
what are the advantages and disadvantages of oral method of temperature measurement?
26
what are the steps of axillary method of temperature measurement?
as oral method but put in axillary space
27
what are the advantages and disadvantages of axillary method of temperature measurement?
28
what are the steps of rectal method of temperature measurement?
as oral method but put in anal canal
29
what are the advantages and disadvantages of rectal method of temperature measurement?
30
what is the definition of fever?
is an elevation of body temperature due to (resetting of the hypothalamic thermostat)
31
pathogenesis of fever
- Release of endogenous pyrogens(EP)
- Resetting of hypothalamic thermostat to higher level
- (EP) include:IL6,IL1 and TNF
32
what are the stages of fever?
- Stage of chills
- Stage of Flush
- Stage of defervescence
33
stage of chills
- The hypothalamic thermostat resetted to new level above 37
- The hypothalamic center feels cold activate anti drop mechanism
- The person feels cold(shivering)
34
stage of flush
- Body temp reach the new set point
- The person feels warm
- Skin become warm and flushed
35
stage of defervescence
- If the causative factor is removed
- The set point drop to normal
- Cutaneous vasodilatation and sweating
36
what are the causes of hypothermia?
- Exposure to cold weather
- Anesthesia
37
what is hyperthermia?
- Increase in body temp without change in set point of the hypothalamic thermostat
38
what are the causes of hyperthermia?
- Severe exercise
- Heat cramb
- Sun stroke
39
what is the definition of metabolic rate?
It is the rate of energy expenditure in the body / unit time
40
determination of metabolic rate
1. Directcalorimetry.
2. Indirectcalorimetry.
41
principle of direct calorimetry
Heat lost from the body by conduction, convection, radiation and evaporation, so when this heat is calculated, it equals MR.
42
what is direct calorimetry formed of?
- It formed of 2 layers of copper with heat insulating material in between to keep temperature inside constant.
It contains a metal tube containing water running from side to side.
- It contains glass filled with H2SO4 to absorb water and another glass with soda lime to absorb CO2.
43
Steps of calculation of metabolic rate
1. Heat lost by conduction, convection and radiation → measured by water running through metal tube which absorbs heat loss by such mechanisms→ (A).
**A = (T2-T1) x amount of water x specific heat of water**
2. b) Heat lost by evaporation → measured by weighting H2SO4 before and after the experiment → the difference is the amount of water vapour through lung and skin→ (B).
**B = weight of evaporated water x 0.58 C (latent heat of evaporation)**
3. Calculation of **MR = A + B**
44
what are the disadvantages of direct calorimetry?
1. Expensive.
2. Few, only 3 present in America.
45
principle of indirect calorimetry
More than 95% of energy expended in the body is derived
from reaction of O2 with different foods.
46
steps of calculation of indirect calorimetry
- Metabolic rate = O2 heat value x O2 consumption.
Steps:
a) Determine heat value of O2.
b) Determination of the oxygen consumption.
47
determination of heat value of oxygen
1. Determine the volume of O2 consumed/hour.
2. Determine the volume of CO2 production/hour
3. Determine RQ which equals carbon dioxide produced divided by oxygen consumed
4. From RQ → determine heat value of O2 using the metabolic tables.
48
determination of O2 consumption
2 methods can determine oxygen consumption
- Open circuit method.
- Closed circuit method.
49
what is the Apparatus used in closed circuit Method of determination of Oxygen consumption?
The apparatus used is a recording spirometer the bell of which is filled with oxygen. The mouth piece is tightly placed in the subject's mouth and his nose is closed.
50
steps of closed circuit method of determination of oxygen consumption
The subject breathes O2 from the apparatus through the inhalation tube, and returns the expiratory air through the exhalation tube, which is connected to a container filled with soda lime to absorb CO2.
51
what is the measuring unit of oxygen consumption?
oxygen consumption/liter/hour
52
steps of open circuit method in determination of O2 consumption
- In this method the subject breathes through a valve system so arranged that it separates the inspired from the expired air.
- The volume of expired air is measured by collecting it in a spirometer (Tissot method) or a rubber bag (Douglas method).
53
what is a simple is easier method of determination of metabolic rate?
1) Determine volume of O2 consumption/hour.
2) Using average RQ of 0.82 which is the RQ of post
absorptive stage 12-14 hours from the last meal,
3) From the table → heat value of O2.
4) MR = O2 consumption x heat value of O2.
54
what is basal metabolic rate?
It is the metabolic rate under basal conditions or it is the rate of heat loss from the body under the basal conditions.
55
what are basal conditions?
1. Complete physical,mental and emotional rest.
2. The subject is in the post-absorptive state 12-14 hours after the last meal to avoid the stimulating effect of food (S.D.A.)
3. Comfortable external temperature neither shivering, nor sweating.
4. Person must be awake because sleep↓es BMR.
5. You must assure the person that the test is simple and harmless.
56
how is basal metabolic rate measured?
**A) By direct calorimetery:**
BMR = A (heat lost by conduction, convection and radiation)+ B (heat lost by evaporation) Body surface area (m2)
**B) By indirect calorimetery:**
BMR = Heat value of O2 x O2 consumption (L/Hr) Body surface area (m2)
**(Body surface is measured from Dubois charts)**
57
what are the physiological values of BMR?
* At birth: 25C/m2/hour
* At 2 years: 60 C/ m2/hour
* In normal adult male 20 years old:
* Male: 40 C/m/hour
* Female: 36 C/m/hour
* Every 10 years increase : BMR decrease by 1 C/ m2/hour.
58
clinical expression of the BMR
Clinically, the B.M.R is calculated as the % deviation from the standard value.
59
what does the percent of deviation of basal metabolic rate equal?
The % deviation= (Measured value – standard value) / standard value x 100 = ± 10 -15 % Standard
60
what are the physiological factors that affect BMR?
1. Age.
2. Sex.(male> female by 10%)
3. Race ( white > dark people)
4. Physical habits (athletes higher by 10 %)
5. Dietetic habits (protein diet consumption increase BMR)
6. Climate (cold zone 10% more)
7. Pregnancy, lactation and menstruation; increase BMR
8. Anxiety and tension; increase BMR
61
what are the pathological factors that affect BMR?
**A. BMR is increased in the following conditions:**
1. Hyperthyroidism.
2. Hyperfunction of adrenal medulla (pheochromocytoma).
3. Hyperfunction of adrenal cortex.
4. Hypoparathyroidism due to increased muscle tone.
5. Fevers.
**B. BMR is decreased in the following conditions:**
1. Hypothyroidism.
2. Hypofunction of adrenal cortex.
3. Prolonged starvation.
4. Hypothermia.
