Thermoregulation Flashcards
1
Q
What is 98.6 in C?
A
37
2
Q
What is 100.4 in C?
Significance?
A
38
number we think when someone is starting to be febrile
3
Q
104 in C?
A
40 Danger zone!
4
Q
How to convert C to F?
A
Celsius x9/5 +32= F
39 x 9= 351
351 divided by 5= 70.2
70.2 + 32= 102.2 degrees F
5
Q
How can we take a bladder temp?
A
They have catheters with thermostats in them
6
Q
Surface measurement temps instead of core?
A
Axillary
Skin of the forehead
(with hand?)
7
Q
How is body temp controlled?
A
Balancing Heat Production Against Heat Loss
8
Q
Heat production is greater than heat loss =
A
rise in body temp
9
Q
What the control center for temp and what does it do?
A
(hypothalamus): Determines the “set point” which is range at which variable is maintained
10
Q
What is a receptor?
A
sensors that monitor environment & responds to changes
11
Q
Whats an effector?
A
Means for the control center’s response (output) to the stimulus
12
Q
What is metabolism determined by?
2 and then 5
A
- Basal rate of metabolism of all cells of the body
- Extra rate of metabolism caused by:
- Muscle activity (including shivering)
- Thyroxine
- Effects of epinephrine, norepinephrine and sympathetic stimulation of cells- speed things up/producing heat
- Increased chemical activity in the cells themselves
- Metabolism needed for digestion, absorption and storage of foods
13
Q
When is most heat produced?
2
A
Most heat is produced in deep organs at rest and skeletal muscles during exercise
14
Q
The rate at which heat is lost depends primarily on two factors:
A
- How rapidly heat can be conducted from where it is primarily produced to the skin
- How rapidly heat can be transferred from the skin to the surroundings
15
Q
What acts together to act as a heat insulator?
A
The skin and especially the subcutaneous tissue
because fat doesnt conduct heat well
16
Q
What kind of blood flow to the skin would happen in colder temps?
A
Low rate of skin flow (which occurs in colder temperatures), decreases heat conduction and less heat is lost
17
Q
What kind of blood flow to the skin would happen in warmer temps?
A
High rate of skin flow (which occurs in warmer temperatures), increases heat conduction and more heat is lost
18
Q
What is radiation?
A
loss of heat in the form of infrared heat rays (all objects not at absolute zero temp radiate such rays, including the walls and objects around us)
19
Q
When temperature of body > temperature of surroundings?
A
a greater quantity of heat is radiated from the body than is radiated to the body
20
Q
What is conduciton?
A
direct loss of heat via kinetics, or the energy of molecular motion. Transfer of heat through physical contact.
21
Q
What is convection?
A
Convection (or in other words, the wind chill process) – the removal of heat from the body by air currents
-Wind removes layer of air immediately adjacent to the skin and replaces it by new air much more rapidly
22
Q
What would happen with the convection process when one wears clothes?
A
Normal suit of clothes decreases heat loss by one half
Arctic-type clothing decreases heat loss to as little as one sixth
23
Q
How about conduction and convection with water?
A
Each unit portion of water adjacent to skin can absorb far greater quantities of heat than air can…
therefore the rate of heat loss to water is usually many times greater than the rate of heat loss to air
24
Q
What is evaporation?
A
loss of heat when water evaporates from body surface
25
What is insensible heat/sweat loss?
when unable to detect sweat – occurs at a rate of about 600-700ml/day
-Natural sweat when you arent expercising
26
How can evaporation of sweat be controlled?
by regulating the rate of sweating not for temp control
27
What part of the nervous system is heat loss controlled by?
sympathetic
28
Two types of sweat glands and what are they activated/regulated by?
Eccrine
Innervated by SNS via acetylcholine
Apocrine
Regulated by androgens - hormone regulated
29
If skin temperature > temperature of surroundings?
heat can be lost by radiation and conduction (along with convection)
30
Once temperature of surroundings > skin temperature?
the body gains heat by both radiation and conduction
31
The only way heat can be lost when the surrounding temp is greater than the skin temp is what?
evaporation
32
Systems responsible for heat loss
skin
cardiovascular
respiratory
33
HOw is skin responsible for heat loss?
vasodilatation and perspiration
34
How is cardiovascular responsible for heat loss?
increased cardiac output to compensate for peripheral vasodilatation with increased volumes of blood to periphery
35
How is respiratory responsible for heat loss?
some degree of evaporation
36
Where are heat sensitive cells located in the hypothalamus?
| And what do they signal
anterior
vasodilation of skin vessels
Decrease in heat production - inhibition of shivering and chemical thermogenesis
37
Where are cold sensitive cells located?
| And what do they signal
posterior hypothalamus
piloerection (goosebumps)
vasocontriction
shivering and thyroxine secretion
38
Predisposing factors to hyperthermia?
| 6
1. Age of the patient - can regulate as well as when they were younger
2. Health of the patient: i.e. diabetics can become hyperthermic more easily because of the damage to their autonomic nervous system
3. Medications: i.e. diuretics >dehydration, Beta Blockers
39
what happens in a heatstroke?
Heatstroke: Critical organ damage, significant mortality, markedly elevated body temperature, usually > 105’
40
What are heat cramps?
Painful contractions of larger muscle groups during or shortly after strenuous exercise in the heat
41
What are heat cramps caused by?
Usually caused by replacement of water without adequate salt resulting in a low sodium state in the muscles
42
How are heat cramps treated?
Treated with cooling measures, fluid and electrolyte replacement via IV
No changes in mental status or fever
43
Heat exhaustion is treated in the same way as heat cramps but what are the different symptoms?
Salt or water depletion in the face of heat stress
| Mild hyperpyrexia, nausea, vomiting, lightheadedness, dehydration with only minimal altered mental status
44
Pathology of heat stroke?
| 3
1. The body’s temperature rises markedly with eventual multisystem organ failure.
2. In sever cases patient may become confused or hostile.
3. Tachycardia and tachypnea with decrease blood pressure
45
Who is affected by exertional heatstroke?
younger, physically fit with normal thermoregulatory systems
46
Who is affected by classic heat stroke?
older or debilitated exposed passively to significant thermal stress over hours or days
47
Treatment of heat stroke?
| 7
1. ABC’s
| 2. Cooling measures to lower the patient’s temp to
48
What is hypothermia defined as?
a core temperature of less than 35C (95F).
49
What is especially at risk for hypothermia?
| 3
Elderly lose their ability to sense cold.
Neonates have large surface-to-volume ratio.
Both groups have limited ability to increase heat production and conserve body heat.
Individuals with an altered sensorium - drink too much and lose sense of cold, pass out in the snow
50
Heat is generated primarily by what and where?
cellular metabolism (prominently heart & liver)
51
How is heat primarily lost? (by what and how)
```
Loss by the skin and lungs:
Evaporation
Radiation
Conduction
Convection
```
52
Name three ways heat is preserved by?
1. Peripheral vasoconstriction
2. Shivering-skeletal muscle
3. Non-shivering thermogenesis
- Increase in metabolic rate from thyroid and adrenal glands
53
Differentiate b/w mild and moderate hypothermia?
mild: Tachypnea, tachycardia, hyperventilation
Moderate: Reductions in pulse rate & cardiac output, hypoventilation, A fib, junctional bradycardia & other arrhythmias can occur
no shivering
54
Whats the first thing to go in hypothermia?
kidney funciton
55
Symptoms of severe hypothermia?
| 5
1. Pulmonary edema
2. Oliguria
3. Areflexia
4. Coma
5. Hypotension, bradycardia, ventricular arrhythmias and asytole
56
What labs would we look at for a hypothermia diagnoses?
| 5
1. Electrolytes
2. Hematocrit
3. Coagulation studies
4. ABG’s
5. EKG: elevation of the J point—J or Osborne wave
57
Management of hypothermia?
| 2
ABCs
| Initiated rewarming by warminng the trunk first and them the extremities.
58
What steps are involved in actvie internal warming?
1. Can be used alone or with active external rewarming.
2. Pleural and peritoneal irrigation w/ warm saline.
3. Hemodialysis and cardiopulmonary bypass.
4. Warm humidified oxygen.
5. Warm IV fluids and bladder or GI irrigation w/ warm saline may be used.
59
How do we treat aarrhythmias caused by hypothermia?
| 3
1. Hypothermic heart very sensitive to movement & rough handling of the pt may precipitate arrhythmias.
2. A fib and flutter usually resolve w/ rewarming.
3. Management of V fib and asystole can be difficult—they may be refractory to therapy until the pt has been rewarmed (core temp of 86-90F).
60
What does the metabolic rate =?
ENERGY EXPENDITURE PER UNIT TIME
| (Calories/hour)
61
Factors influencing metabolic rate?5
Exercise
Food Intake
Shivering
Anxiety
Thyroid hormone
62
Whats the definition of basal metabolic rate?
Energy output of the body to perform essential metabolic functions
BODY’S “IDLING SPEED” (THE MINIMAL WAKING RATE OF INTERNAL ENERGY EXPENDITURE)
63
What is is affected by?
| 2
```
DIRECT CALORIMETERY(MEASURED RATE OF HEAT PRODUCTION)
INDIRECT CALORIMETERY (MEASURED OXYGEN CONSUMPTION)
```
64
Definition of the calorie?
THE AMMOUNT OF HEAT ENERGY NECESSARY TO RAISE THE TEMPERATURE OF 1 GRAM OF WATER 1 DEGREE CENTIGRADE
65
When does neutral energy balance occur?
input and output match
66
When does positive energy balance occur?
WHEN INTAKE EXCEEDS OUTPUT - ENERGY IS STORED AS GLYCOGEN OR FAT
67
Negative energy balance?
OCCURS WHEN OUTPUT EXCEEDS INTAKE- ENERGY STORES ARE DEPLETED
68
food intake is controlled by what and where are they loctaed?
CONTROLED BY HYPOTHALAMUS (partially)
FEEDING CENTERS (Lateral Hypothalamus)
SATIETY CENTERS (Ventromedial Hypothalamus)
69
What is glycogenesis?
conversion of glucose to glycogen when the glucose in the blood exceeds demand
70
What is glycogenolysis?
the breakdown of glycogen to glucose
71
What is gluconeogenesis?
the production of glucose, especially in the liver, from amino acids, fats, and other substances that are not carbohydrates
72
How are fatty acids synthesized?
the creation of fatty acids from acetyl-CoA and malinyl-CoA precursors through action of enzymes called fatty acid synthesis
73
What does fat breakdown end in?
the process in which fatty acids are broken down into their metabolites, in the end generating acetyl-CoA
74
one gram of glucose yeilds how many calories?
4
75
Beta cells produce what?
insulin
76
How does insulin act on blood sugar?
| 4
FACILITIES GLUCOSE ENTRY INTO CELLS
STIMULATES GLYCOGENESIS
INHIBITS GLYCOGENOLYSIS
INHIBITS GLUCONEOGENESIS
77
How does insulin act on fat?
| 3
INCREASES TRANSPORT INTO ADIPOSE CELLS
PROMOTES TRIGLYCERIDE SYNTHESIS
INHIBITS LIPOLYSIS
78
How does insulin act on protein?
| 3
PROMOTES UPTAKE OF AA BY MUSCLE AND OTHER TISSUE
PROMOTES PROTEIN SYNTHESIS
INHIBITS PROTEIN DEGRADATION
79
How is insulin secretion regulated?
| 4
```
Negative feedback mechanism:
regulated by levels of
BLOOD SUGAR
BLOOD AMINO ACIDS
GI HORMONES
PARASYMPATHETIC ACTIVITY
```
When you eat a candy bar or a meal, the presence of glucose, amino acids or fatty acids in the intestine stimulates the pancreas to secrete insulin
80
What is secreted by alpha cells?
glucagon
81
What does glucagon do?
| 5
1. Causes liver to convert stored glycogen to glucose
2. PROMOTE GLYCOGENOLYSIS
3. STIMULATE GLUCONEOGENESIS
4. PROMOTES FAT BREAKDOWN
5. ONLY IN LIVER: PROTEIN CATABOLISM
82
What do epinephrine, cortisol and GH all do?
| 3
1. ALL INCREASE BLOOD GLUCOSE AND FATTY ACIDS
2. CORTISOL INCREASES BLOOD AA AND DECREASES MUSCLE PROTEIN
3. GH DECREASES BLOOD AA AND INCREASES MUSCLE PROTEIN
83
Energy gained from the oxidation of what can be used to convert ADP to ATP?
carbohydrates, proteins & fats
84
What makes the most calories when metabolized?
fats
85
What are the final products of carbohydrate metabolism?
glucose 80%
| and fructose and galactose
86
After absorption from the intestines fructose & galactose are converted in the liver to....? (Why is this so important?)
1. glucose
| 2. so that we have stores of glucose when we need it
87
The liver stores glucose as glycogen** (By what process?)
glycogenesis
88
Describe the 4 things that happen in glycogenolysis?
1. Glycogen is broken down into glucose in the liver & skeletal muscle
2. “Branches” split away by phosphorylation, catalyzed by phosphorylase
3. Glucagon is released by the alpha cells in the pancreas when blood glucose falls
4. Epinephrine gets released when quick energy is needed & acts on the liver & skeletal muscle
89
What is gluconeogenesis?
Synthesis of glucose from noncarbohydrate precursors
90
What stimulates gluconeogenesis?
| 3
glucagon
| also maybe epi and cortisol
91
what signals cortisol to be released and then what does cortisol do?
Low carbohydrate levels in cells stimulate the release of cortisol which mobilizes cells to release proteins that are broken down into AA some of which are used as substrates
92
Look at pic of carb metabolism
statement
93
Where are almost all the fats in the diet absorbed into and via what medium?
absorbed into the intestinal lymph via absorbed into the intestinal lymph via chylomicrons
94
Where do chylomicrons empty into?
juncture of the jugular and subclavian veins
95
The chylomicrons are removed from the blood in the adipose tissue & liver by the activity of what?
lipoprotein lipase
96
What can fatty acids and TG be synthesized from?
from carbs and stored in adipose cells
97
When carbs are low what does insulin do?
reduces the rate of glucose use & increases fat metabolism
98
What do Epinephrine*, norepinephrine*, corticotropin, glucocorticoids and growth hormone activate?
hormone-sensitive triglyceride lipase
99
Where are proteins broken down into AA and where are they absorbed?
in the GI tract & absorbed into the blood
100
What does GH do?
Increases synthesis of cellular proteins
| Decreases glucose release and uses fatty acids for energy
101
What does Glucocorticoids do?
decrease protein in tissue
102
What does testosteroone do?
increases protien intissue
103
In BMI what makes you overweight?
obese?
underweight?
1. 25
2. 30
3.
104
How to find BMI?
BMI = Mass kg/Height m2
BMI = Mass lb/Height in2 x 703
