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Medicine Sem 1 > Physiology 2 week 6 > Flashcards

Physiology 2 week 6 Flashcards

1
Q

When does the body temperature rise?

A

When heat production exceeds heat loss

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2
Q

When does the body temperature decrease?

A

When heat loss surpasses heat production

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3
Q

What is heat a by product of?

A

Metabolism

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4
Q

Name 3factors heat is influenced by?

A
  • Basal metabolic rate of body cells
  • Increased metabolism from muscle activty
  • Effects of hormones like throxyine, growth hormones and testtosterone
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5
Q

Name and describe the 2 steps heat transfer occurs

A
  1. Conducting heat from internal organs to the skin.

2.Transferring heat from the skin to the surroundings

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6
Q

Name insulators in the insulator system and their role

A
  • Skin, subcutaneous tissues and fat
  • They reduce the heat loss
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7
Q

What is the role of insulation system

A

It allows skin temperature to mach the surroundings while maintaining stable internal core temperatures

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8
Q

Explain how the blood vessels in the skin work

A

-Skin has a venous plexus beneath it, recieving blood from the capillaries
- In hands, feet and ears arteriovenous anastomes direclty supply bood to the plexus.

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9
Q

What is the role of High blood flow?

A
  • It effectively conducts heat from the body core to the skin
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10
Q

What is the function of reduced blood flow

A
  • Minimizes heat transfer
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11
Q

What is the blood flow to the skin regulated by and controlled by?

A

-It is regulated by vasoconstriction of arterioles and arteriovenous anastomoses.
Controlled by the sympathetic nervous system in response to changes in body core and environmental temperature.

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12
Q

Name the 3 methods of heat loss

A
  • Radiation
  • Conduction
  • Evaporation
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13
Q

What happens in Radiation?
When does heat loss occur ?

A
  • Heat radiates as infrared rays
  • Heat loss occurs if the bodys temperature is higher than its surroundings ?
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14
Q

What happens in conduction?

How is heat transferred ?
When does heat transfer stop?

A
  • Heat transfers via direct contact
  • Heat transfer stops when air temperature equals skin temperature unless the heated air is replaced
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15
Q

What happens in convection?

How is heat transferred?

A
  • Heat is transferred from the skin to air and carried away by moving air currents
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16
Q

Compare SHC, heat loss and insulating layers in water and air

A
  • Water has a higher SHC than air
  • Heat loss in water is greater than in air
  • Both have not insulating layers
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17
Q

What is insensible evaporation?

A
  • When water evaoprates insensibly from the skin to the lungs even when a person is not sweating
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18
Q

When is evaporation neccessary

A

When the surrounding air temperatures exceeds the skin temperature , so then heat is gained from the environment via conduction and radiation

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19
Q

What happens to individuals with an absence of sweat glands

A

They cannot loose heat effecitvely leading to heatstroke risks

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20
Q

What is the effect of clothing on heat loss

A
  • Clothing traps the air near the skin, reducing heat loss by conduction and convection
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21
Q

What does coating clothes in reflective metals do?

A
  • Enhances insulation by reflecting radiant heat back to the body
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22
Q

Does wet clothes reduce or increase heat loss

A

increases heat loss

23
Q

What is the role of the Anterior hypothalamus preoptic area

A
  • Stimulates sweating in response to heat
24
Q

Explain the Autonomic pathway for sweating

A
  • The sweating signals travel through cholinergic sympathetic nerve fibers, which release acetylcholine
25
Q

Explone the hormonal influence in response to sweating

A
  • Epinephrine and Norepinephrine frome the adrenal medulla can also stimulate sweat glands indirectly during exercise
26
Q

Describe the structure of a sweat gland and its functions

A
  • Coiled secretory protein( produces percursor fluid)
    -Duct portion ( modifies fluid)
27
Q

What happens to Na and Cl at low sweating rates

A
  • ## They are reabsorbed, reducing their concentrations
28
Q

What happens to Na and Cl at high sweating rates

A

-There is less reabsorption, resulting in higher Na and Cl concentrations

29
Q

What is the body temperature regulated by?

A
  • The nervous feedback mechanisms and these mechanisms operate via the temperature regulating centers in the hyopthalamus
30
Q

What does the anterior hypothalamic preoptic area contain?

A
  • Heat senesitive nerons
  • Cold sensitive neurons
31
Q

What happens when the anterior hypothalamic preoptic area is heated?

A
  • Profuse sweating occurs across the body
  • The skin blood vessels dilate
32
Q

What receptors does the skin have?

A

Cold and warmth receptors

33
Q

Where are the deep body receptors found?

A
  • Spinal cord, abdominal viscera around great veins in upper abdomen
34
Q

What is the role of deep body detectors

A
  • They detect core body temperature , focusing in cold detection to prevent hypothermia
35
Q

Name the 3 reflex responses to chilling(cold)

A
  • Shivering- increase heat production
    -Sweating- reduce heat loss
    -Vasconstriction- minimise heat loss from the skin
36
Q

What does the Posterior hypothalamus integrates?

A
  • Peripheral temperature signals
    -central signals from the anterior hypothalamic preoptic area
37
Q

What are the mechanisms that take place to decrease the body temperature when it is too high

A
  • Vasodilation:
  • Sweating
    -Decrease in heat production:
  • inhibiting shivering and chemical thermogenesis
38
Q

What happens in vasodilation

A
  • The blood vessels in the skin dilate due to the inhibition of sympathetic vasoconstrictor centres in the posterior hypothalamus
39
Q

What are the mechanisms that take place to increase the body temperature when it is too cold

A
  • Vasoconstriction
  • Pilo erection
  • Increase in heat production:
    stimulating shivering and thyroxine secretion
40
Q

What is the function of vasoconstriction and what is it caused by

A

-Reduces heat loss
Caused by the stimulation of the posterior hypothalamus sympathetic centers

41
Q

What is the function of throxyine in increasing the body temperature

A
  • Boosts cellular meabolism, enhancing heat production
42
Q

What is shivering controlled by

A
  • Primary Motor center for shivering
43
Q

critical body

What is the set point

A
  • Critical body temperatures that the temperature control mechanisms aim to maintain
44
Q

What happens at temperatures above the set point

A
  • Heat loss exceeds heat production causing a decress in body temperature
45
Q

measure of

What is the feedback gain

A
  • A measure of the effectiveness of temperature regulation
46
Q

What influence does the skin receptors have on the set point

A

-Signals from the skin receptors can modify the hypothalamic set point

47
Q

Give 2 examples of psychological behavioural adjustments

A
  • Feeling cold- move to a warmer area
  • Feeling warm- Move to a cooler area
48
Q

What is the most effective mechanism for maintaining body heat

A
  • Behaviour control
49
Q

What is a fever

A
  • Elevated body temperature beyond the normal range
50
Q

What is a fever caused by

A
  • Brain abnormalities,Toxic substances,infections,brain tumours
51
Q

What is the mechanism of a fever- when does it occur

A
  • When the hypothalamic set point is raised dye to pyrogens
52
Q

Where do pyrogens originate from

A
  • Toxins
53
Q

What is the role of pyrogens

A
  • They act directly on the hypothalamus to increase the set point
    o
  • They act indirectly through intermediates like (cytokines)

Medicine Sem 1 (18 decks)

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