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Human Responses To The Environment > Homeostasis > Flashcards

Homeostasis Flashcards

1
Q

How is homeostasis brought about?

A

Negative feedback

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2
Q

What is negative feedback?

A

A control mechanism where a change from the set point is corrected by bringing about change in the opposite direction

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3
Q

What is the negative feedback system made up of?

A
  • receptor> detects a change, sends info to control centre
  • Control Centre> processes the information, activates corrective mechanisms
  • Effector> responds and corrects change
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4
Q

What are some examples of negative feedback?

A
  1. Glucose (blood sugar) concentration
  2. Carbon Dioxide concentration
  3. Water and salts
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5
Q

What is carbon dioxide negative feedback?

A
  • with a higher concentration of CO2, an increased amount of carbonic acid is produced
  • This lowers the PH,increases the acidity, of body fluids. (lower PH affects metabolism) Therefore excess co2 must be released.
  • Lower PH stimulates chemoreceptors in blood vessels in medula oblongata
  • The control centre (respiratory centre of Medulla) processes information about lower pH, activates corrective mechanism
  • The corrective mechanism, an increased number of impulses, sent to the effectors (respiratory muscles - diaphragm, intercostals)
  • Muscles contract, breathing rate will become faster and deeper, excess co2 will be breathed out , released in the lungs
  • Change in co2 concentration is corrected and conditions are returned to set point.
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6
Q

What is Thermoregulation?

A

The maintenance of a constant body temp by balancing heat production by heat loss

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7
Q

what is another name for heat production?

A

Thermogenesis

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8
Q

what is another name for heat loss?

A

thermolys

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9
Q

How is heat lost from the body?

A

body temp is higher than that of the environment heat by four physical processes

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10
Q

What are the four physical processes

A

Radiation
Conduction
Convection
Evaporation

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11
Q

what is radiation?

A

transfer of heat from a warm body to a cooler environment

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12
Q

what is conduction?

A

The transfer of heat from a hotter to a cooler object.

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13
Q

What is convection?

A

replacing of warm rising air by cooler air

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14
Q

What is evaporation?

A

loss of heat by using body heat to change sweat into water vapour.

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15
Q

How is the skin made up?

A
  • Layers of skin= epidermis, dermis, subcutaneous fat layer
  • sensory receptors = Ruffini corpuscle,Krause corpuscle
  • glands = sweat gland
  • position of capillary network.
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16
Q

How is skin adapted to regulate body temp?

A

It regulate body temperature by sweating, vasconstriction, vasodilation

17
Q

What does it mean when Thermo- receptors are sensitive to environmental temp changes

A

Ruffini corpuscles detect incerease, while Krause detect decrease
The receptors enable body to respond to temp change. Thus adapting to environmental changes

18
Q

What does the blood vessels help with?

A

Increase/ decrease blood flow by vasoconstriction or vasodilation

19
Q

What is the purpose of the sweat glands?

A

Increase/decrease amount of sweat secreted?

20
Q

What is the function of the subcutaneous layer of fat?

A

retain heat.

Fat insulate body against heat loss.

21
Q

why does vasoconstriction occur in the skin when its cold?

A

To prevent heat loss.

22
Q

Why is the hypothalamus regarded as the TEMPERATURE REGULATING CENTRE?

A

It constantly monitors the temp of the blood flowing through it.

23
Q

what are the stimulation that occur when the temp drops below 37°C

A
  • decrease in blood temp

- impulses from skin receptors registering cold environment e.g Krause corpuscles

24
Q

How does Hypothalamus prevent heat loss?

A

when control measures are set up,impulses are sent to the dermal arterioles and sweat glands.

25
Q

What happens when impulses are sent to the dermal arterioles?

A

The constriction of circular muscles which limits the flow of blood to capillary loops

26
Q

what other problem is associated with Vasoconstriction?

A

Reduced sweating by sweat glands, less blood flow to the sweat glands, decreasing secretion of sweat.
Less heat is lost through evaporation

27
Q

what is Hypothermia?

A

Drop in body temp to below 35°C due to uncontrolled exposure to cold

28
Q

What are some of the consequences of Hypothermia?

A

impaired brain activity

If uncorrected, cardiac arrest and coma, death

29
Q

What. The definition of homeostasis?

A

Ability to return to the set point

Human Responses To The Environment (10 decks)

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