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1020 Biosciences 2 > Homeostasis > Flashcards

Homeostasis Flashcards

1
Q

Define the term homeostasis

A

Homeostasis is the maintenance of a stable internal environment in a controlled condition.

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2
Q

Describe the components of a feedback system.

A

A feedback loop is a system used to control the level of a variable in which there is:
- An identifiable receptor (sensor)
- A control centre (integrator or comparator),
- Effectors, and methods of communication.

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3
Q

What is a positive feedback system?

A

A feedback loop that reinforces a changed variable in a controlled environment.

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4
Q

What is a negative feedback system?

A

Negative feedback is the action taken by the body to return something to a normal/optimum level following a deviation from the optimum level.

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5
Q

Give an example of a positive feedback system.

A

When an infant suckles on the breasts of the mother, a chemical called prolactin gets released, which increases milk production. More suckling leads to more prolactin release, which promotes more milk production. When the child is no longer hungry and stops breastfeeding, prolactin stops getting released and as a result, milk production also stops.

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6
Q

What are the 4 principal routes of heat loss from the body to the environment?

A

Radiation

Conduction

Convection

Evaporation

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7
Q

Explain radiation in heat loss.

A

Heat travelling through air.

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8
Q

Explain Conduction in heat loss.

A

Exchanging heat through touch.

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9
Q

Explain Convection in heat loss.

A

The upward movement of heat.

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10
Q

Explain Evaporation in heat loss.

A

Evaporation is the process of losing heat by converting water to gas (evaporation of sweat).

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11
Q

2.1 Compare and contrast different methods of measuring body temperature (oral, axillary, tympanic and rectal)

A

Rectal= 36.6°C to 38°C
Ear = 35.8°C to 38°C
Oral = 35.5°C to 37.5°C
Axillary = 34.7°C to 37.3°C

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12
Q

2.2 State the normal body temperature range, distinguishing between peripheral and core temperatures and identifying the cyclic variations in normal temperature.

A

In a cold environment, thermoregulators send signals to the hypothalamus, which, during effector changes, will send the heat to the core, whereas less heat will go to the peripheral.

Cyclic variations of a healthy body vary by about 0.5 °C.

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13
Q

Discuss the ways the body can gain heat.

A

Shivering (Radiation)

Vasoconstriction (Radiation and Conduction)

Behavioural such as heating and clothes (Radiation and Conduction)

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14
Q

Discuss the ways the body can lose heat.

A

Perspiration. (Evaporation)

Vasodilation. (Radiation and Conduction)

Behavioural, such as opening a window or sitting in front of a fan (Convection)

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15
Q

Discuss the role of the hypothalamus in the regulation of temperature.

A

Internal body regulator (control centre) that regulates the normal (37c) temperature of the body.

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16
Q

Describe the negative feedback system of the temperature parameter when it is low.

A
  1. Body temperature is low.
  2. Thermoreceptors in the hypothalamus stimulate heat-producing mechanisms.

3a. Superficial arteries are constricted, reducing heat loss to the air. Blood flow to the digestive system decreases.
3b. Shivering increases aerobic respiration in the muscles in releasing heat.
3c. Thyroid stimulates cells to increase metabolic heat production.

  1. Body temperature increases.
17
Q

Describe the negative feedback system of the temperature parameter when it is high.

A
  1. Body temperature is high
  2. Thermoreceptors in the hypothalamus stimulate heat-releasing mechanisms.

3a. Superficial arteries are dilated, causing flushing and increasing heat loss to the air. Blood flow is not diverted away from the digestive system.
3b. Sweat initiated in the skin.
3c. Thyroid stimulates cells to decrease metabolic heat production.

  1. Body temperature decreases.
18
Q

Describe the negative feedback system of the blood pressure parameter when it is low.

A

Baroreceptors will detect the low blood pressure, sending nerve impulses to the medulla oblongata (brain), which will send nerve impulses to the heart to increase its rate and the blood vessels to constrict, then returning to homeostasis.

19
Q

Describe the negative feedback system of the blood pressure parameter when it is high.

A

Baroreceptors will detect the high blood pressure, sending nerve impulses to the medulla oblongata (brain), which will send nerve impulses to the heart to decrease its rate and the blood vessels to dilate, then returning to homeostasis.

20
Q

Describe the negative feedback system of the parameter of fluid balance with fluids with ADH

A
21
Q

Describe the negative feedback system of the parameter of fluid balance with fluids with Aldosterone.

A
22
Q

Describe the negative feedback system of the parameter of blood glucose concentration.

A
23
Q

Describe the oral method of measuring body temperature.

A

A glass thermometer placed under the tongue + the lips closed around the probe
- wait 3-5 mins before taking the probe out

24
Q

Describe the axillary method of measuring body temperature

A
  • place the tip of thermometer in centre of the armpit
  • tuck patient’s arm closely against their body
  • leave thermometer for 1 min
25
Q

Describe the tympanic method of measuring body temperature.

A
  • insert the probe into the auditory canal
  • thermometer probe scans + after a few seconds records the amount of infrared energy emitted by the tympanic membrane
26
Q

Describe the rectal method of measuring body temperature.

A
  • lubricated blunt-tipped glass thermometer inserted 4-5 cm into the anal canal at 20-degree angle from horizontal
  • hold for 3 mins
  • used for children + patients who cannot / will not cooperate fully
27
Q

What is the normal range of body temperature? (peripheral + core)

A

Core = 37 degree celcius
Peripheral = 1-6 degrees lower than core temp

28
Q

Identify the cyclic variations in normal temperature.

A
  • circadian temperature rhythm
  • the lowest body temp occurs at around 4am
  • the highest body temp occurs at around 6pm
29
Q

Discuss the importance of regulating basal metabolic rate (BMR) in the control of temperature.

A
  • the rate at which heat is produced = metabolic rate (measurement = BMR)
  • it helps to regulate body temperature when the environmental temp changes
  • e.g when the environment temp increases, the metabolic rate in the body decreases

1020 Biosciences 2 (17 decks)

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