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Y1 - Body Logs > Lecture 1 - Homeostasis > Flashcards

Lecture 1 - Homeostasis Flashcards

1
Q

What is homeostasis?
(Short definition)

A

Homeo = sameness
Stasis = standing still

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2
Q

What is homeotstasis?
(Long definition)

A

The ability of an organism or cell to maintain a stable internal environment by marinating a dynamic equilibrium of conditions despite any changes going on around it.

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3
Q

What type of mechanisms maintain homeostasis?

A

Feedback loops

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4
Q

What are the 2 types of feedback loops?

A

Positive feedback
Negative feedback

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5
Q

How do negative feedback loops work?

A

Stimulus is detected by a receptor
Control centre produces response to act against the change
Effector carries out the response determined by the coordination centre

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6
Q

How does a positive feedback loop work?

A

Stimulus is detected by receptors
The control centre decides to enhance/add to the stimulus
Effector actually enhances the stimulus

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7
Q

Give 3 examples of conditions that are regulated by negative feedback loops:

A

-Temperature
-pH
-Water balance

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8
Q

Give 2 examples of events that are under positive feedback control:

A

-Child birth (Ferguson reflex)
-Blood clotting cascade

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9
Q

In negative feedback loops, when does the negative feeback stop?

A

When the effector ceases

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10
Q

IN positive feedback, when does the positive feedback stop?

A

When the initiator /stimulus ceases

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11
Q

What is the normal core body temperature range?

A

36.5ºC - 37.5ºC

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12
Q

What devices can be used to measure core body temperature?

A

Infra-red skin thermometer
Tympanic thermometer
Temporal thermometer

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13
Q

Where is the temperature control centre in the body?

A

Hypothalamus

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14
Q

What are the responses to thermoreceptors detecting low body temperature?

A

Vasoconstriction
Shivering
Piloerection
Curling up

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15
Q

How does Vasoconstriction help keep core body temperature warm?

A

Arterioles constrict reducing blood flow to skin

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16
Q

How does shivering help increase core body temperature?

A

Rapid contraction and relaxation of skeletal muscle produces heat via respiration

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17
Q

What are the responses to thermoreceptors detecting the body temature is too high?

A

Vasodilation
Sweating
Pilorelaxation
Stretching out

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18
Q

Between what temperature is a person classed as being normal but cold?

A

36.5º - 35º

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19
Q

What is the temperature range for having Mild Hypothermia?

A

35ºC - 32.1ºC

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20
Q

What is the temperature range for having Severe Hypothermia?

A

32ºC - 28ºC

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21
Q

What happpens when the core body temature is below 28ºC?

A

No vital signs

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22
Q

When can you classify someone ass being dead when their core body temperature is below 28ºC?

A

They’re not dead until they are WARM AND DEAD

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23
Q

What temperature range is somebody classed as being normal but warm?

A

37.5ºC - 38ºC

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24
Q

What temperature range doe somebody have a fever?

A

38ºC - 39.9ºC

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25
Q

What temperature range can somebody have heat stroke and heat exhaustion?

A

Over 40ºC

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26
Q

What is the Acid-Base balance?

A

The homeostasis of pH within a very narrow range in the body

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27
Q

What is the normal plasma pH value?

A

7.35 - 7.45

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28
Q

What are the 2 major organs responsible for maintaining acid-base balance?

A

Lungs-Respiratory balance
Kidneys-Metabolic balance

29
Q

How does a change in [H+] by a factor of 2 change pH?

A

Changes pH by 0.3

30
Q

What is used to measure blood pH?

A

Arterial Blood Gas test

31
Q

What are the 3 blood buffer systems in the body which help maintain the acid-base balance?

A

Carbonic acid - Bicarbonate buffer for blood pH

Sodium Phosphate buffering system

Protein buffer systems

32
Q

What do antacids do?

A

Neutralise acids

33
Q

How does solubility affect the effectiveness of an antacid?

A

Insoluble = better

34
Q

What are the pH limits of human tissue survival?

A

6.8 - 7.8

35
Q

What happens when cells receive too little water?

A

Dehydration
Cell death

36
Q

What happens when a cell receives too much water?

A

Swelling
Toxicity, metabolic failure and cell death

37
Q

How much does the average male weigh?

A

70kg

38
Q

Approximately, what percentage of the average man is water?

A

60%

39
Q

Approximately how much water does the average man contain?

A

42L

40
Q

How much of the average mans water content is intracellular and how much of it is extracellular?

A

Extracellular = 1/3 = 14L

Intracellular = 2/3 = 28L

41
Q

How is the 14L of extracellular water in the average man distributed through the body?

A

10.5L interstitial fluid
0.5L transmembrane fluid
3L Plasma

42
Q

How many litres of blood are there in the average 70kg male? How is this volume comprised?

A

5L

3L Plasma
2L Actual blood cells

43
Q

What is the weight of the average female?

A

58kg

44
Q

How does the total body water of a female differ to a male?

A

Females = 50% water
Male = 60%

45
Q

Why do females total body water differ to males?

A

They have a higher fat content

46
Q

How does fat content affect Total Body Water (TBW)?

A

Higher the fat content, the lower the TBW

47
Q

Do infants have a higher or lower TBW than adults?

A

HIGHER

48
Q

What is meant by a isotonic celll?

A

There is an equal amount of water on both sides of the plasma membrane

49
Q

What is meant by a hypertonic cell?

A

There is MORE water inside the cell than outside

The solute concentric outside the cell is higher than the inside

Water moves OUT OF the cell via osmosis

50
Q

What is meant by a Hypotonic cell?

A

There is LESS water inside the cell compared to the outside

The solute concentration inside the cell is higher than the outside

Water moves INTO the cell via osmosis

51
Q

What is Osmolality?

A

The conc of a solution expressed as the total number of SOLUTE PARTICLES PER KG

52
Q

What is Osmolarity?

A

The conc of a solution expressed as Osmolality of solute particles PER LITRE OF SOLUTION

53
Q

What is the normal range of osmolality for a patient?

A

280 - 300 mOsm/kg

54
Q

What happens when there isn’t enough water?

A

Cells absorb water from each other
As tissues die water absorbed from organs
As organs die water absorbed from brain, liver and then the kidneys and heart

55
Q

What happens if there’s too much water?

A

Osmotic pressure high
Cells swell
Enyzmes and proteins stop working
Cells burst

56
Q

If a patient has too much water and they need fluids, what type of fluids must you give them?

A

Isotonic solutions

IV drip of 0.9% NaCl

57
Q

How does lots of water move across a membrane into a cell?

A

Via aquarporins

58
Q

What is Oedema?

A

Fluid retention in tissues

59
Q

What causes Oedema to occur?

A

Hydrostatic pressure > oncotic pressure

60
Q

What conditions can lead to hydrostatic pressure increasing leading to oedema?

A

Congestive heart failure
Liver cirrhosis
Renal disease

61
Q

What is pitting oedema?

A

When the oedema affected skin is pressed, the dent remains

62
Q

How can you tell if someone with Oedema may have Congestive Heart Failure?

A

The Oedema will be pitting

When pressed it will remain dented

63
Q

What produces the Oncotic pressure (the force that draws water back into the blood vessels/capillaries)?

A

Plasma proteins like Albumin

64
Q

What occurs if Albumin moves out of the capilaries into the Intersitial space?

A

Water is drawn out of capillary and remains in interstital space because interstitial fluid osmolarity increases

65
Q

What is pyrexia?

A

Increase in core body temperature

66
Q

What can cause pyrexia?

A

Infections

67
Q

How is pyrexia triggered by infections?

A

When fighting infections white blood cells (mainly macrophages) release pyrogens which travel to the hypothalamus causing the bodies thermostat to be increased

68
Q

Who has the highest total body water % and why?

A

Lean infants since they have the lowest amount of fat

Less fat = more water

69
Q

What temperature may an elderly patient with hypothermia wake up from being comatosed?

A

32ºC

Y1 - Body Logs (25 decks)

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