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Body Logistics > Homeostasis > Flashcards

Homeostasis Flashcards

(52 cards)

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1
Q

Define homeostasis

A

Homeo=sameness stasis=standing still

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2
Q

Detailed homeostasis definition

A

Ability of a living organism to keep the internal conditions at dynamic equilibrium, despite intrinsic and extrinsic changes

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3
Q

What fundamental technique does homeostasis use?

A

Feedback loops

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4
Q

State the four components of a feedback loop

A

Stimulus/variable, sensor, control centre, effector

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5
Q

When does a negative feedback loop stop

A

When the effector ceases

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6
Q

When does a positive feedback stop

A

When the stimulus ceases

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7
Q

What does each feedback loop do to the stimulus? - give an example

A

Negative - removes it, insulin removing glucose
Positive - exaggerates or enhances it, oxytocin causing the uterus to stretch

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8
Q

What is the normal range of human body temperature?

A

36-38 degrees

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9
Q

SSCcE for temperature

A

S - change in temp
S - skin, hypothalamus
Cc - hypothalamus (in the thermostat)
E - fat, hair, blood vessels, sweat glands

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10
Q

What is the range of pH for humans?
And why?

A

7.35-7.45
Normal cellular metabolism happens in this range

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11
Q

Organs responsible for maintaining acid base balance

A

Lungs and kidneys

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12
Q

Range of acidosis and alkalosis

A

7-7.35
7.45-7.8

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13
Q

What is the pH of stomach acid?
What can it cause if it enters the oesophagus
Or through the stomach lining?

A

1.5-3.5
Oesophagitis and stricture (closes)
Gastric ulceration

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14
Q

What is the limit of human tissue survival for pH?

A

6.8 - 7.8

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15
Q

What is the normal plasma pH?

A

7.35-7.45

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16
Q

What is the [H+] for pH of 7.4?
So what is 7.1, 6.8 and 7.7

A

40nM
80, 160, 20

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17
Q

What colour is arterial blood in comparison to venal and why?

A

Bright red, more O2 bonded to haemoglobin to make oxyhaemoglobin - more alkali
Venal blood has more CO2 -more acidic

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18
Q

Symptoms of acidosis

A

Headaches, confusion, tired, tremors, coma

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19
Q

What compounds in the blood are used to control treat acidosis?

A

Bicarbonate solution - increases pH
Mechanical ventilation - drives CO2 out (dissolved CO2 is acidic)

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20
Q

What percentage water is for a standard adult?

A

60%

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21
Q

Proportion of water that is extra cellular and intracellular

22
Q

How is extra cellular water divided?

Study These Flashcards
A

Interstitial - 3/4
Plasma - 1/4 - 0.5L in the transmembrane space

23
Q

What happens if there is not enough or too much water, in general?

Study These Flashcards
A

Dehydration

Toxicity, metabolic failure

24
Q

Comparison of total body water between elderly, man, woman, child?

Study These Flashcards
A

Elderly and women - lower proportion of muscle and higher proportion of fat
Man - higher muscle
Child - high sa:mass so high total body water

More muscle - higher total body water (muscle is mainly made of water)

25
Describe a hypotonic SOLUTION Inc description of osmotic pressure
- higher conc of water - more dilute - lower conc of solutes - lower osmotic pressure
26
What is osmolality?
Conc of a solution, expressed as the total number of solute particles per kg
27
Osmolality calculation when positive metal ions are involved E.g. Sodium 140
You must double the amount with each metal, as it dissociates with Cl- (the Cl- are osmotically active) So Na 140 + Cl 140 = 280
28
Summarise what happens when there is not enough water (outside of the cell)
Shift in osmotic pressure Cells and tissue give up their water into the interstitial fluid compartment They shrink
29
Summarise what happens when there is too much water consumed
Reduction in Na+ conc in the extracellular fluid Shift in osmotic pressure Water osmoses into the cells Cells and tissue swell (oedema)
30
What kind of solutions do patients need?
Isotonic IV = 0.9% NaCl
31
What controls bulk water flow?
Via integral aqua protein
32
What is oedema?
Fluid retention - ‘dropsy’
33
What is an equation that explains how odeomas form?
Hydrostatic pressure>osmotic pressure (Out>in)
34
What is hydrostatic pressure?
Force exerted by fluid on the vessel wall
35
What is osmotic pressure?
Force applied by the solute to prevent osmotic movement across the membrane
36
What is the control centre?
Something that retains the desired value of the variable/stimulus and can compare it to the current value - which is provided by the sensor
37
What happens to the body at high or low temperatures?
High - enzymes denature Low - insufficient energy to maintain metabolic processes
38
What are the two sensors in humans
Skin Hypothalamus
39
What happens to the temperature when infected with bacteria? Why?
Toxins from bacteria and chemicals produced by the immune system Increase the set point in the hypothalamus Initiating shivering and increased metabolic rate Higher temperature
40
What is pyrexia?
A fever Abover 38 degrees
41
Why is a fever good when you are infected?
Immune system works optimally
42
Equation of pH in relation to [H+]
pH=-log10[H+]
43
Two general causes of acidosis Where are they controlled?
Metabolic - kidneys Respiratory - lungs
44
How is stomach protected by gastric juice?
Special issued epithelial cells that secrete substances, like mucus
45
What is the movement of water across semi permeable membranes dependent on? (2) Define both
Hydrostatic pressure - pumping of heart Osmotic pressure - conc of solute particles
46
Describe the protective mechanism, to prevent over consumption of water
Increase in plasma osmolality detected by the hypothalamus Before fluids absorbed from the GI tract Feeling of thirst is quenched
47
Symptoms of dehydration
Dry mouth, thirst, low urine output, fever, dizziness
48
What does a loss of blood plasma volume lead to
Increased conc of blood components (viscosity) ^ so an increased workload of the heart Tachycardia
49
What is the name of the condition when the body temp is above 38 degrees?
Pyrexia
50
What is rigor? What triggers it?
An episode of shaking or exaggerated shivering which can occur with a high fever Triggered by pyrogens
51
What are febrile seizures?
Seizure of an infant between 6 months-3 years Response to high temp
52
What molecule is the highest contributor to oncotic pressure?
Albumin

Body Logistics (9 decks)

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