PPP - homeostasis, body fluids, flow & pressure Flashcards

1
Q

What is the purpose of short term homeostasis?

A

immediate survival

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2
Q

What is the purpose of long term homeostasis?

A

health and reproductive capability

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3
Q

What are some medium-term variables?

A

temperature, metabolic rate, appetite, GI secretions

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4
Q

What is an example of a long term variable?

A

steroid hormone levels

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5
Q

Give an example of hierarchy of importance for physiological variables?

A

Plasma osmolality will be maintained at the expense of blood volume by taking in more water - leading to hypertension

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6
Q

What is the purpose of negative feedback?

A

to move a variable back to a set point when it is altered?

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7
Q

When can the set point of a physiological variable be altered?

A

in fever or exercise

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8
Q

What are the 3 types of negative feedback?

A

neuronal, endocrine and local/chemical

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9
Q

Where are the integrating centres for negative feedback mechanisms?

A

in the midbrain and brainstem

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10
Q

Give examples of peptide hormones?

A

ACH, oxytocin

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11
Q

Example of a polypeptide hormone?

A

GH, insulin

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12
Q

Example of a glycoprotein hormone?

A

LH, FSH, TSH

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13
Q

Exampe of amino acid dervivative hormones?

A

adrenaline, T4

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14
Q

Example of steroid hormones?

A

progesterone, androgens, glucocorticoids

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15
Q

How do protein hormones work?

A

receptor binding on membrane induces 2nd messenger action

- effects are rapid and transient

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16
Q

How do steroid/thyroid hormones work?

A

intracellular receptor binding alters gene transcription

- effects are slow and prolonged

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17
Q

What is an example of local negative feedback?

A

local control of blood flow

control of blood volume

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18
Q

What is feedforward control

A

anticipation of a change brings about a response before the change is detected

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19
Q

What type of feedback is feedforward normally?

A

neuronal

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20
Q

What are examples of feedforward control?

A

Pavlov’s reflex

fight or flight anticipation

21
Q

What is positive feedback, and what kind of control is it normally?

A
  • when a change in varibale triggers amplication of that change
  • usually hormonal
22
Q

What is an example of positive feedback?

A

parturition in labour increasing uterine contractions

23
Q

What 3 compartments is body water distributed into?

A
plasma (5%)
interstitial space (40%)
intracellular space (15%)
24
Q

How do you calculate interstitial space?

A

extracellular space - plasma volume

25
Q

How do you measure fluid compartments?

A

V = S/C

- add known amount of substance to unknown volume and measure the concentration

26
Q

What are the features of a substance for measuring fluid compartments?

A
  • distributes to space of interest
  • non-toxic
  • not metabolised quickly
27
Q

What substances are used to measure plasma volume?

A
  • don’t cross capillaries easily

- albumin, inulin, evans blue

28
Q

What is used to measure extracellular space?

A
  • substances that don’t enter cells easily

- sucrose

29
Q

What is used to measure total body water?

A
  • a substance that distributes with water

- 3H20

30
Q

What are the major constituents of fluids?

A

ions, proteins, dissolved gases, nutrients, metabolites, cells in blood

31
Q

Which ions determine osmolarity?

A

sodium, chloride and potassium

32
Q

What is the unit of osmolarity?

A

osmole

33
Q

What is the difference between osmolarity and osmolality?

A
osmolarity = 1 osmole/L
osmolality = 1 osmole/Kg
34
Q

What is tonicity?

A

The osmolarity when solutions are seperated by a semi-permeable membrane

35
Q

What is crystalloid osmotic pressure?

A

pressure due to small diffusible ions

36
Q

What is oncotic pressure?

A

pressure due to proteins

- around 25mmHg

37
Q

What is the ionic composition of sodium?

A

plasma - 140mmol/L

intracellular - 10mmol/L

38
Q

What is the ionic composition of potassium?

A

plasma - 4mmol/L

intracellular - 120mmol/L

39
Q

What is the ionic composition of calcium?

A

plasma - 2mmol/L

intracellular - 100nmol/L

40
Q

Roughly what is the concentration of plasma proteins?

A

70g/L

41
Q

What are the main plasma proteins?

A

albumin
alpha, beta and gamma globulins
fibrinogen

42
Q

How much is haematocrit?

A

45%

43
Q

What is the concentration of erythrocytes?

A

4.8-5.5 x 10^12/L

44
Q

What is the concentration of leukocytes?

A

4-11 x10^9/L

45
Q

What are the types of leukocytes?

A

lymphocytes (20-40%)
monocytes (2-8%)
granulocytes

46
Q

What are the main types of granulocytes?

A

neutrophils, eosinophils, basophils

47
Q

What is the concentration of platelets?

A

150-400 x 10^9/L

48
Q

What happens to platelets when they are activated?

A

change shape, release granules and stick together