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Flashcards in 107 - Hypovolaemia Deck (32):
1

Where are the baroreceptors found?

  • The carotid sinus
  • Arch of aorta

2

What is Hypovolaemia?

A loss of 20% of the circulating blood volume

3

What does angiotensin II stimulate the release of?

Aldosterone from the adrenal cortex

4

How would you treat collapse caused by infective diarrhoea?

  • Fluid - crystalloid (Hartmann's)
  • Antibiotics

4

Which ion in the blood is the main regulator of extracellular fluid osmolality?

Sodium

4

What response is activated when BP drops below 50mmHg and what does it do?

  • CNS ischamic response
  • Sends out powerful sympathetic innervation

5

What would happen to a cell that is placed in a hypotonic solution?

Water would diffuse into the cell and if excessive would cause lysis

5

What are the sensors of the effective circulatory volume?

  • Carotid sinus
  • Afferent glomerular arteriole
  • Atria

5

What enzyme produces angiotensin II from angiotensin I, and where is it found?

Angiotensin Converting Enzyme (ACE)

It is found in the lungs

5

Why would patients with severe shock present with a reduced haemocrit?

  • Increased glucose production by the liver leads to increases in plasma osmolality.
  • This draws water from intracellular stores and results in haemodilution, with a lower haemocrit

6

Where in the kidneys does ADH act?

  • The late distal tubules
  • Cortical collecting ducts
  • Medullary collecting ducts.

7

What does the macula densa in the kideny sense?

  • Low BP
  • Low sodium concentration

9

What is the osmolality of the extracellular and intracellular fluids?

They are both regulated within 275-295 milliosmoles/Kg

10

What is the function of renin?

To convert the angiotensinogen secreted from the liver into angiotensin I

11

What are the symptoms of shock?

  • Organ failure and sympathetic activation
  • Tachycardia
  • Tachypnoea
  • Poor peripheral perfusion
  • Hypotension

11

What are the 2 body fluid compartments and what percentage of the total body weight is held in each compartment?

  • Extracellular - 20% of body weight
  • Intracellular - 40% of body weight

12

When is atrial natriuretic peptide secreted from the atria?

When the right atria is stretched due to increased blood pressure

14

How much of the body weight is water?

53-64% of a lean man

46-53% of women

16

What are the causes of hypovolaemic shock?

  • GI; vomiting and diarrhoea
  • Bleeding; trauma, surgery or childbirth
  • GU tract; diabetes, high output renal failure
  • Skin; burns and trauma
  • Surgical drains.

18

Where is ADH stored and secreted from?

Neurones in the posterior pituitary gland

19

What is the Starling equation used to describe?

The movement of fluids across capillary membranes

20

What consequences arise from severe shock?

  • Acute respiratory distress syndrome (ARDS)
  • Disseminated intravascular coagulation (DIC)
  • Depression of cardiac muscle function
  • Multi-organ failure

21

How does the sympathetic nervous system help compensate for the fall in BP in shock?

  • Increased HR
  • Venoconstriction
  • Vasoconstriction of splanchnic, cutaneous, renal and skeletal circulations.

22

Which nerves are important for relaying baroreceptor information?

  • Carotid sinus; glossopharyngeal nerve (CN IX)
  • Arch of aorta; vagus nerve (CN X)

24

What would happen to a cell placed in a hypertonic solution?

Water would diffuse out of the cell and the cell would therefore shrink

25

Which is ADH more sensitive to?

Plasma osmolality or Change in blood volume?

Plasma osmolality

26

Where does aldosterone act?

Distal convoluted tubule to stimulate Na uptake

27

What are the 4 types of shock?

  1. Hypovolaemic
  2. Cardiogenic
  3. Maldistributive
  4. Obstructive

28

What determines the oncotic pressure within the capillaries?

The plasma proteins

29

Which cells is renin secreted from?

The juxtaglomerular cells

31

What cells of the brain sense plasma osmolality?

  • Hypothalamic osmoreceptors located in the OVLT and subfornical organ

32

Which division of the nervous system is activated in shock?

Sympathetic