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Y2S1 CARDIO. > Blood Volume > Flashcards

Flashcards in Blood Volume Deck (28)
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1
Q

– Renal-body fluid feedback system

A
  • When arterial pressure increases, urine production increases
  • When arterial pressure decreases, urine production decreases
2
Q

Two primary determinants

A

–The renal output curve for salt and water –The level of salt and water intake

3
Q

Antidiuretic hormone

A

Released by the pituitary gland

4
Q

ADH is released in response to

A

– ↑ osmotic pressure
• Hypothalmic osmoreceptors

– Hypovolemia (10% loss or greater)
• Atrial baroreceptors normally inhibit ADH release
• ↓ volume leads to ↓ firing rate  ↑ ADH release

– Hypotension
• ↓ arterial baroreceptor firing
• ↑ sympathetic activity and ↑ ADH release

– Angiotensin II

5
Q

ADH increases blood volume by

A

– ↑ water permeability in renal collecting ducts •  ↓ urine produc2on

6
Q

ADH action in severe hypovolemic shock

A

– ADH release is high
– Causes vasoconstriction
• ↑ total peripheral resistance

7
Q

Renin

A

Proteolytic enzyme released from the kidneys (juxtaglomerular cells)

8
Q

renin is released in response to what

A

– Sympathetic nerve activation
• Mediated by baroreceptor feedback

– Renal artery hypotension
• Independent of baroreceptor feedback

– Decreased sodium in kidney distal tubules

9
Q

the production of angiotensin II

A

decreased arterial pressure
renin released
renin substrate released from the liver (angiotensinogen)
these mix in the venous system to break down to form angiotensin I
which then travels through the lung and is converted by an enzyme into angiotensin II

10
Q

Angiotensin II

A

acts on resistance vessels

– ↑total peripheral resistance

11
Q

Angiotensin II acts directly on the kidneys

A

– Constrictsrenalarteries↓ blood flow via kidneys

12
Q

what effect does angiotensin II have un the adrenal glands

A

release of aldosterone

– ↑ Na+ and water reabsorption

13
Q

angiotensin II stimulates the release of what from the pituitary

A

ADH

14
Q

Atrial-natriuretic hormone

A

28-amino acid peptide synthesised and stored in muscle cells of the atria

15
Q

when is the atrial-natriuretic hormone

A

– Released in response to stretch of the atria – Helps oppose the effects of the RAAS system

16
Q

Hypovolaemia

A
– Loss of blood volume
• ↓ whole blood, e.g. hemorrhage 
• ↓ plasma, e.g. burns
• ↓ sodium, e.g. vomitting
– ↓↓ in blood pressure
17
Q

Classification of shock

A

– Class 1, 10-15% blood loss
– Class 2, 15-30% blood loss
– Class 3, 30-40% blood loss
– Class 4, >40% blood loss

18
Q

Immediate (reflex) response to hypovolemia - effect on SV

A

decreases on haemorrhage then compensates slightly when baroreceptors kick in

19
Q

Immediate (reflex) response to hypovolemia - effect on HR

A

remains the same until baroreceptors kick in and then there is a slight increase

20
Q

Immediate (reflex) response to hypovolemia - effect on cardiac output

A

drop significantly on haemorrhage then when baroreceptors kick in it makes a compensation

21
Q

Immediate (reflex) response to hypovolemia - effect on total peripheral resistance

A

this remains the same until baroreceptors kick in and then it increases

22
Q

Immediate (reflex) response to hypovolemia - effect on mean arterial blood pressure

A

this decreases on haemorrhage and then makes a full compensation when baroreceptors kick in

23
Q

Later response to hypovolemia

A

Arteriolar constriction
– ↓ hydrostatic pressure in the capillaries
– Favours fluid reabsorption
– Temporary redistribution

Decreased renal blood flow Baroreceptors plus thirst

24
Q

Severe hypovolemia

A

– Damage to tissues and organs can occur
– Heart fails

Fluid replacement required

25
Q

– Resuscitation fluids

A
  • Colloid (gel/starch/albumin) or Hartmann’s
  • Blood

– Fluid challenge algorithm
• Whilst monitoring central venous pressure

26
Q

Cortex

A

– Conscious effects of emotions

• Nerves from cortex to medullary CVC centre

27
Q

Time of day

A

– Diurnal variations due to hormones and cortical input

28
Q

Respiration

A

– Via mechanical movements
– Via chemoreceptors
• Aortic and carotid bodies detect changes in pO2
• If↓pO2 thenrateoffiring↑