Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BDS1 BAMS: Endocrine System > Haemorrhage > Flashcards

Haemorrhage Flashcards

1
Q

Excessive blood loss is a medical emergency. What can it lead to?

A

Decreased blood volume results in a fall in BP and impaired delivery of nutrients to cells. This state is called shock.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 physiological responses to blood loss?

A
  1. Immediate - stop the bleeding
  2. Short term - restore blood pressure
  3. Medium term - restore fluid volume
  4. Long term - replace blood constituents
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the immediate physiological response to blood loss

A

Stopping blood flow - haemostasis

Several components involved: vascular response, platelet response, plasma response (coagulation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the vascular response of the immediate response to blood loss

A

Smooth muscle: spasm due to trauma, myogenic response, humoral factors (vasoconstrictors)
Endothelium: platelet adhesion and aggregation, anticlotting and fibrinolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does haemostasis mean?

A

Stopping the flow of blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the platelet response of the immediate response to blood loss

A

Damage to blood vessel -> turbulent blood flow -> platelets come into contact with blood vessel wall (collagen)
Platelets aggregate
Platelets release chemicals that cause further aggregation
Formation of platelet plug
Effective in sealing small blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the process of coagulation in the immediate response to blood loss

A

Fibrinogen is converted to fibrin
Blood clots are made of fibrin
Numerous clotting factors are involved
The synthesis of several clotting factors requires Vitamin K
Clotting factors are activated in an enzymatic cascade

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which clotting factor converts prothrombin to thrombin?

A

Factor Xa (Ca2+, Factor V, and phospholipids also involved)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does thrombin do?

A

Converts fibrinogen to soluble fibrin

Converts Factor XIII to Factor XIIIa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does factor XIIIa do?

A

Converts soluble fibrin to insoluble fibrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the instrinsic pathway in coagulation

A

Vascular damage, contact activation, involving factors XII, XI, IX and VIII, phospholipid and calcium ions
Convert Factor X to Factor Xa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the intrinsic pathway in coagulation

A

Tissue damage, tissue factors (tissue thromboplastin, factor VII), phospholipid , calcium ions
Convert Factor X to Factor Xa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does Factor Xa do?

A

Converts prothrombin to thrombin in coagulation cascade (immediate response to blood loss)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the relationship between the intrinsic and extrinsic pathways in coagulation (immediate response to blood loss)

A

The 2 pathways interact in a complex manner
Extrinsic pathway = important in initiating clotting after an injury
Intrinsic pathway = maintains the process once it has started
Intrinsic system may have a role in thrombosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is fibrinolysis?

A

The enzymatic breakdown of fibrin in blood clots

Once the blood clot has served its purpose, it is dissolved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which enzyme is responsible for fibrinolysis?

A

Plasmin

17
Q

What does plasminogen activator do?

A

Converts plasminogen to plasmin

18
Q

Describe the short term response in blood loss

A

Fall in blood pressure -> compensatory mechanisms triggered by arterial baroreceptors
Aim to restore blood pressure

19
Q

What are baroreceptor reflexes mediated by?

A

Sympathetic nerves

Hormones: adrenaline, angiotensin II, vasopressin

20
Q

Describe the baroreceptor firing response when blood volume decreases and the effect this has on blood pressure

A

Decreased blood volume -> decreased blood pressure
Decreased baroreceptor firing
This is detected by CVS centres in the brainstem
Leads to increased sympathetic nervous system activity: increased heart rate, increased cardiac output, increased ventricular contraction, increased venous constriction, increased arteriole constriction (increased peripheral resistance)
All of this leads to increased mean arterial blood pressure

21
Q

Describe the medium response to blood loss

A

Restoring blood volume by:

  • Shifting interstitial fluid back into blood vessels
  • Deceasing fluid loss in kidney
  • Increasing fluid intake
22
Q

What does oncotic pressure arise from?

A

Plasma proteins

23
Q

Describe the effects that baroreceptor reflexes have on on capillary blood pressure in response to a decrease in arterial blood pressure

A

Vasoconstriction of arterioles: increased total peripheral resistance, decreased capillary blood pressure
This decreases the hydrostatic blood pressure pushing fluid out of the capillary
More fluid is drawn back into the capillaries by the oncotic pressure

24
Q

Describe the process of decreasing fluid loss in the kidneys

A 
Decreased glomerular filtration 
Increased reabsorption of Na+ and water by stimulating release of: 
- renin-angiotensin-aldosterone 
- ADH
Both of these are vasoconstrictors
25
Q

Decreased plasma volume and increased plasma osmolarity has what effect on ADH?

A

Increased ADH secretion

26
Q

Describe the sensation of ‘thirst’

A

A desire to drink

27
Q

Which part of the brain is an important control area in thirst?

A

Hypothalamus

28
Q

What stimulates thirst?

A

Increased plasma osmolarity, decreased ECF volume, angiotensin II, dry mouth

29
Q

What suppresses thirst?

A

Stretch receptors in the stomach suppress drinking -> feedforward regulation

30
Q

Describe the long-term responses in blood loss

A

Restore blood constituents
Restoring plasma proteins - released from liver (3-4 days)
Replace blood cells, esp RBCs (erythropoiesis)
Return to normal in 2-3 months

31
Q

Where is erythropoietin released from?

A

Kidneys

32
Q

What does erythropoietin do?

A

Stimulates RBC production in bone marrow

33
Q

Describe ‘shock’

A

Shock is characterised by inadequate blood flow to tissues
Often associated with decreased cardiac output, or decreased blood/ECF volume
May be reversible or irreversible
Irreversible shock is usually fatal

34
Q

Name 3 types of ‘shock’

A
  1. Hypovolaemic shock
  2. Low resistance/distributive shock
  3. Cardiogenic shock
35
Q

What is hypovolaemic shock?

A

Decreased ECF volume due to haemorrhage, sweating, diarrhoea, burns, etc

36
Q

What is low resistance/distributive shock?

A

Decreased peripheral resistance due to widespread vasodilation e.g. anaphylactic shock

37
Q

What is cardiogenic shock?

A

Heart fails as a pump

BDS1 BAMS: Endocrine System (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions