Mairead Exam Questions Flashcards
What is the short term fix for low blood volume?
(dehydration or haemorrhage)
(3)
Increase cardiac output
Increase peripheral vasoconstriction
-> done by releasing norepinephrine and epinephrine under control by the sympathetic system
What is the long term fix for low blood volume (dehydration/haemorrhage)?
(5)
Renin-angiotensin system + anti-diuretic hormone
Renin-> angiotensin I -> angiotensin II -> aldosterone
Thirst stimulated
Increased retention of Na and water
Erythropoietin may also be released by kidneys to synthesis new rbcs
What are the responses to high CO2 and low O2
(4)
Cardiac, vasomoter centres and respiratory centre stimulated
Increase Cardiac output and blood pressure
Increased blood flow to skeletal muscle -> decrease in total peripheral resistance
Respiratory centre will increase CO2 elimination and O2 pickup
What happens when blood pressure falls below normal?
(Baroreceptor reflex)
(3 points with 2 subpoints each)
Vasomoter Centres are stimulated
- Vasoconstriction
– blood pressure elevated
Cardioinhibitory centres inhibited
- increased cardiac output
– blood pressure elevated
Cardioacceleratory centres stimulated
- increased cardiac output
– blood pressure elevated
What happens when blood pressure rises above normal
(Baroreceptors)
(3 points with 2 sub-points each)
Cardioacceleratory centres inhibited
- decreased cardiac output
– blood pressure reduced
Cardioinhibitory centres stimulated
- decreased cardiac output
– blood pressure reduced
Vasomoter centres inhibited
- vasodilation occurs
– blood pressure reduced
What does the baroreceptor reflex control?
High or low blood pressure
What three centres do baroreceptors stimulate
Cardioacceleratory centres
Cardioinhibitory centres
Vasomoter centres
What does the bainbridge reflex respond to?
Low/high blood volume
What is the bainbridge reflex
(3)
As the venous return increases, the walls of
the right atrium are stretched. This activates
the ANS through the Bainbridge reflex.
This results in increased sympathetic
activation i.e. increases SA node firing.
The increase in HR matches the increase in
venous return
How is the Bainbridge reflex the opposite of the Barroreceptor reflex
Bainbridge increases heart rate
Barroreceptor decreases heart rate
List the five steps in the spinal reflex
- Arrival of stimulus and activation of receptor
- Activation of sensory neuron
- Information processing in CNS
(Sensation relayed to the brain by collateral)
- Activation of a motor neuron
- Response by effector
What happens when CHP>BCOP
(3)
Fluid is forced out of capillary
25mmHg in
NFP = +10 mmHg
35 mmHg out
24 L/day moves out of capillary
What happens when CHP=BCOP?
(5)
No net movement of fluid
25 mmHg in
NFP = 0
25 mmHg out
No net movement
What happens when BCOP>CHP?
(5)
Fluid moves into capillary
25 mmHg in
NFP = -7
18 mmHg out
20.4 L/d reabsorbed
What happens to the lymph sent to lymphatic capillary?
3.6L/day reabsorbed into lymphatic capillaries
This is returned to circulation
