lecture 10 - controlling heart & blood pressure Flashcards
What structure generates pressure for the systemic circulation?
The left ventricle
What drives blood flow between arteries and veins?
A high pressure difference between high pressure arteries, less pressured arterioles and low pressure veins
What is the symbol for blood flow?
Q
What is the equation for blood flow?
Q= ΔP/R (flow=change in pressure/resistance)
What is blood flow proportional to?
Change in pressure in a vessel, and Mean Arterial Pressure
What is blood flow inversely proportional to?
Resistance in a vessel
What is the equation for Mean Arterial Pressure, in terms of Q and R ?
MAP=QR (mean arterial pressure=blood flow * resistance)
What is mean arterial pressure proportional to?
Blood flow and resistance
What is the equation for Mean arterial pressure, in terms of CO and TPR?
MAP=CO*TPR (mean arterial pressure = cardiac output * total peripheral resistance)
What is the equation for cardiac output?
CO=SV*HR (cardiac output = stroke volume * heart rate)
What is the unit for stroke volume?
L/beat
What is the unit for cardiac output?
L/min
What is control centre of blood pressure homeostasis?
The brain stem
What is the afferent input to the brain stem that regulates blood pressure?
From the CNS and periphery
What is the efferent output to the brain stem that regulates blood pressure?
To the heart and blood vessels
What part of the nervous system is involved in blood pressure homeostasis?
Autonomic - Parasympathetic and sympathetic
What type of receptor are involved in detecting blood pressure change?
Baroreceptors
What type of receptor are baroreceptors?
Stretch receptors
Where are baroreceptors found?
Buried in the walls of blood vessels
How does baroreceptor signalling work?
They send a constant signal to the brain, with the frequency of the action potentials changing as as blood pressure changes
Which parts of the body have the highest concentration of baroreceptors?
The carotid sinus and aortic arch
Why does the carotid sinus have a high concentration of baroreceptors?
Located on the carotid artery, meaning blood pressure to the brain can be carefully managed.
Why is there a high concentration of baroreceptors on the aortic arch?
To measure blood pressure immediately as the blood leaves the heart
What nerve is responsible for parasympathetic decrease of heart rate?
the vagus nerve
What nerve is responsible for sympathetic increase in heart rate?
The sympathetic cardiac nerves
Where does the vagus nerve target?
The SA and AV nodes
Where do the sympathetic cardiac nerves target?
The SA and AV nodes
How do vagus and sympathetic cardiac nerves alter contraction by signalling the AV node?
They alter the pause between atrial and ventricular contraction, altering heart rate
How does the sympathetic nervous system increase the force of heart contraction?
The sympathetic cardiac nerves synapse with the conduction cells on the ventricles of the heart, increasing the force with which the muscle contracts.
