Lecture 10: Control of heart and BP Flashcards
Describe Blood pressures throughout the systemic circulation
Blood pressure high in major
arteries
– Oscillatory
Blood pressure falls steeply across
the arterioles, capillaries, and
venules
– Oscillatory nature is reduced.
Blood pressure is very low in veins.
Large difference in pressure (ΔP)
between the arterial and venous
sides.
– creates a driving force for blood
flow
Which of the following statements about electrical and
contractile cells is CORRECT?
A. Electrical cells have nuclei, while contractile cells
do not
B. Electrical cells have less actin/myosin filaments
than contractile cells
C. Electrical cells have intercalated discs, while
contractile cells do not
D. Electrical cells are heavily striated, while contractile
cells are pale with fewer striations.
B
Describe blood flow in to arteries:
– Ventricular contraction
– Ejection of blood
– CARDIAC OUTPUT
– fills arteries
– increases arterial blood volume
– raises arterial pressure.
Describe blood flow out of arteries:
– Capillary flow
– Controlled by resistance of the arteries
– drains arteries
– decreases arterial blood volume
– lowers arterial pressure.
Describe how Balance flow in / out determines
pressure:
– Increase cardiac output (increase inflow)
– Increase resistance (decrease outflow)
– Increase arterial volume and Pressure
what is the equation for Mean arterial pressure (MAP)?
MAP = CO x TPR
What is the equation for cardiac output (CO)?
CO = SV x HR
Where is Homeostasis of arterial blood pressure controlled?
Coordinated within the
brainstem
– Afferent input from both the CNS and
‘periphery’.
– Efferent output to heart and vessels
Where are the main baroreceptors located?
On the aortic arch and both carotid sinuses (detecting stretch of the arterial wall and therefore BP)
What nerve can be called the ‘brake’ for control of CO?
The vagus nerve (parasympathetic) decreasing heart rate
Interacting with the SA and AV nodes
What nerve can be called the ‘accelerator’ for control of CO?
The sympathetic cardiac nerves increase heart rate and force of contraction. Interaction with the SA/AV node as well as directly to ventricular walls.
Which of the following statements about the human
cardiovascular system is INCORRECT?
A. Blood flow throughout the cardiovascular system is
unidirectional.
B. Arteries in the systemic circuit carry oxygen rich blood,
while arteries in the pulmonary circuit carry oxygen
poor blood.
C. Blood flow is lower in the shorter pulmonary circuit
than in the longer systemic circuit.
D. Blood flows away from the heart in arteries and
towards the heart in veins.
C
