Hypertension 1

Question 1

Determinants of Blood Pressure

Answer 1

BLOOD PRESSURE
= Cardiac Output (CO) x
Peripheral vascular resistance (PVR)
BP = CO x PVR
CARDIAC OUTPUT
= Stroke Volume (SV) x Heart Rate (HR)
ie. CO = SV x HR
SV = EDV – ESV (≡ Ejection fraction L Ven

Question 2

Cardiac output is stimulated by what in the heart

Answer 2

is increased by sympathetic stimulation via activation of B1 adrenoreceptors in the heart.

Question 3

PVR is determined by what?

Answer 3

resistance to blood flow through the arterioles, whose cross-sectional area depends on arteriolar smooth muscle tone in the various vascular beds. Via activation of α1-adrenoceptors, the sympathetic nervous system stimulates arteriolar smooth muscle contraction, and this leads to vasoconstriction.

Question 4

Innervation of the CV system by the ANS

Answer 4

Neurotransmission in the autonomic and somatic nervous systems. The parasympathetic nervous system consists of cranial and sacral nerves with long preganglionic and short postganglionic fibers. The sympathetic nervous system consists of thoracic and lumbar nerves with short preganglionic and long postganglionic fibers. The sympathetic system includes the adrenal medulla, which releases norepinephrine and epinephrine into the blood. The somatic nervous system consists of motor neurons to the skeletal muscle. α, α-Adrenoceptors; ACh, acetylcholine; β, β-adrenoceptors; E, epinephrine; M, muscarinic receptors; N, nicotinic receptors; NE, norepinephrine

Question 5

Central control of BP: The Baroreceptor Reflex

Answer 5

BPWhen BP is too high, the increased arterial pressure activates stretch receptors (Baroreceptors) in the aortic arch and carotid sinus
Impulses are sent to the brainstem vasomotor center, resulting in:
Activation of the vagal motor nucleus → ↑ parasympathetic outflow → ↓ HR → ↓ CO → ↓ BP
↓ Stimulation of spinal intermediolateral neurons that activate sympathetic preganglionic fibers → ↓ sympathetic stimulation of the heart and blood vessels → ↓ CO & PVR → ↓ BP