PSC 2020 LECTURE 2-4 Flashcards
the Sympathetic NS increases heart rate and contractility. What is this called?
Positive chronotropic
Positive inotropic
what is the neurotransmitter in the preganglionic and postganglionic sympathetic system
Ach - preganglionic
Noradrenaline - postganglionic
what is the neurotransmitter in the post and pregnaglonic fibres in the parasympathetic nervous system
Ach in both
which blood vessel are not innervated
capillaries
pre capillary sphincters
met arterioles
what does the vasomotor centre do
transmits sympathetic impulses through the spinal cord and peripheral sympathetic nerves to arteries, arterioles, ands veins
what does sympathetic innervation do within arteries and arterioles
increases resistance to blood flow
decreases rate of blood flow through tissue
ultimately release of Noradrenaline from junctional varicosity in the sympathetic vasoconstrictor fibre increases arterial pressure
which receptors do the following neurotransmitters work on:
Noradrenaline
ATP
Neuropeptide - Y
Noradrenaline - Alpha-1 receptor via IP3 receptor
ATP - P2X receptor (opens Ca channel)
Neuropeptide -Y - NPY-1 receptor (action via G-protein)
what does venoconstriction do
if central BP drops venoconstriction diverts blood to systemic circulation
what does parasympathetic vasodilation do
increases blood flow in response to demands of tissue function not CVS regulation
what are the 4 endocrine systems that regulate blood pressure
adrenaline
antidiuretic hormone (ADH) (arginine vasopressin)
Renin-angiotensin system
natriuretic peptides
which receptors does adrenaline work on and what is its effect
Alpha1 receptors on blood vessel
Beta1 receptors on heart
Beta2 receptors on blood vessels
Adrenaline increases heart rate
what releases ADH
released from hypothalamus - supraoptic nuclei and paraventricular nuclei
ADH is released from 2 different mechanisms - Osmolar control (ADH released ta 280mOsm) and non Osmolar control
describe the Renin-Angiotensin-Aldosterone system
decrease in BP leads to release of Renin, Renin cleaves Angiotensinogen into Angiotensin I, Angiotensin I is acted on by ACE (Angiotensin converting enzyme) to produce Angiotensin II which is a vasoconstrictor
Angiotensin II also increases thirst and stimulates sympathetic nervous system
Aldosterone is also released by this system
ADH inhibitors block the effects of ACE
when are Natriuretic peptides released
when BP is high
these decrease blood volume which decreases blood pressure
what are the key two areas in the medulla oblongata and what do they do
N. Tractus Solitarius and N. Ambiguus
Baroreceptors are stimulated and fire impulses to N. Tractus Solitarius, N. Tractus Solitarius is stimulated and fires impulse to N. Ambiguous, N. Ambiguous gets stimulated and fires impulses to Vagus nerve which releases Ach on Muscarinic receptors in the heart.
result is lower heart rate
