L45 - blood pressure regulation Flashcards
(28 cards)
What is mean arterial pressure regulated by? (2)
- baroreceptors (short term)
- blood volume (kidney - long term)
what do baroreceptor neurons functions as? (2)
- sensors - homeostatic maintenance of MAP
- nerve endings - sensitive to stretch and pressure in artery
where are baroreceptors located? (2)
- located in aortic arch, carotid sinuses - monitor pressure
- in thinner walls that can be stretched by pressure
what is rate of baroreceptor never firing like? (2)
- proportional magnitude - changes in MAP
- response lost in minutes (short term sensors of BP)
what do arterial baroreceptors act as? (2)
- part of -ve fb pathway, regulate MAP via brain (central control)
- actions are coordinated by medulla oblongata (medullary cardiovascular centre)
what is the hormonal regulation of MAP? (2)
- adrenaline - inc MAP
- angiotensin II and vasopressin - inc MAP
what is the ANS regulation of MAP? (2)
- sympathetic - inc MAP
- parasympathetic - dec MAP
how are sympathetic nerves involved in central control? (3)
- mediated by NA via B-adrenergic receptors
- a1-adrenergic receptors in arterioles
- inc cardiac output and peripheral resistance
how are parasympathetic nerves involved in central control? (2)
- mediated by ACh via muscarinic receptors
- inhibit heart rate
What parts of the heart inc B1-AR in sympathetic? (5)
- SA - heart rate
- AV - conduction
- atrial muscle contraction - inc stroke vol
- ventricular muscle contraction - inc stroke vol
what parts of blood vessels inc B1-AR in symptathetic? (2)
- arteriole vasoconstriction - peripheral resistance
- venous vasoconstriction - inc stroke vol
what parts of the heart dec m2-AR in parasympathetic?
SA node - heart rate
What controls blood pressure and blood flow in the ANS? (2)
- cardiac output from the heart
- peripheral resistance
What are the causes of hypotension (reduction in arterial pressure)? (3)
- loss of blood (hemorrhage)
- loss of salts - burns, sweating, diarrhoea/vomiting
- stress or emotions (fainting)
what does standing up do? (2)
- orthostasis
- drop in mean BP
Why does mean BP drop when you stand, how does cardiovascular sys. compensate? (4)
- blood pools in legs due to gravity
- dec blood vol, lowers central venous pressure
- dec venous return, dec end-diastolic pressure, dec stroke vol
- baroreceptor reflex compensates
what is vol of blood primarily determine by venous vol?
venous volume
what is the blood reservoir?
most of blood distributed in veins and venules
what is responsible for long-term regulation of BP?
changes in blood vol regulated by the kidneys (renin-angiotensin system)
what is local flow regulated by? (3)
- local
- neural
- hormonal factors
What are major problems to address during exercise? (3)
- boost O2 uptake and CO2 removal - inc CO
- inc blood flow to muscles, heart and skin
- stabilise arterial BP
How do you boost cardiac output during exercise with central response? (4)
- brain prepares arterial baroreceptors (reset upwards)
- dec parasympathetic output of heart, inc sympathetic output to heart and veins
- inc heart rate and stroke volume
- inc CO
What do you inc/decrease blood flow to during strenuous exercise? (2)
- inc - skeletal muscle, skin, heart - vasodilation of arterioles
- dec - kidneys, abdominal organs - vasoconstriction of arterioles
How do you increase MAP with local response + central? (2)
- dec TPR by vasoconstriction of abdominal organs and kidney and vasodilation of arterioles to skin and muscles
- = mean arterial pressure
