PERIPHERAL RESISTANCE : CONTROLLING BP Flashcards
What’s the normal heart rate range?
60-100 bpm
What is a normal cardiac output?
5L per minute
What is Poiseuilles law?
An equation for blood flow that shows when you double resistance, blood flow decreases by a factor of 8
Describe how vessel size and blood flow can be controlled locally?
The tissue vascular bed e.g. when damaged it can release nitric oxide which can cause vasodilation
Alternatively hypercapnia can cause vasodilation
What is the neural control of blood pressure?
The sympathetic system and occasionally the parasympathetic system
Describe what causes sympathetic activation to increase blood pressure?
When bp decreases we get decreased firing from baroreceptors which sends signals in the vasomotor centre in the medulla to increase sympathetic activation which, in turn, can increase blood pressure
What is the vasomotor tone?
The degree of tension of the smooth muscle within the walls of blood vessels,
Aka the resting baseline of vasoconstriction
What are the 3 endocrine controls of blood pressure?
Renin-angiotensin system
Antidiuretic hormone
Natriuretic peptides
Outline the renin-angiotensin-aldosterone-system?
Renin is secreted from the juxtaglomerular apparatus in response to changes in both and NaCl content in urine
Renin converts angiotensinogen to angiotensin 1
Angiotensin 1 is converted to angiotensin 2 by angiotensin-converting enzyme
Angiotensin 2 causes vasoconstriction, increased sympathetic action, increased ADH secretion, increased renal NaCl reabsorption and increased aldosterone secretion
This increases blood pressure
How does antidiuretic hormone/vasopressin affect bp?
It’s secreted from the posterior pituitary gland in response to high blood osmolarity and low bp. It increases water reabsorption in the kidneys and vasoconstriction
How do natriuretic peptides affect bp?
They are secreted by the heart when my coyotes are stretched
They increase vasodilation and increase excretion of NaCl and water
This reduces bp
What are some possible ways to treat high blood pressure?
Beta blockers to 8nhibit the sympathetic nervous system Angiotensin-converting enzyme inhibitors Angiotensin 2 receptor blockers Mineralocorticoid receptor antagonists Diuretics
